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
23struct 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
39struct soc_button_data {
40 struct platform_device *children[BUTTON_TYPES];
41};
42
43/*
44 * Get the Nth GPIO number from the ACPI object.
45 */
46static 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
62static struct platform_device *
63soc_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
134err_free_pdev:
135 platform_device_put(pd);
136err_free_mem:
137 devm_kfree(&pdev->dev, gpio_keys_pdata);
138 return ERR_PTR(error);
139}
140
141static 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 */
150static 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 */
215static 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 */
221static 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
295out:
296 kfree(buf.pointer);
297 return button_info;
298}
299
300static 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
313static 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 */
375static 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
384static const struct acpi_device_id soc_button_acpi_match[] = {
385 { "PNP0C40", (unsigned long)soc_button_PNP0C40 },
386 { "ACPI0011", 0 },
387 { }
388};
389
390MODULE_DEVICE_TABLE(acpi, soc_button_acpi_match);
391
392static 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};
400module_platform_driver(soc_button_driver);
401
402MODULE_LICENSE("GPL");
403