Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
1/*
2 * Supports for the button array on the Surface tablets.
3 *
4 * (C) Copyright 2016 Red Hat, Inc
5 *
6 * Based on soc_button_array.c:
7 *
8 * {C} Copyright 2014 Intel Corporation
9 *
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License
12 * as published by the Free Software Foundation; version 2
13 * of the License.
14 */
15
16#include <linux/module.h>
17#include <linux/input.h>
18#include <linux/init.h>
19#include <linux/kernel.h>
20#include <linux/i2c.h>
21#include <linux/slab.h>
22#include <linux/acpi.h>
23#include <linux/gpio/consumer.h>
24#include <linux/gpio_keys.h>
25#include <linux/gpio.h>
26#include <linux/platform_device.h>
27
28
29#define SURFACE_BUTTON_OBJ_NAME "TEV2"
30#define MAX_NBUTTONS 4
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/*
40 * Power button, Home button, Volume buttons support is supposed to
41 * be covered by drivers/input/misc/soc_button_array.c, which is implemented
42 * according to "Windows ACPI Design Guide for SoC Platforms".
43 * However surface 3 seems not to obey the specs, instead it uses
44 * device TEV2(MSHW0028) for declaring the GPIOs. The gpios are also slightly
45 * different in which the Home button is active high.
46 * Compared to surfacepro3_button.c which also handles MSHW0028, the Surface 3
47 * is a reduce platform and thus uses GPIOs, not ACPI events.
48 * We choose an I2C driver here because we need to access the resources
49 * declared under the device node, while surfacepro3_button.c only needs
50 * the ACPI companion node.
51 */
52static const struct acpi_device_id surface3_acpi_match[] = {
53 { "MSHW0028", 0 },
54 { }
55};
56MODULE_DEVICE_TABLE(acpi, surface3_acpi_match);
57
58struct surface3_button_info {
59 const char *name;
60 int acpi_index;
61 unsigned int event_type;
62 unsigned int event_code;
63 bool autorepeat;
64 bool wakeup;
65 bool active_low;
66};
67
68struct surface3_button_data {
69 struct platform_device *children[BUTTON_TYPES];
70};
71
72/*
73 * Get the Nth GPIO number from the ACPI object.
74 */
75static int surface3_button_lookup_gpio(struct device *dev, int acpi_index)
76{
77 struct gpio_desc *desc;
78 int gpio;
79
80 desc = gpiod_get_index(dev, NULL, acpi_index, GPIOD_ASIS);
81 if (IS_ERR(desc))
82 return PTR_ERR(desc);
83
84 gpio = desc_to_gpio(desc);
85
86 gpiod_put(desc);
87
88 return gpio;
89}
90
91static struct platform_device *
92surface3_button_device_create(struct i2c_client *client,
93 const struct surface3_button_info *button_info,
94 bool autorepeat)
95{
96 const struct surface3_button_info *info;
97 struct platform_device *pd;
98 struct gpio_keys_button *gpio_keys;
99 struct gpio_keys_platform_data *gpio_keys_pdata;
100 int n_buttons = 0;
101 int gpio;
102 int error;
103
104 gpio_keys_pdata = devm_kzalloc(&client->dev,
105 sizeof(*gpio_keys_pdata) +
106 sizeof(*gpio_keys) * MAX_NBUTTONS,
107 GFP_KERNEL);
108 if (!gpio_keys_pdata)
109 return ERR_PTR(-ENOMEM);
110
111 gpio_keys = (void *)(gpio_keys_pdata + 1);
112
113 for (info = button_info; info->name; info++) {
114 if (info->autorepeat != autorepeat)
115 continue;
116
117 gpio = surface3_button_lookup_gpio(&client->dev,
118 info->acpi_index);
119 if (!gpio_is_valid(gpio))
120 continue;
121
122 gpio_keys[n_buttons].type = info->event_type;
123 gpio_keys[n_buttons].code = info->event_code;
124 gpio_keys[n_buttons].gpio = gpio;
125 gpio_keys[n_buttons].active_low = info->active_low;
126 gpio_keys[n_buttons].desc = info->name;
127 gpio_keys[n_buttons].wakeup = info->wakeup;
128 n_buttons++;
129 }
130
131 if (n_buttons == 0) {
132 error = -ENODEV;
133 goto err_free_mem;
134 }
135
136 gpio_keys_pdata->buttons = gpio_keys;
137 gpio_keys_pdata->nbuttons = n_buttons;
138 gpio_keys_pdata->rep = autorepeat;
139
140 pd = platform_device_alloc("gpio-keys", PLATFORM_DEVID_AUTO);
141 if (!pd) {
142 error = -ENOMEM;
143 goto err_free_mem;
144 }
145
146 error = platform_device_add_data(pd, gpio_keys_pdata,
147 sizeof(*gpio_keys_pdata));
148 if (error)
149 goto err_free_pdev;
150
151 error = platform_device_add(pd);
152 if (error)
153 goto err_free_pdev;
154
155 return pd;
156
157err_free_pdev:
158 platform_device_put(pd);
159err_free_mem:
160 devm_kfree(&client->dev, gpio_keys_pdata);
161 return ERR_PTR(error);
162}
163
164static int surface3_button_remove(struct i2c_client *client)
165{
166 struct surface3_button_data *priv = i2c_get_clientdata(client);
167
168 int i;
169
170 for (i = 0; i < BUTTON_TYPES; i++)
171 if (priv->children[i])
172 platform_device_unregister(priv->children[i]);
173
174 return 0;
175}
176
177static struct surface3_button_info surface3_button_surface3[] = {
178 { "power", 0, EV_KEY, KEY_POWER, false, true, true },
179 { "home", 1, EV_KEY, KEY_LEFTMETA, false, true, false },
180 { "volume_up", 2, EV_KEY, KEY_VOLUMEUP, true, false, true },
181 { "volume_down", 3, EV_KEY, KEY_VOLUMEDOWN, true, false, true },
182 { }
183};
184
185static int surface3_button_probe(struct i2c_client *client,
186 const struct i2c_device_id *id)
187{
188 struct device *dev = &client->dev;
189 struct surface3_button_data *priv;
190 struct platform_device *pd;
191 int i;
192 int error;
193
194 if (strncmp(acpi_device_bid(ACPI_COMPANION(&client->dev)),
195 SURFACE_BUTTON_OBJ_NAME,
196 strlen(SURFACE_BUTTON_OBJ_NAME)))
197 return -ENODEV;
198
199 error = gpiod_count(dev, NULL);
200 if (error < 0) {
201 dev_dbg(dev, "no GPIO attached, ignoring...\n");
202 return error;
203 }
204
205 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
206 if (!priv)
207 return -ENOMEM;
208
209 i2c_set_clientdata(client, priv);
210
211 for (i = 0; i < BUTTON_TYPES; i++) {
212 pd = surface3_button_device_create(client,
213 surface3_button_surface3,
214 i == 0);
215 if (IS_ERR(pd)) {
216 error = PTR_ERR(pd);
217 if (error != -ENODEV) {
218 surface3_button_remove(client);
219 return error;
220 }
221 continue;
222 }
223
224 priv->children[i] = pd;
225 }
226
227 if (!priv->children[0] && !priv->children[1])
228 return -ENODEV;
229
230 return 0;
231}
232
233static const struct i2c_device_id surface3_id[] = {
234 { }
235};
236MODULE_DEVICE_TABLE(i2c, surface3_id);
237
238static struct i2c_driver surface3_driver = {
239 .probe = surface3_button_probe,
240 .remove = surface3_button_remove,
241 .id_table = surface3_id,
242 .driver = {
243 .name = "surface3",
244 .acpi_match_table = ACPI_PTR(surface3_acpi_match),
245 },
246};
247module_i2c_driver(surface3_driver);
248
249MODULE_AUTHOR("Benjamin Tissoires <benjamin.tissoires@gmail.com>");
250MODULE_DESCRIPTION("surface3 button array driver");
251MODULE_LICENSE("GPL v2");