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 == 0x01 && usage == 0xca) {
189 		info->name = "rotation lock switch";
190 		info->event_type = EV_SW;
191 		info->event_code = SW_ROTATE_LOCK;
192 	} else if (upage == 0x07 && usage == 0xe3) {
193 		info->name = "home";
194 		info->event_code = KEY_LEFTMETA;
195 		info->wakeup = true;
196 	} else if (upage == 0x0c && usage == 0xe9) {
197 		info->name = "volume_up";
198 		info->event_code = KEY_VOLUMEUP;
199 		info->autorepeat = true;
200 	} else if (upage == 0x0c && usage == 0xea) {
201 		info->name = "volume_down";
202 		info->event_code = KEY_VOLUMEDOWN;
203 		info->autorepeat = true;
204 	} else {
205 		dev_warn(dev, "Unknown button index %d upage %02x usage %02x, ignoring\n",
206 			 info->acpi_index, upage, usage);
207 		info->name = "unknown";
208 		info->event_code = KEY_RESERVED;
209 	}
210 
211 	return 0;
212 }
213 
214 /* ACPI0011 _DSD btns descriptors UUID: fa6bd625-9ce8-470d-a2c7-b3ca36c4282e */
215 static const u8 btns_desc_uuid[16] = {
216 	0x25, 0xd6, 0x6b, 0xfa, 0xe8, 0x9c, 0x0d, 0x47,
217 	0xa2, 0xc7, 0xb3, 0xca, 0x36, 0xc4, 0x28, 0x2e
218 };
219 
220 /* Parse ACPI0011 _DSD button descriptors */
221 static struct soc_button_info *soc_button_get_button_info(struct device *dev)
222 {
223 	struct acpi_buffer buf = { ACPI_ALLOCATE_BUFFER };
224 	const union acpi_object *desc, *el0, *uuid, *btns_desc = NULL;
225 	struct soc_button_info *button_info;
226 	acpi_status status;
227 	int i, btn, collection_uid = -1;
228 
229 	status = acpi_evaluate_object_typed(ACPI_HANDLE(dev), "_DSD", NULL,
230 					    &buf, ACPI_TYPE_PACKAGE);
231 	if (ACPI_FAILURE(status)) {
232 		dev_err(dev, "ACPI _DSD object not found\n");
233 		return ERR_PTR(-ENODEV);
234 	}
235 
236 	/* Look for the Button Descriptors UUID */
237 	desc = buf.pointer;
238 	for (i = 0; (i + 1) < desc->package.count; i += 2) {
239 		uuid = &desc->package.elements[i];
240 
241 		if (uuid->type != ACPI_TYPE_BUFFER ||
242 		    uuid->buffer.length != 16 ||
243 		    desc->package.elements[i + 1].type != ACPI_TYPE_PACKAGE) {
244 			break;
245 		}
246 
247 		if (memcmp(uuid->buffer.pointer, btns_desc_uuid, 16) == 0) {
248 			btns_desc = &desc->package.elements[i + 1];
249 			break;
250 		}
251 	}
252 
253 	if (!btns_desc) {
254 		dev_err(dev, "ACPI Button Descriptors not found\n");
255 		button_info = ERR_PTR(-ENODEV);
256 		goto out;
257 	}
258 
259 	/* The first package describes the collection */
260 	el0 = &btns_desc->package.elements[0];
261 	if (el0->type == ACPI_TYPE_PACKAGE &&
262 	    el0->package.count == 5 &&
263 	    /* First byte should be 0 (collection) */
264 	    soc_button_get_acpi_object_int(&el0->package.elements[0]) == 0 &&
265 	    /* Third byte should be 0 (top level collection) */
266 	    soc_button_get_acpi_object_int(&el0->package.elements[2]) == 0) {
267 		collection_uid = soc_button_get_acpi_object_int(
268 						&el0->package.elements[1]);
269 	}
270 	if (collection_uid == -1) {
271 		dev_err(dev, "Invalid Button Collection Descriptor\n");
272 		button_info = ERR_PTR(-ENODEV);
273 		goto out;
274 	}
275 
276 	/* There are package.count - 1 buttons + 1 terminating empty entry */
277 	button_info = devm_kcalloc(dev, btns_desc->package.count,
278 				   sizeof(*button_info), GFP_KERNEL);
279 	if (!button_info) {
280 		button_info = ERR_PTR(-ENOMEM);
281 		goto out;
282 	}
283 
284 	/* Parse the button descriptors */
285 	for (i = 1, btn = 0; i < btns_desc->package.count; i++, btn++) {
286 		if (soc_button_parse_btn_desc(dev,
287 					      &btns_desc->package.elements[i],
288 					      collection_uid,
289 					      &button_info[btn])) {
290 			button_info = ERR_PTR(-ENODEV);
291 			goto out;
292 		}
293 	}
294 
295 out:
296 	kfree(buf.pointer);
297 	return button_info;
298 }
299 
300 static int soc_button_remove(struct platform_device *pdev)
301 {
302 	struct soc_button_data *priv = platform_get_drvdata(pdev);
303 
304 	int i;
305 
306 	for (i = 0; i < BUTTON_TYPES; i++)
307 		if (priv->children[i])
308 			platform_device_unregister(priv->children[i]);
309 
310 	return 0;
311 }
312 
313 static int soc_button_probe(struct platform_device *pdev)
314 {
315 	struct device *dev = &pdev->dev;
316 	const struct acpi_device_id *id;
317 	struct soc_button_info *button_info;
318 	struct soc_button_data *priv;
319 	struct platform_device *pd;
320 	int i;
321 	int error;
322 
323 	id = acpi_match_device(dev->driver->acpi_match_table, dev);
324 	if (!id)
325 		return -ENODEV;
326 
327 	if (!id->driver_data) {
328 		button_info = soc_button_get_button_info(dev);
329 		if (IS_ERR(button_info))
330 			return PTR_ERR(button_info);
331 	} else {
332 		button_info = (struct soc_button_info *)id->driver_data;
333 	}
334 
335 	error = gpiod_count(dev, NULL);
336 	if (error < 0) {
337 		dev_dbg(dev, "no GPIO attached, ignoring...\n");
338 		return -ENODEV;
339 	}
340 
341 	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
342 	if (!priv)
343 		return -ENOMEM;
344 
345 	platform_set_drvdata(pdev, priv);
346 
347 	for (i = 0; i < BUTTON_TYPES; i++) {
348 		pd = soc_button_device_create(pdev, button_info, i == 0);
349 		if (IS_ERR(pd)) {
350 			error = PTR_ERR(pd);
351 			if (error != -ENODEV) {
352 				soc_button_remove(pdev);
353 				return error;
354 			}
355 			continue;
356 		}
357 
358 		priv->children[i] = pd;
359 	}
360 
361 	if (!priv->children[0] && !priv->children[1])
362 		return -ENODEV;
363 
364 	if (!id->driver_data)
365 		devm_kfree(dev, button_info);
366 
367 	return 0;
368 }
369 
370 /*
371  * Definition of buttons on the tablet. The ACPI index of each button
372  * is defined in section 2.8.7.2 of "Windows ACPI Design Guide for SoC
373  * Platforms"
374  */
375 static struct soc_button_info soc_button_PNP0C40[] = {
376 	{ "power", 0, EV_KEY, KEY_POWER, false, true },
377 	{ "home", 1, EV_KEY, KEY_LEFTMETA, false, true },
378 	{ "volume_up", 2, EV_KEY, KEY_VOLUMEUP, true, false },
379 	{ "volume_down", 3, EV_KEY, KEY_VOLUMEDOWN, true, false },
380 	{ "rotation_lock", 4, EV_KEY, KEY_ROTATE_LOCK_TOGGLE, false, false },
381 	{ }
382 };
383 
384 static const struct acpi_device_id soc_button_acpi_match[] = {
385 	{ "PNP0C40", (unsigned long)soc_button_PNP0C40 },
386 	{ "ACPI0011", 0 },
387 	{ }
388 };
389 
390 MODULE_DEVICE_TABLE(acpi, soc_button_acpi_match);
391 
392 static struct platform_driver soc_button_driver = {
393 	.probe          = soc_button_probe,
394 	.remove		= soc_button_remove,
395 	.driver		= {
396 		.name = KBUILD_MODNAME,
397 		.acpi_match_table = ACPI_PTR(soc_button_acpi_match),
398 	},
399 };
400 module_platform_driver(soc_button_driver);
401 
402 MODULE_LICENSE("GPL");
403