1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Supports for the button array on SoC tablets originally running
4  * Windows 8.
5  *
6  * (C) Copyright 2014 Intel Corporation
7  */
8 
9 #include <linux/module.h>
10 #include <linux/input.h>
11 #include <linux/init.h>
12 #include <linux/kernel.h>
13 #include <linux/acpi.h>
14 #include <linux/gpio/consumer.h>
15 #include <linux/gpio_keys.h>
16 #include <linux/gpio.h>
17 #include <linux/platform_device.h>
18 
19 struct soc_button_info {
20 	const char *name;
21 	int acpi_index;
22 	unsigned int event_type;
23 	unsigned int event_code;
24 	bool autorepeat;
25 	bool wakeup;
26 };
27 
28 /*
29  * Some of the buttons like volume up/down are auto repeat, while others
30  * are not. To support both, we register two platform devices, and put
31  * buttons into them based on whether the key should be auto repeat.
32  */
33 #define BUTTON_TYPES	2
34 
35 struct soc_button_data {
36 	struct platform_device *children[BUTTON_TYPES];
37 };
38 
39 /*
40  * Get the Nth GPIO number from the ACPI object.
41  */
42 static int soc_button_lookup_gpio(struct device *dev, int acpi_index)
43 {
44 	struct gpio_desc *desc;
45 	int gpio;
46 
47 	desc = gpiod_get_index(dev, NULL, acpi_index, GPIOD_ASIS);
48 	if (IS_ERR(desc))
49 		return PTR_ERR(desc);
50 
51 	gpio = desc_to_gpio(desc);
52 
53 	gpiod_put(desc);
54 
55 	return gpio;
56 }
57 
58 static struct platform_device *
59 soc_button_device_create(struct platform_device *pdev,
60 			 const struct soc_button_info *button_info,
61 			 bool autorepeat)
62 {
63 	const struct soc_button_info *info;
64 	struct platform_device *pd;
65 	struct gpio_keys_button *gpio_keys;
66 	struct gpio_keys_platform_data *gpio_keys_pdata;
67 	int n_buttons = 0;
68 	int gpio;
69 	int error;
70 
71 	for (info = button_info; info->name; info++)
72 		if (info->autorepeat == autorepeat)
73 			n_buttons++;
74 
75 	gpio_keys_pdata = devm_kzalloc(&pdev->dev,
76 				       sizeof(*gpio_keys_pdata) +
77 					sizeof(*gpio_keys) * n_buttons,
78 				       GFP_KERNEL);
79 	if (!gpio_keys_pdata)
80 		return ERR_PTR(-ENOMEM);
81 
82 	gpio_keys = (void *)(gpio_keys_pdata + 1);
83 	n_buttons = 0;
84 
85 	for (info = button_info; info->name; info++) {
86 		if (info->autorepeat != autorepeat)
87 			continue;
88 
89 		gpio = soc_button_lookup_gpio(&pdev->dev, info->acpi_index);
90 		if (!gpio_is_valid(gpio))
91 			continue;
92 
93 		gpio_keys[n_buttons].type = info->event_type;
94 		gpio_keys[n_buttons].code = info->event_code;
95 		gpio_keys[n_buttons].gpio = gpio;
96 		gpio_keys[n_buttons].active_low = 1;
97 		gpio_keys[n_buttons].desc = info->name;
98 		gpio_keys[n_buttons].wakeup = info->wakeup;
99 		/* These devices often use cheap buttons, use 50 ms debounce */
100 		gpio_keys[n_buttons].debounce_interval = 50;
101 		n_buttons++;
102 	}
103 
104 	if (n_buttons == 0) {
105 		error = -ENODEV;
106 		goto err_free_mem;
107 	}
108 
109 	gpio_keys_pdata->buttons = gpio_keys;
110 	gpio_keys_pdata->nbuttons = n_buttons;
111 	gpio_keys_pdata->rep = autorepeat;
112 
113 	pd = platform_device_alloc("gpio-keys", PLATFORM_DEVID_AUTO);
114 	if (!pd) {
115 		error = -ENOMEM;
116 		goto err_free_mem;
117 	}
118 
119 	error = platform_device_add_data(pd, gpio_keys_pdata,
120 					 sizeof(*gpio_keys_pdata));
121 	if (error)
122 		goto err_free_pdev;
123 
124 	error = platform_device_add(pd);
125 	if (error)
126 		goto err_free_pdev;
127 
128 	return pd;
129 
130 err_free_pdev:
131 	platform_device_put(pd);
132 err_free_mem:
133 	devm_kfree(&pdev->dev, gpio_keys_pdata);
134 	return ERR_PTR(error);
135 }
136 
137 static int soc_button_get_acpi_object_int(const union acpi_object *obj)
138 {
139 	if (obj->type != ACPI_TYPE_INTEGER)
140 		return -1;
141 
142 	return obj->integer.value;
143 }
144 
145 /* Parse a single ACPI0011 _DSD button descriptor */
146 static int soc_button_parse_btn_desc(struct device *dev,
147 				     const union acpi_object *desc,
148 				     int collection_uid,
149 				     struct soc_button_info *info)
150 {
151 	int upage, usage;
152 
153 	if (desc->type != ACPI_TYPE_PACKAGE ||
154 	    desc->package.count != 5 ||
155 	    /* First byte should be 1 (control) */
156 	    soc_button_get_acpi_object_int(&desc->package.elements[0]) != 1 ||
157 	    /* Third byte should be collection uid */
158 	    soc_button_get_acpi_object_int(&desc->package.elements[2]) !=
159 							    collection_uid) {
160 		dev_err(dev, "Invalid ACPI Button Descriptor\n");
161 		return -ENODEV;
162 	}
163 
164 	info->event_type = EV_KEY;
165 	info->acpi_index =
166 		soc_button_get_acpi_object_int(&desc->package.elements[1]);
167 	upage = soc_button_get_acpi_object_int(&desc->package.elements[3]);
168 	usage = soc_button_get_acpi_object_int(&desc->package.elements[4]);
169 
170 	/*
171 	 * The UUID: fa6bd625-9ce8-470d-a2c7-b3ca36c4282e descriptors use HID
172 	 * usage page and usage codes, but otherwise the device is not HID
173 	 * compliant: it uses one irq per button instead of generating HID
174 	 * input reports and some buttons should generate wakeups where as
175 	 * others should not, so we cannot use the HID subsystem.
176 	 *
177 	 * Luckily all devices only use a few usage page + usage combinations,
178 	 * so we can simply check for the known combinations here.
179 	 */
180 	if (upage == 0x01 && usage == 0x81) {
181 		info->name = "power";
182 		info->event_code = KEY_POWER;
183 		info->wakeup = true;
184 	} else if (upage == 0x01 && usage == 0xca) {
185 		info->name = "rotation lock switch";
186 		info->event_type = EV_SW;
187 		info->event_code = SW_ROTATE_LOCK;
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 		button_info = ERR_PTR(-ENODEV);
252 		goto out;
253 	}
254 
255 	/* The first package describes the collection */
256 	el0 = &btns_desc->package.elements[0];
257 	if (el0->type == ACPI_TYPE_PACKAGE &&
258 	    el0->package.count == 5 &&
259 	    /* First byte should be 0 (collection) */
260 	    soc_button_get_acpi_object_int(&el0->package.elements[0]) == 0 &&
261 	    /* Third byte should be 0 (top level collection) */
262 	    soc_button_get_acpi_object_int(&el0->package.elements[2]) == 0) {
263 		collection_uid = soc_button_get_acpi_object_int(
264 						&el0->package.elements[1]);
265 	}
266 	if (collection_uid == -1) {
267 		dev_err(dev, "Invalid Button Collection Descriptor\n");
268 		button_info = ERR_PTR(-ENODEV);
269 		goto out;
270 	}
271 
272 	/* There are package.count - 1 buttons + 1 terminating empty entry */
273 	button_info = devm_kcalloc(dev, btns_desc->package.count,
274 				   sizeof(*button_info), GFP_KERNEL);
275 	if (!button_info) {
276 		button_info = ERR_PTR(-ENOMEM);
277 		goto out;
278 	}
279 
280 	/* Parse the button descriptors */
281 	for (i = 1, btn = 0; i < btns_desc->package.count; i++, btn++) {
282 		if (soc_button_parse_btn_desc(dev,
283 					      &btns_desc->package.elements[i],
284 					      collection_uid,
285 					      &button_info[btn])) {
286 			button_info = ERR_PTR(-ENODEV);
287 			goto out;
288 		}
289 	}
290 
291 out:
292 	kfree(buf.pointer);
293 	return button_info;
294 }
295 
296 static int soc_button_remove(struct platform_device *pdev)
297 {
298 	struct soc_button_data *priv = platform_get_drvdata(pdev);
299 
300 	int i;
301 
302 	for (i = 0; i < BUTTON_TYPES; i++)
303 		if (priv->children[i])
304 			platform_device_unregister(priv->children[i]);
305 
306 	return 0;
307 }
308 
309 static int soc_button_probe(struct platform_device *pdev)
310 {
311 	struct device *dev = &pdev->dev;
312 	const struct acpi_device_id *id;
313 	struct soc_button_info *button_info;
314 	struct soc_button_data *priv;
315 	struct platform_device *pd;
316 	int i;
317 	int error;
318 
319 	id = acpi_match_device(dev->driver->acpi_match_table, dev);
320 	if (!id)
321 		return -ENODEV;
322 
323 	if (!id->driver_data) {
324 		button_info = soc_button_get_button_info(dev);
325 		if (IS_ERR(button_info))
326 			return PTR_ERR(button_info);
327 	} else {
328 		button_info = (struct soc_button_info *)id->driver_data;
329 	}
330 
331 	error = gpiod_count(dev, NULL);
332 	if (error < 0) {
333 		dev_dbg(dev, "no GPIO attached, ignoring...\n");
334 		return -ENODEV;
335 	}
336 
337 	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
338 	if (!priv)
339 		return -ENOMEM;
340 
341 	platform_set_drvdata(pdev, priv);
342 
343 	for (i = 0; i < BUTTON_TYPES; i++) {
344 		pd = soc_button_device_create(pdev, button_info, i == 0);
345 		if (IS_ERR(pd)) {
346 			error = PTR_ERR(pd);
347 			if (error != -ENODEV) {
348 				soc_button_remove(pdev);
349 				return error;
350 			}
351 			continue;
352 		}
353 
354 		priv->children[i] = pd;
355 	}
356 
357 	if (!priv->children[0] && !priv->children[1])
358 		return -ENODEV;
359 
360 	if (!id->driver_data)
361 		devm_kfree(dev, button_info);
362 
363 	return 0;
364 }
365 
366 /*
367  * Definition of buttons on the tablet. The ACPI index of each button
368  * is defined in section 2.8.7.2 of "Windows ACPI Design Guide for SoC
369  * Platforms"
370  */
371 static struct soc_button_info soc_button_PNP0C40[] = {
372 	{ "power", 0, EV_KEY, KEY_POWER, false, true },
373 	{ "home", 1, EV_KEY, KEY_LEFTMETA, false, true },
374 	{ "volume_up", 2, EV_KEY, KEY_VOLUMEUP, true, false },
375 	{ "volume_down", 3, EV_KEY, KEY_VOLUMEDOWN, true, false },
376 	{ "rotation_lock", 4, EV_KEY, KEY_ROTATE_LOCK_TOGGLE, false, false },
377 	{ }
378 };
379 
380 static const struct acpi_device_id soc_button_acpi_match[] = {
381 	{ "PNP0C40", (unsigned long)soc_button_PNP0C40 },
382 	{ "ACPI0011", 0 },
383 	{ }
384 };
385 
386 MODULE_DEVICE_TABLE(acpi, soc_button_acpi_match);
387 
388 static struct platform_driver soc_button_driver = {
389 	.probe          = soc_button_probe,
390 	.remove		= soc_button_remove,
391 	.driver		= {
392 		.name = KBUILD_MODNAME,
393 		.acpi_match_table = ACPI_PTR(soc_button_acpi_match),
394 	},
395 };
396 module_platform_driver(soc_button_driver);
397 
398 MODULE_LICENSE("GPL");
399