linux/drivers/input/misc/soc_button_array.c
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   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/platform_device.h>
  21#include <linux/acpi.h>
  22
  23/*
  24 * Definition of buttons on the tablet. The ACPI index of each button
  25 * is defined in section 2.8.7.2 of "Windows ACPI Design Guide for SoC
  26 * Platforms"
  27 */
  28#define MAX_NBUTTONS    5
  29
  30struct soc_button_info {
  31        const char *name;
  32        int acpi_index;
  33        unsigned int event_type;
  34        unsigned int event_code;
  35        bool autorepeat;
  36        bool wakeup;
  37};
  38
  39/*
  40 * Some of the buttons like volume up/down are auto repeat, while others
  41 * are not. To support both, we register two platform devices, and put
  42 * buttons into them based on whether the key should be auto repeat.
  43 */
  44#define BUTTON_TYPES    2
  45
  46struct soc_button_data {
  47        struct platform_device *children[BUTTON_TYPES];
  48};
  49
  50/*
  51 * Get the Nth GPIO number from the ACPI object.
  52 */
  53static int soc_button_lookup_gpio(struct device *dev, int acpi_index)
  54{
  55        struct gpio_desc *desc;
  56        int gpio;
  57
  58        desc = gpiod_get_index(dev, KBUILD_MODNAME, acpi_index, GPIOD_ASIS);
  59        if (IS_ERR(desc))
  60                return PTR_ERR(desc);
  61
  62        gpio = desc_to_gpio(desc);
  63
  64        gpiod_put(desc);
  65
  66        return gpio;
  67}
  68
  69static struct platform_device *
  70soc_button_device_create(struct platform_device *pdev,
  71                         const struct soc_button_info *button_info,
  72                         bool autorepeat)
  73{
  74        const struct soc_button_info *info;
  75        struct platform_device *pd;
  76        struct gpio_keys_button *gpio_keys;
  77        struct gpio_keys_platform_data *gpio_keys_pdata;
  78        int n_buttons = 0;
  79        int gpio;
  80        int error;
  81
  82        gpio_keys_pdata = devm_kzalloc(&pdev->dev,
  83                                       sizeof(*gpio_keys_pdata) +
  84                                        sizeof(*gpio_keys) * MAX_NBUTTONS,
  85                                       GFP_KERNEL);
  86        if (!gpio_keys_pdata)
  87                return ERR_PTR(-ENOMEM);
  88
  89        gpio_keys = (void *)(gpio_keys_pdata + 1);
  90
  91        for (info = button_info; info->name; info++) {
  92                if (info->autorepeat != autorepeat)
  93                        continue;
  94
  95                gpio = soc_button_lookup_gpio(&pdev->dev, info->acpi_index);
  96                if (gpio < 0)
  97                        continue;
  98
  99                gpio_keys[n_buttons].type = info->event_type;
 100                gpio_keys[n_buttons].code = info->event_code;
 101                gpio_keys[n_buttons].gpio = gpio;
 102                gpio_keys[n_buttons].active_low = 1;
 103                gpio_keys[n_buttons].desc = info->name;
 104                gpio_keys[n_buttons].wakeup = info->wakeup;
 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_remove(struct platform_device *pdev)
 142{
 143        struct soc_button_data *priv = platform_get_drvdata(pdev);
 144
 145        int i;
 146
 147        for (i = 0; i < BUTTON_TYPES; i++)
 148                if (priv->children[i])
 149                        platform_device_unregister(priv->children[i]);
 150
 151        return 0;
 152}
 153
 154static int soc_button_probe(struct platform_device *pdev)
 155{
 156        struct device *dev = &pdev->dev;
 157        const struct acpi_device_id *id;
 158        struct soc_button_info *button_info;
 159        struct soc_button_data *priv;
 160        struct platform_device *pd;
 161        int i;
 162        int error;
 163
 164        id = acpi_match_device(dev->driver->acpi_match_table, dev);
 165        if (!id)
 166                return -ENODEV;
 167
 168        button_info = (struct soc_button_info *)id->driver_data;
 169
 170        priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
 171        if (!priv)
 172                return -ENOMEM;
 173
 174        platform_set_drvdata(pdev, priv);
 175
 176        for (i = 0; i < BUTTON_TYPES; i++) {
 177                pd = soc_button_device_create(pdev, button_info, i == 0);
 178                if (IS_ERR(pd)) {
 179                        error = PTR_ERR(pd);
 180                        if (error != -ENODEV) {
 181                                soc_button_remove(pdev);
 182                                return error;
 183                        }
 184                        continue;
 185                }
 186
 187                priv->children[i] = pd;
 188        }
 189
 190        if (!priv->children[0] && !priv->children[1])
 191                return -ENODEV;
 192
 193        return 0;
 194}
 195
 196static struct soc_button_info soc_button_PNP0C40[] = {
 197        { "power", 0, EV_KEY, KEY_POWER, false, true },
 198        { "home", 1, EV_KEY, KEY_HOME, false, true },
 199        { "volume_up", 2, EV_KEY, KEY_VOLUMEUP, true, false },
 200        { "volume_down", 3, EV_KEY, KEY_VOLUMEDOWN, true, false },
 201        { "rotation_lock", 4, EV_SW, SW_ROTATE_LOCK, false, false },
 202        { }
 203};
 204
 205static const struct acpi_device_id soc_button_acpi_match[] = {
 206        { "PNP0C40", (unsigned long)soc_button_PNP0C40 },
 207        { }
 208};
 209
 210MODULE_DEVICE_TABLE(acpi, soc_button_acpi_match);
 211
 212static struct platform_driver soc_button_driver = {
 213        .probe          = soc_button_probe,
 214        .remove         = soc_button_remove,
 215        .driver         = {
 216                .name = KBUILD_MODNAME,
 217                .acpi_match_table = ACPI_PTR(soc_button_acpi_match),
 218        },
 219};
 220module_platform_driver(soc_button_driver);
 221
 222MODULE_LICENSE("GPL");
 223
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