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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 * ■ 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_obj(struct mfi_device);
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 = 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 kfree(mfi);
235}
236
237static struct usb_device_driver mfi_fc_driver = {
238 .name = "apple-mfi-fastcharge",
239 .probe = mfi_fc_probe,
240 .disconnect = mfi_fc_disconnect,
241 .id_table = mfi_fc_id_table,
242 .match = mfi_fc_match,
243 .generic_subclass = 1,
244};
245
246static int __init mfi_fc_driver_init(void)
247{
248 return usb_register_device_driver(&mfi_fc_driver, THIS_MODULE);
249}
250
251static void __exit mfi_fc_driver_exit(void)
252{
253 usb_deregister_device_driver(&mfi_fc_driver);
254}
255
256module_init(mfi_fc_driver_init);
257module_exit(mfi_fc_driver_exit);