drivers/usb/misc/apple-mfi-fastcharge.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Fast-charge control for Apple "MFi" devices
   4  *
   5  * Copyright (C) 2019 Bastien Nocera <[email protected]>
   6  */
   7
   8 /* Standard include files */
   9 #include <linux/module.h>
  10 #include <linux/power_supply.h>
  11 #include <linux/slab.h>
  12 #include <linux/usb.h>
  13
  14 MODULE_AUTHOR("Bastien Nocera <[email protected]>");
  15 MODULE_DESCRIPTION("Fast-charge control for Apple \"MFi\" devices");
  16 MODULE_LICENSE("GPL");
  17
  18 #define TRICKLE_CURRENT_MA              0
  19 #define FAST_CURRENT_MA                 2500
  20
  21 #define APPLE_VENDOR_ID                 0x05ac  /* Apple */
  22
  23 /* The product ID is defined as starting with 0x12nn, as per the
  24  * "Choosing an Apple Device USB Configuration" section in
  25  * release R9 (2012) of the "MFi Accessory Hardware Specification"
  26  *
  27  * To distinguish an Apple device, a USB host can check the device
  28  * descriptor of attached USB devices for the following fields:
  29  * ■ Vendor ID: 0x05AC
  30  * ■ Product ID: 0x12nn
  31  *
  32  * Those checks will be done in .match() and .probe().
  33  */
  34
  35 static const struct usb_device_id mfi_fc_id_table[] = {
  36         { .idVendor = APPLE_VENDOR_ID,
  37           .match_flags = USB_DEVICE_ID_MATCH_VENDOR },
  38         {},
  39 };
  40
  41 MODULE_DEVICE_TABLE(usb, mfi_fc_id_table);
  42
  43 /* Driver-local specific stuff */
  44 struct mfi_device {
  45         struct usb_device *udev;
  46         struct power_supply *battery;
  47         int charge_type;
  48 };
  49
  50 static int apple_mfi_fc_set_charge_type(struct mfi_device *mfi,
  51                                         const union power_supply_propval *val)
  52 {
  53         int current_ma;
  54         int retval;
  55         __u8 request_type;
  56
  57         if (mfi->charge_type == val->intval) {
  58                 dev_dbg(&mfi->udev->dev, "charge type %d already set\n",
  59                                 mfi->charge_type);
  60                 return 0;
  61         }
  62
  63         switch (val->intval) {
  64         case POWER_SUPPLY_CHARGE_TYPE_TRICKLE:
  65                 current_ma = TRICKLE_CURRENT_MA;
  66                 break;
  67         case POWER_SUPPLY_CHARGE_TYPE_FAST:
  68                 current_ma = FAST_CURRENT_MA;
  69                 break;
  70         default:
  71                 return -EINVAL;
  72         }
  73
  74         request_type = USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_DEVICE;
  75         retval = usb_control_msg(mfi->udev, usb_sndctrlpipe(mfi->udev, 0),
  76                                  0x40, /* Vendor‐defined power request */
  77                                  request_type,
  78                                  current_ma, /* wValue, current offset */
  79                                  current_ma, /* wIndex, current offset */
  80                                  NULL, 0, USB_CTRL_GET_TIMEOUT);
  81         if (retval) {
  82                 dev_dbg(&mfi->udev->dev, "retval = %d\n", retval);
  83                 return retval;
  84         }
  85
  86         mfi->charge_type = val->intval;
  87
  88         return 0;
  89 }
  90
  91 static int apple_mfi_fc_get_property(struct power_supply *psy,
  92                 enum power_supply_property psp,
  93                 union power_supply_propval *val)
  94 {
  95         struct mfi_device *mfi = power_supply_get_drvdata(psy);
  96
  97         dev_dbg(&mfi->udev->dev, "prop: %d\n", psp);
  98
  99         switch (psp) {
 100         case POWER_SUPPLY_PROP_CHARGE_TYPE:
 101                 val->intval = mfi->charge_type;
 102                 break;
 103         case POWER_SUPPLY_PROP_SCOPE:
 104                 val->intval = POWER_SUPPLY_SCOPE_DEVICE;
 105                 break;
 106         default:
 107                 return -ENODATA;
 108         }
 109
 110         return 0;
 111 }
 112
 113 static int apple_mfi_fc_set_property(struct power_supply *psy,
 114                 enum power_supply_property psp,
 115                 const union power_supply_propval *val)
 116 {
 117         struct mfi_device *mfi = power_supply_get_drvdata(psy);
 118         int ret;
 119
 120         dev_dbg(&mfi->udev->dev, "prop: %d\n", psp);
 121
 122         ret = pm_runtime_get_sync(&mfi->udev->dev);
 123         if (ret < 0)
 124                 return ret;
 125
 126         switch (psp) {
 127         case POWER_SUPPLY_PROP_CHARGE_TYPE:
 128                 ret = apple_mfi_fc_set_charge_type(mfi, val);
 129                 break;
 130         default:
 131                 ret = -EINVAL;
 132         }
 133
 134         pm_runtime_mark_last_busy(&mfi->udev->dev);
 135         pm_runtime_put_autosuspend(&mfi->udev->dev);
 136
 137         return ret;
 138 }
 139
 140 static int apple_mfi_fc_property_is_writeable(struct power_supply *psy,
 141                                               enum power_supply_property psp)
 142 {
 143         switch (psp) {
 144         case POWER_SUPPLY_PROP_CHARGE_TYPE:
 145                 return 1;
 146         default:
 147                 return 0;
 148         }
 149 }
 150
 151 static enum power_supply_property apple_mfi_fc_properties[] = {
 152         POWER_SUPPLY_PROP_CHARGE_TYPE,
 153         POWER_SUPPLY_PROP_SCOPE
 154 };
 155
 156 static const struct power_supply_desc apple_mfi_fc_desc = {
 157         .name                   = "apple_mfi_fastcharge",
 158         .type                   = POWER_SUPPLY_TYPE_BATTERY,
 159         .properties             = apple_mfi_fc_properties,
 160         .num_properties         = ARRAY_SIZE(apple_mfi_fc_properties),
 161         .get_property           = apple_mfi_fc_get_property,
 162         .set_property           = apple_mfi_fc_set_property,
 163         .property_is_writeable  = apple_mfi_fc_property_is_writeable
 164 };
 165
 166 static int mfi_fc_probe(struct usb_device *udev)
 167 {
 168         struct power_supply_config battery_cfg = {};
 169         struct mfi_device *mfi = NULL;
 170         int err, idProduct;
 171
 172         idProduct = le16_to_cpu(udev->descriptor.idProduct);
 173         /* See comment above mfi_fc_id_table[] */
 174         if (idProduct < 0x1200 || idProduct > 0x12ff) {
 175                 return -ENODEV;
 176         }
 177
 178         mfi = kzalloc(sizeof(struct mfi_device), GFP_KERNEL);
 179         if (!mfi) {
 180                 err = -ENOMEM;
 181                 goto error;
 182         }
 183
 184         battery_cfg.drv_data = mfi;
 185
 186         mfi->charge_type = POWER_SUPPLY_CHARGE_TYPE_TRICKLE;
 187         mfi->battery = power_supply_register(&udev->dev,
 188                                                 &apple_mfi_fc_desc,
 189                                                 &battery_cfg);
 190         if (IS_ERR(mfi->battery)) {
 191                 dev_err(&udev->dev, "Can't register battery\n");
 192                 err = PTR_ERR(mfi->battery);
 193                 goto error;
 194         }
 195
 196         mfi->udev = usb_get_dev(udev);
 197         dev_set_drvdata(&udev->dev, mfi);
 198
 199         return 0;
 200
 201 error:
 202         kfree(mfi);
 203         return err;
 204 }
 205
 206 static void mfi_fc_disconnect(struct usb_device *udev)
 207 {
 208         struct mfi_device *mfi;
 209
 210         mfi = dev_get_drvdata(&udev->dev);
 211         if (mfi->battery)
 212                 power_supply_unregister(mfi->battery);
 213         dev_set_drvdata(&udev->dev, NULL);
 214         usb_put_dev(mfi->udev);
 215         kfree(mfi);
 216 }
 217
 218 static struct usb_device_driver mfi_fc_driver = {
 219         .name =         "apple-mfi-fastcharge",
 220         .probe =        mfi_fc_probe,
 221         .disconnect =   mfi_fc_disconnect,
 222         .id_table =     mfi_fc_id_table,
 223         .generic_subclass = 1,
 224 };
 225
 226 static int __init mfi_fc_driver_init(void)
 227 {
 228         return usb_register_device_driver(&mfi_fc_driver, THIS_MODULE);
 229 }
 230
 231 static void __exit mfi_fc_driver_exit(void)
 232 {
 233         usb_deregister_device_driver(&mfi_fc_driver);
 234 }
 235
 236 module_init(mfi_fc_driver_init);
 237 module_exit(mfi_fc_driver_exit);