drivers/platform/chrome/cros_kbd_led_backlight.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 // Keyboard backlight LED driver for ChromeOS
   3 //
   4 // Copyright (C) 2012 Google, Inc.
   5
   6 #include <linux/acpi.h>
   7 #include <linux/leds.h>
   8 #include <linux/delay.h>
   9 #include <linux/err.h>
  10 #include <linux/module.h>
  11 #include <linux/init.h>
  12 #include <linux/kernel.h>
  13 #include <linux/platform_device.h>
  14 #include <linux/slab.h>
  15
  16 /* Keyboard LED ACPI Device must be defined in firmware */
  17 #define ACPI_KEYBOARD_BACKLIGHT_DEVICE  "\\_SB.KBLT"
  18 #define ACPI_KEYBOARD_BACKLIGHT_READ    ACPI_KEYBOARD_BACKLIGHT_DEVICE ".KBQC"
  19 #define ACPI_KEYBOARD_BACKLIGHT_WRITE   ACPI_KEYBOARD_BACKLIGHT_DEVICE ".KBCM"
  20
  21 #define ACPI_KEYBOARD_BACKLIGHT_MAX             100
  22
  23 static void keyboard_led_set_brightness(struct led_classdev *cdev,
  24                                         enum led_brightness brightness)
  25 {
  26         union acpi_object param;
  27         struct acpi_object_list input;
  28         acpi_status status;
  29
  30         param.type = ACPI_TYPE_INTEGER;
  31         param.integer.value = brightness;
  32         input.count = 1;
  33         input.pointer = &param;
  34
  35         status = acpi_evaluate_object(NULL, ACPI_KEYBOARD_BACKLIGHT_WRITE,
  36                                       &input, NULL);
  37         if (ACPI_FAILURE(status))
  38                 dev_err(cdev->dev, "Error setting keyboard LED value: %d\n",
  39                         status);
  40 }
  41
  42 static enum led_brightness
  43 keyboard_led_get_brightness(struct led_classdev *cdev)
  44 {
  45         unsigned long long brightness;
  46         acpi_status status;
  47
  48         status = acpi_evaluate_integer(NULL, ACPI_KEYBOARD_BACKLIGHT_READ,
  49                                        NULL, &brightness);
  50         if (ACPI_FAILURE(status)) {
  51                 dev_err(cdev->dev, "Error getting keyboard LED value: %d\n",
  52                         status);
  53                 return -EIO;
  54         }
  55
  56         return brightness;
  57 }
  58
  59 static int keyboard_led_probe(struct platform_device *pdev)
  60 {
  61         struct led_classdev *cdev;
  62         acpi_handle handle;
  63         acpi_status status;
  64         int error;
  65
  66         /* Look for the keyboard LED ACPI Device */
  67         status = acpi_get_handle(ACPI_ROOT_OBJECT,
  68                                  ACPI_KEYBOARD_BACKLIGHT_DEVICE,
  69                                  &handle);
  70         if (ACPI_FAILURE(status)) {
  71                 dev_err(&pdev->dev, "Unable to find ACPI device %s: %d\n",
  72                         ACPI_KEYBOARD_BACKLIGHT_DEVICE, status);
  73                 return -ENXIO;
  74         }
  75
  76         cdev = devm_kzalloc(&pdev->dev, sizeof(*cdev), GFP_KERNEL);
  77         if (!cdev)
  78                 return -ENOMEM;
  79
  80         cdev->name = "chromeos::kbd_backlight";
  81         cdev->max_brightness = ACPI_KEYBOARD_BACKLIGHT_MAX;
  82         cdev->flags |= LED_CORE_SUSPENDRESUME;
  83         cdev->brightness_set = keyboard_led_set_brightness;
  84         cdev->brightness_get = keyboard_led_get_brightness;
  85
  86         error = devm_led_classdev_register(&pdev->dev, cdev);
  87         if (error)
  88                 return error;
  89
  90         return 0;
  91 }
  92
  93 static const struct acpi_device_id keyboard_led_id[] = {
  94         { "GOOG0002", 0 },
  95         { }
  96 };
  97 MODULE_DEVICE_TABLE(acpi, keyboard_led_id);
  98
  99 static struct platform_driver keyboard_led_driver = {
 100         .driver         = {
 101                 .name   = "chromeos-keyboard-leds",
 102                 .acpi_match_table = ACPI_PTR(keyboard_led_id),
 103         },
 104         .probe          = keyboard_led_probe,
 105 };
 106 module_platform_driver(keyboard_led_driver);
 107
 108 MODULE_AUTHOR("Simon Que <sque@chromium.org>");
 109 MODULE_DESCRIPTION("ChromeOS Keyboard backlight LED Driver");
 110 MODULE_LICENSE("GPL");
 111 MODULE_ALIAS("platform:chromeos-keyboard-leds");