1 /*
2  * Supports for the button array on SoC tablets originally running
3  * Windows 8.
4  *
5  * (C) Copyright 2014 Intel Corporation
6  *
7  * This program is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU General Public License
9  * as published by the Free Software Foundation; version 2
10  * of the License.
11  */
12 
13 #include <linux/module.h>
14 #include <linux/input.h>
15 #include <linux/init.h>
16 #include <linux/kernel.h>
17 #include <linux/acpi.h>
18 #include <linux/gpio/consumer.h>
19 #include <linux/gpio_keys.h>
20 #include <linux/gpio.h>
21 #include <linux/platform_device.h>
22 
23 struct soc_button_info {
24 	const char *name;
25 	int acpi_index;
26 	unsigned int event_type;
27 	unsigned int event_code;
28 	bool autorepeat;
29 	bool wakeup;
30 };
31 
32 /*
33  * Some of the buttons like volume up/down are auto repeat, while others
34  * are not. To support both, we register two platform devices, and put
35  * buttons into them based on whether the key should be auto repeat.
36  */
37 #define BUTTON_TYPES	2
38 
39 struct soc_button_data {
40 	struct platform_device *children[BUTTON_TYPES];
41 };
42 
43 /*
44  * Get the Nth GPIO number from the ACPI object.
45  */
46 static int soc_button_lookup_gpio(struct device *dev, int acpi_index)
47 {
48 	struct gpio_desc *desc;
49 	int gpio;
50 
51 	desc = gpiod_get_index(dev, NULL, acpi_index, GPIOD_ASIS);
52 	if (IS_ERR(desc))
53 		return PTR_ERR(desc);
54 
55 	gpio = desc_to_gpio(desc);
56 
57 	gpiod_put(desc);
58 
59 	return gpio;
60 }
61 
62 static struct platform_device *
63 soc_button_device_create(struct platform_device *pdev,
64 			 const struct soc_button_info *button_info,
65 			 bool autorepeat)
66 {
67 	const struct soc_button_info *info;
68 	struct platform_device *pd;
69 	struct gpio_keys_button *gpio_keys;
70 	struct gpio_keys_platform_data *gpio_keys_pdata;
71 	int n_buttons = 0;
72 	int gpio;
73 	int error;
74 
75 	for (info = button_info; info->name; info++)
76 		if (info->autorepeat == autorepeat)
77 			n_buttons++;
78 
79 	gpio_keys_pdata = devm_kzalloc(&pdev->dev,
80 				       sizeof(*gpio_keys_pdata) +
81 					sizeof(*gpio_keys) * n_buttons,
82 				       GFP_KERNEL);
83 	if (!gpio_keys_pdata)
84 		return ERR_PTR(-ENOMEM);
85 
86 	gpio_keys = (void *)(gpio_keys_pdata + 1);
87 	n_buttons = 0;
88 
89 	for (info = button_info; info->name; info++) {
90 		if (info->autorepeat != autorepeat)
91 			continue;
92 
93 		gpio = soc_button_lookup_gpio(&pdev->dev, info->acpi_index);
94 		if (!gpio_is_valid(gpio))
95 			continue;
96 
97 		gpio_keys[n_buttons].type = info->event_type;
98 		gpio_keys[n_buttons].code = info->event_code;
99 		gpio_keys[n_buttons].gpio = gpio;
100 		gpio_keys[n_buttons].active_low = 1;
101 		gpio_keys[n_buttons].desc = info->name;
102 		gpio_keys[n_buttons].wakeup = info->wakeup;
103 		/* These devices often use cheap buttons, use 50 ms debounce */
104 		gpio_keys[n_buttons].debounce_interval = 50;
105 		n_buttons++;
106 	}
107 
108 	if (n_buttons == 0) {
109 		error = -ENODEV;
110 		goto err_free_mem;
111 	}
112 
113 	gpio_keys_pdata->buttons = gpio_keys;
114 	gpio_keys_pdata->nbuttons = n_buttons;
115 	gpio_keys_pdata->rep = autorepeat;
116 
117 	pd = platform_device_alloc("gpio-keys", PLATFORM_DEVID_AUTO);
118 	if (!pd) {
119 		error = -ENOMEM;
120 		goto err_free_mem;
121 	}
122 
123 	error = platform_device_add_data(pd, gpio_keys_pdata,
124 					 sizeof(*gpio_keys_pdata));
125 	if (error)
126 		goto err_free_pdev;
127 
128 	error = platform_device_add(pd);
129 	if (error)
130 		goto err_free_pdev;
131 
132 	return pd;
133 
134 err_free_pdev:
135 	platform_device_put(pd);
136 err_free_mem:
137 	devm_kfree(&pdev->dev, gpio_keys_pdata);
138 	return ERR_PTR(error);
139 }
140 
141 static int soc_button_get_acpi_object_int(const union acpi_object *obj)
142 {
143 	if (obj->type != ACPI_TYPE_INTEGER)
144 		return -1;
145 
146 	return obj->integer.value;
147 }
148 
149 /* Parse a single ACPI0011 _DSD button descriptor */
150 static int soc_button_parse_btn_desc(struct device *dev,
151 				     const union acpi_object *desc,
152 				     int collection_uid,
153 				     struct soc_button_info *info)
154 {
155 	int upage, usage;
156 
157 	if (desc->type != ACPI_TYPE_PACKAGE ||
158 	    desc->package.count != 5 ||
159 	    /* First byte should be 1 (control) */
160 	    soc_button_get_acpi_object_int(&desc->package.elements[0]) != 1 ||
161 	    /* Third byte should be collection uid */
162 	    soc_button_get_acpi_object_int(&desc->package.elements[2]) !=
163 							    collection_uid) {
164 		dev_err(dev, "Invalid ACPI Button Descriptor\n");
165 		return -ENODEV;
166 	}
167 
168 	info->event_type = EV_KEY;
169 	info->acpi_index =
170 		soc_button_get_acpi_object_int(&desc->package.elements[1]);
171 	upage = soc_button_get_acpi_object_int(&desc->package.elements[3]);
172 	usage = soc_button_get_acpi_object_int(&desc->package.elements[4]);
173 
174 	/*
175 	 * The UUID: fa6bd625-9ce8-470d-a2c7-b3ca36c4282e descriptors use HID
176 	 * usage page and usage codes, but otherwise the device is not HID
177 	 * compliant: it uses one irq per button instead of generating HID
178 	 * input reports and some buttons should generate wakeups where as
179 	 * others should not, so we cannot use the HID subsystem.
180 	 *
181 	 * Luckily all devices only use a few usage page + usage combinations,
182 	 * so we can simply check for the known combinations here.
183 	 */
184 	if (upage == 0x01 && usage == 0x81) {
185 		info->name = "power";
186 		info->event_code = KEY_POWER;
187 		info->wakeup = true;
188 	} else if (upage == 0x07 && usage == 0xe3) {
189 		info->name = "home";
190 		info->event_code = KEY_LEFTMETA;
191 		info->wakeup = true;
192 	} else if (upage == 0x0c && usage == 0xe9) {
193 		info->name = "volume_up";
194 		info->event_code = KEY_VOLUMEUP;
195 		info->autorepeat = true;
196 	} else if (upage == 0x0c && usage == 0xea) {
197 		info->name = "volume_down";
198 		info->event_code = KEY_VOLUMEDOWN;
199 		info->autorepeat = true;
200 	} else {
201 		dev_warn(dev, "Unknown button index %d upage %02x usage %02x, ignoring\n",
202 			 info->acpi_index, upage, usage);
203 		info->name = "unknown";
204 		info->event_code = KEY_RESERVED;
205 	}
206 
207 	return 0;
208 }
209 
210 /* ACPI0011 _DSD btns descriptors UUID: fa6bd625-9ce8-470d-a2c7-b3ca36c4282e */
211 static const u8 btns_desc_uuid[16] = {
212 	0x25, 0xd6, 0x6b, 0xfa, 0xe8, 0x9c, 0x0d, 0x47,
213 	0xa2, 0xc7, 0xb3, 0xca, 0x36, 0xc4, 0x28, 0x2e
214 };
215 
216 /* Parse ACPI0011 _DSD button descriptors */
217 static struct soc_button_info *soc_button_get_button_info(struct device *dev)
218 {
219 	struct acpi_buffer buf = { ACPI_ALLOCATE_BUFFER };
220 	const union acpi_object *desc, *el0, *uuid, *btns_desc = NULL;
221 	struct soc_button_info *button_info;
222 	acpi_status status;
223 	int i, btn, collection_uid = -1;
224 
225 	status = acpi_evaluate_object_typed(ACPI_HANDLE(dev), "_DSD", NULL,
226 					    &buf, ACPI_TYPE_PACKAGE);
227 	if (ACPI_FAILURE(status)) {
228 		dev_err(dev, "ACPI _DSD object not found\n");
229 		return ERR_PTR(-ENODEV);
230 	}
231 
232 	/* Look for the Button Descriptors UUID */
233 	desc = buf.pointer;
234 	for (i = 0; (i + 1) < desc->package.count; i += 2) {
235 		uuid = &desc->package.elements[i];
236 
237 		if (uuid->type != ACPI_TYPE_BUFFER ||
238 		    uuid->buffer.length != 16 ||
239 		    desc->package.elements[i + 1].type != ACPI_TYPE_PACKAGE) {
240 			break;
241 		}
242 
243 		if (memcmp(uuid->buffer.pointer, btns_desc_uuid, 16) == 0) {
244 			btns_desc = &desc->package.elements[i + 1];
245 			break;
246 		}
247 	}
248 
249 	if (!btns_desc) {
250 		dev_err(dev, "ACPI Button Descriptors not found\n");
251 		return ERR_PTR(-ENODEV);
252 	}
253 
254 	/* The first package describes the collection */
255 	el0 = &btns_desc->package.elements[0];
256 	if (el0->type == ACPI_TYPE_PACKAGE &&
257 	    el0->package.count == 5 &&
258 	    /* First byte should be 0 (collection) */
259 	    soc_button_get_acpi_object_int(&el0->package.elements[0]) == 0 &&
260 	    /* Third byte should be 0 (top level collection) */
261 	    soc_button_get_acpi_object_int(&el0->package.elements[2]) == 0) {
262 		collection_uid = soc_button_get_acpi_object_int(
263 						&el0->package.elements[1]);
264 	}
265 	if (collection_uid == -1) {
266 		dev_err(dev, "Invalid Button Collection Descriptor\n");
267 		return ERR_PTR(-ENODEV);
268 	}
269 
270 	/* There are package.count - 1 buttons + 1 terminating empty entry */
271 	button_info = devm_kcalloc(dev, btns_desc->package.count,
272 				   sizeof(*button_info), GFP_KERNEL);
273 	if (!button_info)
274 		return ERR_PTR(-ENOMEM);
275 
276 	/* Parse the button descriptors */
277 	for (i = 1, btn = 0; i < btns_desc->package.count; i++, btn++) {
278 		if (soc_button_parse_btn_desc(dev,
279 					      &btns_desc->package.elements[i],
280 					      collection_uid,
281 					      &button_info[btn]))
282 			return ERR_PTR(-ENODEV);
283 	}
284 
285 	return button_info;
286 }
287 
288 static int soc_button_remove(struct platform_device *pdev)
289 {
290 	struct soc_button_data *priv = platform_get_drvdata(pdev);
291 
292 	int i;
293 
294 	for (i = 0; i < BUTTON_TYPES; i++)
295 		if (priv->children[i])
296 			platform_device_unregister(priv->children[i]);
297 
298 	return 0;
299 }
300 
301 static int soc_button_probe(struct platform_device *pdev)
302 {
303 	struct device *dev = &pdev->dev;
304 	const struct acpi_device_id *id;
305 	struct soc_button_info *button_info;
306 	struct soc_button_data *priv;
307 	struct platform_device *pd;
308 	int i;
309 	int error;
310 
311 	id = acpi_match_device(dev->driver->acpi_match_table, dev);
312 	if (!id)
313 		return -ENODEV;
314 
315 	if (!id->driver_data) {
316 		button_info = soc_button_get_button_info(dev);
317 		if (IS_ERR(button_info))
318 			return PTR_ERR(button_info);
319 	} else {
320 		button_info = (struct soc_button_info *)id->driver_data;
321 	}
322 
323 	error = gpiod_count(dev, NULL);
324 	if (error < 0) {
325 		dev_dbg(dev, "no GPIO attached, ignoring...\n");
326 		return error;
327 	}
328 
329 	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
330 	if (!priv)
331 		return -ENOMEM;
332 
333 	platform_set_drvdata(pdev, priv);
334 
335 	for (i = 0; i < BUTTON_TYPES; i++) {
336 		pd = soc_button_device_create(pdev, button_info, i == 0);
337 		if (IS_ERR(pd)) {
338 			error = PTR_ERR(pd);
339 			if (error != -ENODEV) {
340 				soc_button_remove(pdev);
341 				return error;
342 			}
343 			continue;
344 		}
345 
346 		priv->children[i] = pd;
347 	}
348 
349 	if (!priv->children[0] && !priv->children[1])
350 		return -ENODEV;
351 
352 	if (!id->driver_data)
353 		devm_kfree(dev, button_info);
354 
355 	return 0;
356 }
357 
358 /*
359  * Definition of buttons on the tablet. The ACPI index of each button
360  * is defined in section 2.8.7.2 of "Windows ACPI Design Guide for SoC
361  * Platforms"
362  */
363 static struct soc_button_info soc_button_PNP0C40[] = {
364 	{ "power", 0, EV_KEY, KEY_POWER, false, true },
365 	{ "home", 1, EV_KEY, KEY_LEFTMETA, false, true },
366 	{ "volume_up", 2, EV_KEY, KEY_VOLUMEUP, true, false },
367 	{ "volume_down", 3, EV_KEY, KEY_VOLUMEDOWN, true, false },
368 	{ "rotation_lock", 4, EV_SW, SW_ROTATE_LOCK, false, false },
369 	{ }
370 };
371 
372 static const struct acpi_device_id soc_button_acpi_match[] = {
373 	{ "PNP0C40", (unsigned long)soc_button_PNP0C40 },
374 	{ "ACPI0011", 0 },
375 	{ }
376 };
377 
378 MODULE_DEVICE_TABLE(acpi, soc_button_acpi_match);
379 
380 static struct platform_driver soc_button_driver = {
381 	.probe          = soc_button_probe,
382 	.remove		= soc_button_remove,
383 	.driver		= {
384 		.name = KBUILD_MODNAME,
385 		.acpi_match_table = ACPI_PTR(soc_button_acpi_match),
386 	},
387 };
388 module_platform_driver(soc_button_driver);
389 
390 MODULE_LICENSE("GPL");
391