drivers/leds/leds-chromeos-keyboard.c

   1 /*
   2  *  leds-chromeos-keyboard.c - 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  *  You should have received a copy of the GNU General Public License
  17  *  along with this program; if not, write to the Free Software
  18  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  19  *
  20  */
  21
  22 #include <linux/acpi.h>
  23 #include <linux/leds.h>
  24 #include <linux/delay.h>
  25 #include <linux/err.h>
  26 #include <linux/module.h>
  27 #include <linux/init.h>
  28 #include <linux/kernel.h>
  29 #include <linux/platform_device.h>
  30 #include <linux/slab.h>
  31
  32 /* Keyboard LED ACPI Device must be defined in firmware */
  33 #define ACPI_KEYBOARD_BACKLIGHT_DEVICE  "\\_SB.KBLT"
  34 #define ACPI_KEYBOARD_BACKLIGHT_READ    ACPI_KEYBOARD_BACKLIGHT_DEVICE ".KBQC"
  35 #define ACPI_KEYBOARD_BACKLIGHT_WRITE   ACPI_KEYBOARD_BACKLIGHT_DEVICE ".KBCM"
  36
  37 #define ACPI_KEYBOARD_BACKLIGHT_MAX             100
  38
  39 static void keyboard_led_set_brightness(struct led_classdev *cdev,
  40         enum led_brightness brightness)
  41 {
  42         union acpi_object param;
  43         struct acpi_object_list input;
  44         acpi_status status;
  45
  46         if (!(cdev->flags & LED_SUSPENDED))
  47                 cdev->brightness = brightness;
  48
  49         param.type = ACPI_TYPE_INTEGER;
  50         param.integer.value = brightness;
  51         input.count = 1;
  52         input.pointer = &param;
  53
  54         status = acpi_evaluate_object(NULL, ACPI_KEYBOARD_BACKLIGHT_WRITE,
  55                                           &input, NULL);
  56         if (ACPI_FAILURE(status))
  57                 dev_err(cdev->dev, "Error setting keyboard LED value");
  58 }
  59
  60 static int keyboard_led_probe(struct platform_device *pdev)
  61 {
  62         struct led_classdev *cdev;
  63         acpi_handle handle;
  64         acpi_status status;
  65         int ret;
  66
  67         /* Look for the keyboard LED ACPI Device */
  68         status = acpi_get_handle(ACPI_ROOT_OBJECT,
  69                                  ACPI_KEYBOARD_BACKLIGHT_DEVICE,
  70                                  &handle);
  71         if (ACPI_FAILURE(status)) {
  72                 dev_err(&pdev->dev, "Unable fo find ACPI device %s\n",
  73                         ACPI_KEYBOARD_BACKLIGHT_DEVICE);
  74                 return -ENODEV;
  75         }
  76
  77         cdev = kzalloc(sizeof(struct led_classdev), GFP_KERNEL);
  78         if (!cdev)
  79                 return -ENOMEM;
  80         cdev->name = "chromeos::kbd_backlight";
  81         cdev->brightness_set = keyboard_led_set_brightness;
  82         cdev->max_brightness = ACPI_KEYBOARD_BACKLIGHT_MAX;
  83         cdev->brightness = cdev->max_brightness;
  84         cdev->flags |= LED_CORE_SUSPENDRESUME;
  85
  86         ret = led_classdev_register(&pdev->dev, cdev);
  87         if (ret)
  88                 goto err;
  89
  90         platform_set_drvdata(pdev, cdev);
  91         return 0;
  92 err:
  93         kfree(cdev);
  94         return ret;
  95 }
  96
  97 static int keyboard_led_remove(struct platform_device *pdev)
  98 {
  99         struct led_classdev *cdev = platform_get_drvdata(pdev);
 100
 101         platform_set_drvdata(pdev, NULL);
 102         kfree(cdev);
 103         return 0;
 104 }
 105
 106 static struct platform_driver keyboard_led_driver = {
 107         .driver         = {
 108                 .name   = "chromeos-keyboard-leds",
 109                 .owner  = THIS_MODULE,
 110         },
 111         .probe          = keyboard_led_probe,
 112         .remove         = keyboard_led_remove,
 113 };
 114
 115 module_platform_driver(keyboard_led_driver);
 116
 117 MODULE_AUTHOR("Simon Que <sque@chromium.org>");
 118 MODULE_DESCRIPTION("ChromeOS Keyboard LED Driver");
 119 MODULE_LICENSE("GPL");
 120 MODULE_ALIAS("platform:chromeos-keyboard-leds");