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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 
14 MODULE_AUTHOR("Bastien Nocera <hadess@hadess.net>");
15 MODULE_DESCRIPTION("Fast-charge control for Apple \"MFi\" devices");
16 MODULE_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 
35 static 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 
41 MODULE_DEVICE_TABLE(usb, mfi_fc_id_table);
42 
43 /* Driver-local specific stuff */
44 struct mfi_device {
45 	struct usb_device *udev;
46 	struct power_supply *battery;
47 	int charge_type;
48 };
49 
apple_mfi_fc_set_charge_type(struct mfi_device * mfi,const union power_supply_propval * val)50 static 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 
apple_mfi_fc_get_property(struct power_supply * psy,enum power_supply_property psp,union power_supply_propval * val)91 static 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 
apple_mfi_fc_set_property(struct power_supply * psy,enum power_supply_property psp,const union power_supply_propval * val)113 static 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 
apple_mfi_fc_property_is_writeable(struct power_supply * psy,enum power_supply_property psp)142 static 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 
153 static enum power_supply_property apple_mfi_fc_properties[] = {
154 	POWER_SUPPLY_PROP_CHARGE_TYPE,
155 	POWER_SUPPLY_PROP_SCOPE
156 };
157 
158 static 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 
mfi_fc_match(struct usb_device * udev)168 static 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 
mfi_fc_probe(struct usb_device * udev)177 static 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 		err = -ENOMEM;
189 		goto error;
190 	}
191 
192 	battery_cfg.drv_data = mfi;
193 
194 	mfi->charge_type = POWER_SUPPLY_CHARGE_TYPE_TRICKLE;
195 	mfi->battery = power_supply_register(&udev->dev,
196 						&apple_mfi_fc_desc,
197 						&battery_cfg);
198 	if (IS_ERR(mfi->battery)) {
199 		dev_err(&udev->dev, "Can't register battery\n");
200 		err = PTR_ERR(mfi->battery);
201 		goto error;
202 	}
203 
204 	mfi->udev = usb_get_dev(udev);
205 	dev_set_drvdata(&udev->dev, mfi);
206 
207 	return 0;
208 
209 error:
210 	kfree(mfi);
211 	return err;
212 }
213 
mfi_fc_disconnect(struct usb_device * udev)214 static void mfi_fc_disconnect(struct usb_device *udev)
215 {
216 	struct mfi_device *mfi;
217 
218 	mfi = dev_get_drvdata(&udev->dev);
219 	if (mfi->battery)
220 		power_supply_unregister(mfi->battery);
221 	dev_set_drvdata(&udev->dev, NULL);
222 	usb_put_dev(mfi->udev);
223 	kfree(mfi);
224 }
225 
226 static struct usb_device_driver mfi_fc_driver = {
227 	.name =		"apple-mfi-fastcharge",
228 	.probe =	mfi_fc_probe,
229 	.disconnect =	mfi_fc_disconnect,
230 	.id_table =	mfi_fc_id_table,
231 	.match =	mfi_fc_match,
232 	.generic_subclass = 1,
233 };
234 
mfi_fc_driver_init(void)235 static int __init mfi_fc_driver_init(void)
236 {
237 	return usb_register_device_driver(&mfi_fc_driver, THIS_MODULE);
238 }
239 
mfi_fc_driver_exit(void)240 static void __exit mfi_fc_driver_exit(void)
241 {
242 	usb_deregister_device_driver(&mfi_fc_driver);
243 }
244 
245 module_init(mfi_fc_driver_init);
246 module_exit(mfi_fc_driver_exit);
247