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"); 230