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/platform_device.h>
  21 #include <linux/pnp.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);
  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 pnp_dev *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         gpio_keys = (void *)(gpio_keys_pdata + 1);
  87
  88         for (info = button_info; info->name; info++) {
  89                 if (info->autorepeat != autorepeat)
  90                         continue;
  91
  92                 gpio = soc_button_lookup_gpio(&pdev->dev, info->acpi_index);
  93                 if (gpio < 0)
  94                         continue;
  95
  96                 gpio_keys[n_buttons].type = info->event_type;
  97                 gpio_keys[n_buttons].code = info->event_code;
  98                 gpio_keys[n_buttons].gpio = gpio;
  99                 gpio_keys[n_buttons].active_low = 1;
 100                 gpio_keys[n_buttons].desc = info->name;
 101                 gpio_keys[n_buttons].wakeup = info->wakeup;
 102                 n_buttons++;
 103         }
 104
 105         if (n_buttons == 0) {
 106                 error = -ENODEV;
 107                 goto err_free_mem;
 108         }
 109
 110         gpio_keys_pdata->buttons = gpio_keys;
 111         gpio_keys_pdata->nbuttons = n_buttons;
 112         gpio_keys_pdata->rep = autorepeat;
 113
 114         pd = platform_device_alloc("gpio-keys", PLATFORM_DEVID_AUTO);
 115         if (!pd) {
 116                 error = -ENOMEM;
 117                 goto err_free_mem;
 118         }
 119
 120         error = platform_device_add_data(pd, gpio_keys_pdata,
 121                                          sizeof(*gpio_keys_pdata));
 122         if (error)
 123                 goto err_free_pdev;
 124
 125         error = platform_device_add(pd);
 126         if (error)
 127                 goto err_free_pdev;
 128
 129         return pd;
 130
 131 err_free_pdev:
 132         platform_device_put(pd);
 133 err_free_mem:
 134         devm_kfree(&pdev->dev, gpio_keys_pdata);
 135         return ERR_PTR(error);
 136 }
 137
 138 static void soc_button_remove(struct pnp_dev *pdev)
 139 {
 140         struct soc_button_data *priv = pnp_get_drvdata(pdev);
 141         int i;
 142
 143         for (i = 0; i < BUTTON_TYPES; i++)
 144                 if (priv->children[i])
 145                         platform_device_unregister(priv->children[i]);
 146 }
 147
 148 static int soc_button_pnp_probe(struct pnp_dev *pdev,
 149                                 const struct pnp_device_id *id)
 150 {
 151         const struct soc_button_info *button_info = (void *)id->driver_data;
 152         struct soc_button_data *priv;
 153         struct platform_device *pd;
 154         int i;
 155         int error;
 156
 157         priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
 158         if (!priv)
 159                 return -ENOMEM;
 160
 161         pnp_set_drvdata(pdev, priv);
 162
 163         for (i = 0; i < BUTTON_TYPES; i++) {
 164                 pd = soc_button_device_create(pdev, button_info, i == 0);
 165                 if (IS_ERR(pd)) {
 166                         error = PTR_ERR(pd);
 167                         if (error != -ENODEV) {
 168                                 soc_button_remove(pdev);
 169                                 return error;
 170                         }
 171                         continue;
 172                 }
 173
 174                 priv->children[i] = pd;
 175         }
 176
 177         if (!priv->children[0] && !priv->children[1])
 178                 return -ENODEV;
 179
 180         return 0;
 181 }
 182
 183 static struct soc_button_info soc_button_PNP0C40[] = {
 184         { "power", 0, EV_KEY, KEY_POWER, false, true },
 185         { "home", 1, EV_KEY, KEY_HOME, false, true },
 186         { "volume_up", 2, EV_KEY, KEY_VOLUMEUP, true, false },
 187         { "volume_down", 3, EV_KEY, KEY_VOLUMEDOWN, true, false },
 188         { "rotation_lock", 4, EV_SW, SW_ROTATE_LOCK, false, false },
 189         { }
 190 };
 191
 192 static const struct pnp_device_id soc_button_pnp_match[] = {
 193         { .id = "PNP0C40", .driver_data = (long)soc_button_PNP0C40 },
 194         { .id = "" }
 195 };
 196 MODULE_DEVICE_TABLE(pnp, soc_button_pnp_match);
 197
 198 static struct pnp_driver soc_button_pnp_driver = {
 199         .name           = KBUILD_MODNAME,
 200         .id_table       = soc_button_pnp_match,
 201         .probe          = soc_button_pnp_probe,
 202         .remove         = soc_button_remove,
 203 };
 204
 205 static int __init soc_button_init(void)
 206 {
 207         return pnp_register_driver(&soc_button_pnp_driver);
 208 }
 209
 210 static void __exit soc_button_exit(void)
 211 {
 212         pnp_unregister_driver(&soc_button_pnp_driver);
 213 }
 214
 215 module_init(soc_button_init);
 216 module_exit(soc_button_exit);
 217
 218 MODULE_LICENSE("GPL");