drivers/platform/x86/surface3_button.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Supports for the button array on the Surface tablets.
   4  *
   5  * (C) Copyright 2016 Red Hat, Inc
   6  *
   7  * Based on soc_button_array.c:
   8  *
   9  * {C} Copyright 2014 Intel Corporation
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/input.h>
  14 #include <linux/init.h>
  15 #include <linux/kernel.h>
  16 #include <linux/i2c.h>
  17 #include <linux/slab.h>
  18 #include <linux/acpi.h>
  19 #include <linux/gpio/consumer.h>
  20 #include <linux/gpio_keys.h>
  21 #include <linux/gpio.h>
  22 #include <linux/platform_device.h>
  23
  24
  25 #define SURFACE_BUTTON_OBJ_NAME         "TEV2"
  26 #define MAX_NBUTTONS                    4
  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 /*
  36  * Power button, Home button, Volume buttons support is supposed to
  37  * be covered by drivers/input/misc/soc_button_array.c, which is implemented
  38  * according to "Windows ACPI Design Guide for SoC Platforms".
  39  * However surface 3 seems not to obey the specs, instead it uses
  40  * device TEV2(MSHW0028) for declaring the GPIOs. The gpios are also slightly
  41  * different in which the Home button is active high.
  42  * Compared to surfacepro3_button.c which also handles MSHW0028, the Surface 3
  43  * is a reduce platform and thus uses GPIOs, not ACPI events.
  44  * We choose an I2C driver here because we need to access the resources
  45  * declared under the device node, while surfacepro3_button.c only needs
  46  * the ACPI companion node.
  47  */
  48 static const struct acpi_device_id surface3_acpi_match[] = {
  49         { "MSHW0028", 0 },
  50         { }
  51 };
  52 MODULE_DEVICE_TABLE(acpi, surface3_acpi_match);
  53
  54 struct surface3_button_info {
  55         const char *name;
  56         int acpi_index;
  57         unsigned int event_type;
  58         unsigned int event_code;
  59         bool autorepeat;
  60         bool wakeup;
  61         bool active_low;
  62 };
  63
  64 struct surface3_button_data {
  65         struct platform_device *children[BUTTON_TYPES];
  66 };
  67
  68 /*
  69  * Get the Nth GPIO number from the ACPI object.
  70  */
  71 static int surface3_button_lookup_gpio(struct device *dev, int acpi_index)
  72 {
  73         struct gpio_desc *desc;
  74         int gpio;
  75
  76         desc = gpiod_get_index(dev, NULL, acpi_index, GPIOD_ASIS);
  77         if (IS_ERR(desc))
  78                 return PTR_ERR(desc);
  79
  80         gpio = desc_to_gpio(desc);
  81
  82         gpiod_put(desc);
  83
  84         return gpio;
  85 }
  86
  87 static struct platform_device *
  88 surface3_button_device_create(struct i2c_client *client,
  89                               const struct surface3_button_info *button_info,
  90                               bool autorepeat)
  91 {
  92         const struct surface3_button_info *info;
  93         struct platform_device *pd;
  94         struct gpio_keys_button *gpio_keys;
  95         struct gpio_keys_platform_data *gpio_keys_pdata;
  96         int n_buttons = 0;
  97         int gpio;
  98         int error;
  99
 100         gpio_keys_pdata = devm_kzalloc(&client->dev,
 101                                        sizeof(*gpio_keys_pdata) +
 102                                        sizeof(*gpio_keys) * MAX_NBUTTONS,
 103                                        GFP_KERNEL);
 104         if (!gpio_keys_pdata)
 105                 return ERR_PTR(-ENOMEM);
 106
 107         gpio_keys = (void *)(gpio_keys_pdata + 1);
 108
 109         for (info = button_info; info->name; info++) {
 110                 if (info->autorepeat != autorepeat)
 111                         continue;
 112
 113                 gpio = surface3_button_lookup_gpio(&client->dev,
 114                                                    info->acpi_index);
 115                 if (!gpio_is_valid(gpio))
 116                         continue;
 117
 118                 gpio_keys[n_buttons].type = info->event_type;
 119                 gpio_keys[n_buttons].code = info->event_code;
 120                 gpio_keys[n_buttons].gpio = gpio;
 121                 gpio_keys[n_buttons].active_low = info->active_low;
 122                 gpio_keys[n_buttons].desc = info->name;
 123                 gpio_keys[n_buttons].wakeup = info->wakeup;
 124                 n_buttons++;
 125         }
 126
 127         if (n_buttons == 0) {
 128                 error = -ENODEV;
 129                 goto err_free_mem;
 130         }
 131
 132         gpio_keys_pdata->buttons = gpio_keys;
 133         gpio_keys_pdata->nbuttons = n_buttons;
 134         gpio_keys_pdata->rep = autorepeat;
 135
 136         pd = platform_device_alloc("gpio-keys", PLATFORM_DEVID_AUTO);
 137         if (!pd) {
 138                 error = -ENOMEM;
 139                 goto err_free_mem;
 140         }
 141
 142         error = platform_device_add_data(pd, gpio_keys_pdata,
 143                                          sizeof(*gpio_keys_pdata));
 144         if (error)
 145                 goto err_free_pdev;
 146
 147         error = platform_device_add(pd);
 148         if (error)
 149                 goto err_free_pdev;
 150
 151         return pd;
 152
 153 err_free_pdev:
 154         platform_device_put(pd);
 155 err_free_mem:
 156         devm_kfree(&client->dev, gpio_keys_pdata);
 157         return ERR_PTR(error);
 158 }
 159
 160 static int surface3_button_remove(struct i2c_client *client)
 161 {
 162         struct surface3_button_data *priv = i2c_get_clientdata(client);
 163
 164         int i;
 165
 166         for (i = 0; i < BUTTON_TYPES; i++)
 167                 if (priv->children[i])
 168                         platform_device_unregister(priv->children[i]);
 169
 170         return 0;
 171 }
 172
 173 static struct surface3_button_info surface3_button_surface3[] = {
 174         { "power", 0, EV_KEY, KEY_POWER, false, true, true },
 175         { "home", 1, EV_KEY, KEY_LEFTMETA, false, true, false },
 176         { "volume_up", 2, EV_KEY, KEY_VOLUMEUP, true, false, true },
 177         { "volume_down", 3, EV_KEY, KEY_VOLUMEDOWN, true, false, true },
 178         { }
 179 };
 180
 181 static int surface3_button_probe(struct i2c_client *client,
 182                                  const struct i2c_device_id *id)
 183 {
 184         struct device *dev = &client->dev;
 185         struct surface3_button_data *priv;
 186         struct platform_device *pd;
 187         int i;
 188         int error;
 189
 190         if (strncmp(acpi_device_bid(ACPI_COMPANION(&client->dev)),
 191                     SURFACE_BUTTON_OBJ_NAME,
 192                     strlen(SURFACE_BUTTON_OBJ_NAME)))
 193                 return -ENODEV;
 194
 195         error = gpiod_count(dev, NULL);
 196         if (error < 0) {
 197                 dev_dbg(dev, "no GPIO attached, ignoring...\n");
 198                 return error;
 199         }
 200
 201         priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 202         if (!priv)
 203                 return -ENOMEM;
 204
 205         i2c_set_clientdata(client, priv);
 206
 207         for (i = 0; i < BUTTON_TYPES; i++) {
 208                 pd = surface3_button_device_create(client,
 209                                                    surface3_button_surface3,
 210                                                    i == 0);
 211                 if (IS_ERR(pd)) {
 212                         error = PTR_ERR(pd);
 213                         if (error != -ENODEV) {
 214                                 surface3_button_remove(client);
 215                                 return error;
 216                         }
 217                         continue;
 218                 }
 219
 220                 priv->children[i] = pd;
 221         }
 222
 223         if (!priv->children[0] && !priv->children[1])
 224                 return -ENODEV;
 225
 226         return 0;
 227 }
 228
 229 static const struct i2c_device_id surface3_id[] = {
 230         { }
 231 };
 232 MODULE_DEVICE_TABLE(i2c, surface3_id);
 233
 234 static struct i2c_driver surface3_driver = {
 235         .probe = surface3_button_probe,
 236         .remove = surface3_button_remove,
 237         .id_table = surface3_id,
 238         .driver = {
 239                 .name = "surface3",
 240                 .acpi_match_table = ACPI_PTR(surface3_acpi_match),
 241         },
 242 };
 243 module_i2c_driver(surface3_driver);
 244
 245 MODULE_AUTHOR("Benjamin Tissoires <benjamin.tissoires@gmail.com>");
 246 MODULE_DESCRIPTION("surface3 button array driver");
 247 MODULE_LICENSE("GPL v2");