Merge branch 'next' (accumulated 3.16 merge window patches) into master

[linux.git] / drivers / usb / core / hub.c

/*
 * USB hub driver.
 *
 * (C) Copyright 1999 Linus Torvalds
 * (C) Copyright 1999 Johannes Erdfelt
 * (C) Copyright 1999 Gregory P. Smith
 * (C) Copyright 2001 Brad Hards ([email protected])
 *
 */

#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/completion.h>
#include <linux/sched.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/ioctl.h>
#include <linux/usb.h>
#include <linux/usbdevice_fs.h>
#include <linux/usb/hcd.h>
#include <linux/usb/otg.h>
#include <linux/usb/quirks.h>
#include <linux/kthread.h>
#include <linux/mutex.h>
#include <linux/freezer.h>
#include <linux/random.h>
#include <linux/pm_qos.h>

#include <asm/uaccess.h>
#include <asm/byteorder.h>

#include "hub.h"

#define USB_VENDOR_GENESYS_LOGIC                0x05e3
#define HUB_QUIRK_CHECK_PORT_AUTOSUSPEND        0x01

/* Protect struct usb_device->state and ->children members
 * Note: Both are also protected by ->dev.sem, except that ->state can
 * change to USB_STATE_NOTATTACHED even when the semaphore isn't held. */
static DEFINE_SPINLOCK(device_state_lock);

/* khubd's worklist and its lock */
static DEFINE_SPINLOCK(hub_event_lock);
static LIST_HEAD(hub_event_list);       /* List of hubs needing servicing */

/* Wakes up khubd */
static DECLARE_WAIT_QUEUE_HEAD(khubd_wait);

static struct task_struct *khubd_task;

/* synchronize hub-port add/remove and peering operations */
DEFINE_MUTEX(usb_port_peer_mutex);

/* cycle leds on hubs that aren't blinking for attention */
static bool blinkenlights = 0;
module_param (blinkenlights, bool, S_IRUGO);
MODULE_PARM_DESC (blinkenlights, "true to cycle leds on hubs");

/*
 * Device SATA8000 FW1.0 from DATAST0R Technology Corp requires about
 * 10 seconds to send reply for the initial 64-byte descriptor request.
 */
/* define initial 64-byte descriptor request timeout in milliseconds */
static int initial_descriptor_timeout = USB_CTRL_GET_TIMEOUT;
module_param(initial_descriptor_timeout, int, S_IRUGO|S_IWUSR);
MODULE_PARM_DESC(initial_descriptor_timeout,
                "initial 64-byte descriptor request timeout in milliseconds "
                "(default 5000 - 5.0 seconds)");

/*
 * As of 2.6.10 we introduce a new USB device initialization scheme which
 * closely resembles the way Windows works.  Hopefully it will be compatible
 * with a wider range of devices than the old scheme.  However some previously
 * working devices may start giving rise to "device not accepting address"
 * errors; if that happens the user can try the old scheme by adjusting the
 * following module parameters.
 *
 * For maximum flexibility there are two boolean parameters to control the
 * hub driver's behavior.  On the first initialization attempt, if the
 * "old_scheme_first" parameter is set then the old scheme will be used,
 * otherwise the new scheme is used.  If that fails and "use_both_schemes"
 * is set, then the driver will make another attempt, using the other scheme.
 */
static bool old_scheme_first = 0;
module_param(old_scheme_first, bool, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(old_scheme_first,
                 "start with the old device initialization scheme");

static bool use_both_schemes = 1;
module_param(use_both_schemes, bool, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(use_both_schemes,
                "try the other device initialization scheme if the "
                "first one fails");

/* Mutual exclusion for EHCI CF initialization.  This interferes with
 * port reset on some companion controllers.
 */
DECLARE_RWSEM(ehci_cf_port_reset_rwsem);
EXPORT_SYMBOL_GPL(ehci_cf_port_reset_rwsem);

#define HUB_DEBOUNCE_TIMEOUT    2000
#define HUB_DEBOUNCE_STEP         25
#define HUB_DEBOUNCE_STABLE      100

static int usb_reset_and_verify_device(struct usb_device *udev);

static inline char *portspeed(struct usb_hub *hub, int portstatus)
{
        if (hub_is_superspeed(hub->hdev))
                return "5.0 Gb/s";
        if (portstatus & USB_PORT_STAT_HIGH_SPEED)
                return "480 Mb/s";
        else if (portstatus & USB_PORT_STAT_LOW_SPEED)
                return "1.5 Mb/s";
        else
                return "12 Mb/s";
}

/* Note that hdev or one of its children must be locked! */
struct usb_hub *usb_hub_to_struct_hub(struct usb_device *hdev)
{
        if (!hdev || !hdev->actconfig || !hdev->maxchild)
                return NULL;
        return usb_get_intfdata(hdev->actconfig->interface[0]);
}

static int usb_device_supports_lpm(struct usb_device *udev)
{
        /* USB 2.1 (and greater) devices indicate LPM support through
         * their USB 2.0 Extended Capabilities BOS descriptor.
         */
        if (udev->speed == USB_SPEED_HIGH) {
                if (udev->bos->ext_cap &&
                        (USB_LPM_SUPPORT &
                         le32_to_cpu(udev->bos->ext_cap->bmAttributes)))
                        return 1;
                return 0;
        }

        /*
         * According to the USB 3.0 spec, all USB 3.0 devices must support LPM.
         * However, there are some that don't, and they set the U1/U2 exit
         * latencies to zero.
         */
        if (!udev->bos->ss_cap) {
                dev_info(&udev->dev, "No LPM exit latency info found, disabling LPM.\n");
                return 0;
        }

        if (udev->bos->ss_cap->bU1devExitLat == 0 &&
                        udev->bos->ss_cap->bU2DevExitLat == 0) {
                if (udev->parent)
                        dev_info(&udev->dev, "LPM exit latency is zeroed, disabling LPM.\n");
                else
                        dev_info(&udev->dev, "We don't know the algorithms for LPM for this host, disabling LPM.\n");
                return 0;
        }

        if (!udev->parent || udev->parent->lpm_capable)
                return 1;
        return 0;
}

/*
 * Set the Maximum Exit Latency (MEL) for the host to initiate a transition from
 * either U1 or U2.
 */
static void usb_set_lpm_mel(struct usb_device *udev,
                struct usb3_lpm_parameters *udev_lpm_params,
                unsigned int udev_exit_latency,
                struct usb_hub *hub,
                struct usb3_lpm_parameters *hub_lpm_params,
                unsigned int hub_exit_latency)
{
        unsigned int total_mel;
        unsigned int device_mel;
        unsigned int hub_mel;

        /*
         * Calculate the time it takes to transition all links from the roothub
         * to the parent hub into U0.  The parent hub must then decode the
         * packet (hub header decode latency) to figure out which port it was
         * bound for.
         *
         * The Hub Header decode latency is expressed in 0.1us intervals (0x1
         * means 0.1us).  Multiply that by 100 to get nanoseconds.
         */
        total_mel = hub_lpm_params->mel +
                (hub->descriptor->u.ss.bHubHdrDecLat * 100);

        /*
         * How long will it take to transition the downstream hub's port into
         * U0?  The greater of either the hub exit latency or the device exit
         * latency.
         *
         * The BOS U1/U2 exit latencies are expressed in 1us intervals.
         * Multiply that by 1000 to get nanoseconds.
         */
        device_mel = udev_exit_latency * 1000;
        hub_mel = hub_exit_latency * 1000;
        if (device_mel > hub_mel)
                total_mel += device_mel;
        else
                total_mel += hub_mel;

        udev_lpm_params->mel = total_mel;
}

/*
 * Set the maximum Device to Host Exit Latency (PEL) for the device to initiate
 * a transition from either U1 or U2.
 */
static void usb_set_lpm_pel(struct usb_device *udev,
                struct usb3_lpm_parameters *udev_lpm_params,
                unsigned int udev_exit_latency,
                struct usb_hub *hub,
                struct usb3_lpm_parameters *hub_lpm_params,
                unsigned int hub_exit_latency,
                unsigned int port_to_port_exit_latency)
{
        unsigned int first_link_pel;
        unsigned int hub_pel;

        /*
         * First, the device sends an LFPS to transition the link between the
         * device and the parent hub into U0.  The exit latency is the bigger of
         * the device exit latency or the hub exit latency.
         */
        if (udev_exit_latency > hub_exit_latency)
                first_link_pel = udev_exit_latency * 1000;
        else
                first_link_pel = hub_exit_latency * 1000;

        /*
         * When the hub starts to receive the LFPS, there is a slight delay for
         * it to figure out that one of the ports is sending an LFPS.  Then it
         * will forward the LFPS to its upstream link.  The exit latency is the
         * delay, plus the PEL that we calculated for this hub.
         */
        hub_pel = port_to_port_exit_latency * 1000 + hub_lpm_params->pel;

        /*
         * According to figure C-7 in the USB 3.0 spec, the PEL for this device
         * is the greater of the two exit latencies.
         */
        if (first_link_pel > hub_pel)
                udev_lpm_params->pel = first_link_pel;
        else
                udev_lpm_params->pel = hub_pel;
}

/*
 * Set the System Exit Latency (SEL) to indicate the total worst-case time from
 * when a device initiates a transition to U0, until when it will receive the
 * first packet from the host controller.
 *
 * Section C.1.5.1 describes the four components to this:
 *  - t1: device PEL
 *  - t2: time for the ERDY to make it from the device to the host.
 *  - t3: a host-specific delay to process the ERDY.
 *  - t4: time for the packet to make it from the host to the device.
 *
 * t3 is specific to both the xHCI host and the platform the host is integrated
 * into.  The Intel HW folks have said it's negligible, FIXME if a different
 * vendor says otherwise.
 */
static void usb_set_lpm_sel(struct usb_device *udev,
                struct usb3_lpm_parameters *udev_lpm_params)
{
        struct usb_device *parent;
        unsigned int num_hubs;
        unsigned int total_sel;

        /* t1 = device PEL */
        total_sel = udev_lpm_params->pel;
        /* How many external hubs are in between the device & the root port. */
        for (parent = udev->parent, num_hubs = 0; parent->parent;
                        parent = parent->parent)
                num_hubs++;
        /* t2 = 2.1us + 250ns * (num_hubs - 1) */
        if (num_hubs > 0)
                total_sel += 2100 + 250 * (num_hubs - 1);

        /* t4 = 250ns * num_hubs */
        total_sel += 250 * num_hubs;

        udev_lpm_params->sel = total_sel;
}

static void usb_set_lpm_parameters(struct usb_device *udev)
{
        struct usb_hub *hub;
        unsigned int port_to_port_delay;
        unsigned int udev_u1_del;
        unsigned int udev_u2_del;
        unsigned int hub_u1_del;
        unsigned int hub_u2_del;

        if (!udev->lpm_capable || udev->speed != USB_SPEED_SUPER)
                return;

        hub = usb_hub_to_struct_hub(udev->parent);
        /* It doesn't take time to transition the roothub into U0, since it
         * doesn't have an upstream link.
         */
        if (!hub)
                return;

        udev_u1_del = udev->bos->ss_cap->bU1devExitLat;
        udev_u2_del = le16_to_cpu(udev->bos->ss_cap->bU2DevExitLat);
        hub_u1_del = udev->parent->bos->ss_cap->bU1devExitLat;
        hub_u2_del = le16_to_cpu(udev->parent->bos->ss_cap->bU2DevExitLat);

        usb_set_lpm_mel(udev, &udev->u1_params, udev_u1_del,
                        hub, &udev->parent->u1_params, hub_u1_del);

        usb_set_lpm_mel(udev, &udev->u2_params, udev_u2_del,
                        hub, &udev->parent->u2_params, hub_u2_del);

        /*
         * Appendix C, section C.2.2.2, says that there is a slight delay from
         * when the parent hub notices the downstream port is trying to
         * transition to U0 to when the hub initiates a U0 transition on its
         * upstream port.  The section says the delays are tPort2PortU1EL and
         * tPort2PortU2EL, but it doesn't define what they are.
         *
         * The hub chapter, sections 10.4.2.4 and 10.4.2.5 seem to be talking
         * about the same delays.  Use the maximum delay calculations from those
         * sections.  For U1, it's tHubPort2PortExitLat, which is 1us max.  For
         * U2, it's tHubPort2PortExitLat + U2DevExitLat - U1DevExitLat.  I
         * assume the device exit latencies they are talking about are the hub
         * exit latencies.
         *
         * What do we do if the U2 exit latency is less than the U1 exit
         * latency?  It's possible, although not likely...
         */
        port_to_port_delay = 1;

        usb_set_lpm_pel(udev, &udev->u1_params, udev_u1_del,
                        hub, &udev->parent->u1_params, hub_u1_del,
                        port_to_port_delay);

        if (hub_u2_del > hub_u1_del)
                port_to_port_delay = 1 + hub_u2_del - hub_u1_del;
        else
                port_to_port_delay = 1 + hub_u1_del;

        usb_set_lpm_pel(udev, &udev->u2_params, udev_u2_del,
                        hub, &udev->parent->u2_params, hub_u2_del,
                        port_to_port_delay);

        /* Now that we've got PEL, calculate SEL. */
        usb_set_lpm_sel(udev, &udev->u1_params);
        usb_set_lpm_sel(udev, &udev->u2_params);
}

/* USB 2.0 spec Section 11.24.4.5 */
static int get_hub_descriptor(struct usb_device *hdev, void *data)
{
        int i, ret, size;
        unsigned dtype;

        if (hub_is_superspeed(hdev)) {
                dtype = USB_DT_SS_HUB;
                size = USB_DT_SS_HUB_SIZE;
        } else {
                dtype = USB_DT_HUB;
                size = sizeof(struct usb_hub_descriptor);
        }

        for (i = 0; i < 3; i++) {
                ret = usb_control_msg(hdev, usb_rcvctrlpipe(hdev, 0),
                        USB_REQ_GET_DESCRIPTOR, USB_DIR_IN | USB_RT_HUB,
                        dtype << 8, 0, data, size,
                        USB_CTRL_GET_TIMEOUT);
                if (ret >= (USB_DT_HUB_NONVAR_SIZE + 2))
                        return ret;
        }
        return -EINVAL;
}

/*
 * USB 2.0 spec Section 11.24.2.1
 */
static int clear_hub_feature(struct usb_device *hdev, int feature)
{
        return usb_control_msg(hdev, usb_sndctrlpipe(hdev, 0),
                USB_REQ_CLEAR_FEATURE, USB_RT_HUB, feature, 0, NULL, 0, 1000);
}

/*
 * USB 2.0 spec Section 11.24.2.2
 */
int usb_clear_port_feature(struct usb_device *hdev, int port1, int feature)
{
        return usb_control_msg(hdev, usb_sndctrlpipe(hdev, 0),
                USB_REQ_CLEAR_FEATURE, USB_RT_PORT, feature, port1,
                NULL, 0, 1000);
}

/*
 * USB 2.0 spec Section 11.24.2.13
 */
static int set_port_feature(struct usb_device *hdev, int port1, int feature)
{
        return usb_control_msg(hdev, usb_sndctrlpipe(hdev, 0),
                USB_REQ_SET_FEATURE, USB_RT_PORT, feature, port1,
                NULL, 0, 1000);
}

static char *to_led_name(int selector)
{
        switch (selector) {
        case HUB_LED_AMBER:
                return "amber";
        case HUB_LED_GREEN:
                return "green";
        case HUB_LED_OFF:
                return "off";
        case HUB_LED_AUTO:
                return "auto";
        default:
                return "??";
        }
}

/*
 * USB 2.0 spec Section 11.24.2.7.1.10 and table 11-7
 * for info about using port indicators
 */
static void set_port_led(struct usb_hub *hub, int port1, int selector)
{
        struct usb_port *port_dev = hub->ports[port1 - 1];
        int status;

        status = set_port_feature(hub->hdev, (selector << 8) | port1,
                        USB_PORT_FEAT_INDICATOR);
        dev_dbg(&port_dev->dev, "indicator %s status %d\n",
                to_led_name(selector), status);
}

#define LED_CYCLE_PERIOD        ((2*HZ)/3)

static void led_work (struct work_struct *work)
{
        struct usb_hub          *hub =
                container_of(work, struct usb_hub, leds.work);
        struct usb_device       *hdev = hub->hdev;
        unsigned                i;
        unsigned                changed = 0;
        int                     cursor = -1;

        if (hdev->state != USB_STATE_CONFIGURED || hub->quiescing)
                return;

        for (i = 0; i < hdev->maxchild; i++) {
                unsigned        selector, mode;

                /* 30%-50% duty cycle */

                switch (hub->indicator[i]) {
                /* cycle marker */
                case INDICATOR_CYCLE:
                        cursor = i;
                        selector = HUB_LED_AUTO;
                        mode = INDICATOR_AUTO;
                        break;
                /* blinking green = sw attention */
                case INDICATOR_GREEN_BLINK:
                        selector = HUB_LED_GREEN;
                        mode = INDICATOR_GREEN_BLINK_OFF;
                        break;
                case INDICATOR_GREEN_BLINK_OFF:
                        selector = HUB_LED_OFF;
                        mode = INDICATOR_GREEN_BLINK;
                        break;
                /* blinking amber = hw attention */
                case INDICATOR_AMBER_BLINK:
                        selector = HUB_LED_AMBER;
                        mode = INDICATOR_AMBER_BLINK_OFF;
                        break;
                case INDICATOR_AMBER_BLINK_OFF:
                        selector = HUB_LED_OFF;
                        mode = INDICATOR_AMBER_BLINK;
                        break;
                /* blink green/amber = reserved */
                case INDICATOR_ALT_BLINK:
                        selector = HUB_LED_GREEN;
                        mode = INDICATOR_ALT_BLINK_OFF;
                        break;
                case INDICATOR_ALT_BLINK_OFF:
                        selector = HUB_LED_AMBER;
                        mode = INDICATOR_ALT_BLINK;
                        break;
                default:
                        continue;
                }
                if (selector != HUB_LED_AUTO)
                        changed = 1;
                set_port_led(hub, i + 1, selector);
                hub->indicator[i] = mode;
        }
        if (!changed && blinkenlights) {
                cursor++;
                cursor %= hdev->maxchild;
                set_port_led(hub, cursor + 1, HUB_LED_GREEN);
                hub->indicator[cursor] = INDICATOR_CYCLE;
                changed++;
        }
        if (changed)
                queue_delayed_work(system_power_efficient_wq,
                                &hub->leds, LED_CYCLE_PERIOD);
}

/* use a short timeout for hub/port status fetches */
#define USB_STS_TIMEOUT         1000
#define USB_STS_RETRIES         5

/*
 * USB 2.0 spec Section 11.24.2.6
 */
static int get_hub_status(struct usb_device *hdev,
                struct usb_hub_status *data)
{
        int i, status = -ETIMEDOUT;

        for (i = 0; i < USB_STS_RETRIES &&
                        (status == -ETIMEDOUT || status == -EPIPE); i++) {
                status = usb_control_msg(hdev, usb_rcvctrlpipe(hdev, 0),
                        USB_REQ_GET_STATUS, USB_DIR_IN | USB_RT_HUB, 0, 0,
                        data, sizeof(*data), USB_STS_TIMEOUT);
        }
        return status;
}

/*
 * USB 2.0 spec Section 11.24.2.7
 */
static int get_port_status(struct usb_device *hdev, int port1,
                struct usb_port_status *data)
{
        int i, status = -ETIMEDOUT;

        for (i = 0; i < USB_STS_RETRIES &&
                        (status == -ETIMEDOUT || status == -EPIPE); i++) {
                status = usb_control_msg(hdev, usb_rcvctrlpipe(hdev, 0),
                        USB_REQ_GET_STATUS, USB_DIR_IN | USB_RT_PORT, 0, port1,
                        data, sizeof(*data), USB_STS_TIMEOUT);
        }
        return status;
}

static int hub_port_status(struct usb_hub *hub, int port1,
                u16 *status, u16 *change)
{
        int ret;

        mutex_lock(&hub->status_mutex);
        ret = get_port_status(hub->hdev, port1, &hub->status->port);
        if (ret < 4) {
                if (ret != -ENODEV)
                        dev_err(hub->intfdev,
                                "%s failed (err = %d)\n", __func__, ret);
                if (ret >= 0)
                        ret = -EIO;
        } else {
                *status = le16_to_cpu(hub->status->port.wPortStatus);
                *change = le16_to_cpu(hub->status->port.wPortChange);

                ret = 0;
        }
        mutex_unlock(&hub->status_mutex);
        return ret;
}

static void kick_khubd(struct usb_hub *hub)
{
        unsigned long   flags;

        spin_lock_irqsave(&hub_event_lock, flags);
        if (!hub->disconnected && list_empty(&hub->event_list)) {
                list_add_tail(&hub->event_list, &hub_event_list);

                /* Suppress autosuspend until khubd runs */
                usb_autopm_get_interface_no_resume(
                                to_usb_interface(hub->intfdev));
                wake_up(&khubd_wait);
        }
        spin_unlock_irqrestore(&hub_event_lock, flags);
}

void usb_kick_khubd(struct usb_device *hdev)
{
        struct usb_hub *hub = usb_hub_to_struct_hub(hdev);

        if (hub)
                kick_khubd(hub);
}

/*
 * Let the USB core know that a USB 3.0 device has sent a Function Wake Device
 * Notification, which indicates it had initiated remote wakeup.
 *
 * USB 3.0 hubs do not report the port link state change from U3 to U0 when the
 * device initiates resume, so the USB core will not receive notice of the
 * resume through the normal hub interrupt URB.
 */
void usb_wakeup_notification(struct usb_device *hdev,
                unsigned int portnum)
{
        struct usb_hub *hub;

        if (!hdev)
                return;

        hub = usb_hub_to_struct_hub(hdev);
        if (hub) {
                set_bit(portnum, hub->wakeup_bits);
                kick_khubd(hub);
        }
}
EXPORT_SYMBOL_GPL(usb_wakeup_notification);

/* completion function, fires on port status changes and various faults */
static void hub_irq(struct urb *urb)
{
        struct usb_hub *hub = urb->context;
        int status = urb->status;
        unsigned i;
        unsigned long bits;

        switch (status) {
        case -ENOENT:           /* synchronous unlink */
        case -ECONNRESET:       /* async unlink */
        case -ESHUTDOWN:        /* hardware going away */
                return;

        default:                /* presumably an error */
                /* Cause a hub reset after 10 consecutive errors */
                dev_dbg (hub->intfdev, "transfer --> %d\n", status);
                if ((++hub->nerrors < 10) || hub->error)
                        goto resubmit;
                hub->error = status;
                /* FALL THROUGH */

        /* let khubd handle things */
        case 0:                 /* we got data:  port status changed */
                bits = 0;
                for (i = 0; i < urb->actual_length; ++i)
                        bits |= ((unsigned long) ((*hub->buffer)[i]))
                                        << (i*8);
                hub->event_bits[0] = bits;
                break;
        }

        hub->nerrors = 0;

        /* Something happened, let khubd figure it out */
        kick_khubd(hub);

resubmit:
        if (hub->quiescing)
                return;

        if ((status = usb_submit_urb (hub->urb, GFP_ATOMIC)) != 0
                        && status != -ENODEV && status != -EPERM)
                dev_err (hub->intfdev, "resubmit --> %d\n", status);
}

/* USB 2.0 spec Section 11.24.2.3 */
static inline int
hub_clear_tt_buffer (struct usb_device *hdev, u16 devinfo, u16 tt)
{
        /* Need to clear both directions for control ep */
        if (((devinfo >> 11) & USB_ENDPOINT_XFERTYPE_MASK) ==
                        USB_ENDPOINT_XFER_CONTROL) {
                int status = usb_control_msg(hdev, usb_sndctrlpipe(hdev, 0),
                                HUB_CLEAR_TT_BUFFER, USB_RT_PORT,
                                devinfo ^ 0x8000, tt, NULL, 0, 1000);
                if (status)
                        return status;
        }
        return usb_control_msg(hdev, usb_sndctrlpipe(hdev, 0),
                               HUB_CLEAR_TT_BUFFER, USB_RT_PORT, devinfo,
                               tt, NULL, 0, 1000);
}

/*
 * enumeration blocks khubd for a long time. we use keventd instead, since
 * long blocking there is the exception, not the rule.  accordingly, HCDs
 * talking to TTs must queue control transfers (not just bulk and iso), so
 * both can talk to the same hub concurrently.
 */
static void hub_tt_work(struct work_struct *work)
{
        struct usb_hub          *hub =
                container_of(work, struct usb_hub, tt.clear_work);
        unsigned long           flags;

        spin_lock_irqsave (&hub->tt.lock, flags);
        while (!list_empty(&hub->tt.clear_list)) {
                struct list_head        *next;
                struct usb_tt_clear     *clear;
                struct usb_device       *hdev = hub->hdev;
                const struct hc_driver  *drv;
                int                     status;

                next = hub->tt.clear_list.next;
                clear = list_entry (next, struct usb_tt_clear, clear_list);
                list_del (&clear->clear_list);

                /* drop lock so HCD can concurrently report other TT errors */
                spin_unlock_irqrestore (&hub->tt.lock, flags);
                status = hub_clear_tt_buffer (hdev, clear->devinfo, clear->tt);
                if (status && status != -ENODEV)
                        dev_err (&hdev->dev,
                                "clear tt %d (%04x) error %d\n",
                                clear->tt, clear->devinfo, status);

                /* Tell the HCD, even if the operation failed */
                drv = clear->hcd->driver;
                if (drv->clear_tt_buffer_complete)
                        (drv->clear_tt_buffer_complete)(clear->hcd, clear->ep);

                kfree(clear);
                spin_lock_irqsave(&hub->tt.lock, flags);
        }
        spin_unlock_irqrestore (&hub->tt.lock, flags);
}

/**
 * usb_hub_set_port_power - control hub port's power state
 * @hdev: USB device belonging to the usb hub
 * @hub: target hub
 * @port1: port index
 * @set: expected status
 *
 * call this function to control port's power via setting or
 * clearing the port's PORT_POWER feature.
 *
 * Return: 0 if successful. A negative error code otherwise.
 */
int usb_hub_set_port_power(struct usb_device *hdev, struct usb_hub *hub,
                           int port1, bool set)
{
        int ret;

        if (set)
                ret = set_port_feature(hdev, port1, USB_PORT_FEAT_POWER);
        else
                ret = usb_clear_port_feature(hdev, port1, USB_PORT_FEAT_POWER);

        if (ret)
                return ret;

        if (set)
                set_bit(port1, hub->power_bits);
        else
                clear_bit(port1, hub->power_bits);
        return 0;
}

/**
 * usb_hub_clear_tt_buffer - clear control/bulk TT state in high speed hub
 * @urb: an URB associated with the failed or incomplete split transaction
 *
 * High speed HCDs use this to tell the hub driver that some split control or
 * bulk transaction failed in a way that requires clearing internal state of
 * a transaction translator.  This is normally detected (and reported) from
 * interrupt context.
 *
 * It may not be possible for that hub to handle additional full (or low)
 * speed transactions until that state is fully cleared out.
 *
 * Return: 0 if successful. A negative error code otherwise.
 */
int usb_hub_clear_tt_buffer(struct urb *urb)
{
        struct usb_device       *udev = urb->dev;
        int                     pipe = urb->pipe;
        struct usb_tt           *tt = udev->tt;
        unsigned long           flags;
        struct usb_tt_clear     *clear;

        /* we've got to cope with an arbitrary number of pending TT clears,
         * since each TT has "at least two" buffers that can need it (and
         * there can be many TTs per hub).  even if they're uncommon.
         */
        if ((clear = kmalloc (sizeof *clear, GFP_ATOMIC)) == NULL) {
                dev_err (&udev->dev, "can't save CLEAR_TT_BUFFER state\n");
                /* FIXME recover somehow ... RESET_TT? */
                return -ENOMEM;
        }

        /* info that CLEAR_TT_BUFFER needs */
        clear->tt = tt->multi ? udev->ttport : 1;
        clear->devinfo = usb_pipeendpoint (pipe);
        clear->devinfo |= udev->devnum << 4;
        clear->devinfo |= usb_pipecontrol (pipe)
                        ? (USB_ENDPOINT_XFER_CONTROL << 11)
                        : (USB_ENDPOINT_XFER_BULK << 11);
        if (usb_pipein (pipe))
                clear->devinfo |= 1 << 15;

        /* info for completion callback */
        clear->hcd = bus_to_hcd(udev->bus);
        clear->ep = urb->ep;

        /* tell keventd to clear state for this TT */
        spin_lock_irqsave (&tt->lock, flags);
        list_add_tail (&clear->clear_list, &tt->clear_list);
        schedule_work(&tt->clear_work);
        spin_unlock_irqrestore (&tt->lock, flags);
        return 0;
}
EXPORT_SYMBOL_GPL(usb_hub_clear_tt_buffer);

static void hub_power_on(struct usb_hub *hub, bool do_delay)
{
        int port1;

        /* Enable power on each port.  Some hubs have reserved values
         * of LPSM (> 2) in their descriptors, even though they are
         * USB 2.0 hubs.  Some hubs do not implement port-power switching
         * but only emulate it.  In all cases, the ports won't work
         * unless we send these messages to the hub.
         */
        if (hub_is_port_power_switchable(hub))
                dev_dbg(hub->intfdev, "enabling power on all ports\n");
        else
                dev_dbg(hub->intfdev, "trying to enable port power on "
                                "non-switchable hub\n");
        for (port1 = 1; port1 <= hub->hdev->maxchild; port1++)
                if (test_bit(port1, hub->power_bits))
                        set_port_feature(hub->hdev, port1, USB_PORT_FEAT_POWER);
                else
                        usb_clear_port_feature(hub->hdev, port1,
                                                USB_PORT_FEAT_POWER);
        if (do_delay)
                msleep(hub_power_on_good_delay(hub));
}

static int hub_hub_status(struct usb_hub *hub,
                u16 *status, u16 *change)
{
        int ret;

        mutex_lock(&hub->status_mutex);
        ret = get_hub_status(hub->hdev, &hub->status->hub);
        if (ret < 0) {
                if (ret != -ENODEV)
                        dev_err(hub->intfdev,
                                "%s failed (err = %d)\n", __func__, ret);
        } else {
                *status = le16_to_cpu(hub->status->hub.wHubStatus);
                *change = le16_to_cpu(hub->status->hub.wHubChange);
                ret = 0;
        }
        mutex_unlock(&hub->status_mutex);
        return ret;
}

static int hub_set_port_link_state(struct usb_hub *hub, int port1,
                        unsigned int link_status)
{
        return set_port_feature(hub->hdev,
                        port1 | (link_status << 3),
                        USB_PORT_FEAT_LINK_STATE);
}

/*
 * If USB 3.0 ports are placed into the Disabled state, they will no longer
 * detect any device connects or disconnects.  This is generally not what the
 * USB core wants, since it expects a disabled port to produce a port status
 * change event when a new device connects.
 *
 * Instead, set the link state to Disabled, wait for the link to settle into
 * that state, clear any change bits, and then put the port into the RxDetect
 * state.
 */
static int hub_usb3_port_disable(struct usb_hub *hub, int port1)
{
        int ret;
        int total_time;
        u16 portchange, portstatus;

        if (!hub_is_superspeed(hub->hdev))
                return -EINVAL;

        ret = hub_set_port_link_state(hub, port1, USB_SS_PORT_LS_SS_DISABLED);
        if (ret)
                return ret;

        /* Wait for the link to enter the disabled state. */
        for (total_time = 0; ; total_time += HUB_DEBOUNCE_STEP) {
                ret = hub_port_status(hub, port1, &portstatus, &portchange);
                if (ret < 0)
                        return ret;

                if ((portstatus & USB_PORT_STAT_LINK_STATE) ==
                                USB_SS_PORT_LS_SS_DISABLED)
                        break;
                if (total_time >= HUB_DEBOUNCE_TIMEOUT)
                        break;
                msleep(HUB_DEBOUNCE_STEP);
        }
        if (total_time >= HUB_DEBOUNCE_TIMEOUT)
                dev_warn(&hub->ports[port1 - 1]->dev,
                                "Could not disable after %d ms\n", total_time);

        return hub_set_port_link_state(hub, port1, USB_SS_PORT_LS_RX_DETECT);
}

static int hub_port_disable(struct usb_hub *hub, int port1, int set_state)
{
        struct usb_port *port_dev = hub->ports[port1 - 1];
        struct usb_device *hdev = hub->hdev;
        int ret = 0;

        if (port_dev->child && set_state)
                usb_set_device_state(port_dev->child, USB_STATE_NOTATTACHED);
        if (!hub->error) {
                if (hub_is_superspeed(hub->hdev))
                        ret = hub_usb3_port_disable(hub, port1);
                else
                        ret = usb_clear_port_feature(hdev, port1,
                                        USB_PORT_FEAT_ENABLE);
        }
        if (ret && ret != -ENODEV)
                dev_err(&port_dev->dev, "cannot disable (err = %d)\n", ret);
        return ret;
}

/*
 * Disable a port and mark a logical connect-change event, so that some
 * time later khubd will disconnect() any existing usb_device on the port
 * and will re-enumerate if there actually is a device attached.
 */
static void hub_port_logical_disconnect(struct usb_hub *hub, int port1)
{
        dev_dbg(&hub->ports[port1 - 1]->dev, "logical disconnect\n");
        hub_port_disable(hub, port1, 1);

        /* FIXME let caller ask to power down the port:
         *  - some devices won't enumerate without a VBUS power cycle
         *  - SRP saves power that way
         *  - ... new call, TBD ...
         * That's easy if this hub can switch power per-port, and
         * khubd reactivates the port later (timer, SRP, etc).
         * Powerdown must be optional, because of reset/DFU.
         */

        set_bit(port1, hub->change_bits);
        kick_khubd(hub);
}

/**
 * usb_remove_device - disable a device's port on its parent hub
 * @udev: device to be disabled and removed
 * Context: @udev locked, must be able to sleep.
 *
 * After @udev's port has been disabled, khubd is notified and it will
 * see that the device has been disconnected.  When the device is
 * physically unplugged and something is plugged in, the events will
 * be received and processed normally.
 *
 * Return: 0 if successful. A negative error code otherwise.
 */
int usb_remove_device(struct usb_device *udev)
{
        struct usb_hub *hub;
        struct usb_interface *intf;

        if (!udev->parent)      /* Can't remove a root hub */
                return -EINVAL;
        hub = usb_hub_to_struct_hub(udev->parent);
        intf = to_usb_interface(hub->intfdev);

        usb_autopm_get_interface(intf);
        set_bit(udev->portnum, hub->removed_bits);
        hub_port_logical_disconnect(hub, udev->portnum);
        usb_autopm_put_interface(intf);
        return 0;
}

enum hub_activation_type {
        HUB_INIT, HUB_INIT2, HUB_INIT3,         /* INITs must come first */
        HUB_POST_RESET, HUB_RESUME, HUB_RESET_RESUME,
};

static void hub_init_func2(struct work_struct *ws);
static void hub_init_func3(struct work_struct *ws);

static void hub_activate(struct usb_hub *hub, enum hub_activation_type type)
{
        struct usb_device *hdev = hub->hdev;
        struct usb_hcd *hcd;
        int ret;
        int port1;
        int status;
        bool need_debounce_delay = false;
        unsigned delay;

        /* Continue a partial initialization */
        if (type == HUB_INIT2)
                goto init2;
        if (type == HUB_INIT3)
                goto init3;

        /* The superspeed hub except for root hub has to use Hub Depth
         * value as an offset into the route string to locate the bits
         * it uses to determine the downstream port number. So hub driver
         * should send a set hub depth request to superspeed hub after
         * the superspeed hub is set configuration in initialization or
         * reset procedure.
         *
         * After a resume, port power should still be on.
         * For any other type of activation, turn it on.
         */
        if (type != HUB_RESUME) {
                if (hdev->parent && hub_is_superspeed(hdev)) {
                        ret = usb_control_msg(hdev, usb_sndctrlpipe(hdev, 0),
                                        HUB_SET_DEPTH, USB_RT_HUB,
                                        hdev->level - 1, 0, NULL, 0,
                                        USB_CTRL_SET_TIMEOUT);
                        if (ret < 0)
                                dev_err(hub->intfdev,
                                                "set hub depth failed\n");
                }

                /* Speed up system boot by using a delayed_work for the
                 * hub's initial power-up delays.  This is pretty awkward
                 * and the implementation looks like a home-brewed sort of
                 * setjmp/longjmp, but it saves at least 100 ms for each
                 * root hub (assuming usbcore is compiled into the kernel
                 * rather than as a module).  It adds up.
                 *
                 * This can't be done for HUB_RESUME or HUB_RESET_RESUME
                 * because for those activation types the ports have to be
                 * operational when we return.  In theory this could be done
                 * for HUB_POST_RESET, but it's easier not to.
                 */
                if (type == HUB_INIT) {
                        unsigned delay = hub_power_on_good_delay(hub);

                        hub_power_on(hub, false);
                        INIT_DELAYED_WORK(&hub->init_work, hub_init_func2);
                        queue_delayed_work(system_power_efficient_wq,
                                        &hub->init_work,
                                        msecs_to_jiffies(delay));

                        /* Suppress autosuspend until init is done */
                        usb_autopm_get_interface_no_resume(
                                        to_usb_interface(hub->intfdev));
                        return;         /* Continues at init2: below */
                } else if (type == HUB_RESET_RESUME) {
                        /* The internal host controller state for the hub device
                         * may be gone after a host power loss on system resume.
                         * Update the device's info so the HW knows it's a hub.
                         */
                        hcd = bus_to_hcd(hdev->bus);
                        if (hcd->driver->update_hub_device) {
                                ret = hcd->driver->update_hub_device(hcd, hdev,
                                                &hub->tt, GFP_NOIO);
                                if (ret < 0) {
                                        dev_err(hub->intfdev, "Host not "
                                                        "accepting hub info "
                                                        "update.\n");
                                        dev_err(hub->intfdev, "LS/FS devices "
                                                        "and hubs may not work "
                                                        "under this hub\n.");
                                }
                        }
                        hub_power_on(hub, true);
                } else {
                        hub_power_on(hub, true);
                }
        }
 init2:

        /*
         * Check each port and set hub->change_bits to let khubd know
         * which ports need attention.
         */
        for (port1 = 1; port1 <= hdev->maxchild; ++port1) {
                struct usb_port *port_dev = hub->ports[port1 - 1];
                struct usb_device *udev = port_dev->child;
                u16 portstatus, portchange;

                portstatus = portchange = 0;
                status = hub_port_status(hub, port1, &portstatus, &portchange);
                if (udev || (portstatus & USB_PORT_STAT_CONNECTION))
                        dev_dbg(&port_dev->dev, "status %04x change %04x\n",
                                        portstatus, portchange);

                /*
                 * After anything other than HUB_RESUME (i.e., initialization
                 * or any sort of reset), every port should be disabled.
                 * Unconnected ports should likewise be disabled (paranoia),
                 * and so should ports for which we have no usb_device.
                 */
                if ((portstatus & USB_PORT_STAT_ENABLE) && (
                                type != HUB_RESUME ||
                                !(portstatus & USB_PORT_STAT_CONNECTION) ||
                                !udev ||
                                udev->state == USB_STATE_NOTATTACHED)) {
                        /*
                         * USB3 protocol ports will automatically transition
                         * to Enabled state when detect an USB3.0 device attach.
                         * Do not disable USB3 protocol ports, just pretend
                         * power was lost
                         */
                        portstatus &= ~USB_PORT_STAT_ENABLE;
                        if (!hub_is_superspeed(hdev))
                                usb_clear_port_feature(hdev, port1,
                                                   USB_PORT_FEAT_ENABLE);
                }

                /* Clear status-change flags; we'll debounce later */
                if (portchange & USB_PORT_STAT_C_CONNECTION) {
                        need_debounce_delay = true;
                        usb_clear_port_feature(hub->hdev, port1,
                                        USB_PORT_FEAT_C_CONNECTION);
                }
                if (portchange & USB_PORT_STAT_C_ENABLE) {
                        need_debounce_delay = true;
                        usb_clear_port_feature(hub->hdev, port1,
                                        USB_PORT_FEAT_C_ENABLE);
                }
                if (portchange & USB_PORT_STAT_C_RESET) {
                        need_debounce_delay = true;
                        usb_clear_port_feature(hub->hdev, port1,
                                        USB_PORT_FEAT_C_RESET);
                }
                if ((portchange & USB_PORT_STAT_C_BH_RESET) &&
                                hub_is_superspeed(hub->hdev)) {
                        need_debounce_delay = true;
                        usb_clear_port_feature(hub->hdev, port1,
                                        USB_PORT_FEAT_C_BH_PORT_RESET);
                }
                /* We can forget about a "removed" device when there's a
                 * physical disconnect or the connect status changes.
                 */
                if (!(portstatus & USB_PORT_STAT_CONNECTION) ||
                                (portchange & USB_PORT_STAT_C_CONNECTION))
                        clear_bit(port1, hub->removed_bits);

                if (!udev || udev->state == USB_STATE_NOTATTACHED) {
                        /* Tell khubd to disconnect the device or
                         * check for a new connection
                         */
                        if (udev || (portstatus & USB_PORT_STAT_CONNECTION) ||
                            (portstatus & USB_PORT_STAT_OVERCURRENT))
                                set_bit(port1, hub->change_bits);

                } else if (portstatus & USB_PORT_STAT_ENABLE) {
                        bool port_resumed = (portstatus &
                                        USB_PORT_STAT_LINK_STATE) ==
                                USB_SS_PORT_LS_U0;
                        /* The power session apparently survived the resume.
                         * If there was an overcurrent or suspend change
                         * (i.e., remote wakeup request), have khubd
                         * take care of it.  Look at the port link state
                         * for USB 3.0 hubs, since they don't have a suspend
                         * change bit, and they don't set the port link change
                         * bit on device-initiated resume.
                         */
                        if (portchange || (hub_is_superspeed(hub->hdev) &&
                                                port_resumed))
                                set_bit(port1, hub->change_bits);

                } else if (udev->persist_enabled) {
#ifdef CONFIG_PM
                        udev->reset_resume = 1;
#endif
                        /* Don't set the change_bits when the device
                         * was powered off.
                         */
                        if (test_bit(port1, hub->power_bits))
                                set_bit(port1, hub->change_bits);

                } else {
                        /* The power session is gone; tell khubd */
                        usb_set_device_state(udev, USB_STATE_NOTATTACHED);
                        set_bit(port1, hub->change_bits);
                }
        }

        /* If no port-status-change flags were set, we don't need any
         * debouncing.  If flags were set we can try to debounce the
         * ports all at once right now, instead of letting khubd do them
         * one at a time later on.
         *
         * If any port-status changes do occur during this delay, khubd
         * will see them later and handle them normally.
         */
        if (need_debounce_delay) {
                delay = HUB_DEBOUNCE_STABLE;

                /* Don't do a long sleep inside a workqueue routine */
                if (type == HUB_INIT2) {
                        INIT_DELAYED_WORK(&hub->init_work, hub_init_func3);
                        queue_delayed_work(system_power_efficient_wq,
                                        &hub->init_work,
                                        msecs_to_jiffies(delay));
                        return;         /* Continues at init3: below */
                } else {
                        msleep(delay);
                }
        }
 init3:
        hub->quiescing = 0;

        status = usb_submit_urb(hub->urb, GFP_NOIO);
        if (status < 0)
                dev_err(hub->intfdev, "activate --> %d\n", status);
        if (hub->has_indicators && blinkenlights)
                queue_delayed_work(system_power_efficient_wq,
                                &hub->leds, LED_CYCLE_PERIOD);

        /* Scan all ports that need attention */
        kick_khubd(hub);

        /* Allow autosuspend if it was suppressed */
        if (type <= HUB_INIT3)
                usb_autopm_put_interface_async(to_usb_interface(hub->intfdev));
}

/* Implement the continuations for the delays above */
static void hub_init_func2(struct work_struct *ws)
{
        struct usb_hub *hub = container_of(ws, struct usb_hub, init_work.work);

        hub_activate(hub, HUB_INIT2);
}

static void hub_init_func3(struct work_struct *ws)
{
        struct usb_hub *hub = container_of(ws, struct usb_hub, init_work.work);

        hub_activate(hub, HUB_INIT3);
}

enum hub_quiescing_type {
        HUB_DISCONNECT, HUB_PRE_RESET, HUB_SUSPEND
};

static void hub_quiesce(struct usb_hub *hub, enum hub_quiescing_type type)
{
        struct usb_device *hdev = hub->hdev;
        int i;

        cancel_delayed_work_sync(&hub->init_work);

        /* khubd and related activity won't re-trigger */
        hub->quiescing = 1;

        if (type != HUB_SUSPEND) {
                /* Disconnect all the children */
                for (i = 0; i < hdev->maxchild; ++i) {
                        if (hub->ports[i]->child)
                                usb_disconnect(&hub->ports[i]->child);
                }
        }

        /* Stop khubd and related activity */
        usb_kill_urb(hub->urb);
        if (hub->has_indicators)
                cancel_delayed_work_sync(&hub->leds);
        if (hub->tt.hub)
                flush_work(&hub->tt.clear_work);
}

static void hub_pm_barrier_for_all_ports(struct usb_hub *hub)
{
        int i;

        for (i = 0; i < hub->hdev->maxchild; ++i)
                pm_runtime_barrier(&hub->ports[i]->dev);
}

/* caller has locked the hub device */
static int hub_pre_reset(struct usb_interface *intf)
{
        struct usb_hub *hub = usb_get_intfdata(intf);

        hub_quiesce(hub, HUB_PRE_RESET);
        hub->in_reset = 1;
        hub_pm_barrier_for_all_ports(hub);
        return 0;
}

/* caller has locked the hub device */
static int hub_post_reset(struct usb_interface *intf)
{
        struct usb_hub *hub = usb_get_intfdata(intf);

        hub->in_reset = 0;
        hub_pm_barrier_for_all_ports(hub);
        hub_activate(hub, HUB_POST_RESET);
        return 0;
}

static int hub_configure(struct usb_hub *hub,
        struct usb_endpoint_descriptor *endpoint)
{
        struct usb_hcd *hcd;
        struct usb_device *hdev = hub->hdev;
        struct device *hub_dev = hub->intfdev;
        u16 hubstatus, hubchange;
        u16 wHubCharacteristics;
        unsigned int pipe;
        int maxp, ret, i;
        char *message = "out of memory";
        unsigned unit_load;
        unsigned full_load;
        unsigned maxchild;

        hub->buffer = kmalloc(sizeof(*hub->buffer), GFP_KERNEL);
        if (!hub->buffer) {
                ret = -ENOMEM;
                goto fail;
        }

        hub->status = kmalloc(sizeof(*hub->status), GFP_KERNEL);
        if (!hub->status) {
                ret = -ENOMEM;
                goto fail;
        }
        mutex_init(&hub->status_mutex);

        hub->descriptor = kmalloc(sizeof(*hub->descriptor), GFP_KERNEL);
        if (!hub->descriptor) {
                ret = -ENOMEM;
                goto fail;
        }

        /* Request the entire hub descriptor.
         * hub->descriptor can handle USB_MAXCHILDREN ports,
         * but the hub can/will return fewer bytes here.
         */
        ret = get_hub_descriptor(hdev, hub->descriptor);
        if (ret < 0) {
                message = "can't read hub descriptor";
                goto fail;
        } else if (hub->descriptor->bNbrPorts > USB_MAXCHILDREN) {
                message = "hub has too many ports!";
                ret = -ENODEV;
                goto fail;
        } else if (hub->descriptor->bNbrPorts == 0) {
                message = "hub doesn't have any ports!";
                ret = -ENODEV;
                goto fail;
        }

        maxchild = hub->descriptor->bNbrPorts;
        dev_info(hub_dev, "%d port%s detected\n", maxchild,
                        (maxchild == 1) ? "" : "s");

        hub->ports = kzalloc(maxchild * sizeof(struct usb_port *), GFP_KERNEL);
        if (!hub->ports) {
                ret = -ENOMEM;
                goto fail;
        }

        wHubCharacteristics = le16_to_cpu(hub->descriptor->wHubCharacteristics);
        if (hub_is_superspeed(hdev)) {
                unit_load = 150;
                full_load = 900;
        } else {
                unit_load = 100;
                full_load = 500;
        }

        /* FIXME for USB 3.0, skip for now */
        if ((wHubCharacteristics & HUB_CHAR_COMPOUND) &&
                        !(hub_is_superspeed(hdev))) {
                int     i;
                char    portstr[USB_MAXCHILDREN + 1];

                for (i = 0; i < maxchild; i++)
                        portstr[i] = hub->descriptor->u.hs.DeviceRemovable
                                    [((i + 1) / 8)] & (1 << ((i + 1) % 8))
                                ? 'F' : 'R';
                portstr[maxchild] = 0;
                dev_dbg(hub_dev, "compound device; port removable status: %s\n", portstr);
        } else
                dev_dbg(hub_dev, "standalone hub\n");

        switch (wHubCharacteristics & HUB_CHAR_LPSM) {
        case HUB_CHAR_COMMON_LPSM:
                dev_dbg(hub_dev, "ganged power switching\n");
                break;
        case HUB_CHAR_INDV_PORT_LPSM:
                dev_dbg(hub_dev, "individual port power switching\n");
                break;
        case HUB_CHAR_NO_LPSM:
        case HUB_CHAR_LPSM:
                dev_dbg(hub_dev, "no power switching (usb 1.0)\n");
                break;
        }

        switch (wHubCharacteristics & HUB_CHAR_OCPM) {
        case HUB_CHAR_COMMON_OCPM:
                dev_dbg(hub_dev, "global over-current protection\n");
                break;
        case HUB_CHAR_INDV_PORT_OCPM:
                dev_dbg(hub_dev, "individual port over-current protection\n");
                break;
        case HUB_CHAR_NO_OCPM:
        case HUB_CHAR_OCPM:
                dev_dbg(hub_dev, "no over-current protection\n");
                break;
        }

        spin_lock_init (&hub->tt.lock);
        INIT_LIST_HEAD (&hub->tt.clear_list);
        INIT_WORK(&hub->tt.clear_work, hub_tt_work);
        switch (hdev->descriptor.bDeviceProtocol) {
        case USB_HUB_PR_FS:
                break;
        case USB_HUB_PR_HS_SINGLE_TT:
                dev_dbg(hub_dev, "Single TT\n");
                hub->tt.hub = hdev;
                break;
        case USB_HUB_PR_HS_MULTI_TT:
                ret = usb_set_interface(hdev, 0, 1);
                if (ret == 0) {
                        dev_dbg(hub_dev, "TT per port\n");
                        hub->tt.multi = 1;
                } else
                        dev_err(hub_dev, "Using single TT (err %d)\n",
                                ret);
                hub->tt.hub = hdev;
                break;
        case USB_HUB_PR_SS:
                /* USB 3.0 hubs don't have a TT */
                break;
        default:
                dev_dbg(hub_dev, "Unrecognized hub protocol %d\n",
                        hdev->descriptor.bDeviceProtocol);
                break;
        }

        /* Note 8 FS bit times == (8 bits / 12000000 bps) ~= 666ns */
        switch (wHubCharacteristics & HUB_CHAR_TTTT) {
        case HUB_TTTT_8_BITS:
                if (hdev->descriptor.bDeviceProtocol != 0) {
                        hub->tt.think_time = 666;
                        dev_dbg(hub_dev, "TT requires at most %d "
                                        "FS bit times (%d ns)\n",
                                8, hub->tt.think_time);
                }
                break;
        case HUB_TTTT_16_BITS:
                hub->tt.think_time = 666 * 2;
                dev_dbg(hub_dev, "TT requires at most %d "
                                "FS bit times (%d ns)\n",
                        16, hub->tt.think_time);
                break;
        case HUB_TTTT_24_BITS:
                hub->tt.think_time = 666 * 3;
                dev_dbg(hub_dev, "TT requires at most %d "
                                "FS bit times (%d ns)\n",
                        24, hub->tt.think_time);
                break;
        case HUB_TTTT_32_BITS:
                hub->tt.think_time = 666 * 4;
                dev_dbg(hub_dev, "TT requires at most %d "
                                "FS bit times (%d ns)\n",
                        32, hub->tt.think_time);
                break;
        }

        /* probe() zeroes hub->indicator[] */
        if (wHubCharacteristics & HUB_CHAR_PORTIND) {
                hub->has_indicators = 1;
                dev_dbg(hub_dev, "Port indicators are supported\n");
        }

        dev_dbg(hub_dev, "power on to power good time: %dms\n",
                hub->descriptor->bPwrOn2PwrGood * 2);

        /* power budgeting mostly matters with bus-powered hubs,
         * and battery-powered root hubs (may provide just 8 mA).
         */
        ret = usb_get_status(hdev, USB_RECIP_DEVICE, 0, &hubstatus);
        if (ret) {
                message = "can't get hub status";
                goto fail;
        }
        hcd = bus_to_hcd(hdev->bus);
        if (hdev == hdev->bus->root_hub) {
                if (hcd->power_budget > 0)
                        hdev->bus_mA = hcd->power_budget;
                else
                        hdev->bus_mA = full_load * maxchild;
                if (hdev->bus_mA >= full_load)
                        hub->mA_per_port = full_load;
                else {
                        hub->mA_per_port = hdev->bus_mA;
                        hub->limited_power = 1;
                }
        } else if ((hubstatus & (1 << USB_DEVICE_SELF_POWERED)) == 0) {
                int remaining = hdev->bus_mA -
                        hub->descriptor->bHubContrCurrent;

                dev_dbg(hub_dev, "hub controller current requirement: %dmA\n",
                        hub->descriptor->bHubContrCurrent);
                hub->limited_power = 1;

                if (remaining < maxchild * unit_load)
                        dev_warn(hub_dev,
                                        "insufficient power available "
                                        "to use all downstream ports\n");
                hub->mA_per_port = unit_load;   /* 7.2.1 */

        } else {        /* Self-powered external hub */
                /* FIXME: What about battery-powered external hubs that
                 * provide less current per port? */
                hub->mA_per_port = full_load;
        }
        if (hub->mA_per_port < full_load)
                dev_dbg(hub_dev, "%umA bus power budget for each child\n",
                                hub->mA_per_port);

        /* Update the HCD's internal representation of this hub before khubd
         * starts getting port status changes for devices under the hub.
         */
        if (hcd->driver->update_hub_device) {
                ret = hcd->driver->update_hub_device(hcd, hdev,
                                &hub->tt, GFP_KERNEL);
                if (ret < 0) {
                        message = "can't update HCD hub info";
                        goto fail;
                }
        }

        ret = hub_hub_status(hub, &hubstatus, &hubchange);
        if (ret < 0) {
                message = "can't get hub status";
                goto fail;
        }

        /* local power status reports aren't always correct */
        if (hdev->actconfig->desc.bmAttributes & USB_CONFIG_ATT_SELFPOWER)
                dev_dbg(hub_dev, "local power source is %s\n",
                        (hubstatus & HUB_STATUS_LOCAL_POWER)
                        ? "lost (inactive)" : "good");

        if ((wHubCharacteristics & HUB_CHAR_OCPM) == 0)
                dev_dbg(hub_dev, "%sover-current condition exists\n",
                        (hubstatus & HUB_STATUS_OVERCURRENT) ? "" : "no ");

        /* set up the interrupt endpoint
         * We use the EP's maxpacket size instead of (PORTS+1+7)/8
         * bytes as USB2.0[11.12.3] says because some hubs are known
         * to send more data (and thus cause overflow). For root hubs,
         * maxpktsize is defined in hcd.c's fake endpoint descriptors
         * to be big enough for at least USB_MAXCHILDREN ports. */
        pipe = usb_rcvintpipe(hdev, endpoint->bEndpointAddress);
        maxp = usb_maxpacket(hdev, pipe, usb_pipeout(pipe));

        if (maxp > sizeof(*hub->buffer))
                maxp = sizeof(*hub->buffer);

        hub->urb = usb_alloc_urb(0, GFP_KERNEL);
        if (!hub->urb) {
                ret = -ENOMEM;
                goto fail;
        }

        usb_fill_int_urb(hub->urb, hdev, pipe, *hub->buffer, maxp, hub_irq,
                hub, endpoint->bInterval);

        /* maybe cycle the hub leds */
        if (hub->has_indicators && blinkenlights)
                hub->indicator[0] = INDICATOR_CYCLE;

        mutex_lock(&usb_port_peer_mutex);
        for (i = 0; i < maxchild; i++) {
                ret = usb_hub_create_port_device(hub, i + 1);
                if (ret < 0) {
                        dev_err(hub->intfdev,
                                "couldn't create port%d device.\n", i + 1);
                        break;
                }
        }
        hdev->maxchild = i;
        mutex_unlock(&usb_port_peer_mutex);
        if (ret < 0)
                goto fail;

        usb_hub_adjust_deviceremovable(hdev, hub->descriptor);

        hub_activate(hub, HUB_INIT);
        return 0;

fail:
        dev_err (hub_dev, "config failed, %s (err %d)\n",
                        message, ret);
        /* hub_disconnect() frees urb and descriptor */
        return ret;
}

static void hub_release(struct kref *kref)
{
        struct usb_hub *hub = container_of(kref, struct usb_hub, kref);

        usb_put_intf(to_usb_interface(hub->intfdev));
        kfree(hub);
}

static unsigned highspeed_hubs;

static void hub_disconnect(struct usb_interface *intf)
{
        struct usb_hub *hub = usb_get_intfdata(intf);
        struct usb_device *hdev = interface_to_usbdev(intf);
        int port1;

        /* Take the hub off the event list and don't let it be added again */
        spin_lock_irq(&hub_event_lock);
        if (!list_empty(&hub->event_list)) {
                list_del_init(&hub->event_list);
                usb_autopm_put_interface_no_suspend(intf);
        }
        hub->disconnected = 1;
        spin_unlock_irq(&hub_event_lock);

        /* Disconnect all children and quiesce the hub */
        hub->error = 0;
        hub_quiesce(hub, HUB_DISCONNECT);

        mutex_lock(&usb_port_peer_mutex);

        /* Avoid races with recursively_mark_NOTATTACHED() */
        spin_lock_irq(&device_state_lock);
        port1 = hdev->maxchild;
        hdev->maxchild = 0;
        usb_set_intfdata(intf, NULL);
        spin_unlock_irq(&device_state_lock);

        for (; port1 > 0; --port1)
                usb_hub_remove_port_device(hub, port1);

        mutex_unlock(&usb_port_peer_mutex);

        if (hub->hdev->speed == USB_SPEED_HIGH)
                highspeed_hubs--;

        usb_free_urb(hub->urb);
        kfree(hub->ports);
        kfree(hub->descriptor);
        kfree(hub->status);
        kfree(hub->buffer);

        pm_suspend_ignore_children(&intf->dev, false);
        kref_put(&hub->kref, hub_release);
}

static int hub_probe(struct usb_interface *intf, const struct usb_device_id *id)
{
        struct usb_host_interface *desc;
        struct usb_endpoint_descriptor *endpoint;
        struct usb_device *hdev;
        struct usb_hub *hub;

        desc = intf->cur_altsetting;
        hdev = interface_to_usbdev(intf);

        /*
         * Set default autosuspend delay as 0 to speedup bus suspend,
         * based on the below considerations:
         *
         * - Unlike other drivers, the hub driver does not rely on the
         *   autosuspend delay to provide enough time to handle a wakeup
         *   event, and the submitted status URB is just to check future
         *   change on hub downstream ports, so it is safe to do it.
         *
         * - The patch might cause one or more auto supend/resume for
         *   below very rare devices when they are plugged into hub
         *   first time:
         *
         *      devices having trouble initializing, and disconnect
         *      themselves from the bus and then reconnect a second
         *      or so later
         *
         *      devices just for downloading firmware, and disconnects
         *      themselves after completing it
         *
         *   For these quite rare devices, their drivers may change the
         *   autosuspend delay of their parent hub in the probe() to one
         *   appropriate value to avoid the subtle problem if someone
         *   does care it.
         *
         * - The patch may cause one or more auto suspend/resume on
         *   hub during running 'lsusb', but it is probably too
         *   infrequent to worry about.
         *
         * - Change autosuspend delay of hub can avoid unnecessary auto
         *   suspend timer for hub, also may decrease power consumption
         *   of USB bus.
         */
        pm_runtime_set_autosuspend_delay(&hdev->dev, 0);

        /*
         * Hubs have proper suspend/resume support, except for root hubs
         * where the controller driver doesn't have bus_suspend and
         * bus_resume methods.
         */
        if (hdev->parent) {             /* normal device */
                usb_enable_autosuspend(hdev);
        } else {                        /* root hub */
                const struct hc_driver *drv = bus_to_hcd(hdev->bus)->driver;

                if (drv->bus_suspend && drv->bus_resume)
                        usb_enable_autosuspend(hdev);
        }

        if (hdev->level == MAX_TOPO_LEVEL) {
                dev_err(&intf->dev,
                        "Unsupported bus topology: hub nested too deep\n");
                return -E2BIG;
        }

#ifdef  CONFIG_USB_OTG_BLACKLIST_HUB
        if (hdev->parent) {
                dev_warn(&intf->dev, "ignoring external hub\n");
                return -ENODEV;
        }
#endif

        /* Some hubs have a subclass of 1, which AFAICT according to the */
        /*  specs is not defined, but it works */
        if ((desc->desc.bInterfaceSubClass != 0) &&
            (desc->desc.bInterfaceSubClass != 1)) {
descriptor_error:
                dev_err (&intf->dev, "bad descriptor, ignoring hub\n");
                return -EIO;
        }

        /* Multiple endpoints? What kind of mutant ninja-hub is this? */
        if (desc->desc.bNumEndpoints != 1)
                goto descriptor_error;

        endpoint = &desc->endpoint[0].desc;

        /* If it's not an interrupt in endpoint, we'd better punt! */
        if (!usb_endpoint_is_int_in(endpoint))
                goto descriptor_error;

        /* We found a hub */
        dev_info (&intf->dev, "USB hub found\n");

        hub = kzalloc(sizeof(*hub), GFP_KERNEL);
        if (!hub) {
                dev_dbg (&intf->dev, "couldn't kmalloc hub struct\n");
                return -ENOMEM;
        }

        kref_init(&hub->kref);
        INIT_LIST_HEAD(&hub->event_list);
        hub->intfdev = &intf->dev;
        hub->hdev = hdev;
        INIT_DELAYED_WORK(&hub->leds, led_work);
        INIT_DELAYED_WORK(&hub->init_work, NULL);
        usb_get_intf(intf);

        usb_set_intfdata (intf, hub);
        intf->needs_remote_wakeup = 1;
        pm_suspend_ignore_children(&intf->dev, true);

        if (hdev->speed == USB_SPEED_HIGH)
                highspeed_hubs++;

        if (id->driver_info & HUB_QUIRK_CHECK_PORT_AUTOSUSPEND)
                hub->quirk_check_port_auto_suspend = 1;

        if (hub_configure(hub, endpoint) >= 0)
                return 0;

        hub_disconnect (intf);
        return -ENODEV;
}

static int
hub_ioctl(struct usb_interface *intf, unsigned int code, void *user_data)
{
        struct usb_device *hdev = interface_to_usbdev (intf);
        struct usb_hub *hub = usb_hub_to_struct_hub(hdev);

        /* assert ifno == 0 (part of hub spec) */
        switch (code) {
        case USBDEVFS_HUB_PORTINFO: {
                struct usbdevfs_hub_portinfo *info = user_data;
                int i;

                spin_lock_irq(&device_state_lock);
                if (hdev->devnum <= 0)
                        info->nports = 0;
                else {
                        info->nports = hdev->maxchild;
                        for (i = 0; i < info->nports; i++) {
                                if (hub->ports[i]->child == NULL)
                                        info->port[i] = 0;
                                else
                                        info->port[i] =
                                                hub->ports[i]->child->devnum;
                        }
                }
                spin_unlock_irq(&device_state_lock);

                return info->nports + 1;
                }

        default:
                return -ENOSYS;
        }
}

/*
 * Allow user programs to claim ports on a hub.  When a device is attached
 * to one of these "claimed" ports, the program will "own" the device.
 */
static int find_port_owner(struct usb_device *hdev, unsigned port1,
                struct usb_dev_state ***ppowner)
{
        struct usb_hub *hub = usb_hub_to_struct_hub(hdev);

        if (hdev->state == USB_STATE_NOTATTACHED)
                return -ENODEV;
        if (port1 == 0 || port1 > hdev->maxchild)
                return -EINVAL;

        /* Devices not managed by the hub driver
         * will always have maxchild equal to 0.
         */
        *ppowner = &(hub->ports[port1 - 1]->port_owner);
        return 0;
}

/* In the following three functions, the caller must hold hdev's lock */
int usb_hub_claim_port(struct usb_device *hdev, unsigned port1,
                       struct usb_dev_state *owner)
{
        int rc;
        struct usb_dev_state **powner;

        rc = find_port_owner(hdev, port1, &powner);
        if (rc)
                return rc;
        if (*powner)
                return -EBUSY;
        *powner = owner;
        return rc;
}
EXPORT_SYMBOL_GPL(usb_hub_claim_port);

int usb_hub_release_port(struct usb_device *hdev, unsigned port1,
                         struct usb_dev_state *owner)
{
        int rc;
        struct usb_dev_state **powner;

        rc = find_port_owner(hdev, port1, &powner);
        if (rc)
                return rc;
        if (*powner != owner)
                return -ENOENT;
        *powner = NULL;
        return rc;
}
EXPORT_SYMBOL_GPL(usb_hub_release_port);

void usb_hub_release_all_ports(struct usb_device *hdev, struct usb_dev_state *owner)
{
        struct usb_hub *hub = usb_hub_to_struct_hub(hdev);
        int n;

        for (n = 0; n < hdev->maxchild; n++) {
                if (hub->ports[n]->port_owner == owner)
                        hub->ports[n]->port_owner = NULL;
        }

}

/* The caller must hold udev's lock */
bool usb_device_is_owned(struct usb_device *udev)
{
        struct usb_hub *hub;

        if (udev->state == USB_STATE_NOTATTACHED || !udev->parent)
                return false;
        hub = usb_hub_to_struct_hub(udev->parent);
        return !!hub->ports[udev->portnum - 1]->port_owner;
}

static void recursively_mark_NOTATTACHED(struct usb_device *udev)
{
        struct usb_hub *hub = usb_hub_to_struct_hub(udev);
        int i;

        for (i = 0; i < udev->maxchild; ++i) {
                if (hub->ports[i]->child)
                        recursively_mark_NOTATTACHED(hub->ports[i]->child);
        }
        if (udev->state == USB_STATE_SUSPENDED)
                udev->active_duration -= jiffies;
        udev->state = USB_STATE_NOTATTACHED;
}

/**
 * usb_set_device_state - change a device's current state (usbcore, hcds)
 * @udev: pointer to device whose state should be changed
 * @new_state: new state value to be stored
 *
 * udev->state is _not_ fully protected by the device lock.  Although
 * most transitions are made only while holding the lock, the state can
 * can change to USB_STATE_NOTATTACHED at almost any time.  This
 * is so that devices can be marked as disconnected as soon as possible,
 * without having to wait for any semaphores to be released.  As a result,
 * all changes to any device's state must be protected by the
 * device_state_lock spinlock.
 *
 * Once a device has been added to the device tree, all changes to its state
 * should be made using this routine.  The state should _not_ be set directly.
 *
 * If udev->state is already USB_STATE_NOTATTACHED then no change is made.
 * Otherwise udev->state is set to new_state, and if new_state is
 * USB_STATE_NOTATTACHED then all of udev's descendants' states are also set
 * to USB_STATE_NOTATTACHED.
 */
void usb_set_device_state(struct usb_device *udev,
                enum usb_device_state new_state)
{
        unsigned long flags;
        int wakeup = -1;

        spin_lock_irqsave(&device_state_lock, flags);
        if (udev->state == USB_STATE_NOTATTACHED)
                ;       /* do nothing */
        else if (new_state != USB_STATE_NOTATTACHED) {

                /* root hub wakeup capabilities are managed out-of-band
                 * and may involve silicon errata ... ignore them here.
                 */
                if (udev->parent) {
                        if (udev->state == USB_STATE_SUSPENDED
                                        || new_state == USB_STATE_SUSPENDED)
                                ;       /* No change to wakeup settings */
                        else if (new_state == USB_STATE_CONFIGURED)
                                wakeup = udev->actconfig->desc.bmAttributes
                                         & USB_CONFIG_ATT_WAKEUP;
                        else
                                wakeup = 0;
                }
                if (udev->state == USB_STATE_SUSPENDED &&
                        new_state != USB_STATE_SUSPENDED)
                        udev->active_duration -= jiffies;
                else if (new_state == USB_STATE_SUSPENDED &&
                                udev->state != USB_STATE_SUSPENDED)
                        udev->active_duration += jiffies;
                udev->state = new_state;
        } else
                recursively_mark_NOTATTACHED(udev);
        spin_unlock_irqrestore(&device_state_lock, flags);
        if (wakeup >= 0)
                device_set_wakeup_capable(&udev->dev, wakeup);
}
EXPORT_SYMBOL_GPL(usb_set_device_state);

/*
 * Choose a device number.
 *
 * Device numbers are used as filenames in usbfs.  On USB-1.1 and
 * USB-2.0 buses they are also used as device addresses, however on
 * USB-3.0 buses the address is assigned by the controller hardware
 * and it usually is not the same as the device number.
 *
 * WUSB devices are simple: they have no hubs behind, so the mapping
 * device <-> virtual port number becomes 1:1. Why? to simplify the
 * life of the device connection logic in
 * drivers/usb/wusbcore/devconnect.c. When we do the initial secret
 * handshake we need to assign a temporary address in the unauthorized
 * space. For simplicity we use the first virtual port number found to
 * be free [drivers/usb/wusbcore/devconnect.c:wusbhc_devconnect_ack()]
 * and that becomes it's address [X < 128] or its unauthorized address
 * [X | 0x80].
 *
 * We add 1 as an offset to the one-based USB-stack port number
 * (zero-based wusb virtual port index) for two reasons: (a) dev addr
 * 0 is reserved by USB for default address; (b) Linux's USB stack
 * uses always #1 for the root hub of the controller. So USB stack's
 * port #1, which is wusb virtual-port #0 has address #2.
 *
 * Devices connected under xHCI are not as simple.  The host controller
 * supports virtualization, so the hardware assigns device addresses and
 * the HCD must setup data structures before issuing a set address
 * command to the hardware.
 */
static void choose_devnum(struct usb_device *udev)
{
        int             devnum;
        struct usb_bus  *bus = udev->bus;

        /* If khubd ever becomes multithreaded, this will need a lock */
        if (udev->wusb) {
                devnum = udev->portnum + 1;
                BUG_ON(test_bit(devnum, bus->devmap.devicemap));
        } else {
                /* Try to allocate the next devnum beginning at
                 * bus->devnum_next. */
                devnum = find_next_zero_bit(bus->devmap.devicemap, 128,
                                            bus->devnum_next);
                if (devnum >= 128)
                        devnum = find_next_zero_bit(bus->devmap.devicemap,
                                                    128, 1);
                bus->devnum_next = (devnum >= 127 ? 1 : devnum + 1);
        }
        if (devnum < 128) {
                set_bit(devnum, bus->devmap.devicemap);
                udev->devnum = devnum;
        }
}

static void release_devnum(struct usb_device *udev)
{
        if (udev->devnum > 0) {
                clear_bit(udev->devnum, udev->bus->devmap.devicemap);
                udev->devnum = -1;
        }
}

static void update_devnum(struct usb_device *udev, int devnum)
{
        /* The address for a WUSB device is managed by wusbcore. */
        if (!udev->wusb)
                udev->devnum = devnum;
}

static void hub_free_dev(struct usb_device *udev)
{
        struct usb_hcd *hcd = bus_to_hcd(udev->bus);

        /* Root hubs aren't real devices, so don't free HCD resources */
        if (hcd->driver->free_dev && udev->parent)
                hcd->driver->free_dev(hcd, udev);
}

static void hub_disconnect_children(struct usb_device *udev)
{
        struct usb_hub *hub = usb_hub_to_struct_hub(udev);
        int i;

        /* Free up all the children before we remove this device */
        for (i = 0; i < udev->maxchild; i++) {
                if (hub->ports[i]->child)
                        usb_disconnect(&hub->ports[i]->child);
        }
}

/**
 * usb_disconnect - disconnect a device (usbcore-internal)
 * @pdev: pointer to device being disconnected
 * Context: !in_interrupt ()
 *
 * Something got disconnected. Get rid of it and all of its children.
 *
 * If *pdev is a normal device then the parent hub must already be locked.
 * If *pdev is a root hub then the caller must hold the usb_bus_list_lock,
 * which protects the set of root hubs as well as the list of buses.
 *
 * Only hub drivers (including virtual root hub drivers for host
 * controllers) should ever call this.
 *
 * This call is synchronous, and may not be used in an interrupt context.
 */
void usb_disconnect(struct usb_device **pdev)
{
        struct usb_port *port_dev = NULL;
        struct usb_device *udev = *pdev;
        struct usb_hub *hub;
        int port1;

        /* mark the device as inactive, so any further urb submissions for
         * this device (and any of its children) will fail immediately.
         * this quiesces everything except pending urbs.
         */
        usb_set_device_state(udev, USB_STATE_NOTATTACHED);
        dev_info(&udev->dev, "USB disconnect, device number %d\n",
                        udev->devnum);

        usb_lock_device(udev);

        hub_disconnect_children(udev);

        /* deallocate hcd/hardware state ... nuking all pending urbs and
         * cleaning up all state associated with the current configuration
         * so that the hardware is now fully quiesced.
         */
        dev_dbg (&udev->dev, "unregistering device\n");
        usb_disable_device(udev, 0);
        usb_hcd_synchronize_unlinks(udev);

        if (udev->parent) {
                port1 = udev->portnum;
                hub = usb_hub_to_struct_hub(udev->parent);
                port_dev = hub->ports[port1 - 1];

                sysfs_remove_link(&udev->dev.kobj, "port");
                sysfs_remove_link(&port_dev->dev.kobj, "device");

                /*
                 * As usb_port_runtime_resume() de-references udev, make
                 * sure no resumes occur during removal
                 */
                if (!test_and_set_bit(port1, hub->child_usage_bits))
                        pm_runtime_get_sync(&port_dev->dev);
        }

        usb_remove_ep_devs(&udev->ep0);
        usb_unlock_device(udev);

        /* Unregister the device.  The device driver is responsible
         * for de-configuring the device and invoking the remove-device
         * notifier chain (used by usbfs and possibly others).
         */
        device_del(&udev->dev);

        /* Free the device number and delete the parent's children[]
         * (or root_hub) pointer.
         */
        release_devnum(udev);

        /* Avoid races with recursively_mark_NOTATTACHED() */
        spin_lock_irq(&device_state_lock);
        *pdev = NULL;
        spin_unlock_irq(&device_state_lock);

        if (port_dev && test_and_clear_bit(port1, hub->child_usage_bits))
                pm_runtime_put(&port_dev->dev);

        hub_free_dev(udev);

        put_device(&udev->dev);
}

#ifdef CONFIG_USB_ANNOUNCE_NEW_DEVICES
static void show_string(struct usb_device *udev, char *id, char *string)
{
        if (!string)
                return;
        dev_info(&udev->dev, "%s: %s\n", id, string);
}

static void announce_device(struct usb_device *udev)
{
        dev_info(&udev->dev, "New USB device found, idVendor=%04x, idProduct=%04x\n",
                le16_to_cpu(udev->descriptor.idVendor),
                le16_to_cpu(udev->descriptor.idProduct));
        dev_info(&udev->dev,
                "New USB device strings: Mfr=%d, Product=%d, SerialNumber=%d\n",
                udev->descriptor.iManufacturer,
                udev->descriptor.iProduct,
                udev->descriptor.iSerialNumber);
        show_string(udev, "Product", udev->product);
        show_string(udev, "Manufacturer", udev->manufacturer);
        show_string(udev, "SerialNumber", udev->serial);
}
#else
static inline void announce_device(struct usb_device *udev) { }
#endif

#ifdef  CONFIG_USB_OTG
#include "otg_whitelist.h"
#endif

/**
 * usb_enumerate_device_otg - FIXME (usbcore-internal)
 * @udev: newly addressed device (in ADDRESS state)
 *
 * Finish enumeration for On-The-Go devices
 *
 * Return: 0 if successful. A negative error code otherwise.
 */
static int usb_enumerate_device_otg(struct usb_device *udev)
{
        int err = 0;

#ifdef  CONFIG_USB_OTG
        /*
         * OTG-aware devices on OTG-capable root hubs may be able to use SRP,
         * to wake us after we've powered off VBUS; and HNP, switching roles
         * "host" to "peripheral".  The OTG descriptor helps figure this out.
         */
        if (!udev->bus->is_b_host
                        && udev->config
                        && udev->parent == udev->bus->root_hub) {
                struct usb_otg_descriptor       *desc = NULL;
                struct usb_bus                  *bus = udev->bus;

                /* descriptor may appear anywhere in config */
                if (__usb_get_extra_descriptor (udev->rawdescriptors[0],
                                        le16_to_cpu(udev->config[0].desc.wTotalLength),
                                        USB_DT_OTG, (void **) &desc) == 0) {
                        if (desc->bmAttributes & USB_OTG_HNP) {
                                unsigned                port1 = udev->portnum;

                                dev_info(&udev->dev,
                                        "Dual-Role OTG device on %sHNP port\n",
                                        (port1 == bus->otg_port)
                                                ? "" : "non-");

                                /* enable HNP before suspend, it's simpler */
                                if (port1 == bus->otg_port)
                                        bus->b_hnp_enable = 1;
                                err = usb_control_msg(udev,
                                        usb_sndctrlpipe(udev, 0),
                                        USB_REQ_SET_FEATURE, 0,
                                        bus->b_hnp_enable
                                                ? USB_DEVICE_B_HNP_ENABLE
                                                : USB_DEVICE_A_ALT_HNP_SUPPORT,
                                        0, NULL, 0, USB_CTRL_SET_TIMEOUT);
                                if (err < 0) {
                                        /* OTG MESSAGE: report errors here,
                                         * customize to match your product.
                                         */
                                        dev_info(&udev->dev,
                                                "can't set HNP mode: %d\n",
                                                err);
                                        bus->b_hnp_enable = 0;
                                }
                        }
                }
        }

        if (!is_targeted(udev)) {

                /* Maybe it can talk to us, though we can't talk to it.
                 * (Includes HNP test device.)
                 */
                if (udev->bus->b_hnp_enable || udev->bus->is_b_host) {
                        err = usb_port_suspend(udev, PMSG_SUSPEND);
                        if (err < 0)
                                dev_dbg(&udev->dev, "HNP fail, %d\n", err);
                }
                err = -ENOTSUPP;
                goto fail;
        }
fail:
#endif
        return err;
}


/**
 * usb_enumerate_device - Read device configs/intfs/otg (usbcore-internal)
 * @udev: newly addressed device (in ADDRESS state)
 *
 * This is only called by usb_new_device() and usb_authorize_device()
 * and FIXME -- all comments that apply to them apply here wrt to
 * environment.
 *
 * If the device is WUSB and not authorized, we don't attempt to read
 * the string descriptors, as they will be errored out by the device
 * until it has been authorized.
 *
 * Return: 0 if successful. A negative error code otherwise.
 */
static int usb_enumerate_device(struct usb_device *udev)
{
        int err;

        if (udev->config == NULL) {
                err = usb_get_configuration(udev);
                if (err < 0) {
                        if (err != -ENODEV)
                                dev_err(&udev->dev, "can't read configurations, error %d\n",
                                                err);
                        return err;
                }
        }

        /* read the standard strings and cache them if present */
        udev->product = usb_cache_string(udev, udev->descriptor.iProduct);
        udev->manufacturer = usb_cache_string(udev,
                                              udev->descriptor.iManufacturer);
        udev->serial = usb_cache_string(udev, udev->descriptor.iSerialNumber);

        err = usb_enumerate_device_otg(udev);
        if (err < 0)
                return err;

        usb_detect_interface_quirks(udev);

        return 0;
}

static void set_usb_port_removable(struct usb_device *udev)
{
        struct usb_device *hdev = udev->parent;
        struct usb_hub *hub;
        u8 port = udev->portnum;
        u16 wHubCharacteristics;
        bool removable = true;

        if (!hdev)
                return;

        hub = usb_hub_to_struct_hub(udev->parent);

        wHubCharacteristics = le16_to_cpu(hub->descriptor->wHubCharacteristics);

        if (!(wHubCharacteristics & HUB_CHAR_COMPOUND))
                return;

        if (hub_is_superspeed(hdev)) {
                if (le16_to_cpu(hub->descriptor->u.ss.DeviceRemovable)
                                & (1 << port))
                        removable = false;
        } else {
                if (hub->descriptor->u.hs.DeviceRemovable[port / 8] & (1 << (port % 8)))
                        removable = false;
        }

        if (removable)
                udev->removable = USB_DEVICE_REMOVABLE;
        else
                udev->removable = USB_DEVICE_FIXED;

        /*
         * Platform firmware may have populated an alternative value for
         * removable.  If the parent port has a known connect_type use
         * that instead.
         */
        switch (hub->ports[udev->portnum - 1]->connect_type) {
        case USB_PORT_CONNECT_TYPE_HOT_PLUG:
                udev->removable = USB_DEVICE_REMOVABLE;
                break;
        case USB_PORT_CONNECT_TYPE_HARD_WIRED:
                udev->removable = USB_DEVICE_FIXED;
                break;
        default: /* use what was set above */
                break;
        }
}

/**
 * usb_new_device - perform initial device setup (usbcore-internal)
 * @udev: newly addressed device (in ADDRESS state)
 *
 * This is called with devices which have been detected but not fully
 * enumerated.  The device descriptor is available, but not descriptors
 * for any device configuration.  The caller must have locked either
 * the parent hub (if udev is a normal device) or else the
 * usb_bus_list_lock (if udev is a root hub).  The parent's pointer to
 * udev has already been installed, but udev is not yet visible through
 * sysfs or other filesystem code.
 *
 * This call is synchronous, and may not be used in an interrupt context.
 *
 * Only the hub driver or root-hub registrar should ever call this.
 *
 * Return: Whether the device is configured properly or not. Zero if the
 * interface was registered with the driver core; else a negative errno
 * value.
 *
 */
int usb_new_device(struct usb_device *udev)
{
        int err;

        if (udev->parent) {
                /* Initialize non-root-hub device wakeup to disabled;
                 * device (un)configuration controls wakeup capable
                 * sysfs power/wakeup controls wakeup enabled/disabled
                 */
                device_init_wakeup(&udev->dev, 0);
        }

        /* Tell the runtime-PM framework the device is active */
        pm_runtime_set_active(&udev->dev);
        pm_runtime_get_noresume(&udev->dev);
        pm_runtime_use_autosuspend(&udev->dev);
        pm_runtime_enable(&udev->dev);

        /* By default, forbid autosuspend for all devices.  It will be
         * allowed for hubs during binding.
         */
        usb_disable_autosuspend(udev);

        err = usb_enumerate_device(udev);       /* Read descriptors */
        if (err < 0)
                goto fail;
        dev_dbg(&udev->dev, "udev %d, busnum %d, minor = %d\n",
                        udev->devnum, udev->bus->busnum,
                        (((udev->bus->busnum-1) * 128) + (udev->devnum-1)));
        /* export the usbdev device-node for libusb */
        udev->dev.devt = MKDEV(USB_DEVICE_MAJOR,
                        (((udev->bus->busnum-1) * 128) + (udev->devnum-1)));

        /* Tell the world! */
        announce_device(udev);

        if (udev->serial)
                add_device_randomness(udev->serial, strlen(udev->serial));
        if (udev->product)
                add_device_randomness(udev->product, strlen(udev->product));
        if (udev->manufacturer)
                add_device_randomness(udev->manufacturer,
                                      strlen(udev->manufacturer));

        device_enable_async_suspend(&udev->dev);

        /* check whether the hub or firmware marks this port as non-removable */
        if (udev->parent)
                set_usb_port_removable(udev);

        /* Register the device.  The device driver is responsible
         * for configuring the device and invoking the add-device
         * notifier chain (used by usbfs and possibly others).
         */
        err = device_add(&udev->dev);
        if (err) {
                dev_err(&udev->dev, "can't device_add, error %d\n", err);
                goto fail;
        }

        /* Create link files between child device and usb port device. */
        if (udev->parent) {
                struct usb_hub *hub = usb_hub_to_struct_hub(udev->parent);
                int port1 = udev->portnum;
                struct usb_port *port_dev = hub->ports[port1 - 1];

                err = sysfs_create_link(&udev->dev.kobj,
                                &port_dev->dev.kobj, "port");
                if (err)
                        goto fail;

                err = sysfs_create_link(&port_dev->dev.kobj,
                                &udev->dev.kobj, "device");
                if (err) {
                        sysfs_remove_link(&udev->dev.kobj, "port");
                        goto fail;
                }

                if (!test_and_set_bit(port1, hub->child_usage_bits))
                        pm_runtime_get_sync(&port_dev->dev);
        }

        (void) usb_create_ep_devs(&udev->dev, &udev->ep0, udev);
        usb_mark_last_busy(udev);
        pm_runtime_put_sync_autosuspend(&udev->dev);
        return err;

fail:
        usb_set_device_state(udev, USB_STATE_NOTATTACHED);
        pm_runtime_disable(&udev->dev);
        pm_runtime_set_suspended(&udev->dev);
        return err;
}


/**
 * usb_deauthorize_device - deauthorize a device (usbcore-internal)
 * @usb_dev: USB device
 *
 * Move the USB device to a very basic state where interfaces are disabled
 * and the device is in fact unconfigured and unusable.
 *
 * We share a lock (that we have) with device_del(), so we need to
 * defer its call.
 *
 * Return: 0.
 */
int usb_deauthorize_device(struct usb_device *usb_dev)
{
        usb_lock_device(usb_dev);
        if (usb_dev->authorized == 0)
                goto out_unauthorized;

        usb_dev->authorized = 0;
        usb_set_configuration(usb_dev, -1);

out_unauthorized:
        usb_unlock_device(usb_dev);
        return 0;
}


int usb_authorize_device(struct usb_device *usb_dev)
{
        int result = 0, c;

        usb_lock_device(usb_dev);
        if (usb_dev->authorized == 1)
                goto out_authorized;

        result = usb_autoresume_device(usb_dev);
        if (result < 0) {
                dev_err(&usb_dev->dev,
                        "can't autoresume for authorization: %d\n", result);
                goto error_autoresume;
        }
        result = usb_get_device_descriptor(usb_dev, sizeof(usb_dev->descriptor));
        if (result < 0) {
                dev_err(&usb_dev->dev, "can't re-read device descriptor for "
                        "authorization: %d\n", result);
                goto error_device_descriptor;
        }

        usb_dev->authorized = 1;
        /* Choose and set the configuration.  This registers the interfaces
         * with the driver core and lets interface drivers bind to them.
         */
        c = usb_choose_configuration(usb_dev);
        if (c >= 0) {
                result = usb_set_configuration(usb_dev, c);
                if (result) {
                        dev_err(&usb_dev->dev,
                                "can't set config #%d, error %d\n", c, result);
                        /* This need not be fatal.  The user can try to
                         * set other configurations. */
                }
        }
        dev_info(&usb_dev->dev, "authorized to connect\n");

error_device_descriptor:
        usb_autosuspend_device(usb_dev);
error_autoresume:
out_authorized:
        usb_unlock_device(usb_dev);     /* complements locktree */
        return result;
}


/* Returns 1 if @hub is a WUSB root hub, 0 otherwise */
static unsigned hub_is_wusb(struct usb_hub *hub)
{
        struct usb_hcd *hcd;
        if (hub->hdev->parent != NULL)  /* not a root hub? */
                return 0;
        hcd = container_of(hub->hdev->bus, struct usb_hcd, self);
        return hcd->wireless;
}


#define PORT_RESET_TRIES        5
#define SET_ADDRESS_TRIES       2
#define GET_DESCRIPTOR_TRIES    2
#define SET_CONFIG_TRIES        (2 * (use_both_schemes + 1))
#define USE_NEW_SCHEME(i)       ((i) / 2 == (int)old_scheme_first)

#define HUB_ROOT_RESET_TIME     50      /* times are in msec */
#define HUB_SHORT_RESET_TIME    10
#define HUB_BH_RESET_TIME       50
#define HUB_LONG_RESET_TIME     200
#define HUB_RESET_TIMEOUT       800

/*
 * "New scheme" enumeration causes an extra state transition to be
 * exposed to an xhci host and causes USB3 devices to receive control
 * commands in the default state.  This has been seen to cause
 * enumeration failures, so disable this enumeration scheme for USB3
 * devices.
 */
static bool use_new_scheme(struct usb_device *udev, int retry)
{
        if (udev->speed == USB_SPEED_SUPER)
                return false;

        return USE_NEW_SCHEME(retry);
}

static int hub_port_reset(struct usb_hub *hub, int port1,
                        struct usb_device *udev, unsigned int delay, bool warm);

/* Is a USB 3.0 port in the Inactive or Compliance Mode state?
 * Port worm reset is required to recover
 */
static bool hub_port_warm_reset_required(struct usb_hub *hub, u16 portstatus)
{
        return hub_is_superspeed(hub->hdev) &&
                (((portstatus & USB_PORT_STAT_LINK_STATE) ==
                  USB_SS_PORT_LS_SS_INACTIVE) ||
                 ((portstatus & USB_PORT_STAT_LINK_STATE) ==
                  USB_SS_PORT_LS_COMP_MOD)) ;
}

static int hub_port_wait_reset(struct usb_hub *hub, int port1,
                        struct usb_device *udev, unsigned int delay, bool warm)
{
        int delay_time, ret;
        u16 portstatus;
        u16 portchange;

        for (delay_time = 0;
                        delay_time < HUB_RESET_TIMEOUT;
                        delay_time += delay) {
                /* wait to give the device a chance to reset */
                msleep(delay);

                /* read and decode port status */
                ret = hub_port_status(hub, port1, &portstatus, &portchange);
                if (ret < 0)
                        return ret;

                /* The port state is unknown until the reset completes. */
                if (!(portstatus & USB_PORT_STAT_RESET))
                        break;

                /* switch to the long delay after two short delay failures */
                if (delay_time >= 2 * HUB_SHORT_RESET_TIME)
                        delay = HUB_LONG_RESET_TIME;

                dev_dbg(&hub->ports[port1 - 1]->dev,
                                "not %sreset yet, waiting %dms\n",
                                warm ? "warm " : "", delay);
        }

        if ((portstatus & USB_PORT_STAT_RESET))
                return -EBUSY;

        if (hub_port_warm_reset_required(hub, portstatus))
                return -ENOTCONN;

        /* Device went away? */
        if (!(portstatus & USB_PORT_STAT_CONNECTION))
                return -ENOTCONN;

        /* bomb out completely if the connection bounced.  A USB 3.0
         * connection may bounce if multiple warm resets were issued,
         * but the device may have successfully re-connected. Ignore it.
         */
        if (!hub_is_superspeed(hub->hdev) &&
                        (portchange & USB_PORT_STAT_C_CONNECTION))
                return -ENOTCONN;

        if (!(portstatus & USB_PORT_STAT_ENABLE))
                return -EBUSY;

        if (!udev)
                return 0;

        if (hub_is_wusb(hub))
                udev->speed = USB_SPEED_WIRELESS;
        else if (hub_is_superspeed(hub->hdev))
                udev->speed = USB_SPEED_SUPER;
        else if (portstatus & USB_PORT_STAT_HIGH_SPEED)
                udev->speed = USB_SPEED_HIGH;
        else if (portstatus & USB_PORT_STAT_LOW_SPEED)
                udev->speed = USB_SPEED_LOW;
        else
                udev->speed = USB_SPEED_FULL;
        return 0;
}

static void hub_port_finish_reset(struct usb_hub *hub, int port1,
                        struct usb_device *udev, int *status)
{
        switch (*status) {
        case 0:
                /* TRSTRCY = 10 ms; plus some extra */
                msleep(10 + 40);
                if (udev) {
                        struct usb_hcd *hcd = bus_to_hcd(udev->bus);

                        update_devnum(udev, 0);
                        /* The xHC may think the device is already reset,
                         * so ignore the status.
                         */
                        if (hcd->driver->reset_device)
                                hcd->driver->reset_device(hcd, udev);
                }
                /* FALL THROUGH */
        case -ENOTCONN:
        case -ENODEV:
                usb_clear_port_feature(hub->hdev,
                                port1, USB_PORT_FEAT_C_RESET);
                if (hub_is_superspeed(hub->hdev)) {
                        usb_clear_port_feature(hub->hdev, port1,
                                        USB_PORT_FEAT_C_BH_PORT_RESET);
                        usb_clear_port_feature(hub->hdev, port1,
                                        USB_PORT_FEAT_C_PORT_LINK_STATE);
                        usb_clear_port_feature(hub->hdev, port1,
                                        USB_PORT_FEAT_C_CONNECTION);
                }
                if (udev)
                        usb_set_device_state(udev, *status
                                        ? USB_STATE_NOTATTACHED
                                        : USB_STATE_DEFAULT);
                break;
        }
}

/* Handle port reset and port warm(BH) reset (for USB3 protocol ports) */
static int hub_port_reset(struct usb_hub *hub, int port1,
                        struct usb_device *udev, unsigned int delay, bool warm)
{
        int i, status;
        u16 portchange, portstatus;
        struct usb_port *port_dev = hub->ports[port1 - 1];

        if (!hub_is_superspeed(hub->hdev)) {
                if (warm) {
                        dev_err(hub->intfdev, "only USB3 hub support "
                                                "warm reset\n");
                        return -EINVAL;
                }
                /* Block EHCI CF initialization during the port reset.
                 * Some companion controllers don't like it when they mix.
                 */
                down_read(&ehci_cf_port_reset_rwsem);
        } else if (!warm) {
                /*
                 * If the caller hasn't explicitly requested a warm reset,
                 * double check and see if one is needed.
                 */
                status = hub_port_status(hub, port1,
                                        &portstatus, &portchange);
                if (status < 0)
                        goto done;

                if (hub_port_warm_reset_required(hub, portstatus))
                        warm = true;
        }

        /* Reset the port */
        for (i = 0; i < PORT_RESET_TRIES; i++) {
                status = set_port_feature(hub->hdev, port1, (warm ?
                                        USB_PORT_FEAT_BH_PORT_RESET :
                                        USB_PORT_FEAT_RESET));
                if (status == -ENODEV) {
                        ;       /* The hub is gone */
                } else if (status) {
                        dev_err(&port_dev->dev,
                                        "cannot %sreset (err = %d)\n",
                                        warm ? "warm " : "", status);
                } else {
                        status = hub_port_wait_reset(hub, port1, udev, delay,
                                                                warm);
                        if (status && status != -ENOTCONN && status != -ENODEV)
                                dev_dbg(hub->intfdev,
                                                "port_wait_reset: err = %d\n",
                                                status);
                }

                /* Check for disconnect or reset */
                if (status == 0 || status == -ENOTCONN || status == -ENODEV) {
                        hub_port_finish_reset(hub, port1, udev, &status);

                        if (!hub_is_superspeed(hub->hdev))
                                goto done;

                        /*
                         * If a USB 3.0 device migrates from reset to an error
                         * state, re-issue the warm reset.
                         */
                        if (hub_port_status(hub, port1,
                                        &portstatus, &portchange) < 0)
                                goto done;

                        if (!hub_port_warm_reset_required(hub, portstatus))
                                goto done;

                        /*
                         * If the port is in SS.Inactive or Compliance Mode, the
                         * hot or warm reset failed.  Try another warm reset.
                         */
                        if (!warm) {
                                dev_dbg(&port_dev->dev,
                                                "hot reset failed, warm reset\n");
                                warm = true;
                        }
                }

                dev_dbg(&port_dev->dev,
                                "not enabled, trying %sreset again...\n",
                                warm ? "warm " : "");
                delay = HUB_LONG_RESET_TIME;
        }

        dev_err(&port_dev->dev, "Cannot enable. Maybe the USB cable is bad?\n");

done:
        if (!hub_is_superspeed(hub->hdev))
                up_read(&ehci_cf_port_reset_rwsem);

        return status;
}

/* Check if a port is power on */
static int port_is_power_on(struct usb_hub *hub, unsigned portstatus)
{
        int ret = 0;

        if (hub_is_superspeed(hub->hdev)) {
                if (portstatus & USB_SS_PORT_STAT_POWER)
                        ret = 1;
        } else {
                if (portstatus & USB_PORT_STAT_POWER)
                        ret = 1;
        }

        return ret;
}

static void usb_lock_port(struct usb_port *port_dev)
                __acquires(&port_dev->status_lock)
{
        mutex_lock(&port_dev->status_lock);
        __acquire(&port_dev->status_lock);
}

static void usb_unlock_port(struct usb_port *port_dev)
                __releases(&port_dev->status_lock)
{
        mutex_unlock(&port_dev->status_lock);
        __release(&port_dev->status_lock);
}

#ifdef  CONFIG_PM

/* Check if a port is suspended(USB2.0 port) or in U3 state(USB3.0 port) */
static int port_is_suspended(struct usb_hub *hub, unsigned portstatus)
{
        int ret = 0;

        if (hub_is_superspeed(hub->hdev)) {
                if ((portstatus & USB_PORT_STAT_LINK_STATE)
                                == USB_SS_PORT_LS_U3)
                        ret = 1;
        } else {
                if (portstatus & USB_PORT_STAT_SUSPEND)
                        ret = 1;
        }

        return ret;
}

/* Determine whether the device on a port is ready for a normal resume,
 * is ready for a reset-resume, or should be disconnected.
 */
static int check_port_resume_type(struct usb_device *udev,
                struct usb_hub *hub, int port1,
                int status, unsigned portchange, unsigned portstatus)
{
        struct usb_port *port_dev = hub->ports[port1 - 1];

        /* Is the device still present? */
        if (status || port_is_suspended(hub, portstatus) ||
                        !port_is_power_on(hub, portstatus) ||
                        !(portstatus & USB_PORT_STAT_CONNECTION)) {
                if (status >= 0)
                        status = -ENODEV;
        }

        /* Can't do a normal resume if the port isn't enabled,
         * so try a reset-resume instead.
         */
        else if (!(portstatus & USB_PORT_STAT_ENABLE) && !udev->reset_resume) {
                if (udev->persist_enabled)
                        udev->reset_resume = 1;
                else
                        status = -ENODEV;
        }

        if (status) {
                dev_dbg(&port_dev->dev, "status %04x.%04x after resume, %d\n",
                                portchange, portstatus, status);
        } else if (udev->reset_resume) {

                /* Late port handoff can set status-change bits */
                if (portchange & USB_PORT_STAT_C_CONNECTION)
                        usb_clear_port_feature(hub->hdev, port1,
                                        USB_PORT_FEAT_C_CONNECTION);
                if (portchange & USB_PORT_STAT_C_ENABLE)
                        usb_clear_port_feature(hub->hdev, port1,
                                        USB_PORT_FEAT_C_ENABLE);
        }

        return status;
}

int usb_disable_ltm(struct usb_device *udev)
{
        struct usb_hcd *hcd = bus_to_hcd(udev->bus);

        /* Check if the roothub and device supports LTM. */
        if (!usb_device_supports_ltm(hcd->self.root_hub) ||
                        !usb_device_supports_ltm(udev))
                return 0;

        /* Clear Feature LTM Enable can only be sent if the device is
         * configured.
         */
        if (!udev->actconfig)
                return 0;

        return usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
                        USB_REQ_CLEAR_FEATURE, USB_RECIP_DEVICE,
                        USB_DEVICE_LTM_ENABLE, 0, NULL, 0,
                        USB_CTRL_SET_TIMEOUT);
}
EXPORT_SYMBOL_GPL(usb_disable_ltm);

void usb_enable_ltm(struct usb_device *udev)
{
        struct usb_hcd *hcd = bus_to_hcd(udev->bus);

        /* Check if the roothub and device supports LTM. */
        if (!usb_device_supports_ltm(hcd->self.root_hub) ||
                        !usb_device_supports_ltm(udev))
                return;

        /* Set Feature LTM Enable can only be sent if the device is
         * configured.
         */
        if (!udev->actconfig)
                return;

        usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
                        USB_REQ_SET_FEATURE, USB_RECIP_DEVICE,
                        USB_DEVICE_LTM_ENABLE, 0, NULL, 0,
                        USB_CTRL_SET_TIMEOUT);
}
EXPORT_SYMBOL_GPL(usb_enable_ltm);

/*
 * usb_enable_remote_wakeup - enable remote wakeup for a device
 * @udev: target device
 *
 * For USB-2 devices: Set the device's remote wakeup feature.
 *
 * For USB-3 devices: Assume there's only one function on the device and
 * enable remote wake for the first interface.  FIXME if the interface
 * association descriptor shows there's more than one function.
 */
static int usb_enable_remote_wakeup(struct usb_device *udev)
{
        if (udev->speed < USB_SPEED_SUPER)
                return usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
                                USB_REQ_SET_FEATURE, USB_RECIP_DEVICE,
                                USB_DEVICE_REMOTE_WAKEUP, 0, NULL, 0,
                                USB_CTRL_SET_TIMEOUT);
        else
                return usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
                                USB_REQ_SET_FEATURE, USB_RECIP_INTERFACE,
                                USB_INTRF_FUNC_SUSPEND,
                                USB_INTRF_FUNC_SUSPEND_RW |
                                        USB_INTRF_FUNC_SUSPEND_LP,
                                NULL, 0, USB_CTRL_SET_TIMEOUT);
}

/*
 * usb_disable_remote_wakeup - disable remote wakeup for a device
 * @udev: target device
 *
 * For USB-2 devices: Clear the device's remote wakeup feature.
 *
 * For USB-3 devices: Assume there's only one function on the device and
 * disable remote wake for the first interface.  FIXME if the interface
 * association descriptor shows there's more than one function.
 */
static int usb_disable_remote_wakeup(struct usb_device *udev)
{
        if (udev->speed < USB_SPEED_SUPER)
                return usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
                                USB_REQ_CLEAR_FEATURE, USB_RECIP_DEVICE,
                                USB_DEVICE_REMOTE_WAKEUP, 0, NULL, 0,
                                USB_CTRL_SET_TIMEOUT);
        else
                return usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
                                USB_REQ_CLEAR_FEATURE, USB_RECIP_INTERFACE,
                                USB_INTRF_FUNC_SUSPEND, 0, NULL, 0,
                                USB_CTRL_SET_TIMEOUT);
}

/* Count of wakeup-enabled devices at or below udev */
static unsigned wakeup_enabled_descendants(struct usb_device *udev)
{
        struct usb_hub *hub = usb_hub_to_struct_hub(udev);

        return udev->do_remote_wakeup +
                        (hub ? hub->wakeup_enabled_descendants : 0);
}

/*
 * usb_port_suspend - suspend a usb device's upstream port
 * @udev: device that's no longer in active use, not a root hub
 * Context: must be able to sleep; device not locked; pm locks held
 *
 * Suspends a USB device that isn't in active use, conserving power.
 * Devices may wake out of a suspend, if anything important happens,
 * using the remote wakeup mechanism.  They may also be taken out of
 * suspend by the host, using usb_port_resume().  It's also routine
 * to disconnect devices while they are suspended.
 *
 * This only affects the USB hardware for a device; its interfaces
 * (and, for hubs, child devices) must already have been suspended.
 *
 * Selective port suspend reduces power; most suspended devices draw
 * less than 500 uA.  It's also used in OTG, along with remote wakeup.
 * All devices below the suspended port are also suspended.
 *
 * Devices leave suspend state when the host wakes them up.  Some devices
 * also support "remote wakeup", where the device can activate the USB
 * tree above them to deliver data, such as a keypress or packet.  In
 * some cases, this wakes the USB host.
 *
 * Suspending OTG devices may trigger HNP, if that's been enabled
 * between a pair of dual-role devices.  That will change roles, such
 * as from A-Host to A-Peripheral or from B-Host back to B-Peripheral.
 *
 * Devices on USB hub ports have only one "suspend" state, corresponding
 * to ACPI D2, "may cause the device to lose some context".
 * State transitions include:
 *
 *   - suspend, resume ... when the VBUS power link stays live
 *   - suspend, disconnect ... VBUS lost
 *
 * Once VBUS drop breaks the circuit, the port it's using has to go through
 * normal re-enumeration procedures, starting with enabling VBUS power.
 * Other than re-initializing the hub (plug/unplug, except for root hubs),
 * Linux (2.6) currently has NO mechanisms to initiate that:  no khubd
 * timer, no SRP, no requests through sysfs.
 *
 * If Runtime PM isn't enabled or used, non-SuperSpeed devices may not get
 * suspended until their bus goes into global suspend (i.e., the root
 * hub is suspended).  Nevertheless, we change @udev->state to
 * USB_STATE_SUSPENDED as this is the device's "logical" state.  The actual
 * upstream port setting is stored in @udev->port_is_suspended.
 *
 * Returns 0 on success, else negative errno.
 */
int usb_port_suspend(struct usb_device *udev, pm_message_t msg)
{
        struct usb_hub  *hub = usb_hub_to_struct_hub(udev->parent);
        struct usb_port *port_dev = hub->ports[udev->portnum - 1];
        int             port1 = udev->portnum;
        int             status;
        bool            really_suspend = true;

        usb_lock_port(port_dev);

        /* enable remote wakeup when appropriate; this lets the device
         * wake up the upstream hub (including maybe the root hub).
         *
         * NOTE:  OTG devices may issue remote wakeup (or SRP) even when
         * we don't explicitly enable it here.
         */
        if (udev->do_remote_wakeup) {
                status = usb_enable_remote_wakeup(udev);
                if (status) {
                        dev_dbg(&udev->dev, "won't remote wakeup, status %d\n",
                                        status);
                        /* bail if autosuspend is requested */
                        if (PMSG_IS_AUTO(msg))
                                goto err_wakeup;
                }
        }

        /* disable USB2 hardware LPM */
        if (udev->usb2_hw_lpm_enabled == 1)
                usb_set_usb2_hardware_lpm(udev, 0);

        if (usb_disable_ltm(udev)) {
                dev_err(&udev->dev, "Failed to disable LTM before suspend\n.");
                status = -ENOMEM;
                if (PMSG_IS_AUTO(msg))
                        goto err_ltm;
        }
        if (usb_unlocked_disable_lpm(udev)) {
                dev_err(&udev->dev, "Failed to disable LPM before suspend\n.");
                status = -ENOMEM;
                if (PMSG_IS_AUTO(msg))
                        goto err_lpm3;
        }

        /* see 7.1.7.6 */
        if (hub_is_superspeed(hub->hdev))
                status = hub_set_port_link_state(hub, port1, USB_SS_PORT_LS_U3);

        /*
         * For system suspend, we do not need to enable the suspend feature
         * on individual USB-2 ports.  The devices will automatically go
         * into suspend a few ms after the root hub stops sending packets.
         * The USB 2.0 spec calls this "global suspend".
         *
         * However, many USB hubs have a bug: They don't relay wakeup requests
         * from a downstream port if the port's suspend feature isn't on.
         * Therefore we will turn on the suspend feature if udev or any of its
         * descendants is enabled for remote wakeup.
         */
        else if (PMSG_IS_AUTO(msg) || wakeup_enabled_descendants(udev) > 0)
                status = set_port_feature(hub->hdev, port1,
                                USB_PORT_FEAT_SUSPEND);
        else {
                really_suspend = false;
                status = 0;
        }
        if (status) {
                dev_dbg(&port_dev->dev, "can't suspend, status %d\n", status);

                /* Try to enable USB3 LPM and LTM again */
                usb_unlocked_enable_lpm(udev);
 err_lpm3:
                usb_enable_ltm(udev);
 err_ltm:
                /* Try to enable USB2 hardware LPM again */
                if (udev->usb2_hw_lpm_capable == 1)
                        usb_set_usb2_hardware_lpm(udev, 1);

                if (udev->do_remote_wakeup)
                        (void) usb_disable_remote_wakeup(udev);
 err_wakeup:

                /* System sleep transitions should never fail */
                if (!PMSG_IS_AUTO(msg))
                        status = 0;
        } else {
                dev_dbg(&udev->dev, "usb %ssuspend, wakeup %d\n",
                                (PMSG_IS_AUTO(msg) ? "auto-" : ""),
                                udev->do_remote_wakeup);
                if (really_suspend) {
                        udev->port_is_suspended = 1;

                        /* device has up to 10 msec to fully suspend */
                        msleep(10);
                }
                usb_set_device_state(udev, USB_STATE_SUSPENDED);
        }

        if (status == 0 && !udev->do_remote_wakeup && udev->persist_enabled
                        && test_and_clear_bit(port1, hub->child_usage_bits))
                pm_runtime_put_sync(&port_dev->dev);

        usb_mark_last_busy(hub->hdev);

        usb_unlock_port(port_dev);
        return status;
}

/*
 * If the USB "suspend" state is in use (rather than "global suspend"),
 * many devices will be individually taken out of suspend state using
 * special "resume" signaling.  This routine kicks in shortly after
 * hardware resume signaling is finished, either because of selective
 * resume (by host) or remote wakeup (by device) ... now see what changed
 * in the tree that's rooted at this device.
 *
 * If @udev->reset_resume is set then the device is reset before the
 * status check is done.
 */
static int finish_port_resume(struct usb_device *udev)
{
        int     status = 0;
        u16     devstatus = 0;

        /* caller owns the udev device lock */
        dev_dbg(&udev->dev, "%s\n",
                udev->reset_resume ? "finish reset-resume" : "finish resume");

        /* usb ch9 identifies four variants of SUSPENDED, based on what
         * state the device resumes to.  Linux currently won't see the
         * first two on the host side; they'd be inside hub_port_init()
         * during many timeouts, but khubd can't suspend until later.
         */
        usb_set_device_state(udev, udev->actconfig
                        ? USB_STATE_CONFIGURED
                        : USB_STATE_ADDRESS);

        /* 10.5.4.5 says not to reset a suspended port if the attached
         * device is enabled for remote wakeup.  Hence the reset
         * operation is carried out here, after the port has been
         * resumed.
         */
        if (udev->reset_resume) {
                /*
                 * If the device morphs or switches modes when it is reset,
                 * we don't want to perform a reset-resume.  We'll fail the
                 * resume, which will cause a logical disconnect, and then
                 * the device will be rediscovered.
                 */
 retry_reset_resume:
                if (udev->quirks & USB_QUIRK_RESET)
                        status = -ENODEV;
                else
                        status = usb_reset_and_verify_device(udev);
        }

        /* 10.5.4.5 says be sure devices in the tree are still there.
         * For now let's assume the device didn't go crazy on resume,
         * and device drivers will know about any resume quirks.
         */
        if (status == 0) {
                devstatus = 0;
                status = usb_get_status(udev, USB_RECIP_DEVICE, 0, &devstatus);

                /* If a normal resume failed, try doing a reset-resume */
                if (status && !udev->reset_resume && udev->persist_enabled) {
                        dev_dbg(&udev->dev, "retry with reset-resume\n");
                        udev->reset_resume = 1;
                        goto retry_reset_resume;
                }
        }

        if (status) {
                dev_dbg(&udev->dev, "gone after usb resume? status %d\n",
                                status);
        /*
         * There are a few quirky devices which violate the standard
         * by claiming to have remote wakeup enabled after a reset,
         * which crash if the feature is cleared, hence check for
         * udev->reset_resume
         */
        } else if (udev->actconfig && !udev->reset_resume) {
                if (udev->speed < USB_SPEED_SUPER) {
                        if (devstatus & (1 << USB_DEVICE_REMOTE_WAKEUP))
                                status = usb_disable_remote_wakeup(udev);
                } else {
                        status = usb_get_status(udev, USB_RECIP_INTERFACE, 0,
                                        &devstatus);
                        if (!status && devstatus & (USB_INTRF_STAT_FUNC_RW_CAP
                                        | USB_INTRF_STAT_FUNC_RW))
                                status = usb_disable_remote_wakeup(udev);
                }

                if (status)
                        dev_dbg(&udev->dev,
                                "disable remote wakeup, status %d\n",
                                status);
                status = 0;
        }
        return status;
}

/*
 * usb_port_resume - re-activate a suspended usb device's upstream port
 * @udev: device to re-activate, not a root hub
 * Context: must be able to sleep; device not locked; pm locks held
 *
 * This will re-activate the suspended device, increasing power usage
 * while letting drivers communicate again with its endpoints.
 * USB resume explicitly guarantees that the power session between
 * the host and the device is the same as it was when the device
 * suspended.
 *
 * If @udev->reset_resume is set then this routine won't check that the
 * port is still enabled.  Furthermore, finish_port_resume() above will
 * reset @udev.  The end result is that a broken power session can be
 * recovered and @udev will appear to persist across a loss of VBUS power.
 *
 * For example, if a host controller doesn't maintain VBUS suspend current
 * during a system sleep or is reset when the system wakes up, all the USB
 * power sessions below it will be broken.  This is especially troublesome
 * for mass-storage devices containing mounted filesystems, since the
 * device will appear to have disconnected and all the memory mappings
 * to it will be lost.  Using the USB_PERSIST facility, the device can be
 * made to appear as if it had not disconnected.
 *
 * This facility can be dangerous.  Although usb_reset_and_verify_device() makes
 * every effort to insure that the same device is present after the
 * reset as before, it cannot provide a 100% guarantee.  Furthermore it's
 * quite possible for a device to remain unaltered but its media to be
 * changed.  If the user replaces a flash memory card while the system is
 * asleep, he will have only himself to blame when the filesystem on the
 * new card is corrupted and the system crashes.
 *
 * Returns 0 on success, else negative errno.
 */
int usb_port_resume(struct usb_device *udev, pm_message_t msg)
{
        struct usb_hub  *hub = usb_hub_to_struct_hub(udev->parent);
        struct usb_port *port_dev = hub->ports[udev->portnum  - 1];
        int             port1 = udev->portnum;
        int             status;
        u16             portchange, portstatus;

        if (!test_and_set_bit(port1, hub->child_usage_bits)) {
                status = pm_runtime_get_sync(&port_dev->dev);
                if (status < 0) {
                        dev_dbg(&udev->dev, "can't resume usb port, status %d\n",
                                        status);
                        return status;
                }
        }

        usb_lock_port(port_dev);

        /* Skip the initial Clear-Suspend step for a remote wakeup */
        status = hub_port_status(hub, port1, &portstatus, &portchange);
        if (status == 0 && !port_is_suspended(hub, portstatus))
                goto SuspendCleared;

        /* see 7.1.7.7; affects power usage, but not budgeting */
        if (hub_is_superspeed(hub->hdev))
                status = hub_set_port_link_state(hub, port1, USB_SS_PORT_LS_U0);
        else
                status = usb_clear_port_feature(hub->hdev,
                                port1, USB_PORT_FEAT_SUSPEND);
        if (status) {
                dev_dbg(&port_dev->dev, "can't resume, status %d\n", status);
        } else {
                /* drive resume for at least 20 msec */
                dev_dbg(&udev->dev, "usb %sresume\n",
                                (PMSG_IS_AUTO(msg) ? "auto-" : ""));
                msleep(25);

                /* Virtual root hubs can trigger on GET_PORT_STATUS to
                 * stop resume signaling.  Then finish the resume
                 * sequence.
                 */
                status = hub_port_status(hub, port1, &portstatus, &portchange);

                /* TRSMRCY = 10 msec */
                msleep(10);
        }

 SuspendCleared:
        if (status == 0) {
                udev->port_is_suspended = 0;
                if (hub_is_superspeed(hub->hdev)) {
                        if (portchange & USB_PORT_STAT_C_LINK_STATE)
                                usb_clear_port_feature(hub->hdev, port1,
                                        USB_PORT_FEAT_C_PORT_LINK_STATE);
                } else {
                        if (portchange & USB_PORT_STAT_C_SUSPEND)
                                usb_clear_port_feature(hub->hdev, port1,
                                                USB_PORT_FEAT_C_SUSPEND);
                }
        }

        status = check_port_resume_type(udev,
                        hub, port1, status, portchange, portstatus);
        if (status == 0)
                status = finish_port_resume(udev);
        if (status < 0) {
                dev_dbg(&udev->dev, "can't resume, status %d\n", status);
                hub_port_logical_disconnect(hub, port1);
        } else  {
                /* Try to enable USB2 hardware LPM */
                if (udev->usb2_hw_lpm_capable == 1)
                        usb_set_usb2_hardware_lpm(udev, 1);

                /* Try to enable USB3 LTM and LPM */
                usb_enable_ltm(udev);
                usb_unlocked_enable_lpm(udev);
        }

        usb_unlock_port(port_dev);

        return status;
}

#ifdef  CONFIG_PM_RUNTIME

int usb_remote_wakeup(struct usb_device *udev)
{
        int     status = 0;

        usb_lock_device(udev);
        if (udev->state == USB_STATE_SUSPENDED) {
                dev_dbg(&udev->dev, "usb %sresume\n", "wakeup-");
                status = usb_autoresume_device(udev);
                if (status == 0) {
                        /* Let the drivers do their thing, then... */
                        usb_autosuspend_device(udev);
                }
        }
        usb_unlock_device(udev);
        return status;
}

/* Returns 1 if there was a remote wakeup and a connect status change. */
static int hub_handle_remote_wakeup(struct usb_hub *hub, unsigned int port,
                u16 portstatus, u16 portchange)
                __must_hold(&port_dev->status_lock)
{
        struct usb_port *port_dev = hub->ports[port - 1];
        struct usb_device *hdev;
        struct usb_device *udev;
        int connect_change = 0;
        int ret;

        hdev = hub->hdev;
        udev = port_dev->child;
        if (!hub_is_superspeed(hdev)) {
                if (!(portchange & USB_PORT_STAT_C_SUSPEND))
                        return 0;
                usb_clear_port_feature(hdev, port, USB_PORT_FEAT_C_SUSPEND);
        } else {
                if (!udev || udev->state != USB_STATE_SUSPENDED ||
                                 (portstatus & USB_PORT_STAT_LINK_STATE) !=
                                 USB_SS_PORT_LS_U0)
                        return 0;
        }

        if (udev) {
                /* TRSMRCY = 10 msec */
                msleep(10);

                usb_unlock_port(port_dev);
                ret = usb_remote_wakeup(udev);
                usb_lock_port(port_dev);
                if (ret < 0)
                        connect_change = 1;
        } else {
                ret = -ENODEV;
                hub_port_disable(hub, port, 1);
        }
        dev_dbg(&port_dev->dev, "resume, status %d\n", ret);
        return connect_change;
}

#else

static int hub_handle_remote_wakeup(struct usb_hub *hub, unsigned int port,
                u16 portstatus, u16 portchange)
{
        return 0;
}

#endif

static int check_ports_changed(struct usb_hub *hub)
{
        int port1;

        for (port1 = 1; port1 <= hub->hdev->maxchild; ++port1) {
                u16 portstatus, portchange;
                int status;

                status = hub_port_status(hub, port1, &portstatus, &portchange);
                if (!status && portchange)
                        return 1;
        }
        return 0;
}

static int hub_suspend(struct usb_interface *intf, pm_message_t msg)
{
        struct usb_hub          *hub = usb_get_intfdata (intf);
        struct usb_device       *hdev = hub->hdev;
        unsigned                port1;
        int                     status;

        /*
         * Warn if children aren't already suspended.
         * Also, add up the number of wakeup-enabled descendants.
         */
        hub->wakeup_enabled_descendants = 0;
        for (port1 = 1; port1 <= hdev->maxchild; port1++) {
                struct usb_port *port_dev = hub->ports[port1 - 1];
                struct usb_device *udev = port_dev->child;

                if (udev && udev->can_submit) {
                        dev_warn(&port_dev->dev, "not suspended yet\n");
                        if (PMSG_IS_AUTO(msg))
                                return -EBUSY;
                }
                if (udev)
                        hub->wakeup_enabled_descendants +=
                                        wakeup_enabled_descendants(udev);
        }

        if (hdev->do_remote_wakeup && hub->quirk_check_port_auto_suspend) {
                /* check if there are changes pending on hub ports */
                if (check_ports_changed(hub)) {
                        if (PMSG_IS_AUTO(msg))
                                return -EBUSY;
                        pm_wakeup_event(&hdev->dev, 2000);
                }
        }

        if (hub_is_superspeed(hdev) && hdev->do_remote_wakeup) {
                /* Enable hub to send remote wakeup for all ports. */
                for (port1 = 1; port1 <= hdev->maxchild; port1++) {
                        status = set_port_feature(hdev,
                                        port1 |
                                        USB_PORT_FEAT_REMOTE_WAKE_CONNECT |
                                        USB_PORT_FEAT_REMOTE_WAKE_DISCONNECT |
                                        USB_PORT_FEAT_REMOTE_WAKE_OVER_CURRENT,
                                        USB_PORT_FEAT_REMOTE_WAKE_MASK);
                }
        }

        dev_dbg(&intf->dev, "%s\n", __func__);

        /* stop khubd and related activity */
        hub_quiesce(hub, HUB_SUSPEND);
        return 0;
}

static int hub_resume(struct usb_interface *intf)
{
        struct usb_hub *hub = usb_get_intfdata(intf);

        dev_dbg(&intf->dev, "%s\n", __func__);
        hub_activate(hub, HUB_RESUME);
        return 0;
}

static int hub_reset_resume(struct usb_interface *intf)
{
        struct usb_hub *hub = usb_get_intfdata(intf);

        dev_dbg(&intf->dev, "%s\n", __func__);
        hub_activate(hub, HUB_RESET_RESUME);
        return 0;
}

/**
 * usb_root_hub_lost_power - called by HCD if the root hub lost Vbus power
 * @rhdev: struct usb_device for the root hub
 *
 * The USB host controller driver calls this function when its root hub
 * is resumed and Vbus power has been interrupted or the controller
 * has been reset.  The routine marks @rhdev as having lost power.
 * When the hub driver is resumed it will take notice and carry out
 * power-session recovery for all the "USB-PERSIST"-enabled child devices;
 * the others will be disconnected.
 */
void usb_root_hub_lost_power(struct usb_device *rhdev)
{
        dev_warn(&rhdev->dev, "root hub lost power or was reset\n");
        rhdev->reset_resume = 1;
}
EXPORT_SYMBOL_GPL(usb_root_hub_lost_power);

static const char * const usb3_lpm_names[]  = {
        "U0",
        "U1",
        "U2",
        "U3",
};

/*
 * Send a Set SEL control transfer to the device, prior to enabling
 * device-initiated U1 or U2.  This lets the device know the exit latencies from
 * the time the device initiates a U1 or U2 exit, to the time it will receive a
 * packet from the host.
 *
 * This function will fail if the SEL or PEL values for udev are greater than
 * the maximum allowed values for the link state to be enabled.
 */
static int usb_req_set_sel(struct usb_device *udev, enum usb3_link_state state)
{
        struct usb_set_sel_req *sel_values;
        unsigned long long u1_sel;
        unsigned long long u1_pel;
        unsigned long long u2_sel;
        unsigned long long u2_pel;
        int ret;

        if (udev->state != USB_STATE_CONFIGURED)
                return 0;

        /* Convert SEL and PEL stored in ns to us */
        u1_sel = DIV_ROUND_UP(udev->u1_params.sel, 1000);
        u1_pel = DIV_ROUND_UP(udev->u1_params.pel, 1000);
        u2_sel = DIV_ROUND_UP(udev->u2_params.sel, 1000);
        u2_pel = DIV_ROUND_UP(udev->u2_params.pel, 1000);

        /*
         * Make sure that the calculated SEL and PEL values for the link
         * state we're enabling aren't bigger than the max SEL/PEL
         * value that will fit in the SET SEL control transfer.
         * Otherwise the device would get an incorrect idea of the exit
         * latency for the link state, and could start a device-initiated
         * U1/U2 when the exit latencies are too high.
         */
        if ((state == USB3_LPM_U1 &&
                                (u1_sel > USB3_LPM_MAX_U1_SEL_PEL ||
                                 u1_pel > USB3_LPM_MAX_U1_SEL_PEL)) ||
                        (state == USB3_LPM_U2 &&
                         (u2_sel > USB3_LPM_MAX_U2_SEL_PEL ||
                          u2_pel > USB3_LPM_MAX_U2_SEL_PEL))) {
                dev_dbg(&udev->dev, "Device-initiated %s disabled due to long SEL %llu us or PEL %llu us\n",
                                usb3_lpm_names[state], u1_sel, u1_pel);
                return -EINVAL;
        }

        /*
         * If we're enabling device-initiated LPM for one link state,
         * but the other link state has a too high SEL or PEL value,
         * just set those values to the max in the Set SEL request.
         */
        if (u1_sel > USB3_LPM_MAX_U1_SEL_PEL)
                u1_sel = USB3_LPM_MAX_U1_SEL_PEL;

        if (u1_pel > USB3_LPM_MAX_U1_SEL_PEL)
                u1_pel = USB3_LPM_MAX_U1_SEL_PEL;

        if (u2_sel > USB3_LPM_MAX_U2_SEL_PEL)
                u2_sel = USB3_LPM_MAX_U2_SEL_PEL;

        if (u2_pel > USB3_LPM_MAX_U2_SEL_PEL)
                u2_pel = USB3_LPM_MAX_U2_SEL_PEL;

        /*
         * usb_enable_lpm() can be called as part of a failed device reset,
         * which may be initiated by an error path of a mass storage driver.
         * Therefore, use GFP_NOIO.
         */
        sel_values = kmalloc(sizeof *(sel_values), GFP_NOIO);
        if (!sel_values)
                return -ENOMEM;

        sel_values->u1_sel = u1_sel;
        sel_values->u1_pel = u1_pel;
        sel_values->u2_sel = cpu_to_le16(u2_sel);
        sel_values->u2_pel = cpu_to_le16(u2_pel);

        ret = usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
                        USB_REQ_SET_SEL,
                        USB_RECIP_DEVICE,
                        0, 0,
                        sel_values, sizeof *(sel_values),
                        USB_CTRL_SET_TIMEOUT);
        kfree(sel_values);
        return ret;
}

/*
 * Enable or disable device-initiated U1 or U2 transitions.
 */
static int usb_set_device_initiated_lpm(struct usb_device *udev,
                enum usb3_link_state state, bool enable)
{
        int ret;
        int feature;

        switch (state) {
        case USB3_LPM_U1:
                feature = USB_DEVICE_U1_ENABLE;
                break;
        case USB3_LPM_U2:
                feature = USB_DEVICE_U2_ENABLE;
                break;
        default:
                dev_warn(&udev->dev, "%s: Can't %s non-U1 or U2 state.\n",
                                __func__, enable ? "enable" : "disable");
                return -EINVAL;
        }

        if (udev->state != USB_STATE_CONFIGURED) {
                dev_dbg(&udev->dev, "%s: Can't %s %s state "
                                "for unconfigured device.\n",
                                __func__, enable ? "enable" : "disable",
                                usb3_lpm_names[state]);
                return 0;
        }

        if (enable) {
                /*
                 * Now send the control transfer to enable device-initiated LPM
                 * for either U1 or U2.
                 */
                ret = usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
                                USB_REQ_SET_FEATURE,
                                USB_RECIP_DEVICE,
                                feature,
                                0, NULL, 0,
                                USB_CTRL_SET_TIMEOUT);
        } else {
                ret = usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
                                USB_REQ_CLEAR_FEATURE,
                                USB_RECIP_DEVICE,
                                feature,
                                0, NULL, 0,
                                USB_CTRL_SET_TIMEOUT);
        }
        if (ret < 0) {
                dev_warn(&udev->dev, "%s of device-initiated %s failed.\n",
                                enable ? "Enable" : "Disable",
                                usb3_lpm_names[state]);
                return -EBUSY;
        }
        return 0;
}

static int usb_set_lpm_timeout(struct usb_device *udev,
                enum usb3_link_state state, int timeout)
{
        int ret;
        int feature;

        switch (state) {
        case USB3_LPM_U1:
                feature = USB_PORT_FEAT_U1_TIMEOUT;
                break;
        case USB3_LPM_U2:
                feature = USB_PORT_FEAT_U2_TIMEOUT;
                break;
        default:
                dev_warn(&udev->dev, "%s: Can't set timeout for non-U1 or U2 state.\n",
                                __func__);
                return -EINVAL;
        }

        if (state == USB3_LPM_U1 && timeout > USB3_LPM_U1_MAX_TIMEOUT &&
                        timeout != USB3_LPM_DEVICE_INITIATED) {
                dev_warn(&udev->dev, "Failed to set %s timeout to 0x%x, "
                                "which is a reserved value.\n",
                                usb3_lpm_names[state], timeout);
                return -EINVAL;
        }

        ret = set_port_feature(udev->parent,
                        USB_PORT_LPM_TIMEOUT(timeout) | udev->portnum,
                        feature);
        if (ret < 0) {
                dev_warn(&udev->dev, "Failed to set %s timeout to 0x%x,"
                                "error code %i\n", usb3_lpm_names[state],
                                timeout, ret);
                return -EBUSY;
        }
        if (state == USB3_LPM_U1)
                udev->u1_params.timeout = timeout;
        else
                udev->u2_params.timeout = timeout;
        return 0;
}

/*
 * Enable the hub-initiated U1/U2 idle timeouts, and enable device-initiated
 * U1/U2 entry.
 *
 * We will attempt to enable U1 or U2, but there are no guarantees that the
 * control transfers to set the hub timeout or enable device-initiated U1/U2
 * will be successful.
 *
 * If we cannot set the parent hub U1/U2 timeout, we attempt to let the xHCI
 * driver know about it.  If that call fails, it should be harmless, and just
 * take up more slightly more bus bandwidth for unnecessary U1/U2 exit latency.
 */
static void usb_enable_link_state(struct usb_hcd *hcd, struct usb_device *udev,
                enum usb3_link_state state)
{
        int timeout, ret;
        __u8 u1_mel = udev->bos->ss_cap->bU1devExitLat;
        __le16 u2_mel = udev->bos->ss_cap->bU2DevExitLat;

        /* If the device says it doesn't have *any* exit latency to come out of
         * U1 or U2, it's probably lying.  Assume it doesn't implement that link
         * state.
         */
        if ((state == USB3_LPM_U1 && u1_mel == 0) ||
                        (state == USB3_LPM_U2 && u2_mel == 0))
                return;

        /*
         * First, let the device know about the exit latencies
         * associated with the link state we're about to enable.
         */
        ret = usb_req_set_sel(udev, state);
        if (ret < 0) {
                dev_warn(&udev->dev, "Set SEL for device-initiated %s failed.\n",
                                usb3_lpm_names[state]);
                return;
        }

        /* We allow the host controller to set the U1/U2 timeout internally
         * first, so that it can change its schedule to account for the
         * additional latency to send data to a device in a lower power
         * link state.
         */
        timeout = hcd->driver->enable_usb3_lpm_timeout(hcd, udev, state);

        /* xHCI host controller doesn't want to enable this LPM state. */
        if (timeout == 0)
                return;

        if (timeout < 0) {
                dev_warn(&udev->dev, "Could not enable %s link state, "
                                "xHCI error %i.\n", usb3_lpm_names[state],
                                timeout);
                return;
        }

        if (usb_set_lpm_timeout(udev, state, timeout))
                /* If we can't set the parent hub U1/U2 timeout,
                 * device-initiated LPM won't be allowed either, so let the xHCI
                 * host know that this link state won't be enabled.
                 */
                hcd->driver->disable_usb3_lpm_timeout(hcd, udev, state);

        /* Only a configured device will accept the Set Feature U1/U2_ENABLE */
        else if (udev->actconfig)
                usb_set_device_initiated_lpm(udev, state, true);

}

/*
 * Disable the hub-initiated U1/U2 idle timeouts, and disable device-initiated
 * U1/U2 entry.
 *
 * If this function returns -EBUSY, the parent hub will still allow U1/U2 entry.
 * If zero is returned, the parent will not allow the link to go into U1/U2.
 *
 * If zero is returned, device-initiated U1/U2 entry may still be enabled, but
 * it won't have an effect on the bus link state because the parent hub will
 * still disallow device-initiated U1/U2 entry.
 *
 * If zero is returned, the xHCI host controller may still think U1/U2 entry is
 * possible.  The result will be slightly more bus bandwidth will be taken up
 * (to account for U1/U2 exit latency), but it should be harmless.
 */
static int usb_disable_link_state(struct usb_hcd *hcd, struct usb_device *udev,
                enum usb3_link_state state)
{
        int feature;

        switch (state) {
        case USB3_LPM_U1:
                feature = USB_PORT_FEAT_U1_TIMEOUT;
                break;
        case USB3_LPM_U2:
                feature = USB_PORT_FEAT_U2_TIMEOUT;
                break;
        default:
                dev_warn(&udev->dev, "%s: Can't disable non-U1 or U2 state.\n",
                                __func__);
                return -EINVAL;
        }

        if (usb_set_lpm_timeout(udev, state, 0))
                return -EBUSY;

        usb_set_device_initiated_lpm(udev, state, false);

        if (hcd->driver->disable_usb3_lpm_timeout(hcd, udev, state))
                dev_warn(&udev->dev, "Could not disable xHCI %s timeout, "
                                "bus schedule bandwidth may be impacted.\n",
                                usb3_lpm_names[state]);
        return 0;
}

/*
 * Disable hub-initiated and device-initiated U1 and U2 entry.
 * Caller must own the bandwidth_mutex.
 *
 * This will call usb_enable_lpm() on failure, which will decrement
 * lpm_disable_count, and will re-enable LPM if lpm_disable_count reaches zero.
 */
int usb_disable_lpm(struct usb_device *udev)
{
        struct usb_hcd *hcd;

        if (!udev || !udev->parent ||
                        udev->speed != USB_SPEED_SUPER ||
                        !udev->lpm_capable)
                return 0;

        hcd = bus_to_hcd(udev->bus);
        if (!hcd || !hcd->driver->disable_usb3_lpm_timeout)
                return 0;

        udev->lpm_disable_count++;
        if ((udev->u1_params.timeout == 0 && udev->u2_params.timeout == 0))
                return 0;

        /* If LPM is enabled, attempt to disable it. */
        if (usb_disable_link_state(hcd, udev, USB3_LPM_U1))
                goto enable_lpm;
        if (usb_disable_link_state(hcd, udev, USB3_LPM_U2))
                goto enable_lpm;

        return 0;

enable_lpm:
        usb_enable_lpm(udev);
        return -EBUSY;
}
EXPORT_SYMBOL_GPL(usb_disable_lpm);

/* Grab the bandwidth_mutex before calling usb_disable_lpm() */
int usb_unlocked_disable_lpm(struct usb_device *udev)
{
        struct usb_hcd *hcd = bus_to_hcd(udev->bus);
        int ret;

        if (!hcd)
                return -EINVAL;

        mutex_lock(hcd->bandwidth_mutex);
        ret = usb_disable_lpm(udev);
        mutex_unlock(hcd->bandwidth_mutex);

        return ret;
}
EXPORT_SYMBOL_GPL(usb_unlocked_disable_lpm);

/*
 * Attempt to enable device-initiated and hub-initiated U1 and U2 entry.  The
 * xHCI host policy may prevent U1 or U2 from being enabled.
 *
 * Other callers may have disabled link PM, so U1 and U2 entry will be disabled
 * until the lpm_disable_count drops to zero.  Caller must own the
 * bandwidth_mutex.
 */
void usb_enable_lpm(struct usb_device *udev)
{
        struct usb_hcd *hcd;

        if (!udev || !udev->parent ||
                        udev->speed != USB_SPEED_SUPER ||
                        !udev->lpm_capable)
                return;

        udev->lpm_disable_count--;
        hcd = bus_to_hcd(udev->bus);
        /* Double check that we can both enable and disable LPM.
         * Device must be configured to accept set feature U1/U2 timeout.
         */
        if (!hcd || !hcd->driver->enable_usb3_lpm_timeout ||
                        !hcd->driver->disable_usb3_lpm_timeout)
                return;

        if (udev->lpm_disable_count > 0)
                return;

        usb_enable_link_state(hcd, udev, USB3_LPM_U1);
        usb_enable_link_state(hcd, udev, USB3_LPM_U2);
}
EXPORT_SYMBOL_GPL(usb_enable_lpm);

/* Grab the bandwidth_mutex before calling usb_enable_lpm() */
void usb_unlocked_enable_lpm(struct usb_device *udev)
{
        struct usb_hcd *hcd = bus_to_hcd(udev->bus);

        if (!hcd)
                return;

        mutex_lock(hcd->bandwidth_mutex);
        usb_enable_lpm(udev);
        mutex_unlock(hcd->bandwidth_mutex);
}
EXPORT_SYMBOL_GPL(usb_unlocked_enable_lpm);


#else   /* CONFIG_PM */

#define hub_suspend             NULL
#define hub_resume              NULL
#define hub_reset_resume        NULL

int usb_disable_lpm(struct usb_device *udev)
{
        return 0;
}
EXPORT_SYMBOL_GPL(usb_disable_lpm);

void usb_enable_lpm(struct usb_device *udev) { }
EXPORT_SYMBOL_GPL(usb_enable_lpm);

int usb_unlocked_disable_lpm(struct usb_device *udev)
{
        return 0;
}
EXPORT_SYMBOL_GPL(usb_unlocked_disable_lpm);

void usb_unlocked_enable_lpm(struct usb_device *udev) { }
EXPORT_SYMBOL_GPL(usb_unlocked_enable_lpm);

int usb_disable_ltm(struct usb_device *udev)
{
        return 0;
}
EXPORT_SYMBOL_GPL(usb_disable_ltm);

void usb_enable_ltm(struct usb_device *udev) { }
EXPORT_SYMBOL_GPL(usb_enable_ltm);

static int hub_handle_remote_wakeup(struct usb_hub *hub, unsigned int port,
                u16 portstatus, u16 portchange)
{
        return 0;
}

#endif  /* CONFIG_PM */


/* USB 2.0 spec, 7.1.7.3 / fig 7-29:
 *
 * Between connect detection and reset signaling there must be a delay
 * of 100ms at least for debounce and power-settling.  The corresponding
 * timer shall restart whenever the downstream port detects a disconnect.
 *
 * Apparently there are some bluetooth and irda-dongles and a number of
 * low-speed devices for which this debounce period may last over a second.
 * Not covered by the spec - but easy to deal with.
 *
 * This implementation uses a 1500ms total debounce timeout; if the
 * connection isn't stable by then it returns -ETIMEDOUT.  It checks
 * every 25ms for transient disconnects.  When the port status has been
 * unchanged for 100ms it returns the port status.
 */
int hub_port_debounce(struct usb_hub *hub, int port1, bool must_be_connected)
{
        int ret;
        u16 portchange, portstatus;
        unsigned connection = 0xffff;
        int total_time, stable_time = 0;
        struct usb_port *port_dev = hub->ports[port1 - 1];

        for (total_time = 0; ; total_time += HUB_DEBOUNCE_STEP) {
                ret = hub_port_status(hub, port1, &portstatus, &portchange);
                if (ret < 0)
                        return ret;

                if (!(portchange & USB_PORT_STAT_C_CONNECTION) &&
                     (portstatus & USB_PORT_STAT_CONNECTION) == connection) {
                        if (!must_be_connected ||
                             (connection == USB_PORT_STAT_CONNECTION))
                                stable_time += HUB_DEBOUNCE_STEP;
                        if (stable_time >= HUB_DEBOUNCE_STABLE)
                                break;
                } else {
                        stable_time = 0;
                        connection = portstatus & USB_PORT_STAT_CONNECTION;
                }

                if (portchange & USB_PORT_STAT_C_CONNECTION) {
                        usb_clear_port_feature(hub->hdev, port1,
                                        USB_PORT_FEAT_C_CONNECTION);
                }

                if (total_time >= HUB_DEBOUNCE_TIMEOUT)
                        break;
                msleep(HUB_DEBOUNCE_STEP);
        }

        dev_dbg(&port_dev->dev, "debounce total %dms stable %dms status 0x%x\n",
                        total_time, stable_time, portstatus);

        if (stable_time < HUB_DEBOUNCE_STABLE)
                return -ETIMEDOUT;
        return portstatus;
}

void usb_ep0_reinit(struct usb_device *udev)
{
        usb_disable_endpoint(udev, 0 + USB_DIR_IN, true);
        usb_disable_endpoint(udev, 0 + USB_DIR_OUT, true);
        usb_enable_endpoint(udev, &udev->ep0, true);
}
EXPORT_SYMBOL_GPL(usb_ep0_reinit);

#define usb_sndaddr0pipe()      (PIPE_CONTROL << 30)
#define usb_rcvaddr0pipe()      ((PIPE_CONTROL << 30) | USB_DIR_IN)

static int hub_set_address(struct usb_device *udev, int devnum)
{
        int retval;
        struct usb_hcd *hcd = bus_to_hcd(udev->bus);

        /*
         * The host controller will choose the device address,
         * instead of the core having chosen it earlier
         */
        if (!hcd->driver->address_device && devnum <= 1)
                return -EINVAL;
        if (udev->state == USB_STATE_ADDRESS)
                return 0;
        if (udev->state != USB_STATE_DEFAULT)
                return -EINVAL;
        if (hcd->driver->address_device)
                retval = hcd->driver->address_device(hcd, udev);
        else
                retval = usb_control_msg(udev, usb_sndaddr0pipe(),
                                USB_REQ_SET_ADDRESS, 0, devnum, 0,
                                NULL, 0, USB_CTRL_SET_TIMEOUT);
        if (retval == 0) {
                update_devnum(udev, devnum);
                /* Device now using proper address. */
                usb_set_device_state(udev, USB_STATE_ADDRESS);
                usb_ep0_reinit(udev);
        }
        return retval;
}

/*
 * There are reports of USB 3.0 devices that say they support USB 2.0 Link PM
 * when they're plugged into a USB 2.0 port, but they don't work when LPM is
 * enabled.
 *
 * Only enable USB 2.0 Link PM if the port is internal (hardwired), or the
 * device says it supports the new USB 2.0 Link PM errata by setting the BESL
 * support bit in the BOS descriptor.
 */
static void hub_set_initial_usb2_lpm_policy(struct usb_device *udev)
{
        struct usb_hub *hub = usb_hub_to_struct_hub(udev->parent);
        int connect_type = USB_PORT_CONNECT_TYPE_UNKNOWN;

        if (!udev->usb2_hw_lpm_capable)
                return;

        if (hub)
                connect_type = hub->ports[udev->portnum - 1]->connect_type;

        if ((udev->bos->ext_cap->bmAttributes & cpu_to_le32(USB_BESL_SUPPORT)) ||
                        connect_type == USB_PORT_CONNECT_TYPE_HARD_WIRED) {
                udev->usb2_hw_lpm_allowed = 1;
                usb_set_usb2_hardware_lpm(udev, 1);
        }
}

static int hub_enable_device(struct usb_device *udev)
{
        struct usb_hcd *hcd = bus_to_hcd(udev->bus);

        if (!hcd->driver->enable_device)
                return 0;
        if (udev->state == USB_STATE_ADDRESS)
                return 0;
        if (udev->state != USB_STATE_DEFAULT)
                return -EINVAL;

        return hcd->driver->enable_device(hcd, udev);
}

/* Reset device, (re)assign address, get device descriptor.
 * Device connection must be stable, no more debouncing needed.
 * Returns device in USB_STATE_ADDRESS, except on error.
 *
 * If this is called for an already-existing device (as part of
 * usb_reset_and_verify_device), the caller must own the device lock and
 * the port lock.  For a newly detected device that is not accessible
 * through any global pointers, it's not necessary to lock the device,
 * but it is still necessary to lock the port.
 */
static int
hub_port_init (struct usb_hub *hub, struct usb_device *udev, int port1,
                int retry_counter)
{
        struct usb_device       *hdev = hub->hdev;
        struct usb_hcd          *hcd = bus_to_hcd(hdev->bus);
        int                     i, j, retval;
        unsigned                delay = HUB_SHORT_RESET_TIME;
        enum usb_device_speed   oldspeed = udev->speed;
        const char              *speed;
        int                     devnum = udev->devnum;

        /* root hub ports have a slightly longer reset period
         * (from USB 2.0 spec, section 7.1.7.5)
         */
        if (!hdev->parent) {
                delay = HUB_ROOT_RESET_TIME;
                if (port1 == hdev->bus->otg_port)
                        hdev->bus->b_hnp_enable = 0;
        }

        /* Some low speed devices have problems with the quick delay, so */
        /*  be a bit pessimistic with those devices. RHbug #23670 */
        if (oldspeed == USB_SPEED_LOW)
                delay = HUB_LONG_RESET_TIME;

        mutex_lock(&hdev->bus->usb_address0_mutex);

        /* Reset the device; full speed may morph to high speed */
        /* FIXME a USB 2.0 device may morph into SuperSpeed on reset. */
        retval = hub_port_reset(hub, port1, udev, delay, false);
        if (retval < 0)         /* error or disconnect */
                goto fail;
        /* success, speed is known */

        retval = -ENODEV;

        if (oldspeed != USB_SPEED_UNKNOWN && oldspeed != udev->speed) {
                dev_dbg(&udev->dev, "device reset changed speed!\n");
                goto fail;
        }
        oldspeed = udev->speed;

        /* USB 2.0 section 5.5.3 talks about ep0 maxpacket ...
         * it's fixed size except for full speed devices.
         * For Wireless USB devices, ep0 max packet is always 512 (tho
         * reported as 0xff in the device descriptor). WUSB1.0[4.8.1].
         */
        switch (udev->speed) {
        case USB_SPEED_SUPER:
        case USB_SPEED_WIRELESS:        /* fixed at 512 */
                udev->ep0.desc.wMaxPacketSize = cpu_to_le16(512);
                break;
        case USB_SPEED_HIGH:            /* fixed at 64 */
                udev->ep0.desc.wMaxPacketSize = cpu_to_le16(64);
                break;
        case USB_SPEED_FULL:            /* 8, 16, 32, or 64 */
                /* to determine the ep0 maxpacket size, try to read
                 * the device descriptor to get bMaxPacketSize0 and
                 * then correct our initial guess.
                 */
                udev->ep0.desc.wMaxPacketSize = cpu_to_le16(64);
                break;
        case USB_SPEED_LOW:             /* fixed at 8 */
                udev->ep0.desc.wMaxPacketSize = cpu_to_le16(8);
                break;
        default:
                goto fail;
        }

        if (udev->speed == USB_SPEED_WIRELESS)
                speed = "variable speed Wireless";
        else
                speed = usb_speed_string(udev->speed);

        if (udev->speed != USB_SPEED_SUPER)
                dev_info(&udev->dev,
                                "%s %s USB device number %d using %s\n",
                                (udev->config) ? "reset" : "new", speed,
                                devnum, udev->bus->controller->driver->name);

        /* Set up TT records, if needed  */
        if (hdev->tt) {
                udev->tt = hdev->tt;
                udev->ttport = hdev->ttport;
        } else if (udev->speed != USB_SPEED_HIGH
                        && hdev->speed == USB_SPEED_HIGH) {
                if (!hub->tt.hub) {
                        dev_err(&udev->dev, "parent hub has no TT\n");
                        retval = -EINVAL;
                        goto fail;
                }
                udev->tt = &hub->tt;
                udev->ttport = port1;
        }

        /* Why interleave GET_DESCRIPTOR and SET_ADDRESS this way?
         * Because device hardware and firmware is sometimes buggy in
         * this area, and this is how Linux has done it for ages.
         * Change it cautiously.
         *
         * NOTE:  If use_new_scheme() is true we will start by issuing
         * a 64-byte GET_DESCRIPTOR request.  This is what Windows does,
         * so it may help with some non-standards-compliant devices.
         * Otherwise we start with SET_ADDRESS and then try to read the
         * first 8 bytes of the device descriptor to get the ep0 maxpacket
         * value.
         */
        for (i = 0; i < GET_DESCRIPTOR_TRIES; (++i, msleep(100))) {
                bool did_new_scheme = false;

                if (use_new_scheme(udev, retry_counter)) {
                        struct usb_device_descriptor *buf;
                        int r = 0;

                        did_new_scheme = true;
                        retval = hub_enable_device(udev);
                        if (retval < 0) {
                                dev_err(&udev->dev,
                                        "hub failed to enable device, error %d\n",
                                        retval);
                                goto fail;
                        }

#define GET_DESCRIPTOR_BUFSIZE  64
                        buf = kmalloc(GET_DESCRIPTOR_BUFSIZE, GFP_NOIO);
                        if (!buf) {
                                retval = -ENOMEM;
                                continue;
                        }

                        /* Retry on all errors; some devices are flakey.
                         * 255 is for WUSB devices, we actually need to use
                         * 512 (WUSB1.0[4.8.1]).
                         */
                        for (j = 0; j < 3; ++j) {
                                buf->bMaxPacketSize0 = 0;
                                r = usb_control_msg(udev, usb_rcvaddr0pipe(),
                                        USB_REQ_GET_DESCRIPTOR, USB_DIR_IN,
                                        USB_DT_DEVICE << 8, 0,
                                        buf, GET_DESCRIPTOR_BUFSIZE,
                                        initial_descriptor_timeout);
                                switch (buf->bMaxPacketSize0) {
                                case 8: case 16: case 32: case 64: case 255:
                                        if (buf->bDescriptorType ==
                                                        USB_DT_DEVICE) {
                                                r = 0;
                                                break;
                                        }
                                        /* FALL THROUGH */
                                default:
                                        if (r == 0)
                                                r = -EPROTO;
                                        break;
                                }
                                if (r == 0)
                                        break;
                        }
                        udev->descriptor.bMaxPacketSize0 =
                                        buf->bMaxPacketSize0;
                        kfree(buf);

                        retval = hub_port_reset(hub, port1, udev, delay, false);
                        if (retval < 0)         /* error or disconnect */
                                goto fail;
                        if (oldspeed != udev->speed) {
                                dev_dbg(&udev->dev,
                                        "device reset changed speed!\n");
                                retval = -ENODEV;
                                goto fail;
                        }
                        if (r) {
                                if (r != -ENODEV)
                                        dev_err(&udev->dev, "device descriptor read/64, error %d\n",
                                                        r);
                                retval = -EMSGSIZE;
                                continue;
                        }
#undef GET_DESCRIPTOR_BUFSIZE
                }

                /*
                 * If device is WUSB, we already assigned an
                 * unauthorized address in the Connect Ack sequence;
                 * authorization will assign the final address.
                 */
                if (udev->wusb == 0) {
                        for (j = 0; j < SET_ADDRESS_TRIES; ++j) {
                                retval = hub_set_address(udev, devnum);
                                if (retval >= 0)
                                        break;
                                msleep(200);
                        }
                        if (retval < 0) {
                                if (retval != -ENODEV)
                                        dev_err(&udev->dev, "device not accepting address %d, error %d\n",
                                                        devnum, retval);
                                goto fail;
                        }
                        if (udev->speed == USB_SPEED_SUPER) {
                                devnum = udev->devnum;
                                dev_info(&udev->dev,
                                                "%s SuperSpeed USB device number %d using %s\n",
                                                (udev->config) ? "reset" : "new",
                                                devnum, udev->bus->controller->driver->name);
                        }

                        /* cope with hardware quirkiness:
                         *  - let SET_ADDRESS settle, some device hardware wants it
                         *  - read ep0 maxpacket even for high and low speed,
                         */
                        msleep(10);
                        /* use_new_scheme() checks the speed which may have
                         * changed since the initial look so we cache the result
                         * in did_new_scheme
                         */
                        if (did_new_scheme)
                                break;
                }

                retval = usb_get_device_descriptor(udev, 8);
                if (retval < 8) {
                        if (retval != -ENODEV)
                                dev_err(&udev->dev,
                                        "device descriptor read/8, error %d\n",
                                        retval);
                        if (retval >= 0)
                                retval = -EMSGSIZE;
                } else {
                        retval = 0;
                        break;
                }
        }
        if (retval)
                goto fail;

        if (hcd->phy && !hdev->parent)
                usb_phy_notify_connect(hcd->phy, udev->speed);

        /*
         * Some superspeed devices have finished the link training process
         * and attached to a superspeed hub port, but the device descriptor
         * got from those devices show they aren't superspeed devices. Warm
         * reset the port attached by the devices can fix them.
         */
        if ((udev->speed == USB_SPEED_SUPER) &&
                        (le16_to_cpu(udev->descriptor.bcdUSB) < 0x0300)) {
                dev_err(&udev->dev, "got a wrong device descriptor, "
                                "warm reset device\n");
                hub_port_reset(hub, port1, udev,
                                HUB_BH_RESET_TIME, true);
                retval = -EINVAL;
                goto fail;
        }

        if (udev->descriptor.bMaxPacketSize0 == 0xff ||
                        udev->speed == USB_SPEED_SUPER)
                i = 512;
        else
                i = udev->descriptor.bMaxPacketSize0;
        if (usb_endpoint_maxp(&udev->ep0.desc) != i) {
                if (udev->speed == USB_SPEED_LOW ||
                                !(i == 8 || i == 16 || i == 32 || i == 64)) {
                        dev_err(&udev->dev, "Invalid ep0 maxpacket: %d\n", i);
                        retval = -EMSGSIZE;
                        goto fail;
                }
                if (udev->speed == USB_SPEED_FULL)
                        dev_dbg(&udev->dev, "ep0 maxpacket = %d\n", i);
                else
                        dev_warn(&udev->dev, "Using ep0 maxpacket: %d\n", i);
                udev->ep0.desc.wMaxPacketSize = cpu_to_le16(i);
                usb_ep0_reinit(udev);
        }

        retval = usb_get_device_descriptor(udev, USB_DT_DEVICE_SIZE);
        if (retval < (signed)sizeof(udev->descriptor)) {
                if (retval != -ENODEV)
                        dev_err(&udev->dev, "device descriptor read/all, error %d\n",
                                        retval);
                if (retval >= 0)
                        retval = -ENOMSG;
                goto fail;
        }

        if (udev->wusb == 0 && le16_to_cpu(udev->descriptor.bcdUSB) >= 0x0201) {
                retval = usb_get_bos_descriptor(udev);
                if (!retval) {
                        udev->lpm_capable = usb_device_supports_lpm(udev);
                        usb_set_lpm_parameters(udev);
                }
        }

        retval = 0;
        /* notify HCD that we have a device connected and addressed */
        if (hcd->driver->update_device)
                hcd->driver->update_device(hcd, udev);
        hub_set_initial_usb2_lpm_policy(udev);
fail:
        if (retval) {
                hub_port_disable(hub, port1, 0);
                update_devnum(udev, devnum);    /* for disconnect processing */
        }
        mutex_unlock(&hdev->bus->usb_address0_mutex);
        return retval;
}

static void
check_highspeed (struct usb_hub *hub, struct usb_device *udev, int port1)
{
        struct usb_qualifier_descriptor *qual;
        int                             status;

        qual = kmalloc (sizeof *qual, GFP_KERNEL);
        if (qual == NULL)
                return;

        status = usb_get_descriptor (udev, USB_DT_DEVICE_QUALIFIER, 0,
                        qual, sizeof *qual);
        if (status == sizeof *qual) {
                dev_info(&udev->dev, "not running at top speed; "
                        "connect to a high speed hub\n");
                /* hub LEDs are probably harder to miss than syslog */
                if (hub->has_indicators) {
                        hub->indicator[port1-1] = INDICATOR_GREEN_BLINK;
                        queue_delayed_work(system_power_efficient_wq,
                                        &hub->leds, 0);
                }
        }
        kfree(qual);
}

static unsigned
hub_power_remaining (struct usb_hub *hub)
{
        struct usb_device *hdev = hub->hdev;
        int remaining;
        int port1;

        if (!hub->limited_power)
                return 0;

        remaining = hdev->bus_mA - hub->descriptor->bHubContrCurrent;
        for (port1 = 1; port1 <= hdev->maxchild; ++port1) {
                struct usb_port *port_dev = hub->ports[port1 - 1];
                struct usb_device *udev = port_dev->child;
                unsigned unit_load;
                int delta;

                if (!udev)
                        continue;
                if (hub_is_superspeed(udev))
                        unit_load = 150;
                else
                        unit_load = 100;

                /*
                 * Unconfigured devices may not use more than one unit load,
                 * or 8mA for OTG ports
                 */
                if (udev->actconfig)
                        delta = usb_get_max_power(udev, udev->actconfig);
                else if (port1 != udev->bus->otg_port || hdev->parent)
                        delta = unit_load;
                else
                        delta = 8;
                if (delta > hub->mA_per_port)
                        dev_warn(&port_dev->dev, "%dmA is over %umA budget!\n",
                                        delta, hub->mA_per_port);
                remaining -= delta;
        }
        if (remaining < 0) {
                dev_warn(hub->intfdev, "%dmA over power budget!\n",
                        -remaining);
                remaining = 0;
        }
        return remaining;
}

static void hub_port_connect(struct usb_hub *hub, int port1, u16 portstatus,
                u16 portchange)
{
        int status, i;
        unsigned unit_load;
        struct usb_device *hdev = hub->hdev;
        struct usb_hcd *hcd = bus_to_hcd(hdev->bus);
        struct usb_port *port_dev = hub->ports[port1 - 1];
        struct usb_device *udev = port_dev->child;

        /* Disconnect any existing devices under this port */
        if (udev) {
                if (hcd->phy && !hdev->parent &&
                                !(portstatus & USB_PORT_STAT_CONNECTION))
                        usb_phy_notify_disconnect(hcd->phy, udev->speed);
                usb_disconnect(&port_dev->child);
        }

        /* We can forget about a "removed" device when there's a physical
         * disconnect or the connect status changes.
         */
        if (!(portstatus & USB_PORT_STAT_CONNECTION) ||
                        (portchange & USB_PORT_STAT_C_CONNECTION))
                clear_bit(port1, hub->removed_bits);

        if (portchange & (USB_PORT_STAT_C_CONNECTION |
                                USB_PORT_STAT_C_ENABLE)) {
                status = hub_port_debounce_be_stable(hub, port1);
                if (status < 0) {
                        if (status != -ENODEV && printk_ratelimit())
                                dev_err(&port_dev->dev,
                                                "connect-debounce failed\n");
                        portstatus &= ~USB_PORT_STAT_CONNECTION;
                } else {
                        portstatus = status;
                }
        }

        /* Return now if debouncing failed or nothing is connected or
         * the device was "removed".
         */
        if (!(portstatus & USB_PORT_STAT_CONNECTION) ||
                        test_bit(port1, hub->removed_bits)) {

                /* maybe switch power back on (e.g. root hub was reset) */
                if (hub_is_port_power_switchable(hub)
                                && !port_is_power_on(hub, portstatus))
                        set_port_feature(hdev, port1, USB_PORT_FEAT_POWER);

                if (portstatus & USB_PORT_STAT_ENABLE)
                        goto done;
                return;
        }
        if (hub_is_superspeed(hub->hdev))
                unit_load = 150;
        else
                unit_load = 100;

        status = 0;
        for (i = 0; i < SET_CONFIG_TRIES; i++) {

                /* reallocate for each attempt, since references
                 * to the previous one can escape in various ways
                 */
                udev = usb_alloc_dev(hdev, hdev->bus, port1);
                if (!udev) {
                        dev_err(&port_dev->dev,
                                        "couldn't allocate usb_device\n");
                        goto done;
                }

                usb_set_device_state(udev, USB_STATE_POWERED);
                udev->bus_mA = hub->mA_per_port;
                udev->level = hdev->level + 1;
                udev->wusb = hub_is_wusb(hub);

                /* Only USB 3.0 devices are connected to SuperSpeed hubs. */
                if (hub_is_superspeed(hub->hdev))
                        udev->speed = USB_SPEED_SUPER;
                else
                        udev->speed = USB_SPEED_UNKNOWN;

                choose_devnum(udev);
                if (udev->devnum <= 0) {
                        status = -ENOTCONN;     /* Don't retry */
                        goto loop;
                }

                /* reset (non-USB 3.0 devices) and get descriptor */
                usb_lock_port(port_dev);
                status = hub_port_init(hub, udev, port1, i);
                usb_unlock_port(port_dev);
                if (status < 0)
                        goto loop;

                usb_detect_quirks(udev);
                if (udev->quirks & USB_QUIRK_DELAY_INIT)
                        msleep(1000);

                /* consecutive bus-powered hubs aren't reliable; they can
                 * violate the voltage drop budget.  if the new child has
                 * a "powered" LED, users should notice we didn't enable it
                 * (without reading syslog), even without per-port LEDs
                 * on the parent.
                 */
                if (udev->descriptor.bDeviceClass == USB_CLASS_HUB
                                && udev->bus_mA <= unit_load) {
                        u16     devstat;

                        status = usb_get_status(udev, USB_RECIP_DEVICE, 0,
                                        &devstat);
                        if (status) {
                                dev_dbg(&udev->dev, "get status %d ?\n", status);
                                goto loop_disable;
                        }
                        if ((devstat & (1 << USB_DEVICE_SELF_POWERED)) == 0) {
                                dev_err(&udev->dev,
                                        "can't connect bus-powered hub "
                                        "to this port\n");
                                if (hub->has_indicators) {
                                        hub->indicator[port1-1] =
                                                INDICATOR_AMBER_BLINK;
                                        queue_delayed_work(
                                                system_power_efficient_wq,
                                                &hub->leds, 0);
                                }
                                status = -ENOTCONN;     /* Don't retry */
                                goto loop_disable;
                        }
                }

                /* check for devices running slower than they could */
                if (le16_to_cpu(udev->descriptor.bcdUSB) >= 0x0200
                                && udev->speed == USB_SPEED_FULL
                                && highspeed_hubs != 0)
                        check_highspeed (hub, udev, port1);

                /* Store the parent's children[] pointer.  At this point
                 * udev becomes globally accessible, although presumably
                 * no one will look at it until hdev is unlocked.
                 */
                status = 0;

                mutex_lock(&usb_port_peer_mutex);

                /* We mustn't add new devices if the parent hub has
                 * been disconnected; we would race with the
                 * recursively_mark_NOTATTACHED() routine.
                 */
                spin_lock_irq(&device_state_lock);
                if (hdev->state == USB_STATE_NOTATTACHED)
                        status = -ENOTCONN;
                else
                        port_dev->child = udev;
                spin_unlock_irq(&device_state_lock);
                mutex_unlock(&usb_port_peer_mutex);

                /* Run it through the hoops (find a driver, etc) */
                if (!status) {
                        status = usb_new_device(udev);
                        if (status) {
                                mutex_lock(&usb_port_peer_mutex);
                                spin_lock_irq(&device_state_lock);
                                port_dev->child = NULL;
                                spin_unlock_irq(&device_state_lock);
                                mutex_unlock(&usb_port_peer_mutex);
                        }
                }

                if (status)
                        goto loop_disable;

                status = hub_power_remaining(hub);
                if (status)
                        dev_dbg(hub->intfdev, "%dmA power budget left\n", status);

                return;

loop_disable:
                hub_port_disable(hub, port1, 1);
loop:
                usb_ep0_reinit(udev);
                release_devnum(udev);
                hub_free_dev(udev);
                usb_put_dev(udev);
                if ((status == -ENOTCONN) || (status == -ENOTSUPP))
                        break;
        }
        if (hub->hdev->parent ||
                        !hcd->driver->port_handed_over ||
                        !(hcd->driver->port_handed_over)(hcd, port1)) {
                if (status != -ENOTCONN && status != -ENODEV)
                        dev_err(&port_dev->dev,
                                        "unable to enumerate USB device\n");
        }

done:
        hub_port_disable(hub, port1, 1);
        if (hcd->driver->relinquish_port && !hub->hdev->parent)
                hcd->driver->relinquish_port(hcd, port1);

}

/* Handle physical or logical connection change events.
 * This routine is called when:
 *      a port connection-change occurs;
 *      a port enable-change occurs (often caused by EMI);
 *      usb_reset_and_verify_device() encounters changed descriptors (as from
 *              a firmware download)
 * caller already locked the hub
 */
static void hub_port_connect_change(struct usb_hub *hub, int port1,
                                        u16 portstatus, u16 portchange)
                __must_hold(&port_dev->status_lock)
{
        struct usb_port *port_dev = hub->ports[port1 - 1];
        struct usb_device *udev = port_dev->child;
        int status = -ENODEV;

        dev_dbg(&port_dev->dev, "status %04x, change %04x, %s\n", portstatus,
                        portchange, portspeed(hub, portstatus));

        if (hub->has_indicators) {
                set_port_led(hub, port1, HUB_LED_AUTO);
                hub->indicator[port1-1] = INDICATOR_AUTO;
        }

#ifdef  CONFIG_USB_OTG
        /* during HNP, don't repeat the debounce */
        if (hub->hdev->bus->is_b_host)
                portchange &= ~(USB_PORT_STAT_C_CONNECTION |
                                USB_PORT_STAT_C_ENABLE);
#endif

        /* Try to resuscitate an existing device */
        if ((portstatus & USB_PORT_STAT_CONNECTION) && udev &&
                        udev->state != USB_STATE_NOTATTACHED) {
                if (portstatus & USB_PORT_STAT_ENABLE) {
                        status = 0;             /* Nothing to do */
#ifdef CONFIG_PM_RUNTIME
                } else if (udev->state == USB_STATE_SUSPENDED &&
                                udev->persist_enabled) {
                        /* For a suspended device, treat this as a
                         * remote wakeup event.
                         */
                        usb_unlock_port(port_dev);
                        status = usb_remote_wakeup(udev);
                        usb_lock_port(port_dev);
#endif
                } else {
                        /* Don't resuscitate */;
                }
        }
        clear_bit(port1, hub->change_bits);

        /* successfully revalidated the connection */
        if (status == 0)
                return;

        usb_unlock_port(port_dev);
        hub_port_connect(hub, port1, portstatus, portchange);
        usb_lock_port(port_dev);
}

static void port_event(struct usb_hub *hub, int port1)
                __must_hold(&port_dev->status_lock)
{
        int connect_change, reset_device = 0;
        struct usb_port *port_dev = hub->ports[port1 - 1];
        struct usb_device *udev = port_dev->child;
        struct usb_device *hdev = hub->hdev;
        u16 portstatus, portchange;

        connect_change = test_bit(port1, hub->change_bits);
        clear_bit(port1, hub->event_bits);
        clear_bit(port1, hub->wakeup_bits);

        if (hub_port_status(hub, port1, &portstatus, &portchange) < 0)
                return;

        if (portchange & USB_PORT_STAT_C_CONNECTION) {
                usb_clear_port_feature(hdev, port1, USB_PORT_FEAT_C_CONNECTION);
                connect_change = 1;
        }

        if (portchange & USB_PORT_STAT_C_ENABLE) {
                if (!connect_change)
                        dev_dbg(&port_dev->dev, "enable change, status %08x\n",
                                        portstatus);
                usb_clear_port_feature(hdev, port1, USB_PORT_FEAT_C_ENABLE);

                /*
                 * EM interference sometimes causes badly shielded USB devices
                 * to be shutdown by the hub, this hack enables them again.
                 * Works at least with mouse driver.
                 */
                if (!(portstatus & USB_PORT_STAT_ENABLE)
                    && !connect_change && udev) {
                        dev_err(&port_dev->dev, "disabled by hub (EMI?), re-enabling...\n");
                        connect_change = 1;
                }
        }

        if (portchange & USB_PORT_STAT_C_OVERCURRENT) {
                u16 status = 0, unused;

                dev_dbg(&port_dev->dev, "over-current change\n");
                usb_clear_port_feature(hdev, port1,
                                USB_PORT_FEAT_C_OVER_CURRENT);
                msleep(100);    /* Cool down */
                hub_power_on(hub, true);
                hub_port_status(hub, port1, &status, &unused);
                if (status & USB_PORT_STAT_OVERCURRENT)
                        dev_err(&port_dev->dev, "over-current condition\n");
        }

        if (portchange & USB_PORT_STAT_C_RESET) {
                dev_dbg(&port_dev->dev, "reset change\n");
                usb_clear_port_feature(hdev, port1, USB_PORT_FEAT_C_RESET);
        }
        if ((portchange & USB_PORT_STAT_C_BH_RESET)
            && hub_is_superspeed(hdev)) {
                dev_dbg(&port_dev->dev, "warm reset change\n");
                usb_clear_port_feature(hdev, port1,
                                USB_PORT_FEAT_C_BH_PORT_RESET);
        }
        if (portchange & USB_PORT_STAT_C_LINK_STATE) {
                dev_dbg(&port_dev->dev, "link state change\n");
                usb_clear_port_feature(hdev, port1,
                                USB_PORT_FEAT_C_PORT_LINK_STATE);
        }
        if (portchange & USB_PORT_STAT_C_CONFIG_ERROR) {
                dev_warn(&port_dev->dev, "config error\n");
                usb_clear_port_feature(hdev, port1,
                                USB_PORT_FEAT_C_PORT_CONFIG_ERROR);
        }

        /* skip port actions that require the port to be powered on */
        if (!pm_runtime_active(&port_dev->dev))
                return;

        if (hub_handle_remote_wakeup(hub, port1, portstatus, portchange))
                connect_change = 1;

        /*
         * Warm reset a USB3 protocol port if it's in
         * SS.Inactive state.
         */
        if (hub_port_warm_reset_required(hub, portstatus)) {
                dev_dbg(&port_dev->dev, "do warm reset\n");
                if (!udev || !(portstatus & USB_PORT_STAT_CONNECTION)
                                || udev->state == USB_STATE_NOTATTACHED) {
                        if (hub_port_reset(hub, port1, NULL,
                                        HUB_BH_RESET_TIME, true) < 0)
                                hub_port_disable(hub, port1, 1);
                } else
                        reset_device = 1;
        }

        /*
         * On disconnect USB3 protocol ports transit from U0 to
         * SS.Inactive to Rx.Detect. If this happens a warm-
         * reset is not needed, but a (re)connect may happen
         * before khubd runs and sees the disconnect, and the
         * device may be an unknown state.
         *
         * If the port went through SS.Inactive without khubd
         * seeing it the C_LINK_STATE change flag will be set,
         * and we reset the dev to put it in a known state.
         */
        if (reset_device || (udev && hub_is_superspeed(hub->hdev)
                                && (portchange & USB_PORT_STAT_C_LINK_STATE)
                                && (portstatus & USB_PORT_STAT_CONNECTION))) {
                usb_unlock_port(port_dev);
                usb_lock_device(udev);
                usb_reset_device(udev);
                usb_unlock_device(udev);
                usb_lock_port(port_dev);
                connect_change = 0;
        }

        if (connect_change)
                hub_port_connect_change(hub, port1, portstatus, portchange);
}


static void hub_events(void)
{
        struct list_head *tmp;
        struct usb_device *hdev;
        struct usb_interface *intf;
        struct usb_hub *hub;
        struct device *hub_dev;
        u16 hubstatus;
        u16 hubchange;
        int i, ret;

        /*
         *  We restart the list every time to avoid a deadlock with
         * deleting hubs downstream from this one. This should be
         * safe since we delete the hub from the event list.
         * Not the most efficient, but avoids deadlocks.
         */
        while (1) {

                /* Grab the first entry at the beginning of the list */
                spin_lock_irq(&hub_event_lock);
                if (list_empty(&hub_event_list)) {
                        spin_unlock_irq(&hub_event_lock);
                        break;
                }

                tmp = hub_event_list.next;
                list_del_init(tmp);

                hub = list_entry(tmp, struct usb_hub, event_list);
                kref_get(&hub->kref);
                spin_unlock_irq(&hub_event_lock);

                hdev = hub->hdev;
                hub_dev = hub->intfdev;
                intf = to_usb_interface(hub_dev);
                dev_dbg(hub_dev, "state %d ports %d chg %04x evt %04x\n",
                                hdev->state, hdev->maxchild,
                                /* NOTE: expects max 15 ports... */
                                (u16) hub->change_bits[0],
                                (u16) hub->event_bits[0]);

                /* Lock the device, then check to see if we were
                 * disconnected while waiting for the lock to succeed. */
                usb_lock_device(hdev);
                if (unlikely(hub->disconnected))
                        goto loop_disconnected;

                /* If the hub has died, clean up after it */
                if (hdev->state == USB_STATE_NOTATTACHED) {
                        hub->error = -ENODEV;
                        hub_quiesce(hub, HUB_DISCONNECT);
                        goto loop;
                }

                /* Autoresume */
                ret = usb_autopm_get_interface(intf);
                if (ret) {
                        dev_dbg(hub_dev, "Can't autoresume: %d\n", ret);
                        goto loop;
                }

                /* If this is an inactive hub, do nothing */
                if (hub->quiescing)
                        goto loop_autopm;

                if (hub->error) {
                        dev_dbg (hub_dev, "resetting for error %d\n",
                                hub->error);

                        ret = usb_reset_device(hdev);
                        if (ret) {
                                dev_dbg (hub_dev,
                                        "error resetting hub: %d\n", ret);
                                goto loop_autopm;
                        }

                        hub->nerrors = 0;
                        hub->error = 0;
                }

                /* deal with port status changes */
                for (i = 1; i <= hdev->maxchild; i++) {
                        struct usb_port *port_dev = hub->ports[i - 1];

                        if (test_bit(i, hub->event_bits)
                                        || test_bit(i, hub->change_bits)
                                        || test_bit(i, hub->wakeup_bits)) {
                                /*
                                 * The get_noresume and barrier ensure that if
                                 * the port was in the process of resuming, we
                                 * flush that work and keep the port active for
                                 * the duration of the port_event().  However,
                                 * if the port is runtime pm suspended
                                 * (powered-off), we leave it in that state, run
                                 * an abbreviated port_event(), and move on.
                                 */
                                pm_runtime_get_noresume(&port_dev->dev);
                                pm_runtime_barrier(&port_dev->dev);
                                usb_lock_port(port_dev);
                                port_event(hub, i);
                                usb_unlock_port(port_dev);
                                pm_runtime_put_sync(&port_dev->dev);
                        }
                }

                /* deal with hub status changes */
                if (test_and_clear_bit(0, hub->event_bits) == 0)
                        ;       /* do nothing */
                else if (hub_hub_status(hub, &hubstatus, &hubchange) < 0)
                        dev_err (hub_dev, "get_hub_status failed\n");
                else {
                        if (hubchange & HUB_CHANGE_LOCAL_POWER) {
                                dev_dbg (hub_dev, "power change\n");
                                clear_hub_feature(hdev, C_HUB_LOCAL_POWER);
                                if (hubstatus & HUB_STATUS_LOCAL_POWER)
                                        /* FIXME: Is this always true? */
                                        hub->limited_power = 1;
                                else
                                        hub->limited_power = 0;
                        }
                        if (hubchange & HUB_CHANGE_OVERCURRENT) {
                                u16 status = 0;
                                u16 unused;

                                dev_dbg(hub_dev, "over-current change\n");
                                clear_hub_feature(hdev, C_HUB_OVER_CURRENT);
                                msleep(500);    /* Cool down */
                                hub_power_on(hub, true);
                                hub_hub_status(hub, &status, &unused);
                                if (status & HUB_STATUS_OVERCURRENT)
                                        dev_err(hub_dev, "over-current "
                                                "condition\n");
                        }
                }

 loop_autopm:
                /* Balance the usb_autopm_get_interface() above */
                usb_autopm_put_interface_no_suspend(intf);
 loop:
                /* Balance the usb_autopm_get_interface_no_resume() in
                 * kick_khubd() and allow autosuspend.
                 */
                usb_autopm_put_interface(intf);
 loop_disconnected:
                usb_unlock_device(hdev);
                kref_put(&hub->kref, hub_release);

        } /* end while (1) */
}

static int hub_thread(void *__unused)
{
        /* khubd needs to be freezable to avoid interfering with USB-PERSIST
         * port handover.  Otherwise it might see that a full-speed device
         * was gone before the EHCI controller had handed its port over to
         * the companion full-speed controller.
         */
        set_freezable();

        do {
                hub_events();
                wait_event_freezable(khubd_wait,
                                !list_empty(&hub_event_list) ||
                                kthread_should_stop());
        } while (!kthread_should_stop() || !list_empty(&hub_event_list));

        pr_debug("%s: khubd exiting\n", usbcore_name);
        return 0;
}

static const struct usb_device_id hub_id_table[] = {
    { .match_flags = USB_DEVICE_ID_MATCH_VENDOR
                        | USB_DEVICE_ID_MATCH_INT_CLASS,
      .idVendor = USB_VENDOR_GENESYS_LOGIC,
      .bInterfaceClass = USB_CLASS_HUB,
      .driver_info = HUB_QUIRK_CHECK_PORT_AUTOSUSPEND},
    { .match_flags = USB_DEVICE_ID_MATCH_DEV_CLASS,
      .bDeviceClass = USB_CLASS_HUB},
    { .match_flags = USB_DEVICE_ID_MATCH_INT_CLASS,
      .bInterfaceClass = USB_CLASS_HUB},
    { }                                         /* Terminating entry */
};

MODULE_DEVICE_TABLE (usb, hub_id_table);

static struct usb_driver hub_driver = {
        .name =         "hub",
        .probe =        hub_probe,
        .disconnect =   hub_disconnect,
        .suspend =      hub_suspend,
        .resume =       hub_resume,
        .reset_resume = hub_reset_resume,
        .pre_reset =    hub_pre_reset,
        .post_reset =   hub_post_reset,
        .unlocked_ioctl = hub_ioctl,
        .id_table =     hub_id_table,
        .supports_autosuspend = 1,
};

int usb_hub_init(void)
{
        if (usb_register(&hub_driver) < 0) {
                printk(KERN_ERR "%s: can't register hub driver\n",
                        usbcore_name);
                return -1;
        }

        khubd_task = kthread_run(hub_thread, NULL, "khubd");
        if (!IS_ERR(khubd_task))
                return 0;

        /* Fall through if kernel_thread failed */
        usb_deregister(&hub_driver);
        printk(KERN_ERR "%s: can't start khubd\n", usbcore_name);

        return -1;
}

void usb_hub_cleanup(void)
{
        kthread_stop(khubd_task);

        /*
         * Hub resources are freed for us by usb_deregister. It calls
         * usb_driver_purge on every device which in turn calls that
         * devices disconnect function if it is using this driver.
         * The hub_disconnect function takes care of releasing the
         * individual hub resources. -greg
         */
        usb_deregister(&hub_driver);
} /* usb_hub_cleanup() */

static int descriptors_changed(struct usb_device *udev,
                struct usb_device_descriptor *old_device_descriptor,
                struct usb_host_bos *old_bos)
{
        int             changed = 0;
        unsigned        index;
        unsigned        serial_len = 0;
        unsigned        len;
        unsigned        old_length;
        int             length;
        char            *buf;

        if (memcmp(&udev->descriptor, old_device_descriptor,
                        sizeof(*old_device_descriptor)) != 0)
                return 1;

        if ((old_bos && !udev->bos) || (!old_bos && udev->bos))
                return 1;
        if (udev->bos) {
                len = le16_to_cpu(udev->bos->desc->wTotalLength);
                if (len != le16_to_cpu(old_bos->desc->wTotalLength))
                        return 1;
                if (memcmp(udev->bos->desc, old_bos->desc, len))
                        return 1;
        }

        /* Since the idVendor, idProduct, and bcdDevice values in the
         * device descriptor haven't changed, we will assume the
         * Manufacturer and Product strings haven't changed either.
         * But the SerialNumber string could be different (e.g., a
         * different flash card of the same brand).
         */
        if (udev->serial)
                serial_len = strlen(udev->serial) + 1;

        len = serial_len;
        for (index = 0; index < udev->descriptor.bNumConfigurations; index++) {
                old_length = le16_to_cpu(udev->config[index].desc.wTotalLength);
                len = max(len, old_length);
        }

        buf = kmalloc(len, GFP_NOIO);
        if (buf == NULL) {
                dev_err(&udev->dev, "no mem to re-read configs after reset\n");
                /* assume the worst */
                return 1;
        }
        for (index = 0; index < udev->descriptor.bNumConfigurations; index++) {
                old_length = le16_to_cpu(udev->config[index].desc.wTotalLength);
                length = usb_get_descriptor(udev, USB_DT_CONFIG, index, buf,
                                old_length);
                if (length != old_length) {
                        dev_dbg(&udev->dev, "config index %d, error %d\n",
                                        index, length);
                        changed = 1;
                        break;
                }
                if (memcmp (buf, udev->rawdescriptors[index], old_length)
                                != 0) {
                        dev_dbg(&udev->dev, "config index %d changed (#%d)\n",
                                index,
                                ((struct usb_config_descriptor *) buf)->
                                        bConfigurationValue);
                        changed = 1;
                        break;
                }
        }

        if (!changed && serial_len) {
                length = usb_string(udev, udev->descriptor.iSerialNumber,
                                buf, serial_len);
                if (length + 1 != serial_len) {
                        dev_dbg(&udev->dev, "serial string error %d\n",
                                        length);
                        changed = 1;
                } else if (memcmp(buf, udev->serial, length) != 0) {
                        dev_dbg(&udev->dev, "serial string changed\n");
                        changed = 1;
                }
        }

        kfree(buf);
        return changed;
}

/**
 * usb_reset_and_verify_device - perform a USB port reset to reinitialize a device
 * @udev: device to reset (not in SUSPENDED or NOTATTACHED state)
 *
 * WARNING - don't use this routine to reset a composite device
 * (one with multiple interfaces owned by separate drivers)!
 * Use usb_reset_device() instead.
 *
 * Do a port reset, reassign the device's address, and establish its
 * former operating configuration.  If the reset fails, or the device's
 * descriptors change from their values before the reset, or the original
 * configuration and altsettings cannot be restored, a flag will be set
 * telling khubd to pretend the device has been disconnected and then
 * re-connected.  All drivers will be unbound, and the device will be
 * re-enumerated and probed all over again.
 *
 * Return: 0 if the reset succeeded, -ENODEV if the device has been
 * flagged for logical disconnection, or some other negative error code
 * if the reset wasn't even attempted.
 *
 * Note:
 * The caller must own the device lock and the port lock, the latter is
 * taken by usb_reset_device().  For example, it's safe to use
 * usb_reset_device() from a driver probe() routine after downloading
 * new firmware.  For calls that might not occur during probe(), drivers
 * should lock the device using usb_lock_device_for_reset().
 *
 * Locking exception: This routine may also be called from within an
 * autoresume handler.  Such usage won't conflict with other tasks
 * holding the device lock because these tasks should always call
 * usb_autopm_resume_device(), thereby preventing any unwanted
 * autoresume.  The autoresume handler is expected to have already
 * acquired the port lock before calling this routine.
 */
static int usb_reset_and_verify_device(struct usb_device *udev)
{
        struct usb_device               *parent_hdev = udev->parent;
        struct usb_hub                  *parent_hub;
        struct usb_hcd                  *hcd = bus_to_hcd(udev->bus);
        struct usb_device_descriptor    descriptor = udev->descriptor;
        struct usb_host_bos             *bos;
        int                             i, j, ret = 0;
        int                             port1 = udev->portnum;

        if (udev->state == USB_STATE_NOTATTACHED ||
                        udev->state == USB_STATE_SUSPENDED) {
                dev_dbg(&udev->dev, "device reset not allowed in state %d\n",
                                udev->state);
                return -EINVAL;
        }

        if (!parent_hdev)
                return -EISDIR;

        parent_hub = usb_hub_to_struct_hub(parent_hdev);

        /* Disable USB2 hardware LPM.
         * It will be re-enabled by the enumeration process.
         */
        if (udev->usb2_hw_lpm_enabled == 1)
                usb_set_usb2_hardware_lpm(udev, 0);

        bos = udev->bos;
        udev->bos = NULL;

        /* Disable LPM and LTM while we reset the device and reinstall the alt
         * settings.  Device-initiated LPM settings, and system exit latency
         * settings are cleared when the device is reset, so we have to set
         * them up again.
         */
        ret = usb_unlocked_disable_lpm(udev);
        if (ret) {
                dev_err(&udev->dev, "%s Failed to disable LPM\n.", __func__);
                goto re_enumerate;
        }
        ret = usb_disable_ltm(udev);
        if (ret) {
                dev_err(&udev->dev, "%s Failed to disable LTM\n.",
                                __func__);
                goto re_enumerate;
        }

        for (i = 0; i < SET_CONFIG_TRIES; ++i) {

                /* ep0 maxpacket size may change; let the HCD know about it.
                 * Other endpoints will be handled by re-enumeration. */
                usb_ep0_reinit(udev);
                ret = hub_port_init(parent_hub, udev, port1, i);
                if (ret >= 0 || ret == -ENOTCONN || ret == -ENODEV)
                        break;
        }

        if (ret < 0)
                goto re_enumerate;

        /* Device might have changed firmware (DFU or similar) */
        if (descriptors_changed(udev, &descriptor, bos)) {
                dev_info(&udev->dev, "device firmware changed\n");
                udev->descriptor = descriptor;  /* for disconnect() calls */
                goto re_enumerate;
        }

        /* Restore the device's previous configuration */
        if (!udev->actconfig)
                goto done;

        mutex_lock(hcd->bandwidth_mutex);
        ret = usb_hcd_alloc_bandwidth(udev, udev->actconfig, NULL, NULL);
        if (ret < 0) {
                dev_warn(&udev->dev,
                                "Busted HC?  Not enough HCD resources for "
                                "old configuration.\n");
                mutex_unlock(hcd->bandwidth_mutex);
                goto re_enumerate;
        }
        ret = usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
                        USB_REQ_SET_CONFIGURATION, 0,
                        udev->actconfig->desc.bConfigurationValue, 0,
                        NULL, 0, USB_CTRL_SET_TIMEOUT);
        if (ret < 0) {
                dev_err(&udev->dev,
                        "can't restore configuration #%d (error=%d)\n",
                        udev->actconfig->desc.bConfigurationValue, ret);
                mutex_unlock(hcd->bandwidth_mutex);
                goto re_enumerate;
        }
        mutex_unlock(hcd->bandwidth_mutex);
        usb_set_device_state(udev, USB_STATE_CONFIGURED);

        /* Put interfaces back into the same altsettings as before.
         * Don't bother to send the Set-Interface request for interfaces
         * that were already in altsetting 0; besides being unnecessary,
         * many devices can't handle it.  Instead just reset the host-side
         * endpoint state.
         */
        for (i = 0; i < udev->actconfig->desc.bNumInterfaces; i++) {
                struct usb_host_config *config = udev->actconfig;
                struct usb_interface *intf = config->interface[i];
                struct usb_interface_descriptor *desc;

                desc = &intf->cur_altsetting->desc;
                if (desc->bAlternateSetting == 0) {
                        usb_disable_interface(udev, intf, true);
                        usb_enable_interface(udev, intf, true);
                        ret = 0;
                } else {
                        /* Let the bandwidth allocation function know that this
                         * device has been reset, and it will have to use
                         * alternate setting 0 as the current alternate setting.
                         */
                        intf->resetting_device = 1;
                        ret = usb_set_interface(udev, desc->bInterfaceNumber,
                                        desc->bAlternateSetting);
                        intf->resetting_device = 0;
                }
                if (ret < 0) {
                        dev_err(&udev->dev, "failed to restore interface %d "
                                "altsetting %d (error=%d)\n",
                                desc->bInterfaceNumber,
                                desc->bAlternateSetting,
                                ret);
                        goto re_enumerate;
                }
                /* Resetting also frees any allocated streams */
                for (j = 0; j < intf->cur_altsetting->desc.bNumEndpoints; j++)
                        intf->cur_altsetting->endpoint[j].streams = 0;
        }

done:
        /* Now that the alt settings are re-installed, enable LTM and LPM. */
        usb_set_usb2_hardware_lpm(udev, 1);
        usb_unlocked_enable_lpm(udev);
        usb_enable_ltm(udev);
        usb_release_bos_descriptor(udev);
        udev->bos = bos;
        return 0;

re_enumerate:
        /* LPM state doesn't matter when we're about to destroy the device. */
        hub_port_logical_disconnect(parent_hub, port1);
        usb_release_bos_descriptor(udev);
        udev->bos = bos;
        return -ENODEV;
}

/**
 * usb_reset_device - warn interface drivers and perform a USB port reset
 * @udev: device to reset (not in SUSPENDED or NOTATTACHED state)
 *
 * Warns all drivers bound to registered interfaces (using their pre_reset
 * method), performs the port reset, and then lets the drivers know that
 * the reset is over (using their post_reset method).
 *
 * Return: The same as for usb_reset_and_verify_device().
 *
 * Note:
 * The caller must own the device lock.  For example, it's safe to use
 * this from a driver probe() routine after downloading new firmware.
 * For calls that might not occur during probe(), drivers should lock
 * the device using usb_lock_device_for_reset().
 *
 * If an interface is currently being probed or disconnected, we assume
 * its driver knows how to handle resets.  For all other interfaces,
 * if the driver doesn't have pre_reset and post_reset methods then
 * we attempt to unbind it and rebind afterward.
 */
int usb_reset_device(struct usb_device *udev)
{
        int ret;
        int i;
        unsigned int noio_flag;
        struct usb_port *port_dev;
        struct usb_host_config *config = udev->actconfig;
        struct usb_hub *hub = usb_hub_to_struct_hub(udev->parent);

        if (udev->state == USB_STATE_NOTATTACHED ||
                        udev->state == USB_STATE_SUSPENDED) {
                dev_dbg(&udev->dev, "device reset not allowed in state %d\n",
                                udev->state);
                return -EINVAL;
        }

        if (!udev->parent) {
                /* this requires hcd-specific logic; see ohci_restart() */
                dev_dbg(&udev->dev, "%s for root hub!\n", __func__);
                return -EISDIR;
        }

        port_dev = hub->ports[udev->portnum - 1];

        /*
         * Don't allocate memory with GFP_KERNEL in current
         * context to avoid possible deadlock if usb mass
         * storage interface or usbnet interface(iSCSI case)
         * is included in current configuration. The easist
         * approach is to do it for every device reset,
         * because the device 'memalloc_noio' flag may have
         * not been set before reseting the usb device.
         */
        noio_flag = memalloc_noio_save();

        /* Prevent autosuspend during the reset */
        usb_autoresume_device(udev);

        if (config) {
                for (i = 0; i < config->desc.bNumInterfaces; ++i) {
                        struct usb_interface *cintf = config->interface[i];
                        struct usb_driver *drv;
                        int unbind = 0;

                        if (cintf->dev.driver) {
                                drv = to_usb_driver(cintf->dev.driver);
                                if (drv->pre_reset && drv->post_reset)
                                        unbind = (drv->pre_reset)(cintf);
                                else if (cintf->condition ==
                                                USB_INTERFACE_BOUND)
                                        unbind = 1;
                                if (unbind)
                                        usb_forced_unbind_intf(cintf);
                        }
                }
        }

        usb_lock_port(port_dev);
        ret = usb_reset_and_verify_device(udev);
        usb_unlock_port(port_dev);

        if (config) {
                for (i = config->desc.bNumInterfaces - 1; i >= 0; --i) {
                        struct usb_interface *cintf = config->interface[i];
                        struct usb_driver *drv;
                        int rebind = cintf->needs_binding;

                        if (!rebind && cintf->dev.driver) {
                                drv = to_usb_driver(cintf->dev.driver);
                                if (drv->post_reset)
                                        rebind = (drv->post_reset)(cintf);
                                else if (cintf->condition ==
                                                USB_INTERFACE_BOUND)
                                        rebind = 1;
                                if (rebind)
                                        cintf->needs_binding = 1;
                        }
                }
                usb_unbind_and_rebind_marked_interfaces(udev);
        }

        usb_autosuspend_device(udev);
        memalloc_noio_restore(noio_flag);
        return ret;
}
EXPORT_SYMBOL_GPL(usb_reset_device);


/**
 * usb_queue_reset_device - Reset a USB device from an atomic context
 * @iface: USB interface belonging to the device to reset
 *
 * This function can be used to reset a USB device from an atomic
 * context, where usb_reset_device() won't work (as it blocks).
 *
 * Doing a reset via this method is functionally equivalent to calling
 * usb_reset_device(), except for the fact that it is delayed to a
 * workqueue. This means that any drivers bound to other interfaces
 * might be unbound, as well as users from usbfs in user space.
 *
 * Corner cases:
 *
 * - Scheduling two resets at the same time from two different drivers
 *   attached to two different interfaces of the same device is
 *   possible; depending on how the driver attached to each interface
 *   handles ->pre_reset(), the second reset might happen or not.
 *
 * - If a driver is unbound and it had a pending reset, the reset will
 *   be cancelled.
 *
 * - This function can be called during .probe() or .disconnect()
 *   times. On return from .disconnect(), any pending resets will be
 *   cancelled.
 *
 * There is no no need to lock/unlock the @reset_ws as schedule_work()
 * does its own.
 *
 * NOTE: We don't do any reference count tracking because it is not
 *     needed. The lifecycle of the work_struct is tied to the
 *     usb_interface. Before destroying the interface we cancel the
 *     work_struct, so the fact that work_struct is queued and or
 *     running means the interface (and thus, the device) exist and
 *     are referenced.
 */
void usb_queue_reset_device(struct usb_interface *iface)
{
        schedule_work(&iface->reset_ws);
}
EXPORT_SYMBOL_GPL(usb_queue_reset_device);

/**
 * usb_hub_find_child - Get the pointer of child device
 * attached to the port which is specified by @port1.
 * @hdev: USB device belonging to the usb hub
 * @port1: port num to indicate which port the child device
 *      is attached to.
 *
 * USB drivers call this function to get hub's child device
 * pointer.
 *
 * Return: %NULL if input param is invalid and
 * child's usb_device pointer if non-NULL.
 */
struct usb_device *usb_hub_find_child(struct usb_device *hdev,
                int port1)
{
        struct usb_hub *hub = usb_hub_to_struct_hub(hdev);

        if (port1 < 1 || port1 > hdev->maxchild)
                return NULL;
        return hub->ports[port1 - 1]->child;
}
EXPORT_SYMBOL_GPL(usb_hub_find_child);

void usb_hub_adjust_deviceremovable(struct usb_device *hdev,
                struct usb_hub_descriptor *desc)
{
        struct usb_hub *hub = usb_hub_to_struct_hub(hdev);
        enum usb_port_connect_type connect_type;
        int i;

        if (!hub)
                return;

        if (!hub_is_superspeed(hdev)) {
                for (i = 1; i <= hdev->maxchild; i++) {
                        struct usb_port *port_dev = hub->ports[i - 1];

                        connect_type = port_dev->connect_type;
                        if (connect_type == USB_PORT_CONNECT_TYPE_HARD_WIRED) {
                                u8 mask = 1 << (i%8);

                                if (!(desc->u.hs.DeviceRemovable[i/8] & mask)) {
                                        dev_dbg(&port_dev->dev, "DeviceRemovable is changed to 1 according to platform information.\n");
                                        desc->u.hs.DeviceRemovable[i/8] |= mask;
                                }
                        }
                }
        } else {
                u16 port_removable = le16_to_cpu(desc->u.ss.DeviceRemovable);

                for (i = 1; i <= hdev->maxchild; i++) {
                        struct usb_port *port_dev = hub->ports[i - 1];

                        connect_type = port_dev->connect_type;
                        if (connect_type == USB_PORT_CONNECT_TYPE_HARD_WIRED) {
                                u16 mask = 1 << i;

                                if (!(port_removable & mask)) {
                                        dev_dbg(&port_dev->dev, "DeviceRemovable is changed to 1 according to platform information.\n");
                                        port_removable |= mask;
                                }
                        }
                }

                desc->u.ss.DeviceRemovable = cpu_to_le16(port_removable);
        }
}

#ifdef CONFIG_ACPI
/**
 * usb_get_hub_port_acpi_handle - Get the usb port's acpi handle
 * @hdev: USB device belonging to the usb hub
 * @port1: port num of the port
 *
 * Return: Port's acpi handle if successful, %NULL if params are
 * invalid.
 */
acpi_handle usb_get_hub_port_acpi_handle(struct usb_device *hdev,
        int port1)
{
        struct usb_hub *hub = usb_hub_to_struct_hub(hdev);

        if (!hub)
                return NULL;

        return ACPI_HANDLE(&hub->ports[port1 - 1]->dev);
}
#endif