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
  22 /*
  23  * Definition of buttons on the tablet. The ACPI index of each button
  24  * is defined in section 2.8.7.2 of "Windows ACPI Design Guide for SoC
  25  * Platforms"
  26  */
  27 #define MAX_NBUTTONS    5
  28
  29 struct soc_button_info {
  30         const char *name;
  31         int acpi_index;
  32         unsigned int event_type;
  33         unsigned int event_code;
  34         bool autorepeat;
  35         bool wakeup;
  36 };
  37
  38 /*
  39  * Some of the buttons like volume up/down are auto repeat, while others
  40  * are not. To support both, we register two platform devices, and put
  41  * buttons into them based on whether the key should be auto repeat.
  42  */
  43 #define BUTTON_TYPES    2
  44
  45 struct soc_button_data {
  46         struct platform_device *children[BUTTON_TYPES];
  47 };
  48
  49 /*
  50  * Get the Nth GPIO number from the ACPI object.
  51  */
  52 static int soc_button_lookup_gpio(struct device *dev, int acpi_index)
  53 {
  54         struct gpio_desc *desc;
  55         int gpio;
  56
  57         desc = gpiod_get_index(dev, KBUILD_MODNAME, acpi_index, GPIOD_ASIS);
  58         if (IS_ERR(desc))
  59                 return PTR_ERR(desc);
  60
  61         gpio = desc_to_gpio(desc);
  62
  63         gpiod_put(desc);
  64
  65         return gpio;
  66 }
  67
  68 static struct platform_device *
  69 soc_button_device_create(struct platform_device *pdev,
  70                          const struct soc_button_info *button_info,
  71                          bool autorepeat)
  72 {
  73         const struct soc_button_info *info;
  74         struct platform_device *pd;
  75         struct gpio_keys_button *gpio_keys;
  76         struct gpio_keys_platform_data *gpio_keys_pdata;
  77         int n_buttons = 0;
  78         int gpio;
  79         int error;
  80
  81         gpio_keys_pdata = devm_kzalloc(&pdev->dev,
  82                                        sizeof(*gpio_keys_pdata) +
  83                                         sizeof(*gpio_keys) * MAX_NBUTTONS,
  84                                        GFP_KERNEL);
  85         if (!gpio_keys_pdata)
  86                 return ERR_PTR(-ENOMEM);
  87
  88         gpio_keys = (void *)(gpio_keys_pdata + 1);
  89
  90         for (info = button_info; info->name; info++) {
  91                 if (info->autorepeat != autorepeat)
  92                         continue;
  93
  94                 gpio = soc_button_lookup_gpio(&pdev->dev, info->acpi_index);
  95                 if (gpio < 0)
  96                         continue;
  97
  98                 gpio_keys[n_buttons].type = info->event_type;
  99                 gpio_keys[n_buttons].code = info->event_code;
 100                 gpio_keys[n_buttons].gpio = gpio;
 101                 gpio_keys[n_buttons].active_low = 1;
 102                 gpio_keys[n_buttons].desc = info->name;
 103                 gpio_keys[n_buttons].wakeup = info->wakeup;
 104                 n_buttons++;
 105         }
 106
 107         if (n_buttons == 0) {
 108                 error = -ENODEV;
 109                 goto err_free_mem;
 110         }
 111
 112         gpio_keys_pdata->buttons = gpio_keys;
 113         gpio_keys_pdata->nbuttons = n_buttons;
 114         gpio_keys_pdata->rep = autorepeat;
 115
 116         pd = platform_device_alloc("gpio-keys", PLATFORM_DEVID_AUTO);
 117         if (!pd) {
 118                 error = -ENOMEM;
 119                 goto err_free_mem;
 120         }
 121
 122         error = platform_device_add_data(pd, gpio_keys_pdata,
 123                                          sizeof(*gpio_keys_pdata));
 124         if (error)
 125                 goto err_free_pdev;
 126
 127         error = platform_device_add(pd);
 128         if (error)
 129                 goto err_free_pdev;
 130
 131         return pd;
 132
 133 err_free_pdev:
 134         platform_device_put(pd);
 135 err_free_mem:
 136         devm_kfree(&pdev->dev, gpio_keys_pdata);
 137         return ERR_PTR(error);
 138 }
 139
 140 static int soc_button_remove(struct platform_device *pdev)
 141 {
 142         struct soc_button_data *priv = platform_get_drvdata(pdev);
 143
 144         int i;
 145
 146         for (i = 0; i < BUTTON_TYPES; i++)
 147                 if (priv->children[i])
 148                         platform_device_unregister(priv->children[i]);
 149
 150         return 0;
 151 }
 152
 153 static int soc_button_probe(struct platform_device *pdev)
 154 {
 155         struct device *dev = &pdev->dev;
 156         const struct acpi_device_id *id;
 157         struct soc_button_info *button_info;
 158         struct soc_button_data *priv;
 159         struct platform_device *pd;
 160         int i;
 161         int error;
 162
 163         id = acpi_match_device(dev->driver->acpi_match_table, dev);
 164         if (!id)
 165                 return -ENODEV;
 166
 167         button_info = (struct soc_button_info *)id->driver_data;
 168
 169         priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
 170         if (!priv)
 171                 return -ENOMEM;
 172
 173         platform_set_drvdata(pdev, priv);
 174
 175         for (i = 0; i < BUTTON_TYPES; i++) {
 176                 pd = soc_button_device_create(pdev, button_info, i == 0);
 177                 if (IS_ERR(pd)) {
 178                         error = PTR_ERR(pd);
 179                         if (error != -ENODEV) {
 180                                 soc_button_remove(pdev);
 181                                 return error;
 182                         }
 183                         continue;
 184                 }
 185
 186                 priv->children[i] = pd;
 187         }
 188
 189         if (!priv->children[0] && !priv->children[1])
 190                 return -ENODEV;
 191
 192         return 0;
 193 }
 194
 195 static struct soc_button_info soc_button_PNP0C40[] = {
 196         { "power", 0, EV_KEY, KEY_POWER, false, true },
 197         { "home", 1, EV_KEY, KEY_LEFTMETA, false, true },
 198         { "volume_up", 2, EV_KEY, KEY_VOLUMEUP, true, false },
 199         { "volume_down", 3, EV_KEY, KEY_VOLUMEDOWN, true, false },
 200         { "rotation_lock", 4, EV_SW, SW_ROTATE_LOCK, false, false },
 201         { }
 202 };
 203
 204 static const struct acpi_device_id soc_button_acpi_match[] = {
 205         { "PNP0C40", (unsigned long)soc_button_PNP0C40 },
 206         { }
 207 };
 208
 209 MODULE_DEVICE_TABLE(acpi, soc_button_acpi_match);
 210
 211 static struct platform_driver soc_button_driver = {
 212         .probe          = soc_button_probe,
 213         .remove         = soc_button_remove,
 214         .driver         = {
 215                 .name = KBUILD_MODNAME,
 216                 .acpi_match_table = ACPI_PTR(soc_button_acpi_match),
 217         },
 218 };
 219 module_platform_driver(soc_button_driver);
 220
 221 MODULE_LICENSE("GPL");