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 <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 * ■ Vendor ID: 0x05AC
 30 * ■ 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	struct power_supply_desc battery_desc;
 48	int charge_type;
 49};
 50
 51static int apple_mfi_fc_set_charge_type(struct mfi_device *mfi,
 52					const union power_supply_propval *val)
 53{
 54	int current_ma;
 55	int retval;
 56	__u8 request_type;
 57
 58	if (mfi->charge_type == val->intval) {
 59		dev_dbg(&mfi->udev->dev, "charge type %d already set\n",
 60				mfi->charge_type);
 61		return 0;
 62	}
 63
 64	switch (val->intval) {
 65	case POWER_SUPPLY_CHARGE_TYPE_TRICKLE:
 66		current_ma = TRICKLE_CURRENT_MA;
 67		break;
 68	case POWER_SUPPLY_CHARGE_TYPE_FAST:
 69		current_ma = FAST_CURRENT_MA;
 70		break;
 71	default:
 72		return -EINVAL;
 73	}
 74
 75	request_type = USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_DEVICE;
 76	retval = usb_control_msg(mfi->udev, usb_sndctrlpipe(mfi->udev, 0),
 77				 0x40, /* Vendor‐defined power request */
 78				 request_type,
 79				 current_ma, /* wValue, current offset */
 80				 current_ma, /* wIndex, current offset */
 81				 NULL, 0, USB_CTRL_GET_TIMEOUT);
 82	if (retval) {
 83		dev_dbg(&mfi->udev->dev, "retval = %d\n", retval);
 84		return retval;
 85	}
 86
 87	mfi->charge_type = val->intval;
 88
 89	return 0;
 90}
 91
 92static int apple_mfi_fc_get_property(struct power_supply *psy,
 93		enum power_supply_property psp,
 94		union power_supply_propval *val)
 95{
 96	struct mfi_device *mfi = power_supply_get_drvdata(psy);
 97
 98	dev_dbg(&mfi->udev->dev, "prop: %d\n", psp);
 99
100	switch (psp) {
101	case POWER_SUPPLY_PROP_CHARGE_TYPE:
102		val->intval = mfi->charge_type;
103		break;
104	case POWER_SUPPLY_PROP_SCOPE:
105		val->intval = POWER_SUPPLY_SCOPE_DEVICE;
106		break;
107	default:
108		return -ENODATA;
109	}
110
111	return 0;
112}
113
114static int apple_mfi_fc_set_property(struct power_supply *psy,
115		enum power_supply_property psp,
116		const union power_supply_propval *val)
117{
118	struct mfi_device *mfi = power_supply_get_drvdata(psy);
119	int ret;
120
121	dev_dbg(&mfi->udev->dev, "prop: %d\n", psp);
122
123	ret = pm_runtime_get_sync(&mfi->udev->dev);
124	if (ret < 0) {
125		pm_runtime_put_noidle(&mfi->udev->dev);
126		return ret;
127	}
128
129	switch (psp) {
130	case POWER_SUPPLY_PROP_CHARGE_TYPE:
131		ret = apple_mfi_fc_set_charge_type(mfi, val);
132		break;
133	default:
134		ret = -EINVAL;
135	}
136
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	char *battery_name;
182	int err;
183
184	if (!mfi_fc_match(udev))
185		return -ENODEV;
186
187	mfi = kzalloc(sizeof(struct mfi_device), GFP_KERNEL);
188	if (!mfi)
189		return -ENOMEM;
190
191	battery_name = kasprintf(GFP_KERNEL, "apple_mfi_fastcharge_%d-%d",
192				 udev->bus->busnum, udev->devnum);
193	if (!battery_name) {
194		err = -ENOMEM;
195		goto err_free_mfi;
196	}
197
198	mfi->battery_desc = apple_mfi_fc_desc;
199	mfi->battery_desc.name = battery_name;
200
201	battery_cfg.drv_data = mfi;
202
203	mfi->charge_type = POWER_SUPPLY_CHARGE_TYPE_TRICKLE;
204	mfi->battery = power_supply_register(&udev->dev,
205						&mfi->battery_desc,
206						&battery_cfg);
207	if (IS_ERR(mfi->battery)) {
208		dev_err(&udev->dev, "Can't register battery\n");
209		err = PTR_ERR(mfi->battery);
210		goto err_free_name;
211	}
212
213	mfi->udev = usb_get_dev(udev);
214	dev_set_drvdata(&udev->dev, mfi);
215
216	return 0;
217
218err_free_name:
219	kfree(battery_name);
220err_free_mfi:
221	kfree(mfi);
222	return err;
223}
224
225static void mfi_fc_disconnect(struct usb_device *udev)
226{
227	struct mfi_device *mfi;
228
229	mfi = dev_get_drvdata(&udev->dev);
230	if (mfi->battery)
231		power_supply_unregister(mfi->battery);
232	kfree(mfi->battery_desc.name);
233	dev_set_drvdata(&udev->dev, NULL);
234	usb_put_dev(mfi->udev);
235	kfree(mfi);
236}
237
238static struct usb_device_driver mfi_fc_driver = {
239	.name =		"apple-mfi-fastcharge",
240	.probe =	mfi_fc_probe,
241	.disconnect =	mfi_fc_disconnect,
242	.id_table =	mfi_fc_id_table,
243	.match =	mfi_fc_match,
244	.generic_subclass = 1,
245};
246
247static int __init mfi_fc_driver_init(void)
248{
249	return usb_register_device_driver(&mfi_fc_driver, THIS_MODULE);
250}
251
252static void __exit mfi_fc_driver_exit(void)
253{
254	usb_deregister_device_driver(&mfi_fc_driver);
255}
256
257module_init(mfi_fc_driver_init);
258module_exit(mfi_fc_driver_exit);