apple-mfi-fastcharge.c
// SPDX-License-Identifier: GPL-2.0+
/*
* Fast-charge control for Apple "MFi" devices
*
* Copyright (C) 2019 Bastien Nocera <hadess@hadess.net>
*/
/* Standard include files */
#include <linux/module.h>
#include <linux/power_supply.h>
#include <linux/slab.h>
#include <linux/usb.h>
MODULE_AUTHOR("Bastien Nocera <hadess@hadess.net>");
MODULE_DESCRIPTION("Fast-charge control for Apple \"MFi\" devices");
MODULE_LICENSE("GPL");
#define TRICKLE_CURRENT_MA 0
#define FAST_CURRENT_MA 2500
#define APPLE_VENDOR_ID 0x05ac /* Apple */
/* The product ID is defined as starting with 0x12nn, as per the
* "Choosing an Apple Device USB Configuration" section in
* release R9 (2012) of the "MFi Accessory Hardware Specification"
*
* To distinguish an Apple device, a USB host can check the device
* descriptor of attached USB devices for the following fields:
* ■ Vendor ID: 0x05AC
* ■ Product ID: 0x12nn
*
* Those checks will be done in .match() and .probe().
*/
static const struct usb_device_id mfi_fc_id_table[] = {
{ .idVendor = APPLE_VENDOR_ID,
.match_flags = USB_DEVICE_ID_MATCH_VENDOR },
{},
};
MODULE_DEVICE_TABLE(usb, mfi_fc_id_table);
/* Driver-local specific stuff */
struct mfi_device {
struct usb_device *udev;
struct power_supply *battery;
int charge_type;
};
static int apple_mfi_fc_set_charge_type(struct mfi_device *mfi,
const union power_supply_propval *val)
{
int current_ma;
int retval;
__u8 request_type;
if (mfi->charge_type == val->intval) {
dev_dbg(&mfi->udev->dev, "charge type %d already set\n",
mfi->charge_type);
return 0;
}
switch (val->intval) {
case POWER_SUPPLY_CHARGE_TYPE_TRICKLE:
current_ma = TRICKLE_CURRENT_MA;
break;
case POWER_SUPPLY_CHARGE_TYPE_FAST:
current_ma = FAST_CURRENT_MA;
break;
default:
return -EINVAL;
}
request_type = USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_DEVICE;
retval = usb_control_msg(mfi->udev, usb_sndctrlpipe(mfi->udev, 0),
0x40, /* Vendor‐defined power request */
request_type,
current_ma, /* wValue, current offset */
current_ma, /* wIndex, current offset */
NULL, 0, USB_CTRL_GET_TIMEOUT);
if (retval) {
dev_dbg(&mfi->udev->dev, "retval = %d\n", retval);
return retval;
}
mfi->charge_type = val->intval;
return 0;
}
static int apple_mfi_fc_get_property(struct power_supply *psy,
enum power_supply_property psp,
union power_supply_propval *val)
{
struct mfi_device *mfi = power_supply_get_drvdata(psy);
dev_dbg(&mfi->udev->dev, "prop: %d\n", psp);
switch (psp) {
case POWER_SUPPLY_PROP_CHARGE_TYPE:
val->intval = mfi->charge_type;
break;
case POWER_SUPPLY_PROP_SCOPE:
val->intval = POWER_SUPPLY_SCOPE_DEVICE;
break;
default:
return -ENODATA;
}
return 0;
}
static int apple_mfi_fc_set_property(struct power_supply *psy,
enum power_supply_property psp,
const union power_supply_propval *val)
{
struct mfi_device *mfi = power_supply_get_drvdata(psy);
int ret;
dev_dbg(&mfi->udev->dev, "prop: %d\n", psp);
ret = pm_runtime_get_sync(&mfi->udev->dev);
if (ret < 0) {
pm_runtime_put_noidle(&mfi->udev->dev);
return ret;
}
switch (psp) {
case POWER_SUPPLY_PROP_CHARGE_TYPE:
ret = apple_mfi_fc_set_charge_type(mfi, val);
break;
default:
ret = -EINVAL;
}
pm_runtime_mark_last_busy(&mfi->udev->dev);
pm_runtime_put_autosuspend(&mfi->udev->dev);
return ret;
}
static int apple_mfi_fc_property_is_writeable(struct power_supply *psy,
enum power_supply_property psp)
{
switch (psp) {
case POWER_SUPPLY_PROP_CHARGE_TYPE:
return 1;
default:
return 0;
}
}
static enum power_supply_property apple_mfi_fc_properties[] = {
POWER_SUPPLY_PROP_CHARGE_TYPE,
POWER_SUPPLY_PROP_SCOPE
};
static const struct power_supply_desc apple_mfi_fc_desc = {
.name = "apple_mfi_fastcharge",
.type = POWER_SUPPLY_TYPE_BATTERY,
.properties = apple_mfi_fc_properties,
.num_properties = ARRAY_SIZE(apple_mfi_fc_properties),
.get_property = apple_mfi_fc_get_property,
.set_property = apple_mfi_fc_set_property,
.property_is_writeable = apple_mfi_fc_property_is_writeable
};
static bool mfi_fc_match(struct usb_device *udev)
{
int idProduct;
idProduct = le16_to_cpu(udev->descriptor.idProduct);
/* See comment above mfi_fc_id_table[] */
return (idProduct >= 0x1200 && idProduct <= 0x12ff);
}
static int mfi_fc_probe(struct usb_device *udev)
{
struct power_supply_config battery_cfg = {};
struct mfi_device *mfi = NULL;
int err;
if (!mfi_fc_match(udev))
return -ENODEV;
mfi = kzalloc(sizeof(struct mfi_device), GFP_KERNEL);
if (!mfi)
return -ENOMEM;
battery_cfg.drv_data = mfi;
mfi->charge_type = POWER_SUPPLY_CHARGE_TYPE_TRICKLE;
mfi->battery = power_supply_register(&udev->dev,
&apple_mfi_fc_desc,
&battery_cfg);
if (IS_ERR(mfi->battery)) {
dev_err(&udev->dev, "Can't register battery\n");
err = PTR_ERR(mfi->battery);
kfree(mfi);
return err;
}
mfi->udev = usb_get_dev(udev);
dev_set_drvdata(&udev->dev, mfi);
return 0;
}
static void mfi_fc_disconnect(struct usb_device *udev)
{
struct mfi_device *mfi;
mfi = dev_get_drvdata(&udev->dev);
if (mfi->battery)
power_supply_unregister(mfi->battery);
dev_set_drvdata(&udev->dev, NULL);
usb_put_dev(mfi->udev);
kfree(mfi);
}
static struct usb_device_driver mfi_fc_driver = {
.name = "apple-mfi-fastcharge",
.probe = mfi_fc_probe,
.disconnect = mfi_fc_disconnect,
.id_table = mfi_fc_id_table,
.match = mfi_fc_match,
.generic_subclass = 1,
};
static int __init mfi_fc_driver_init(void)
{
return usb_register_device_driver(&mfi_fc_driver, THIS_MODULE);
}
static void __exit mfi_fc_driver_exit(void)
{
usb_deregister_device_driver(&mfi_fc_driver);
}
module_init(mfi_fc_driver_init);
module_exit(mfi_fc_driver_exit);