drivers/input/misc/soc_button_array.c

   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/gpio.h>
  21 #include <linux/platform_device.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
  30 struct 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
  46 struct soc_button_data {
  47         struct platform_device *children[BUTTON_TYPES];
  48 };
  49
  50 /*
  51  * Get the Nth GPIO number from the ACPI object.
  52  */
  53 static 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
  69 static struct platform_device *
  70 soc_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_is_valid(gpio))
  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                 /* These devices often use cheap buttons, use 50 ms debounce */
 106                 gpio_keys[n_buttons].debounce_interval = 50;
 107                 n_buttons++;
 108         }
 109
 110         if (n_buttons == 0) {
 111                 error = -ENODEV;
 112                 goto err_free_mem;
 113         }
 114
 115         gpio_keys_pdata->buttons = gpio_keys;
 116         gpio_keys_pdata->nbuttons = n_buttons;
 117         gpio_keys_pdata->rep = autorepeat;
 118
 119         pd = platform_device_alloc("gpio-keys", PLATFORM_DEVID_AUTO);
 120         if (!pd) {
 121                 error = -ENOMEM;
 122                 goto err_free_mem;
 123         }
 124
 125         error = platform_device_add_data(pd, gpio_keys_pdata,
 126                                          sizeof(*gpio_keys_pdata));
 127         if (error)
 128                 goto err_free_pdev;
 129
 130         error = platform_device_add(pd);
 131         if (error)
 132                 goto err_free_pdev;
 133
 134         return pd;
 135
 136 err_free_pdev:
 137         platform_device_put(pd);
 138 err_free_mem:
 139         devm_kfree(&pdev->dev, gpio_keys_pdata);
 140         return ERR_PTR(error);
 141 }
 142
 143 static int soc_button_remove(struct platform_device *pdev)
 144 {
 145         struct soc_button_data *priv = platform_get_drvdata(pdev);
 146
 147         int i;
 148
 149         for (i = 0; i < BUTTON_TYPES; i++)
 150                 if (priv->children[i])
 151                         platform_device_unregister(priv->children[i]);
 152
 153         return 0;
 154 }
 155
 156 static int soc_button_probe(struct platform_device *pdev)
 157 {
 158         struct device *dev = &pdev->dev;
 159         const struct acpi_device_id *id;
 160         struct soc_button_info *button_info;
 161         struct soc_button_data *priv;
 162         struct platform_device *pd;
 163         int i;
 164         int error;
 165
 166         id = acpi_match_device(dev->driver->acpi_match_table, dev);
 167         if (!id)
 168                 return -ENODEV;
 169
 170         button_info = (struct soc_button_info *)id->driver_data;
 171
 172         if (gpiod_count(dev, KBUILD_MODNAME) <= 0) {
 173                 dev_dbg(dev, "no GPIO attached, ignoring...\n");
 174                 return -ENODEV;
 175         }
 176
 177         priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 178         if (!priv)
 179                 return -ENOMEM;
 180
 181         platform_set_drvdata(pdev, priv);
 182
 183         for (i = 0; i < BUTTON_TYPES; i++) {
 184                 pd = soc_button_device_create(pdev, button_info, i == 0);
 185                 if (IS_ERR(pd)) {
 186                         error = PTR_ERR(pd);
 187                         if (error != -ENODEV) {
 188                                 soc_button_remove(pdev);
 189                                 return error;
 190                         }
 191                         continue;
 192                 }
 193
 194                 priv->children[i] = pd;
 195         }
 196
 197         if (!priv->children[0] && !priv->children[1])
 198                 return -ENODEV;
 199
 200         return 0;
 201 }
 202
 203 static struct soc_button_info soc_button_PNP0C40[] = {
 204         { "power", 0, EV_KEY, KEY_POWER, false, true },
 205         { "home", 1, EV_KEY, KEY_LEFTMETA, false, true },
 206         { "volume_up", 2, EV_KEY, KEY_VOLUMEUP, true, false },
 207         { "volume_down", 3, EV_KEY, KEY_VOLUMEDOWN, true, false },
 208         { "rotation_lock", 4, EV_SW, SW_ROTATE_LOCK, false, false },
 209         { }
 210 };
 211
 212 static const struct acpi_device_id soc_button_acpi_match[] = {
 213         { "PNP0C40", (unsigned long)soc_button_PNP0C40 },
 214         { }
 215 };
 216
 217 MODULE_DEVICE_TABLE(acpi, soc_button_acpi_match);
 218
 219 static struct platform_driver soc_button_driver = {
 220         .probe          = soc_button_probe,
 221         .remove         = soc_button_remove,
 222         .driver         = {
 223                 .name = KBUILD_MODNAME,
 224                 .acpi_match_table = ACPI_PTR(soc_button_acpi_match),
 225         },
 226 };
 227 module_platform_driver(soc_button_driver);
 228
 229 MODULE_LICENSE("GPL");