mptcp: ensure snd_nxt is properly initialized on connect

[linux.git] / drivers / s390 / crypto / ap_bus.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * Copyright IBM Corp. 2006, 2023
 * Author(s): Cornelia Huck <[email protected]>
 *            Martin Schwidefsky <[email protected]>
 *            Ralph Wuerthner <[email protected]>
 *            Felix Beck <[email protected]>
 *            Holger Dengler <[email protected]>
 *            Harald Freudenberger <[email protected]>
 *
 * Adjunct processor bus.
 */

#define KMSG_COMPONENT "ap"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

#include <linux/kernel_stat.h>
#include <linux/moduleparam.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/freezer.h>
#include <linux/interrupt.h>
#include <linux/workqueue.h>
#include <linux/slab.h>
#include <linux/notifier.h>
#include <linux/kthread.h>
#include <linux/mutex.h>
#include <asm/airq.h>
#include <asm/tpi.h>
#include <linux/atomic.h>
#include <asm/isc.h>
#include <linux/hrtimer.h>
#include <linux/ktime.h>
#include <asm/facility.h>
#include <linux/crypto.h>
#include <linux/mod_devicetable.h>
#include <linux/debugfs.h>
#include <linux/ctype.h>
#include <linux/module.h>
#include <asm/uv.h>

#include "ap_bus.h"
#include "ap_debug.h"

/*
 * Module parameters; note though this file itself isn't modular.
 */
int ap_domain_index = -1;       /* Adjunct Processor Domain Index */
static DEFINE_SPINLOCK(ap_domain_lock);
module_param_named(domain, ap_domain_index, int, 0440);
MODULE_PARM_DESC(domain, "domain index for ap devices");
EXPORT_SYMBOL(ap_domain_index);

static int ap_thread_flag;
module_param_named(poll_thread, ap_thread_flag, int, 0440);
MODULE_PARM_DESC(poll_thread, "Turn on/off poll thread, default is 0 (off).");

static char *apm_str;
module_param_named(apmask, apm_str, charp, 0440);
MODULE_PARM_DESC(apmask, "AP bus adapter mask.");

static char *aqm_str;
module_param_named(aqmask, aqm_str, charp, 0440);
MODULE_PARM_DESC(aqmask, "AP bus domain mask.");

static int ap_useirq = 1;
module_param_named(useirq, ap_useirq, int, 0440);
MODULE_PARM_DESC(useirq, "Use interrupt if available, default is 1 (on).");

atomic_t ap_max_msg_size = ATOMIC_INIT(AP_DEFAULT_MAX_MSG_SIZE);
EXPORT_SYMBOL(ap_max_msg_size);

static struct device *ap_root_device;

/* Hashtable of all queue devices on the AP bus */
DEFINE_HASHTABLE(ap_queues, 8);
/* lock used for the ap_queues hashtable */
DEFINE_SPINLOCK(ap_queues_lock);

/* Default permissions (ioctl, card and domain masking) */
struct ap_perms ap_perms;
EXPORT_SYMBOL(ap_perms);
DEFINE_MUTEX(ap_perms_mutex);
EXPORT_SYMBOL(ap_perms_mutex);

/* # of bindings complete since init */
static atomic64_t ap_bindings_complete_count = ATOMIC64_INIT(0);

/* completion for APQN bindings complete */
static DECLARE_COMPLETION(ap_apqn_bindings_complete);

static struct ap_config_info *ap_qci_info;
static struct ap_config_info *ap_qci_info_old;

/*
 * AP bus related debug feature things.
 */
debug_info_t *ap_dbf_info;

/*
 * AP bus rescan related things.
 */
static bool ap_scan_bus(void);
static bool ap_scan_bus_result; /* result of last ap_scan_bus() */
static DEFINE_MUTEX(ap_scan_bus_mutex); /* mutex ap_scan_bus() invocations */
static atomic64_t ap_scan_bus_count; /* counter ap_scan_bus() invocations */
static int ap_scan_bus_time = AP_CONFIG_TIME;
static struct timer_list ap_scan_bus_timer;
static void ap_scan_bus_wq_callback(struct work_struct *);
static DECLARE_WORK(ap_scan_bus_work, ap_scan_bus_wq_callback);

/*
 * Tasklet & timer for AP request polling and interrupts
 */
static void ap_tasklet_fn(unsigned long);
static DECLARE_TASKLET_OLD(ap_tasklet, ap_tasklet_fn);
static DECLARE_WAIT_QUEUE_HEAD(ap_poll_wait);
static struct task_struct *ap_poll_kthread;
static DEFINE_MUTEX(ap_poll_thread_mutex);
static DEFINE_SPINLOCK(ap_poll_timer_lock);
static struct hrtimer ap_poll_timer;
/*
 * In LPAR poll with 4kHz frequency. Poll every 250000 nanoseconds.
 * If z/VM change to 1500000 nanoseconds to adjust to z/VM polling.
 */
static unsigned long poll_high_timeout = 250000UL;

/*
 * Some state machine states only require a low frequency polling.
 * We use 25 Hz frequency for these.
 */
static unsigned long poll_low_timeout = 40000000UL;

/* Maximum domain id, if not given via qci */
static int ap_max_domain_id = 15;
/* Maximum adapter id, if not given via qci */
static int ap_max_adapter_id = 63;

static const struct bus_type ap_bus_type;

/* Adapter interrupt definitions */
static void ap_interrupt_handler(struct airq_struct *airq,
                                 struct tpi_info *tpi_info);

static bool ap_irq_flag;

static struct airq_struct ap_airq = {
        .handler = ap_interrupt_handler,
        .isc = AP_ISC,
};

/**
 * ap_airq_ptr() - Get the address of the adapter interrupt indicator
 *
 * Returns the address of the local-summary-indicator of the adapter
 * interrupt handler for AP, or NULL if adapter interrupts are not
 * available.
 */
void *ap_airq_ptr(void)
{
        if (ap_irq_flag)
                return ap_airq.lsi_ptr;
        return NULL;
}

/**
 * ap_interrupts_available(): Test if AP interrupts are available.
 *
 * Returns 1 if AP interrupts are available.
 */
static int ap_interrupts_available(void)
{
        return test_facility(65);
}

/**
 * ap_qci_available(): Test if AP configuration
 * information can be queried via QCI subfunction.
 *
 * Returns 1 if subfunction PQAP(QCI) is available.
 */
static int ap_qci_available(void)
{
        return test_facility(12);
}

/**
 * ap_apft_available(): Test if AP facilities test (APFT)
 * facility is available.
 *
 * Returns 1 if APFT is available.
 */
static int ap_apft_available(void)
{
        return test_facility(15);
}

/*
 * ap_qact_available(): Test if the PQAP(QACT) subfunction is available.
 *
 * Returns 1 if the QACT subfunction is available.
 */
static inline int ap_qact_available(void)
{
        if (ap_qci_info)
                return ap_qci_info->qact;
        return 0;
}

/*
 * ap_sb_available(): Test if the AP secure binding facility is available.
 *
 * Returns 1 if secure binding facility is available.
 */
int ap_sb_available(void)
{
        if (ap_qci_info)
                return ap_qci_info->apsb;
        return 0;
}

/*
 * ap_is_se_guest(): Check for SE guest with AP pass-through support.
 */
bool ap_is_se_guest(void)
{
        return is_prot_virt_guest() && ap_sb_available();
}
EXPORT_SYMBOL(ap_is_se_guest);

/*
 * ap_fetch_qci_info(): Fetch cryptographic config info
 *
 * Returns the ap configuration info fetched via PQAP(QCI).
 * On success 0 is returned, on failure a negative errno
 * is returned, e.g. if the PQAP(QCI) instruction is not
 * available, the return value will be -EOPNOTSUPP.
 */
static inline int ap_fetch_qci_info(struct ap_config_info *info)
{
        if (!ap_qci_available())
                return -EOPNOTSUPP;
        if (!info)
                return -EINVAL;
        return ap_qci(info);
}

/**
 * ap_init_qci_info(): Allocate and query qci config info.
 * Does also update the static variables ap_max_domain_id
 * and ap_max_adapter_id if this info is available.
 */
static void __init ap_init_qci_info(void)
{
        if (!ap_qci_available()) {
                AP_DBF_INFO("%s QCI not supported\n", __func__);
                return;
        }

        ap_qci_info = kzalloc(sizeof(*ap_qci_info), GFP_KERNEL);
        if (!ap_qci_info)
                return;
        ap_qci_info_old = kzalloc(sizeof(*ap_qci_info_old), GFP_KERNEL);
        if (!ap_qci_info_old) {
                kfree(ap_qci_info);
                ap_qci_info = NULL;
                return;
        }
        if (ap_fetch_qci_info(ap_qci_info) != 0) {
                kfree(ap_qci_info);
                kfree(ap_qci_info_old);
                ap_qci_info = NULL;
                ap_qci_info_old = NULL;
                return;
        }
        AP_DBF_INFO("%s successful fetched initial qci info\n", __func__);

        if (ap_qci_info->apxa) {
                if (ap_qci_info->na) {
                        ap_max_adapter_id = ap_qci_info->na;
                        AP_DBF_INFO("%s new ap_max_adapter_id is %d\n",
                                    __func__, ap_max_adapter_id);
                }
                if (ap_qci_info->nd) {
                        ap_max_domain_id = ap_qci_info->nd;
                        AP_DBF_INFO("%s new ap_max_domain_id is %d\n",
                                    __func__, ap_max_domain_id);
                }
        }

        memcpy(ap_qci_info_old, ap_qci_info, sizeof(*ap_qci_info));
}

/*
 * ap_test_config(): helper function to extract the nrth bit
 *                   within the unsigned int array field.
 */
static inline int ap_test_config(unsigned int *field, unsigned int nr)
{
        return ap_test_bit((field + (nr >> 5)), (nr & 0x1f));
}

/*
 * ap_test_config_card_id(): Test, whether an AP card ID is configured.
 *
 * Returns 0 if the card is not configured
 *         1 if the card is configured or
 *           if the configuration information is not available
 */
static inline int ap_test_config_card_id(unsigned int id)
{
        if (id > ap_max_adapter_id)
                return 0;
        if (ap_qci_info)
                return ap_test_config(ap_qci_info->apm, id);
        return 1;
}

/*
 * ap_test_config_usage_domain(): Test, whether an AP usage domain
 * is configured.
 *
 * Returns 0 if the usage domain is not configured
 *         1 if the usage domain is configured or
 *           if the configuration information is not available
 */
int ap_test_config_usage_domain(unsigned int domain)
{
        if (domain > ap_max_domain_id)
                return 0;
        if (ap_qci_info)
                return ap_test_config(ap_qci_info->aqm, domain);
        return 1;
}
EXPORT_SYMBOL(ap_test_config_usage_domain);

/*
 * ap_test_config_ctrl_domain(): Test, whether an AP control domain
 * is configured.
 * @domain AP control domain ID
 *
 * Returns 1 if the control domain is configured
 *         0 in all other cases
 */
int ap_test_config_ctrl_domain(unsigned int domain)
{
        if (!ap_qci_info || domain > ap_max_domain_id)
                return 0;
        return ap_test_config(ap_qci_info->adm, domain);
}
EXPORT_SYMBOL(ap_test_config_ctrl_domain);

/*
 * ap_queue_info(): Check and get AP queue info.
 * Returns: 1 if APQN exists and info is filled,
 *          0 if APQN seems to exist but there is no info
 *            available (eg. caused by an asynch pending error)
 *         -1 invalid APQN, TAPQ error or AP queue status which
 *            indicates there is no APQN.
 */
static int ap_queue_info(ap_qid_t qid, struct ap_tapq_hwinfo *hwinfo,
                         bool *decfg, bool *cstop)
{
        struct ap_queue_status status;

        hwinfo->value = 0;

        /* make sure we don't run into a specifiation exception */
        if (AP_QID_CARD(qid) > ap_max_adapter_id ||
            AP_QID_QUEUE(qid) > ap_max_domain_id)
                return -1;

        /* call TAPQ on this APQN */
        status = ap_test_queue(qid, ap_apft_available(), hwinfo);

        switch (status.response_code) {
        case AP_RESPONSE_NORMAL:
        case AP_RESPONSE_RESET_IN_PROGRESS:
        case AP_RESPONSE_DECONFIGURED:
        case AP_RESPONSE_CHECKSTOPPED:
        case AP_RESPONSE_BUSY:
                /* For all these RCs the tapq info should be available */
                break;
        default:
                /* On a pending async error the info should be available */
                if (!status.async)
                        return -1;
                break;
        }

        /* There should be at least one of the mode bits set */
        if (WARN_ON_ONCE(!hwinfo->value))
                return 0;

        *decfg = status.response_code == AP_RESPONSE_DECONFIGURED;
        *cstop = status.response_code == AP_RESPONSE_CHECKSTOPPED;

        return 1;
}

void ap_wait(enum ap_sm_wait wait)
{
        ktime_t hr_time;

        switch (wait) {
        case AP_SM_WAIT_AGAIN:
        case AP_SM_WAIT_INTERRUPT:
                if (ap_irq_flag)
                        break;
                if (ap_poll_kthread) {
                        wake_up(&ap_poll_wait);
                        break;
                }
                fallthrough;
        case AP_SM_WAIT_LOW_TIMEOUT:
        case AP_SM_WAIT_HIGH_TIMEOUT:
                spin_lock_bh(&ap_poll_timer_lock);
                if (!hrtimer_is_queued(&ap_poll_timer)) {
                        hr_time =
                                wait == AP_SM_WAIT_LOW_TIMEOUT ?
                                poll_low_timeout : poll_high_timeout;
                        hrtimer_forward_now(&ap_poll_timer, hr_time);
                        hrtimer_restart(&ap_poll_timer);
                }
                spin_unlock_bh(&ap_poll_timer_lock);
                break;
        case AP_SM_WAIT_NONE:
        default:
                break;
        }
}

/**
 * ap_request_timeout(): Handling of request timeouts
 * @t: timer making this callback
 *
 * Handles request timeouts.
 */
void ap_request_timeout(struct timer_list *t)
{
        struct ap_queue *aq = from_timer(aq, t, timeout);

        spin_lock_bh(&aq->lock);
        ap_wait(ap_sm_event(aq, AP_SM_EVENT_TIMEOUT));
        spin_unlock_bh(&aq->lock);
}

/**
 * ap_poll_timeout(): AP receive polling for finished AP requests.
 * @unused: Unused pointer.
 *
 * Schedules the AP tasklet using a high resolution timer.
 */
static enum hrtimer_restart ap_poll_timeout(struct hrtimer *unused)
{
        tasklet_schedule(&ap_tasklet);
        return HRTIMER_NORESTART;
}

/**
 * ap_interrupt_handler() - Schedule ap_tasklet on interrupt
 * @airq: pointer to adapter interrupt descriptor
 * @tpi_info: ignored
 */
static void ap_interrupt_handler(struct airq_struct *airq,
                                 struct tpi_info *tpi_info)
{
        inc_irq_stat(IRQIO_APB);
        tasklet_schedule(&ap_tasklet);
}

/**
 * ap_tasklet_fn(): Tasklet to poll all AP devices.
 * @dummy: Unused variable
 *
 * Poll all AP devices on the bus.
 */
static void ap_tasklet_fn(unsigned long dummy)
{
        int bkt;
        struct ap_queue *aq;
        enum ap_sm_wait wait = AP_SM_WAIT_NONE;

        /* Reset the indicator if interrupts are used. Thus new interrupts can
         * be received. Doing it in the beginning of the tasklet is therefore
         * important that no requests on any AP get lost.
         */
        if (ap_irq_flag)
                xchg(ap_airq.lsi_ptr, 0);

        spin_lock_bh(&ap_queues_lock);
        hash_for_each(ap_queues, bkt, aq, hnode) {
                spin_lock_bh(&aq->lock);
                wait = min(wait, ap_sm_event_loop(aq, AP_SM_EVENT_POLL));
                spin_unlock_bh(&aq->lock);
        }
        spin_unlock_bh(&ap_queues_lock);

        ap_wait(wait);
}

static int ap_pending_requests(void)
{
        int bkt;
        struct ap_queue *aq;

        spin_lock_bh(&ap_queues_lock);
        hash_for_each(ap_queues, bkt, aq, hnode) {
                if (aq->queue_count == 0)
                        continue;
                spin_unlock_bh(&ap_queues_lock);
                return 1;
        }
        spin_unlock_bh(&ap_queues_lock);
        return 0;
}

/**
 * ap_poll_thread(): Thread that polls for finished requests.
 * @data: Unused pointer
 *
 * AP bus poll thread. The purpose of this thread is to poll for
 * finished requests in a loop if there is a "free" cpu - that is
 * a cpu that doesn't have anything better to do. The polling stops
 * as soon as there is another task or if all messages have been
 * delivered.
 */
static int ap_poll_thread(void *data)
{
        DECLARE_WAITQUEUE(wait, current);

        set_user_nice(current, MAX_NICE);
        set_freezable();
        while (!kthread_should_stop()) {
                add_wait_queue(&ap_poll_wait, &wait);
                set_current_state(TASK_INTERRUPTIBLE);
                if (!ap_pending_requests()) {
                        schedule();
                        try_to_freeze();
                }
                set_current_state(TASK_RUNNING);
                remove_wait_queue(&ap_poll_wait, &wait);
                if (need_resched()) {
                        schedule();
                        try_to_freeze();
                        continue;
                }
                ap_tasklet_fn(0);
        }

        return 0;
}

static int ap_poll_thread_start(void)
{
        int rc;

        if (ap_irq_flag || ap_poll_kthread)
                return 0;
        mutex_lock(&ap_poll_thread_mutex);
        ap_poll_kthread = kthread_run(ap_poll_thread, NULL, "appoll");
        rc = PTR_ERR_OR_ZERO(ap_poll_kthread);
        if (rc)
                ap_poll_kthread = NULL;
        mutex_unlock(&ap_poll_thread_mutex);
        return rc;
}

static void ap_poll_thread_stop(void)
{
        if (!ap_poll_kthread)
                return;
        mutex_lock(&ap_poll_thread_mutex);
        kthread_stop(ap_poll_kthread);
        ap_poll_kthread = NULL;
        mutex_unlock(&ap_poll_thread_mutex);
}

#define is_card_dev(x) ((x)->parent == ap_root_device)
#define is_queue_dev(x) ((x)->parent != ap_root_device)

/**
 * ap_bus_match()
 * @dev: Pointer to device
 * @drv: Pointer to device_driver
 *
 * AP bus driver registration/unregistration.
 */
static int ap_bus_match(struct device *dev, struct device_driver *drv)
{
        struct ap_driver *ap_drv = to_ap_drv(drv);
        struct ap_device_id *id;

        /*
         * Compare device type of the device with the list of
         * supported types of the device_driver.
         */
        for (id = ap_drv->ids; id->match_flags; id++) {
                if (is_card_dev(dev) &&
                    id->match_flags & AP_DEVICE_ID_MATCH_CARD_TYPE &&
                    id->dev_type == to_ap_dev(dev)->device_type)
                        return 1;
                if (is_queue_dev(dev) &&
                    id->match_flags & AP_DEVICE_ID_MATCH_QUEUE_TYPE &&
                    id->dev_type == to_ap_dev(dev)->device_type)
                        return 1;
        }
        return 0;
}

/**
 * ap_uevent(): Uevent function for AP devices.
 * @dev: Pointer to device
 * @env: Pointer to kobj_uevent_env
 *
 * It sets up a single environment variable DEV_TYPE which contains the
 * hardware device type.
 */
static int ap_uevent(const struct device *dev, struct kobj_uevent_env *env)
{
        int rc = 0;
        const struct ap_device *ap_dev = to_ap_dev(dev);

        /* Uevents from ap bus core don't need extensions to the env */
        if (dev == ap_root_device)
                return 0;

        if (is_card_dev(dev)) {
                struct ap_card *ac = to_ap_card(&ap_dev->device);

                /* Set up DEV_TYPE environment variable. */
                rc = add_uevent_var(env, "DEV_TYPE=%04X", ap_dev->device_type);
                if (rc)
                        return rc;
                /* Add MODALIAS= */
                rc = add_uevent_var(env, "MODALIAS=ap:t%02X", ap_dev->device_type);
                if (rc)
                        return rc;

                /* Add MODE=<accel|cca|ep11> */
                if (ac->hwinfo.accel)
                        rc = add_uevent_var(env, "MODE=accel");
                else if (ac->hwinfo.cca)
                        rc = add_uevent_var(env, "MODE=cca");
                else if (ac->hwinfo.ep11)
                        rc = add_uevent_var(env, "MODE=ep11");
                if (rc)
                        return rc;
        } else {
                struct ap_queue *aq = to_ap_queue(&ap_dev->device);

                /* Add MODE=<accel|cca|ep11> */
                if (aq->card->hwinfo.accel)
                        rc = add_uevent_var(env, "MODE=accel");
                else if (aq->card->hwinfo.cca)
                        rc = add_uevent_var(env, "MODE=cca");
                else if (aq->card->hwinfo.ep11)
                        rc = add_uevent_var(env, "MODE=ep11");
                if (rc)
                        return rc;
        }

        return 0;
}

static void ap_send_init_scan_done_uevent(void)
{
        char *envp[] = { "INITSCAN=done", NULL };

        kobject_uevent_env(&ap_root_device->kobj, KOBJ_CHANGE, envp);
}

static void ap_send_bindings_complete_uevent(void)
{
        char buf[32];
        char *envp[] = { "BINDINGS=complete", buf, NULL };

        snprintf(buf, sizeof(buf), "COMPLETECOUNT=%llu",
                 atomic64_inc_return(&ap_bindings_complete_count));
        kobject_uevent_env(&ap_root_device->kobj, KOBJ_CHANGE, envp);
}

void ap_send_config_uevent(struct ap_device *ap_dev, bool cfg)
{
        char buf[16];
        char *envp[] = { buf, NULL };

        snprintf(buf, sizeof(buf), "CONFIG=%d", cfg ? 1 : 0);

        kobject_uevent_env(&ap_dev->device.kobj, KOBJ_CHANGE, envp);
}
EXPORT_SYMBOL(ap_send_config_uevent);

void ap_send_online_uevent(struct ap_device *ap_dev, int online)
{
        char buf[16];
        char *envp[] = { buf, NULL };

        snprintf(buf, sizeof(buf), "ONLINE=%d", online ? 1 : 0);

        kobject_uevent_env(&ap_dev->device.kobj, KOBJ_CHANGE, envp);
}
EXPORT_SYMBOL(ap_send_online_uevent);

static void ap_send_mask_changed_uevent(unsigned long *newapm,
                                        unsigned long *newaqm)
{
        char buf[100];
        char *envp[] = { buf, NULL };

        if (newapm)
                snprintf(buf, sizeof(buf),
                         "APMASK=0x%016lx%016lx%016lx%016lx\n",
                         newapm[0], newapm[1], newapm[2], newapm[3]);
        else
                snprintf(buf, sizeof(buf),
                         "AQMASK=0x%016lx%016lx%016lx%016lx\n",
                         newaqm[0], newaqm[1], newaqm[2], newaqm[3]);

        kobject_uevent_env(&ap_root_device->kobj, KOBJ_CHANGE, envp);
}

/*
 * calc # of bound APQNs
 */

struct __ap_calc_ctrs {
        unsigned int apqns;
        unsigned int bound;
};

static int __ap_calc_helper(struct device *dev, void *arg)
{
        struct __ap_calc_ctrs *pctrs = (struct __ap_calc_ctrs *)arg;

        if (is_queue_dev(dev)) {
                pctrs->apqns++;
                if (dev->driver)
                        pctrs->bound++;
        }

        return 0;
}

static void ap_calc_bound_apqns(unsigned int *apqns, unsigned int *bound)
{
        struct __ap_calc_ctrs ctrs;

        memset(&ctrs, 0, sizeof(ctrs));
        bus_for_each_dev(&ap_bus_type, NULL, (void *)&ctrs, __ap_calc_helper);

        *apqns = ctrs.apqns;
        *bound = ctrs.bound;
}

/*
 * After ap bus scan do check if all existing APQNs are
 * bound to device drivers.
 */
static void ap_check_bindings_complete(void)
{
        unsigned int apqns, bound;

        if (atomic64_read(&ap_scan_bus_count) >= 1) {
                ap_calc_bound_apqns(&apqns, &bound);
                if (bound == apqns) {
                        if (!completion_done(&ap_apqn_bindings_complete)) {
                                complete_all(&ap_apqn_bindings_complete);
                                pr_debug("%s all apqn bindings complete\n", __func__);
                        }
                        ap_send_bindings_complete_uevent();
                }
        }
}

/*
 * Interface to wait for the AP bus to have done one initial ap bus
 * scan and all detected APQNs have been bound to device drivers.
 * If these both conditions are not fulfilled, this function blocks
 * on a condition with wait_for_completion_interruptible_timeout().
 * If these both conditions are fulfilled (before the timeout hits)
 * the return value is 0. If the timeout (in jiffies) hits instead
 * -ETIME is returned. On failures negative return values are
 * returned to the caller.
 */
int ap_wait_apqn_bindings_complete(unsigned long timeout)
{
        int rc = 0;
        long l;

        if (completion_done(&ap_apqn_bindings_complete))
                return 0;

        if (timeout)
                l = wait_for_completion_interruptible_timeout(
                        &ap_apqn_bindings_complete, timeout);
        else
                l = wait_for_completion_interruptible(
                        &ap_apqn_bindings_complete);
        if (l < 0)
                rc = l == -ERESTARTSYS ? -EINTR : l;
        else if (l == 0 && timeout)
                rc = -ETIME;

        pr_debug("%s rc=%d\n", __func__, rc);
        return rc;
}
EXPORT_SYMBOL(ap_wait_apqn_bindings_complete);

static int __ap_queue_devices_with_id_unregister(struct device *dev, void *data)
{
        if (is_queue_dev(dev) &&
            AP_QID_CARD(to_ap_queue(dev)->qid) == (int)(long)data)
                device_unregister(dev);
        return 0;
}

static int __ap_revise_reserved(struct device *dev, void *dummy)
{
        int rc, card, queue, devres, drvres;

        if (is_queue_dev(dev)) {
                card = AP_QID_CARD(to_ap_queue(dev)->qid);
                queue = AP_QID_QUEUE(to_ap_queue(dev)->qid);
                mutex_lock(&ap_perms_mutex);
                devres = test_bit_inv(card, ap_perms.apm) &&
                        test_bit_inv(queue, ap_perms.aqm);
                mutex_unlock(&ap_perms_mutex);
                drvres = to_ap_drv(dev->driver)->flags
                        & AP_DRIVER_FLAG_DEFAULT;
                if (!!devres != !!drvres) {
                        pr_debug("%s reprobing queue=%02x.%04x\n",
                                 __func__, card, queue);
                        rc = device_reprobe(dev);
                        if (rc)
                                AP_DBF_WARN("%s reprobing queue=%02x.%04x failed\n",
                                            __func__, card, queue);
                }
        }

        return 0;
}

static void ap_bus_revise_bindings(void)
{
        bus_for_each_dev(&ap_bus_type, NULL, NULL, __ap_revise_reserved);
}

/**
 * ap_owned_by_def_drv: indicates whether an AP adapter is reserved for the
 *                      default host driver or not.
 * @card: the APID of the adapter card to check
 * @queue: the APQI of the queue to check
 *
 * Note: the ap_perms_mutex must be locked by the caller of this function.
 *
 * Return: an int specifying whether the AP adapter is reserved for the host (1)
 *         or not (0).
 */
int ap_owned_by_def_drv(int card, int queue)
{
        int rc = 0;

        if (card < 0 || card >= AP_DEVICES || queue < 0 || queue >= AP_DOMAINS)
                return -EINVAL;

        if (test_bit_inv(card, ap_perms.apm) &&
            test_bit_inv(queue, ap_perms.aqm))
                rc = 1;

        return rc;
}
EXPORT_SYMBOL(ap_owned_by_def_drv);

/**
 * ap_apqn_in_matrix_owned_by_def_drv: indicates whether every APQN contained in
 *                                     a set is reserved for the host drivers
 *                                     or not.
 * @apm: a bitmap specifying a set of APIDs comprising the APQNs to check
 * @aqm: a bitmap specifying a set of APQIs comprising the APQNs to check
 *
 * Note: the ap_perms_mutex must be locked by the caller of this function.
 *
 * Return: an int specifying whether each APQN is reserved for the host (1) or
 *         not (0)
 */
int ap_apqn_in_matrix_owned_by_def_drv(unsigned long *apm,
                                       unsigned long *aqm)
{
        int card, queue, rc = 0;

        for (card = 0; !rc && card < AP_DEVICES; card++)
                if (test_bit_inv(card, apm) &&
                    test_bit_inv(card, ap_perms.apm))
                        for (queue = 0; !rc && queue < AP_DOMAINS; queue++)
                                if (test_bit_inv(queue, aqm) &&
                                    test_bit_inv(queue, ap_perms.aqm))
                                        rc = 1;

        return rc;
}
EXPORT_SYMBOL(ap_apqn_in_matrix_owned_by_def_drv);

static int ap_device_probe(struct device *dev)
{
        struct ap_device *ap_dev = to_ap_dev(dev);
        struct ap_driver *ap_drv = to_ap_drv(dev->driver);
        int card, queue, devres, drvres, rc = -ENODEV;

        if (!get_device(dev))
                return rc;

        if (is_queue_dev(dev)) {
                /*
                 * If the apqn is marked as reserved/used by ap bus and
                 * default drivers, only probe with drivers with the default
                 * flag set. If it is not marked, only probe with drivers
                 * with the default flag not set.
                 */
                card = AP_QID_CARD(to_ap_queue(dev)->qid);
                queue = AP_QID_QUEUE(to_ap_queue(dev)->qid);
                mutex_lock(&ap_perms_mutex);
                devres = test_bit_inv(card, ap_perms.apm) &&
                        test_bit_inv(queue, ap_perms.aqm);
                mutex_unlock(&ap_perms_mutex);
                drvres = ap_drv->flags & AP_DRIVER_FLAG_DEFAULT;
                if (!!devres != !!drvres)
                        goto out;
        }

        /* Add queue/card to list of active queues/cards */
        spin_lock_bh(&ap_queues_lock);
        if (is_queue_dev(dev))
                hash_add(ap_queues, &to_ap_queue(dev)->hnode,
                         to_ap_queue(dev)->qid);
        spin_unlock_bh(&ap_queues_lock);

        rc = ap_drv->probe ? ap_drv->probe(ap_dev) : -ENODEV;

        if (rc) {
                spin_lock_bh(&ap_queues_lock);
                if (is_queue_dev(dev))
                        hash_del(&to_ap_queue(dev)->hnode);
                spin_unlock_bh(&ap_queues_lock);
        }

out:
        if (rc)
                put_device(dev);
        return rc;
}

static void ap_device_remove(struct device *dev)
{
        struct ap_device *ap_dev = to_ap_dev(dev);
        struct ap_driver *ap_drv = to_ap_drv(dev->driver);

        /* prepare ap queue device removal */
        if (is_queue_dev(dev))
                ap_queue_prepare_remove(to_ap_queue(dev));

        /* driver's chance to clean up gracefully */
        if (ap_drv->remove)
                ap_drv->remove(ap_dev);

        /* now do the ap queue device remove */
        if (is_queue_dev(dev))
                ap_queue_remove(to_ap_queue(dev));

        /* Remove queue/card from list of active queues/cards */
        spin_lock_bh(&ap_queues_lock);
        if (is_queue_dev(dev))
                hash_del(&to_ap_queue(dev)->hnode);
        spin_unlock_bh(&ap_queues_lock);

        put_device(dev);
}

struct ap_queue *ap_get_qdev(ap_qid_t qid)
{
        int bkt;
        struct ap_queue *aq;

        spin_lock_bh(&ap_queues_lock);
        hash_for_each(ap_queues, bkt, aq, hnode) {
                if (aq->qid == qid) {
                        get_device(&aq->ap_dev.device);
                        spin_unlock_bh(&ap_queues_lock);
                        return aq;
                }
        }
        spin_unlock_bh(&ap_queues_lock);

        return NULL;
}
EXPORT_SYMBOL(ap_get_qdev);

int ap_driver_register(struct ap_driver *ap_drv, struct module *owner,
                       char *name)
{
        struct device_driver *drv = &ap_drv->driver;

        drv->bus = &ap_bus_type;
        drv->owner = owner;
        drv->name = name;
        return driver_register(drv);
}
EXPORT_SYMBOL(ap_driver_register);

void ap_driver_unregister(struct ap_driver *ap_drv)
{
        driver_unregister(&ap_drv->driver);
}
EXPORT_SYMBOL(ap_driver_unregister);

/*
 * Enforce a synchronous AP bus rescan.
 * Returns true if the bus scan finds a change in the AP configuration
 * and AP devices have been added or deleted when this function returns.
 */
bool ap_bus_force_rescan(void)
{
        unsigned long scan_counter = atomic64_read(&ap_scan_bus_count);
        bool rc = false;

        pr_debug(">%s scan counter=%lu\n", __func__, scan_counter);

        /* Only trigger AP bus scans after the initial scan is done */
        if (scan_counter <= 0)
                goto out;

        /* Try to acquire the AP scan bus mutex */
        if (mutex_trylock(&ap_scan_bus_mutex)) {
                /* mutex acquired, run the AP bus scan */
                ap_scan_bus_result = ap_scan_bus();
                rc = ap_scan_bus_result;
                mutex_unlock(&ap_scan_bus_mutex);
                goto out;
        }

        /*
         * Mutex acquire failed. So there is currently another task
         * already running the AP bus scan. Then let's simple wait
         * for the lock which means the other task has finished and
         * stored the result in ap_scan_bus_result.
         */
        if (mutex_lock_interruptible(&ap_scan_bus_mutex)) {
                /* some error occurred, ignore and go out */
                goto out;
        }
        rc = ap_scan_bus_result;
        mutex_unlock(&ap_scan_bus_mutex);

out:
        pr_debug("%s rc=%d\n", __func__, rc);
        return rc;
}
EXPORT_SYMBOL(ap_bus_force_rescan);

/*
 * A config change has happened, force an ap bus rescan.
 */
void ap_bus_cfg_chg(void)
{
        pr_debug("%s config change, forcing bus rescan\n", __func__);

        ap_bus_force_rescan();
}

/*
 * hex2bitmap() - parse hex mask string and set bitmap.
 * Valid strings are "0x012345678" with at least one valid hex number.
 * Rest of the bitmap to the right is padded with 0. No spaces allowed
 * within the string, the leading 0x may be omitted.
 * Returns the bitmask with exactly the bits set as given by the hex
 * string (both in big endian order).
 */
static int hex2bitmap(const char *str, unsigned long *bitmap, int bits)
{
        int i, n, b;

        /* bits needs to be a multiple of 8 */
        if (bits & 0x07)
                return -EINVAL;

        if (str[0] == '0' && str[1] == 'x')
                str++;
        if (*str == 'x')
                str++;

        for (i = 0; isxdigit(*str) && i < bits; str++) {
                b = hex_to_bin(*str);
                for (n = 0; n < 4; n++)
                        if (b & (0x08 >> n))
                                set_bit_inv(i + n, bitmap);
                i += 4;
        }

        if (*str == '\n')
                str++;
        if (*str)
                return -EINVAL;
        return 0;
}

/*
 * modify_bitmap() - parse bitmask argument and modify an existing
 * bit mask accordingly. A concatenation (done with ',') of these
 * terms is recognized:
 *   +<bitnr>[-<bitnr>] or -<bitnr>[-<bitnr>]
 * <bitnr> may be any valid number (hex, decimal or octal) in the range
 * 0...bits-1; the leading + or - is required. Here are some examples:
 *   +0-15,+32,-128,-0xFF
 *   -0-255,+1-16,+0x128
 *   +1,+2,+3,+4,-5,-7-10
 * Returns the new bitmap after all changes have been applied. Every
 * positive value in the string will set a bit and every negative value
 * in the string will clear a bit. As a bit may be touched more than once,
 * the last 'operation' wins:
 * +0-255,-128 = first bits 0-255 will be set, then bit 128 will be
 * cleared again. All other bits are unmodified.
 */
static int modify_bitmap(const char *str, unsigned long *bitmap, int bits)
{
        int a, i, z;
        char *np, sign;

        /* bits needs to be a multiple of 8 */
        if (bits & 0x07)
                return -EINVAL;

        while (*str) {
                sign = *str++;
                if (sign != '+' && sign != '-')
                        return -EINVAL;
                a = z = simple_strtoul(str, &np, 0);
                if (str == np || a >= bits)
                        return -EINVAL;
                str = np;
                if (*str == '-') {
                        z = simple_strtoul(++str, &np, 0);
                        if (str == np || a > z || z >= bits)
                                return -EINVAL;
                        str = np;
                }
                for (i = a; i <= z; i++)
                        if (sign == '+')
                                set_bit_inv(i, bitmap);
                        else
                                clear_bit_inv(i, bitmap);
                while (*str == ',' || *str == '\n')
                        str++;
        }

        return 0;
}

static int ap_parse_bitmap_str(const char *str, unsigned long *bitmap, int bits,
                               unsigned long *newmap)
{
        unsigned long size;
        int rc;

        size = BITS_TO_LONGS(bits) * sizeof(unsigned long);
        if (*str == '+' || *str == '-') {
                memcpy(newmap, bitmap, size);
                rc = modify_bitmap(str, newmap, bits);
        } else {
                memset(newmap, 0, size);
                rc = hex2bitmap(str, newmap, bits);
        }
        return rc;
}

int ap_parse_mask_str(const char *str,
                      unsigned long *bitmap, int bits,
                      struct mutex *lock)
{
        unsigned long *newmap, size;
        int rc;

        /* bits needs to be a multiple of 8 */
        if (bits & 0x07)
                return -EINVAL;

        size = BITS_TO_LONGS(bits) * sizeof(unsigned long);
        newmap = kmalloc(size, GFP_KERNEL);
        if (!newmap)
                return -ENOMEM;
        if (mutex_lock_interruptible(lock)) {
                kfree(newmap);
                return -ERESTARTSYS;
        }
        rc = ap_parse_bitmap_str(str, bitmap, bits, newmap);
        if (rc == 0)
                memcpy(bitmap, newmap, size);
        mutex_unlock(lock);
        kfree(newmap);
        return rc;
}
EXPORT_SYMBOL(ap_parse_mask_str);

/*
 * AP bus attributes.
 */

static ssize_t ap_domain_show(const struct bus_type *bus, char *buf)
{
        return sysfs_emit(buf, "%d\n", ap_domain_index);
}

static ssize_t ap_domain_store(const struct bus_type *bus,
                               const char *buf, size_t count)
{
        int domain;

        if (sscanf(buf, "%i\n", &domain) != 1 ||
            domain < 0 || domain > ap_max_domain_id ||
            !test_bit_inv(domain, ap_perms.aqm))
                return -EINVAL;

        spin_lock_bh(&ap_domain_lock);
        ap_domain_index = domain;
        spin_unlock_bh(&ap_domain_lock);

        AP_DBF_INFO("%s stored new default domain=%d\n",
                    __func__, domain);

        return count;
}

static BUS_ATTR_RW(ap_domain);

static ssize_t ap_control_domain_mask_show(const struct bus_type *bus, char *buf)
{
        if (!ap_qci_info)       /* QCI not supported */
                return sysfs_emit(buf, "not supported\n");

        return sysfs_emit(buf, "0x%08x%08x%08x%08x%08x%08x%08x%08x\n",
                          ap_qci_info->adm[0], ap_qci_info->adm[1],
                          ap_qci_info->adm[2], ap_qci_info->adm[3],
                          ap_qci_info->adm[4], ap_qci_info->adm[5],
                          ap_qci_info->adm[6], ap_qci_info->adm[7]);
}

static BUS_ATTR_RO(ap_control_domain_mask);

static ssize_t ap_usage_domain_mask_show(const struct bus_type *bus, char *buf)
{
        if (!ap_qci_info)       /* QCI not supported */
                return sysfs_emit(buf, "not supported\n");

        return sysfs_emit(buf, "0x%08x%08x%08x%08x%08x%08x%08x%08x\n",
                          ap_qci_info->aqm[0], ap_qci_info->aqm[1],
                          ap_qci_info->aqm[2], ap_qci_info->aqm[3],
                          ap_qci_info->aqm[4], ap_qci_info->aqm[5],
                          ap_qci_info->aqm[6], ap_qci_info->aqm[7]);
}

static BUS_ATTR_RO(ap_usage_domain_mask);

static ssize_t ap_adapter_mask_show(const struct bus_type *bus, char *buf)
{
        if (!ap_qci_info)       /* QCI not supported */
                return sysfs_emit(buf, "not supported\n");

        return sysfs_emit(buf, "0x%08x%08x%08x%08x%08x%08x%08x%08x\n",
                          ap_qci_info->apm[0], ap_qci_info->apm[1],
                          ap_qci_info->apm[2], ap_qci_info->apm[3],
                          ap_qci_info->apm[4], ap_qci_info->apm[5],
                          ap_qci_info->apm[6], ap_qci_info->apm[7]);
}

static BUS_ATTR_RO(ap_adapter_mask);

static ssize_t ap_interrupts_show(const struct bus_type *bus, char *buf)
{
        return sysfs_emit(buf, "%d\n", ap_irq_flag ? 1 : 0);
}

static BUS_ATTR_RO(ap_interrupts);

static ssize_t config_time_show(const struct bus_type *bus, char *buf)
{
        return sysfs_emit(buf, "%d\n", ap_scan_bus_time);
}

static ssize_t config_time_store(const struct bus_type *bus,
                                 const char *buf, size_t count)
{
        int time;

        if (sscanf(buf, "%d\n", &time) != 1 || time < 5 || time > 120)
                return -EINVAL;
        ap_scan_bus_time = time;
        mod_timer(&ap_scan_bus_timer, jiffies + ap_scan_bus_time * HZ);
        return count;
}

static BUS_ATTR_RW(config_time);

static ssize_t poll_thread_show(const struct bus_type *bus, char *buf)
{
        return sysfs_emit(buf, "%d\n", ap_poll_kthread ? 1 : 0);
}

static ssize_t poll_thread_store(const struct bus_type *bus,
                                 const char *buf, size_t count)
{
        bool value;
        int rc;

        rc = kstrtobool(buf, &value);
        if (rc)
                return rc;

        if (value) {
                rc = ap_poll_thread_start();
                if (rc)
                        count = rc;
        } else {
                ap_poll_thread_stop();
        }
        return count;
}

static BUS_ATTR_RW(poll_thread);

static ssize_t poll_timeout_show(const struct bus_type *bus, char *buf)
{
        return sysfs_emit(buf, "%lu\n", poll_high_timeout);
}

static ssize_t poll_timeout_store(const struct bus_type *bus, const char *buf,
                                  size_t count)
{
        unsigned long value;
        ktime_t hr_time;
        int rc;

        rc = kstrtoul(buf, 0, &value);
        if (rc)
                return rc;

        /* 120 seconds = maximum poll interval */
        if (value > 120000000000UL)
                return -EINVAL;
        poll_high_timeout = value;
        hr_time = poll_high_timeout;

        spin_lock_bh(&ap_poll_timer_lock);
        hrtimer_cancel(&ap_poll_timer);
        hrtimer_set_expires(&ap_poll_timer, hr_time);
        hrtimer_start_expires(&ap_poll_timer, HRTIMER_MODE_ABS);
        spin_unlock_bh(&ap_poll_timer_lock);

        return count;
}

static BUS_ATTR_RW(poll_timeout);

static ssize_t ap_max_domain_id_show(const struct bus_type *bus, char *buf)
{
        return sysfs_emit(buf, "%d\n", ap_max_domain_id);
}

static BUS_ATTR_RO(ap_max_domain_id);

static ssize_t ap_max_adapter_id_show(const struct bus_type *bus, char *buf)
{
        return sysfs_emit(buf, "%d\n", ap_max_adapter_id);
}

static BUS_ATTR_RO(ap_max_adapter_id);

static ssize_t apmask_show(const struct bus_type *bus, char *buf)
{
        int rc;

        if (mutex_lock_interruptible(&ap_perms_mutex))
                return -ERESTARTSYS;
        rc = sysfs_emit(buf, "0x%016lx%016lx%016lx%016lx\n",
                        ap_perms.apm[0], ap_perms.apm[1],
                        ap_perms.apm[2], ap_perms.apm[3]);
        mutex_unlock(&ap_perms_mutex);

        return rc;
}

static int __verify_card_reservations(struct device_driver *drv, void *data)
{
        int rc = 0;
        struct ap_driver *ap_drv = to_ap_drv(drv);
        unsigned long *newapm = (unsigned long *)data;

        /*
         * increase the driver's module refcounter to be sure it is not
         * going away when we invoke the callback function.
         */
        if (!try_module_get(drv->owner))
                return 0;

        if (ap_drv->in_use) {
                rc = ap_drv->in_use(newapm, ap_perms.aqm);
                if (rc)
                        rc = -EBUSY;
        }

        /* release the driver's module */
        module_put(drv->owner);

        return rc;
}

static int apmask_commit(unsigned long *newapm)
{
        int rc;
        unsigned long reserved[BITS_TO_LONGS(AP_DEVICES)];

        /*
         * Check if any bits in the apmask have been set which will
         * result in queues being removed from non-default drivers
         */
        if (bitmap_andnot(reserved, newapm, ap_perms.apm, AP_DEVICES)) {
                rc = bus_for_each_drv(&ap_bus_type, NULL, reserved,
                                      __verify_card_reservations);
                if (rc)
                        return rc;
        }

        memcpy(ap_perms.apm, newapm, APMASKSIZE);

        return 0;
}

static ssize_t apmask_store(const struct bus_type *bus, const char *buf,
                            size_t count)
{
        int rc, changes = 0;
        DECLARE_BITMAP(newapm, AP_DEVICES);

        if (mutex_lock_interruptible(&ap_perms_mutex))
                return -ERESTARTSYS;

        rc = ap_parse_bitmap_str(buf, ap_perms.apm, AP_DEVICES, newapm);
        if (rc)
                goto done;

        changes = memcmp(ap_perms.apm, newapm, APMASKSIZE);
        if (changes)
                rc = apmask_commit(newapm);

done:
        mutex_unlock(&ap_perms_mutex);
        if (rc)
                return rc;

        if (changes) {
                ap_bus_revise_bindings();
                ap_send_mask_changed_uevent(newapm, NULL);
        }

        return count;
}

static BUS_ATTR_RW(apmask);

static ssize_t aqmask_show(const struct bus_type *bus, char *buf)
{
        int rc;

        if (mutex_lock_interruptible(&ap_perms_mutex))
                return -ERESTARTSYS;
        rc = sysfs_emit(buf, "0x%016lx%016lx%016lx%016lx\n",
                        ap_perms.aqm[0], ap_perms.aqm[1],
                        ap_perms.aqm[2], ap_perms.aqm[3]);
        mutex_unlock(&ap_perms_mutex);

        return rc;
}

static int __verify_queue_reservations(struct device_driver *drv, void *data)
{
        int rc = 0;
        struct ap_driver *ap_drv = to_ap_drv(drv);
        unsigned long *newaqm = (unsigned long *)data;

        /*
         * increase the driver's module refcounter to be sure it is not
         * going away when we invoke the callback function.
         */
        if (!try_module_get(drv->owner))
                return 0;

        if (ap_drv->in_use) {
                rc = ap_drv->in_use(ap_perms.apm, newaqm);
                if (rc)
                        rc = -EBUSY;
        }

        /* release the driver's module */
        module_put(drv->owner);

        return rc;
}

static int aqmask_commit(unsigned long *newaqm)
{
        int rc;
        unsigned long reserved[BITS_TO_LONGS(AP_DOMAINS)];

        /*
         * Check if any bits in the aqmask have been set which will
         * result in queues being removed from non-default drivers
         */
        if (bitmap_andnot(reserved, newaqm, ap_perms.aqm, AP_DOMAINS)) {
                rc = bus_for_each_drv(&ap_bus_type, NULL, reserved,
                                      __verify_queue_reservations);
                if (rc)
                        return rc;
        }

        memcpy(ap_perms.aqm, newaqm, AQMASKSIZE);

        return 0;
}

static ssize_t aqmask_store(const struct bus_type *bus, const char *buf,
                            size_t count)
{
        int rc, changes = 0;
        DECLARE_BITMAP(newaqm, AP_DOMAINS);

        if (mutex_lock_interruptible(&ap_perms_mutex))
                return -ERESTARTSYS;

        rc = ap_parse_bitmap_str(buf, ap_perms.aqm, AP_DOMAINS, newaqm);
        if (rc)
                goto done;

        changes = memcmp(ap_perms.aqm, newaqm, APMASKSIZE);
        if (changes)
                rc = aqmask_commit(newaqm);

done:
        mutex_unlock(&ap_perms_mutex);
        if (rc)
                return rc;

        if (changes) {
                ap_bus_revise_bindings();
                ap_send_mask_changed_uevent(NULL, newaqm);
        }

        return count;
}

static BUS_ATTR_RW(aqmask);

static ssize_t scans_show(const struct bus_type *bus, char *buf)
{
        return sysfs_emit(buf, "%llu\n", atomic64_read(&ap_scan_bus_count));
}

static ssize_t scans_store(const struct bus_type *bus, const char *buf,
                           size_t count)
{
        AP_DBF_INFO("%s force AP bus rescan\n", __func__);

        ap_bus_force_rescan();

        return count;
}

static BUS_ATTR_RW(scans);

static ssize_t bindings_show(const struct bus_type *bus, char *buf)
{
        int rc;
        unsigned int apqns, n;

        ap_calc_bound_apqns(&apqns, &n);
        if (atomic64_read(&ap_scan_bus_count) >= 1 && n == apqns)
                rc = sysfs_emit(buf, "%u/%u (complete)\n", n, apqns);
        else
                rc = sysfs_emit(buf, "%u/%u\n", n, apqns);

        return rc;
}

static BUS_ATTR_RO(bindings);

static ssize_t features_show(const struct bus_type *bus, char *buf)
{
        int n = 0;

        if (!ap_qci_info)       /* QCI not supported */
                return sysfs_emit(buf, "-\n");

        if (ap_qci_info->apsc)
                n += sysfs_emit_at(buf, n, "APSC ");
        if (ap_qci_info->apxa)
                n += sysfs_emit_at(buf, n, "APXA ");
        if (ap_qci_info->qact)
                n += sysfs_emit_at(buf, n, "QACT ");
        if (ap_qci_info->rc8a)
                n += sysfs_emit_at(buf, n, "RC8A ");
        if (ap_qci_info->apsb)
                n += sysfs_emit_at(buf, n, "APSB ");

        sysfs_emit_at(buf, n == 0 ? 0 : n - 1, "\n");

        return n;
}

static BUS_ATTR_RO(features);

static struct attribute *ap_bus_attrs[] = {
        &bus_attr_ap_domain.attr,
        &bus_attr_ap_control_domain_mask.attr,
        &bus_attr_ap_usage_domain_mask.attr,
        &bus_attr_ap_adapter_mask.attr,
        &bus_attr_config_time.attr,
        &bus_attr_poll_thread.attr,
        &bus_attr_ap_interrupts.attr,
        &bus_attr_poll_timeout.attr,
        &bus_attr_ap_max_domain_id.attr,
        &bus_attr_ap_max_adapter_id.attr,
        &bus_attr_apmask.attr,
        &bus_attr_aqmask.attr,
        &bus_attr_scans.attr,
        &bus_attr_bindings.attr,
        &bus_attr_features.attr,
        NULL,
};
ATTRIBUTE_GROUPS(ap_bus);

static const struct bus_type ap_bus_type = {
        .name = "ap",
        .bus_groups = ap_bus_groups,
        .match = &ap_bus_match,
        .uevent = &ap_uevent,
        .probe = ap_device_probe,
        .remove = ap_device_remove,
};

/**
 * ap_select_domain(): Select an AP domain if possible and we haven't
 * already done so before.
 */
static void ap_select_domain(void)
{
        struct ap_queue_status status;
        int card, dom;

        /*
         * Choose the default domain. Either the one specified with
         * the "domain=" parameter or the first domain with at least
         * one valid APQN.
         */
        spin_lock_bh(&ap_domain_lock);
        if (ap_domain_index >= 0) {
                /* Domain has already been selected. */
                goto out;
        }
        for (dom = 0; dom <= ap_max_domain_id; dom++) {
                if (!ap_test_config_usage_domain(dom) ||
                    !test_bit_inv(dom, ap_perms.aqm))
                        continue;
                for (card = 0; card <= ap_max_adapter_id; card++) {
                        if (!ap_test_config_card_id(card) ||
                            !test_bit_inv(card, ap_perms.apm))
                                continue;
                        status = ap_test_queue(AP_MKQID(card, dom),
                                               ap_apft_available(),
                                               NULL);
                        if (status.response_code == AP_RESPONSE_NORMAL)
                                break;
                }
                if (card <= ap_max_adapter_id)
                        break;
        }
        if (dom <= ap_max_domain_id) {
                ap_domain_index = dom;
                AP_DBF_INFO("%s new default domain is %d\n",
                            __func__, ap_domain_index);
        }
out:
        spin_unlock_bh(&ap_domain_lock);
}

/*
 * This function checks the type and returns either 0 for not
 * supported or the highest compatible type value (which may
 * include the input type value).
 */
static int ap_get_compatible_type(ap_qid_t qid, int rawtype, unsigned int func)
{
        int comp_type = 0;

        /* < CEX4 is not supported */
        if (rawtype < AP_DEVICE_TYPE_CEX4) {
                AP_DBF_WARN("%s queue=%02x.%04x unsupported type %d\n",
                            __func__, AP_QID_CARD(qid),
                            AP_QID_QUEUE(qid), rawtype);
                return 0;
        }
        /* up to CEX8 known and fully supported */
        if (rawtype <= AP_DEVICE_TYPE_CEX8)
                return rawtype;
        /*
         * unknown new type > CEX8, check for compatibility
         * to the highest known and supported type which is
         * currently CEX8 with the help of the QACT function.
         */
        if (ap_qact_available()) {
                struct ap_queue_status status;
                union ap_qact_ap_info apinfo = {0};

                apinfo.mode = (func >> 26) & 0x07;
                apinfo.cat = AP_DEVICE_TYPE_CEX8;
                status = ap_qact(qid, 0, &apinfo);
                if (status.response_code == AP_RESPONSE_NORMAL &&
                    apinfo.cat >= AP_DEVICE_TYPE_CEX4 &&
                    apinfo.cat <= AP_DEVICE_TYPE_CEX8)
                        comp_type = apinfo.cat;
        }
        if (!comp_type)
                AP_DBF_WARN("%s queue=%02x.%04x unable to map type %d\n",
                            __func__, AP_QID_CARD(qid),
                            AP_QID_QUEUE(qid), rawtype);
        else if (comp_type != rawtype)
                AP_DBF_INFO("%s queue=%02x.%04x map type %d to %d\n",
                            __func__, AP_QID_CARD(qid), AP_QID_QUEUE(qid),
                            rawtype, comp_type);
        return comp_type;
}

/*
 * Helper function to be used with bus_find_dev
 * matches for the card device with the given id
 */
static int __match_card_device_with_id(struct device *dev, const void *data)
{
        return is_card_dev(dev) && to_ap_card(dev)->id == (int)(long)(void *)data;
}

/*
 * Helper function to be used with bus_find_dev
 * matches for the queue device with a given qid
 */
static int __match_queue_device_with_qid(struct device *dev, const void *data)
{
        return is_queue_dev(dev) && to_ap_queue(dev)->qid == (int)(long)data;
}

/*
 * Helper function to be used with bus_find_dev
 * matches any queue device with given queue id
 */
static int __match_queue_device_with_queue_id(struct device *dev, const void *data)
{
        return is_queue_dev(dev) &&
                AP_QID_QUEUE(to_ap_queue(dev)->qid) == (int)(long)data;
}

/* Helper function for notify_config_changed */
static int __drv_notify_config_changed(struct device_driver *drv, void *data)
{
        struct ap_driver *ap_drv = to_ap_drv(drv);

        if (try_module_get(drv->owner)) {
                if (ap_drv->on_config_changed)
                        ap_drv->on_config_changed(ap_qci_info, ap_qci_info_old);
                module_put(drv->owner);
        }

        return 0;
}

/* Notify all drivers about an qci config change */
static inline void notify_config_changed(void)
{
        bus_for_each_drv(&ap_bus_type, NULL, NULL,
                         __drv_notify_config_changed);
}

/* Helper function for notify_scan_complete */
static int __drv_notify_scan_complete(struct device_driver *drv, void *data)
{
        struct ap_driver *ap_drv = to_ap_drv(drv);

        if (try_module_get(drv->owner)) {
                if (ap_drv->on_scan_complete)
                        ap_drv->on_scan_complete(ap_qci_info,
                                                 ap_qci_info_old);
                module_put(drv->owner);
        }

        return 0;
}

/* Notify all drivers about bus scan complete */
static inline void notify_scan_complete(void)
{
        bus_for_each_drv(&ap_bus_type, NULL, NULL,
                         __drv_notify_scan_complete);
}

/*
 * Helper function for ap_scan_bus().
 * Remove card device and associated queue devices.
 */
static inline void ap_scan_rm_card_dev_and_queue_devs(struct ap_card *ac)
{
        bus_for_each_dev(&ap_bus_type, NULL,
                         (void *)(long)ac->id,
                         __ap_queue_devices_with_id_unregister);
        device_unregister(&ac->ap_dev.device);
}

/*
 * Helper function for ap_scan_bus().
 * Does the scan bus job for all the domains within
 * a valid adapter given by an ap_card ptr.
 */
static inline void ap_scan_domains(struct ap_card *ac)
{
        struct ap_tapq_hwinfo hwinfo;
        bool decfg, chkstop;
        struct ap_queue *aq;
        struct device *dev;
        ap_qid_t qid;
        int rc, dom;

        /*
         * Go through the configuration for the domains and compare them
         * to the existing queue devices. Also take care of the config
         * and error state for the queue devices.
         */

        for (dom = 0; dom <= ap_max_domain_id; dom++) {
                qid = AP_MKQID(ac->id, dom);
                dev = bus_find_device(&ap_bus_type, NULL,
                                      (void *)(long)qid,
                                      __match_queue_device_with_qid);
                aq = dev ? to_ap_queue(dev) : NULL;
                if (!ap_test_config_usage_domain(dom)) {
                        if (dev) {
                                AP_DBF_INFO("%s(%d,%d) not in config anymore, rm queue dev\n",
                                            __func__, ac->id, dom);
                                device_unregister(dev);
                        }
                        goto put_dev_and_continue;
                }
                /* domain is valid, get info from this APQN */
                rc = ap_queue_info(qid, &hwinfo, &decfg, &chkstop);
                switch (rc) {
                case -1:
                        if (dev) {
                                AP_DBF_INFO("%s(%d,%d) queue_info() failed, rm queue dev\n",
                                            __func__, ac->id, dom);
                                device_unregister(dev);
                        }
                        fallthrough;
                case 0:
                        goto put_dev_and_continue;
                default:
                        break;
                }
                /* if no queue device exists, create a new one */
                if (!aq) {
                        aq = ap_queue_create(qid, ac->ap_dev.device_type);
                        if (!aq) {
                                AP_DBF_WARN("%s(%d,%d) ap_queue_create() failed\n",
                                            __func__, ac->id, dom);
                                continue;
                        }
                        aq->card = ac;
                        aq->config = !decfg;
                        aq->chkstop = chkstop;
                        aq->se_bstate = hwinfo.bs;
                        dev = &aq->ap_dev.device;
                        dev->bus = &ap_bus_type;
                        dev->parent = &ac->ap_dev.device;
                        dev_set_name(dev, "%02x.%04x", ac->id, dom);
                        /* register queue device */
                        rc = device_register(dev);
                        if (rc) {
                                AP_DBF_WARN("%s(%d,%d) device_register() failed\n",
                                            __func__, ac->id, dom);
                                goto put_dev_and_continue;
                        }
                        /* get it and thus adjust reference counter */
                        get_device(dev);
                        if (decfg) {
                                AP_DBF_INFO("%s(%d,%d) new (decfg) queue dev created\n",
                                            __func__, ac->id, dom);
                        } else if (chkstop) {
                                AP_DBF_INFO("%s(%d,%d) new (chkstop) queue dev created\n",
                                            __func__, ac->id, dom);
                        } else {
                                /* nudge the queue's state machine */
                                ap_queue_init_state(aq);
                                AP_DBF_INFO("%s(%d,%d) new queue dev created\n",
                                            __func__, ac->id, dom);
                        }
                        goto put_dev_and_continue;
                }
                /* handle state changes on already existing queue device */
                spin_lock_bh(&aq->lock);
                /* SE bind state */
                aq->se_bstate = hwinfo.bs;
                /* checkstop state */
                if (chkstop && !aq->chkstop) {
                        /* checkstop on */
                        aq->chkstop = true;
                        if (aq->dev_state > AP_DEV_STATE_UNINITIATED) {
                                aq->dev_state = AP_DEV_STATE_ERROR;
                                aq->last_err_rc = AP_RESPONSE_CHECKSTOPPED;
                        }
                        spin_unlock_bh(&aq->lock);
                        pr_debug("%s(%d,%d) queue dev checkstop on\n",
                                 __func__, ac->id, dom);
                        /* 'receive' pending messages with -EAGAIN */
                        ap_flush_queue(aq);
                        goto put_dev_and_continue;
                } else if (!chkstop && aq->chkstop) {
                        /* checkstop off */
                        aq->chkstop = false;
                        if (aq->dev_state > AP_DEV_STATE_UNINITIATED)
                                _ap_queue_init_state(aq);
                        spin_unlock_bh(&aq->lock);
                        pr_debug("%s(%d,%d) queue dev checkstop off\n",
                                 __func__, ac->id, dom);
                        goto put_dev_and_continue;
                }
                /* config state change */
                if (decfg && aq->config) {
                        /* config off this queue device */
                        aq->config = false;
                        if (aq->dev_state > AP_DEV_STATE_UNINITIATED) {
                                aq->dev_state = AP_DEV_STATE_ERROR;
                                aq->last_err_rc = AP_RESPONSE_DECONFIGURED;
                        }
                        spin_unlock_bh(&aq->lock);
                        pr_debug("%s(%d,%d) queue dev config off\n",
                                 __func__, ac->id, dom);
                        ap_send_config_uevent(&aq->ap_dev, aq->config);
                        /* 'receive' pending messages with -EAGAIN */
                        ap_flush_queue(aq);
                        goto put_dev_and_continue;
                } else if (!decfg && !aq->config) {
                        /* config on this queue device */
                        aq->config = true;
                        if (aq->dev_state > AP_DEV_STATE_UNINITIATED)
                                _ap_queue_init_state(aq);
                        spin_unlock_bh(&aq->lock);
                        pr_debug("%s(%d,%d) queue dev config on\n",
                                 __func__, ac->id, dom);
                        ap_send_config_uevent(&aq->ap_dev, aq->config);
                        goto put_dev_and_continue;
                }
                /* handle other error states */
                if (!decfg && aq->dev_state == AP_DEV_STATE_ERROR) {
                        spin_unlock_bh(&aq->lock);
                        /* 'receive' pending messages with -EAGAIN */
                        ap_flush_queue(aq);
                        /* re-init (with reset) the queue device */
                        ap_queue_init_state(aq);
                        AP_DBF_INFO("%s(%d,%d) queue dev reinit enforced\n",
                                    __func__, ac->id, dom);
                        goto put_dev_and_continue;
                }
                spin_unlock_bh(&aq->lock);
put_dev_and_continue:
                put_device(dev);
        }
}

/*
 * Helper function for ap_scan_bus().
 * Does the scan bus job for the given adapter id.
 */
static inline void ap_scan_adapter(int ap)
{
        struct ap_tapq_hwinfo hwinfo;
        int rc, dom, comp_type;
        bool decfg, chkstop;
        struct ap_card *ac;
        struct device *dev;
        ap_qid_t qid;

        /* Is there currently a card device for this adapter ? */
        dev = bus_find_device(&ap_bus_type, NULL,
                              (void *)(long)ap,
                              __match_card_device_with_id);
        ac = dev ? to_ap_card(dev) : NULL;

        /* Adapter not in configuration ? */
        if (!ap_test_config_card_id(ap)) {
                if (ac) {
                        AP_DBF_INFO("%s(%d) ap not in config any more, rm card and queue devs\n",
                                    __func__, ap);
                        ap_scan_rm_card_dev_and_queue_devs(ac);
                        put_device(dev);
                }
                return;
        }

        /*
         * Adapter ap is valid in the current configuration. So do some checks:
         * If no card device exists, build one. If a card device exists, check
         * for type and functions changed. For all this we need to find a valid
         * APQN first.
         */

        for (dom = 0; dom <= ap_max_domain_id; dom++)
                if (ap_test_config_usage_domain(dom)) {
                        qid = AP_MKQID(ap, dom);
                        if (ap_queue_info(qid, &hwinfo, &decfg, &chkstop) > 0)
                                break;
                }
        if (dom > ap_max_domain_id) {
                /* Could not find one valid APQN for this adapter */
                if (ac) {
                        AP_DBF_INFO("%s(%d) no type info (no APQN found), rm card and queue devs\n",
                                    __func__, ap);
                        ap_scan_rm_card_dev_and_queue_devs(ac);
                        put_device(dev);
                } else {
                        pr_debug("%s(%d) no type info (no APQN found), ignored\n",
                                 __func__, ap);
                }
                return;
        }
        if (!hwinfo.at) {
                /* No apdater type info available, an unusable adapter */
                if (ac) {
                        AP_DBF_INFO("%s(%d) no valid type (0) info, rm card and queue devs\n",
                                    __func__, ap);
                        ap_scan_rm_card_dev_and_queue_devs(ac);
                        put_device(dev);
                } else {
                        pr_debug("%s(%d) no valid type (0) info, ignored\n",
                                 __func__, ap);
                }
                return;
        }
        hwinfo.value &= TAPQ_CARD_HWINFO_MASK; /* filter card specific hwinfo */
        if (ac) {
                /* Check APQN against existing card device for changes */
                if (ac->hwinfo.at != hwinfo.at) {
                        AP_DBF_INFO("%s(%d) hwtype %d changed, rm card and queue devs\n",
                                    __func__, ap, hwinfo.at);
                        ap_scan_rm_card_dev_and_queue_devs(ac);
                        put_device(dev);
                        ac = NULL;
                } else if (ac->hwinfo.fac != hwinfo.fac) {
                        AP_DBF_INFO("%s(%d) functions 0x%08x changed, rm card and queue devs\n",
                                    __func__, ap, hwinfo.fac);
                        ap_scan_rm_card_dev_and_queue_devs(ac);
                        put_device(dev);
                        ac = NULL;
                } else {
                        /* handle checkstop state change */
                        if (chkstop && !ac->chkstop) {
                                /* checkstop on */
                                ac->chkstop = true;
                                AP_DBF_INFO("%s(%d) card dev checkstop on\n",
                                            __func__, ap);
                        } else if (!chkstop && ac->chkstop) {
                                /* checkstop off */
                                ac->chkstop = false;
                                AP_DBF_INFO("%s(%d) card dev checkstop off\n",
                                            __func__, ap);
                        }
                        /* handle config state change */
                        if (decfg && ac->config) {
                                ac->config = false;
                                AP_DBF_INFO("%s(%d) card dev config off\n",
                                            __func__, ap);
                                ap_send_config_uevent(&ac->ap_dev, ac->config);
                        } else if (!decfg && !ac->config) {
                                ac->config = true;
                                AP_DBF_INFO("%s(%d) card dev config on\n",
                                            __func__, ap);
                                ap_send_config_uevent(&ac->ap_dev, ac->config);
                        }
                }
        }

        if (!ac) {
                /* Build a new card device */
                comp_type = ap_get_compatible_type(qid, hwinfo.at, hwinfo.fac);
                if (!comp_type) {
                        AP_DBF_WARN("%s(%d) type %d, can't get compatibility type\n",
                                    __func__, ap, hwinfo.at);
                        return;
                }
                ac = ap_card_create(ap, hwinfo, comp_type);
                if (!ac) {
                        AP_DBF_WARN("%s(%d) ap_card_create() failed\n",
                                    __func__, ap);
                        return;
                }
                ac->config = !decfg;
                ac->chkstop = chkstop;
                dev = &ac->ap_dev.device;
                dev->bus = &ap_bus_type;
                dev->parent = ap_root_device;
                dev_set_name(dev, "card%02x", ap);
                /* maybe enlarge ap_max_msg_size to support this card */
                if (ac->maxmsgsize > atomic_read(&ap_max_msg_size)) {
                        atomic_set(&ap_max_msg_size, ac->maxmsgsize);
                        AP_DBF_INFO("%s(%d) ap_max_msg_size update to %d byte\n",
                                    __func__, ap,
                                    atomic_read(&ap_max_msg_size));
                }
                /* Register the new card device with AP bus */
                rc = device_register(dev);
                if (rc) {
                        AP_DBF_WARN("%s(%d) device_register() failed\n",
                                    __func__, ap);
                        put_device(dev);
                        return;
                }
                /* get it and thus adjust reference counter */
                get_device(dev);
                if (decfg)
                        AP_DBF_INFO("%s(%d) new (decfg) card dev type=%d func=0x%08x created\n",
                                    __func__, ap, hwinfo.at, hwinfo.fac);
                else if (chkstop)
                        AP_DBF_INFO("%s(%d) new (chkstop) card dev type=%d func=0x%08x created\n",
                                    __func__, ap, hwinfo.at, hwinfo.fac);
                else
                        AP_DBF_INFO("%s(%d) new card dev type=%d func=0x%08x created\n",
                                    __func__, ap, hwinfo.at, hwinfo.fac);
        }

        /* Verify the domains and the queue devices for this card */
        ap_scan_domains(ac);

        /* release the card device */
        put_device(&ac->ap_dev.device);
}

/**
 * ap_get_configuration - get the host AP configuration
 *
 * Stores the host AP configuration information returned from the previous call
 * to Query Configuration Information (QCI), then retrieves and stores the
 * current AP configuration returned from QCI.
 *
 * Return: true if the host AP configuration changed between calls to QCI;
 * otherwise, return false.
 */
static bool ap_get_configuration(void)
{
        if (!ap_qci_info)       /* QCI not supported */
                return false;

        memcpy(ap_qci_info_old, ap_qci_info, sizeof(*ap_qci_info));
        ap_fetch_qci_info(ap_qci_info);

        return memcmp(ap_qci_info, ap_qci_info_old,
                      sizeof(struct ap_config_info)) != 0;
}

/*
 * ap_config_has_new_aps - Check current against old qci info if
 * new adapters have appeared. Returns true if at least one new
 * adapter in the apm mask is showing up. Existing adapters or
 * receding adapters are not counted.
 */
static bool ap_config_has_new_aps(void)
{

        unsigned long m[BITS_TO_LONGS(AP_DEVICES)];

        if (!ap_qci_info)
                return false;

        bitmap_andnot(m, (unsigned long *)ap_qci_info->apm,
                      (unsigned long *)ap_qci_info_old->apm, AP_DEVICES);
        if (!bitmap_empty(m, AP_DEVICES))
                return true;

        return false;
}

/*
 * ap_config_has_new_doms - Check current against old qci info if
 * new (usage) domains have appeared. Returns true if at least one
 * new domain in the aqm mask is showing up. Existing domains or
 * receding domains are not counted.
 */
static bool ap_config_has_new_doms(void)
{
        unsigned long m[BITS_TO_LONGS(AP_DOMAINS)];

        if (!ap_qci_info)
                return false;

        bitmap_andnot(m, (unsigned long *)ap_qci_info->aqm,
                      (unsigned long *)ap_qci_info_old->aqm, AP_DOMAINS);
        if (!bitmap_empty(m, AP_DOMAINS))
                return true;

        return false;
}

/**
 * ap_scan_bus(): Scan the AP bus for new devices
 * Always run under mutex ap_scan_bus_mutex protection
 * which needs to get locked/unlocked by the caller!
 * Returns true if any config change has been detected
 * during the scan, otherwise false.
 */
static bool ap_scan_bus(void)
{
        bool config_changed;
        int ap;

        pr_debug(">%s\n", __func__);

        /* (re-)fetch configuration via QCI */
        config_changed = ap_get_configuration();
        if (config_changed) {
                if (ap_config_has_new_aps() || ap_config_has_new_doms()) {
                        /*
                         * Appearance of new adapters and/or domains need to
                         * build new ap devices which need to get bound to an
                         * device driver. Thus reset the APQN bindings complete
                         * completion.
                         */
                        reinit_completion(&ap_apqn_bindings_complete);
                }
                /* post a config change notify */
                notify_config_changed();
        }
        ap_select_domain();

        /* loop over all possible adapters */
        for (ap = 0; ap <= ap_max_adapter_id; ap++)
                ap_scan_adapter(ap);

        /* scan complete notify */
        if (config_changed)
                notify_scan_complete();

        /* check if there is at least one queue available with default domain */
        if (ap_domain_index >= 0) {
                struct device *dev =
                        bus_find_device(&ap_bus_type, NULL,
                                        (void *)(long)ap_domain_index,
                                        __match_queue_device_with_queue_id);
                if (dev)
                        put_device(dev);
                else
                        AP_DBF_INFO("%s no queue device with default domain %d available\n",
                                    __func__, ap_domain_index);
        }

        if (atomic64_inc_return(&ap_scan_bus_count) == 1) {
                pr_debug("%s init scan complete\n", __func__);
                ap_send_init_scan_done_uevent();
        }

        ap_check_bindings_complete();

        mod_timer(&ap_scan_bus_timer, jiffies + ap_scan_bus_time * HZ);

        pr_debug("<%s config_changed=%d\n", __func__, config_changed);

        return config_changed;
}

/*
 * Callback for the ap_scan_bus_timer
 * Runs periodically, workqueue timer (ap_scan_bus_time)
 */
static void ap_scan_bus_timer_callback(struct timer_list *unused)
{
        /*
         * schedule work into the system long wq which when
         * the work is finally executed, calls the AP bus scan.
         */
        queue_work(system_long_wq, &ap_scan_bus_work);
}

/*
 * Callback for the ap_scan_bus_work
 */
static void ap_scan_bus_wq_callback(struct work_struct *unused)
{
        /*
         * Try to invoke an ap_scan_bus(). If the mutex acquisition
         * fails there is currently another task already running the
         * AP scan bus and there is no need to wait and re-trigger the
         * scan again. Please note at the end of the scan bus function
         * the AP scan bus timer is re-armed which triggers then the
         * ap_scan_bus_timer_callback which enqueues a work into the
         * system_long_wq which invokes this function here again.
         */
        if (mutex_trylock(&ap_scan_bus_mutex)) {
                ap_scan_bus_result = ap_scan_bus();
                mutex_unlock(&ap_scan_bus_mutex);
        }
}

static int __init ap_debug_init(void)
{
        ap_dbf_info = debug_register("ap", 2, 1,
                                     AP_DBF_MAX_SPRINTF_ARGS * sizeof(long));
        debug_register_view(ap_dbf_info, &debug_sprintf_view);
        debug_set_level(ap_dbf_info, DBF_ERR);

        return 0;
}

static void __init ap_perms_init(void)
{
        /* all resources usable if no kernel parameter string given */
        memset(&ap_perms.ioctlm, 0xFF, sizeof(ap_perms.ioctlm));
        memset(&ap_perms.apm, 0xFF, sizeof(ap_perms.apm));
        memset(&ap_perms.aqm, 0xFF, sizeof(ap_perms.aqm));

        /* apm kernel parameter string */
        if (apm_str) {
                memset(&ap_perms.apm, 0, sizeof(ap_perms.apm));
                ap_parse_mask_str(apm_str, ap_perms.apm, AP_DEVICES,
                                  &ap_perms_mutex);
        }

        /* aqm kernel parameter string */
        if (aqm_str) {
                memset(&ap_perms.aqm, 0, sizeof(ap_perms.aqm));
                ap_parse_mask_str(aqm_str, ap_perms.aqm, AP_DOMAINS,
                                  &ap_perms_mutex);
        }
}

/**
 * ap_module_init(): The module initialization code.
 *
 * Initializes the module.
 */
static int __init ap_module_init(void)
{
        int rc;

        rc = ap_debug_init();
        if (rc)
                return rc;

        if (!ap_instructions_available()) {
                pr_warn("The hardware system does not support AP instructions\n");
                return -ENODEV;
        }

        /* init ap_queue hashtable */
        hash_init(ap_queues);

        /* set up the AP permissions (ioctls, ap and aq masks) */
        ap_perms_init();

        /* Get AP configuration data if available */
        ap_init_qci_info();

        /* check default domain setting */
        if (ap_domain_index < -1 || ap_domain_index > ap_max_domain_id ||
            (ap_domain_index >= 0 &&
             !test_bit_inv(ap_domain_index, ap_perms.aqm))) {
                pr_warn("%d is not a valid cryptographic domain\n",
                        ap_domain_index);
                ap_domain_index = -1;
        }

        /* enable interrupts if available */
        if (ap_interrupts_available() && ap_useirq) {
                rc = register_adapter_interrupt(&ap_airq);
                ap_irq_flag = (rc == 0);
        }

        /* Create /sys/bus/ap. */
        rc = bus_register(&ap_bus_type);
        if (rc)
                goto out;

        /* Create /sys/devices/ap. */
        ap_root_device = root_device_register("ap");
        rc = PTR_ERR_OR_ZERO(ap_root_device);
        if (rc)
                goto out_bus;
        ap_root_device->bus = &ap_bus_type;

        /* Setup the AP bus rescan timer. */
        timer_setup(&ap_scan_bus_timer, ap_scan_bus_timer_callback, 0);

        /*
         * Setup the high resolution poll timer.
         * If we are running under z/VM adjust polling to z/VM polling rate.
         */
        if (MACHINE_IS_VM)
                poll_high_timeout = 1500000;
        hrtimer_init(&ap_poll_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
        ap_poll_timer.function = ap_poll_timeout;

        /* Start the low priority AP bus poll thread. */
        if (ap_thread_flag) {
                rc = ap_poll_thread_start();
                if (rc)
                        goto out_work;
        }

        queue_work(system_long_wq, &ap_scan_bus_work);

        return 0;

out_work:
        hrtimer_cancel(&ap_poll_timer);
        root_device_unregister(ap_root_device);
out_bus:
        bus_unregister(&ap_bus_type);
out:
        if (ap_irq_flag)
                unregister_adapter_interrupt(&ap_airq);
        kfree(ap_qci_info);
        return rc;
}
device_initcall(ap_module_init);