drivers/platform/x86/surface3_button.c

   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  */
  52 static const struct acpi_device_id surface3_acpi_match[] = {
  53         { "MSHW0028", 0 },
  54         { }
  55 };
  56 MODULE_DEVICE_TABLE(acpi, surface3_acpi_match);
  57
  58 struct 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
  68 struct surface3_button_data {
  69         struct platform_device *children[BUTTON_TYPES];
  70 };
  71
  72 /*
  73  * Get the Nth GPIO number from the ACPI object.
  74  */
  75 static 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
  91 static struct platform_device *
  92 surface3_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
 157 err_free_pdev:
 158         platform_device_put(pd);
 159 err_free_mem:
 160         devm_kfree(&client->dev, gpio_keys_pdata);
 161         return ERR_PTR(error);
 162 }
 163
 164 static 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
 177 static 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
 185 static 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
 233 static const struct i2c_device_id surface3_id[] = {
 234         { }
 235 };
 236 MODULE_DEVICE_TABLE(i2c, surface3_id);
 237
 238 static 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 };
 247 module_i2c_driver(surface3_driver);
 248
 249 MODULE_AUTHOR("Benjamin Tissoires <benjamin.tissoires@gmail.com>");
 250 MODULE_DESCRIPTION("surface3 button array driver");
 251 MODULE_LICENSE("GPL v2");