drivers/platform/chrome/cros_kbd_led_backlight.c

   1 /*
   2  *  Keyboard backlight LED driver for Chrome OS.
   3  *
   4  *  Copyright (C) 2012 Google, Inc.
   5  *
   6  *  This program is free software; you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License as published by
   8  *  the Free Software Foundation; either version 2 of the License, or
   9  *  (at your option) any later version.
  10  *
  11  *  This program is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  */
  16
  17 #include <linux/acpi.h>
  18 #include <linux/leds.h>
  19 #include <linux/delay.h>
  20 #include <linux/err.h>
  21 #include <linux/module.h>
  22 #include <linux/init.h>
  23 #include <linux/kernel.h>
  24 #include <linux/platform_device.h>
  25 #include <linux/slab.h>
  26
  27 /* Keyboard LED ACPI Device must be defined in firmware */
  28 #define ACPI_KEYBOARD_BACKLIGHT_DEVICE  "\\_SB.KBLT"
  29 #define ACPI_KEYBOARD_BACKLIGHT_READ    ACPI_KEYBOARD_BACKLIGHT_DEVICE ".KBQC"
  30 #define ACPI_KEYBOARD_BACKLIGHT_WRITE   ACPI_KEYBOARD_BACKLIGHT_DEVICE ".KBCM"
  31
  32 #define ACPI_KEYBOARD_BACKLIGHT_MAX             100
  33
  34 static void keyboard_led_set_brightness(struct led_classdev *cdev,
  35                                         enum led_brightness brightness)
  36 {
  37         union acpi_object param;
  38         struct acpi_object_list input;
  39         acpi_status status;
  40
  41         param.type = ACPI_TYPE_INTEGER;
  42         param.integer.value = brightness;
  43         input.count = 1;
  44         input.pointer = &param;
  45
  46         status = acpi_evaluate_object(NULL, ACPI_KEYBOARD_BACKLIGHT_WRITE,
  47                                       &input, NULL);
  48         if (ACPI_FAILURE(status))
  49                 dev_err(cdev->dev, "Error setting keyboard LED value: %d\n",
  50                         status);
  51 }
  52
  53 static enum led_brightness
  54 keyboard_led_get_brightness(struct led_classdev *cdev)
  55 {
  56         unsigned long long brightness;
  57         acpi_status status;
  58
  59         status = acpi_evaluate_integer(NULL, ACPI_KEYBOARD_BACKLIGHT_READ,
  60                                        NULL, &brightness);
  61         if (ACPI_FAILURE(status)) {
  62                 dev_err(cdev->dev, "Error getting keyboard LED value: %d\n",
  63                         status);
  64                 return -EIO;
  65         }
  66
  67         return brightness;
  68 }
  69
  70 static int keyboard_led_probe(struct platform_device *pdev)
  71 {
  72         struct led_classdev *cdev;
  73         acpi_handle handle;
  74         acpi_status status;
  75         int error;
  76
  77         /* Look for the keyboard LED ACPI Device */
  78         status = acpi_get_handle(ACPI_ROOT_OBJECT,
  79                                  ACPI_KEYBOARD_BACKLIGHT_DEVICE,
  80                                  &handle);
  81         if (ACPI_FAILURE(status)) {
  82                 dev_err(&pdev->dev, "Unable to find ACPI device %s: %d\n",
  83                         ACPI_KEYBOARD_BACKLIGHT_DEVICE, status);
  84                 return -ENXIO;
  85         }
  86
  87         cdev = devm_kzalloc(&pdev->dev, sizeof(*cdev), GFP_KERNEL);
  88         if (!cdev)
  89                 return -ENOMEM;
  90
  91         cdev->name = "chromeos::kbd_backlight";
  92         cdev->max_brightness = ACPI_KEYBOARD_BACKLIGHT_MAX;
  93         cdev->flags |= LED_CORE_SUSPENDRESUME;
  94         cdev->brightness_set = keyboard_led_set_brightness;
  95         cdev->brightness_get = keyboard_led_get_brightness;
  96
  97         error = devm_led_classdev_register(&pdev->dev, cdev);
  98         if (error)
  99                 return error;
 100
 101         return 0;
 102 }
 103
 104 static const struct acpi_device_id keyboard_led_id[] = {
 105         { "GOOG0002", 0 },
 106         { }
 107 };
 108 MODULE_DEVICE_TABLE(acpi, keyboard_led_id);
 109
 110 static struct platform_driver keyboard_led_driver = {
 111         .driver         = {
 112                 .name   = "chromeos-keyboard-leds",
 113                 .acpi_match_table = ACPI_PTR(keyboard_led_id),
 114         },
 115         .probe          = keyboard_led_probe,
 116 };
 117 module_platform_driver(keyboard_led_driver);
 118
 119 MODULE_AUTHOR("Simon Que <sque@chromium.org>");
 120 MODULE_DESCRIPTION("ChromeOS Keyboard backlight LED Driver");
 121 MODULE_LICENSE("GPL");
 122 MODULE_ALIAS("platform:chromeos-keyboard-leds");