linux/drivers/platform/surface/surface3_button.c
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   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 */
  48static const struct acpi_device_id surface3_acpi_match[] = {
  49        { "MSHW0028", 0 },
  50        { }
  51};
  52MODULE_DEVICE_TABLE(acpi, surface3_acpi_match);
  53
  54struct 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
  64struct surface3_button_data {
  65        struct platform_device *children[BUTTON_TYPES];
  66};
  67
  68/*
  69 * Get the Nth GPIO number from the ACPI object.
  70 */
  71static 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
  87static struct platform_device *
  88surface3_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
 153err_free_pdev:
 154        platform_device_put(pd);
 155err_free_mem:
 156        devm_kfree(&client->dev, gpio_keys_pdata);
 157        return ERR_PTR(error);
 158}
 159
 160static 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
 173static 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
 181static 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
 229static const struct i2c_device_id surface3_id[] = {
 230        { }
 231};
 232MODULE_DEVICE_TABLE(i2c, surface3_id);
 233
 234static 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};
 243module_i2c_driver(surface3_driver);
 244
 245MODULE_AUTHOR("Benjamin Tissoires <benjamin.tissoires@gmail.com>");
 246MODULE_DESCRIPTION("surface3 button array driver");
 247MODULE_LICENSE("GPL v2");
 248