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	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���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
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