linux/drivers/usb/misc/apple-mfi-fastcharge.c
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   1// SPDX-License-Identifier: GPL-2.0+
   2/*
   3 * Fast-charge control for Apple "MFi" devices
   4 *
   5 * Copyright (C) 2019 Bastien Nocera <hadess@hadess.net>
   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
  14MODULE_AUTHOR("Bastien Nocera <hadess@hadess.net>");
  15MODULE_DESCRIPTION("Fast-charge control for Apple \"MFi\" devices");
  16MODULE_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 * \xE2\x96\xA0 Vendor ID: 0x05AC
  30 * \xE2\x96\xA0 Product ID: 0x12nn
  31 *
  32 * Those checks will be done in .match() and .probe().
  33 */
  34
  35static 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
  41MODULE_DEVICE_TABLE(usb, mfi_fc_id_table);
  42
  43/* Driver-local specific stuff */
  44struct mfi_device {
  45        struct usb_device *udev;
  46        struct power_supply *battery;
  47        int charge_type;
  48};
  49
  50static 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\xE2\x80\x90defined 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
  91static 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
 113static 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                pm_runtime_put_noidle(&mfi->udev->dev);
 125                return ret;
 126        }
 127
 128        switch (psp) {
 129        case POWER_SUPPLY_PROP_CHARGE_TYPE:
 130                ret = apple_mfi_fc_set_charge_type(mfi, val);
 131                break;
 132        default:
 133                ret = -EINVAL;
 134        }
 135
 136        pm_runtime_mark_last_busy(&mfi->udev->dev);
 137        pm_runtime_put_autosuspend(&mfi->udev->dev);
 138
 139        return ret;
 140}
 141
 142static int apple_mfi_fc_property_is_writeable(struct power_supply *psy,
 143                                              enum power_supply_property psp)
 144{
 145        switch (psp) {
 146        case POWER_SUPPLY_PROP_CHARGE_TYPE:
 147                return 1;
 148        default:
 149                return 0;
 150        }
 151}
 152
 153static enum power_supply_property apple_mfi_fc_properties[] = {
 154        POWER_SUPPLY_PROP_CHARGE_TYPE,
 155        POWER_SUPPLY_PROP_SCOPE
 156};
 157
 158static const struct power_supply_desc apple_mfi_fc_desc = {
 159        .name                   = "apple_mfi_fastcharge",
 160        .type                   = POWER_SUPPLY_TYPE_BATTERY,
 161        .properties             = apple_mfi_fc_properties,
 162        .num_properties         = ARRAY_SIZE(apple_mfi_fc_properties),
 163        .get_property           = apple_mfi_fc_get_property,
 164        .set_property           = apple_mfi_fc_set_property,
 165        .property_is_writeable  = apple_mfi_fc_property_is_writeable
 166};
 167
 168static bool mfi_fc_match(struct usb_device *udev)
 169{
 170        int idProduct;
 171
 172        idProduct = le16_to_cpu(udev->descriptor.idProduct);
 173        /* See comment above mfi_fc_id_table[] */
 174        return (idProduct >= 0x1200 && idProduct <= 0x12ff);
 175}
 176
 177static int mfi_fc_probe(struct usb_device *udev)
 178{
 179        struct power_supply_config battery_cfg = {};
 180        struct mfi_device *mfi = NULL;
 181        int err;
 182
 183        if (!mfi_fc_match(udev))
 184                return -ENODEV;
 185
 186        mfi = kzalloc(sizeof(struct mfi_device), GFP_KERNEL);
 187        if (!mfi)
 188                return -ENOMEM;
 189
 190        battery_cfg.drv_data = mfi;
 191
 192        mfi->charge_type = POWER_SUPPLY_CHARGE_TYPE_TRICKLE;
 193        mfi->battery = power_supply_register(&udev->dev,
 194                                                &apple_mfi_fc_desc,
 195                                                &battery_cfg);
 196        if (IS_ERR(mfi->battery)) {
 197                dev_err(&udev->dev, "Can't register battery\n");
 198                err = PTR_ERR(mfi->battery);
 199                kfree(mfi);
 200                return err;
 201        }
 202
 203        mfi->udev = usb_get_dev(udev);
 204        dev_set_drvdata(&udev->dev, mfi);
 205
 206        return 0;
 207}
 208
 209static void mfi_fc_disconnect(struct usb_device *udev)
 210{
 211        struct mfi_device *mfi;
 212
 213        mfi = dev_get_drvdata(&udev->dev);
 214        if (mfi->battery)
 215                power_supply_unregister(mfi->battery);
 216        dev_set_drvdata(&udev->dev, NULL);
 217        usb_put_dev(mfi->udev);
 218        kfree(mfi);
 219}
 220
 221static struct usb_device_driver mfi_fc_driver = {
 222        .name =         "apple-mfi-fastcharge",
 223        .probe =        mfi_fc_probe,
 224        .disconnect =   mfi_fc_disconnect,
 225        .id_table =     mfi_fc_id_table,
 226        .match =        mfi_fc_match,
 227        .generic_subclass = 1,
 228};
 229
 230static int __init mfi_fc_driver_init(void)
 231{
 232        return usb_register_device_driver(&mfi_fc_driver, THIS_MODULE);
 233}
 234
 235static void __exit mfi_fc_driver_exit(void)
 236{
 237        usb_deregister_device_driver(&mfi_fc_driver);
 238}
 239
 240module_init(mfi_fc_driver_init);
 241module_exit(mfi_fc_driver_exit);
 242