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This is a driver for ACPI-based keyboard backlight LEDs found on Chromebooks. The driver locates \\_SB.KBLT ACPI device and exports backlight as "chromeos::kbd_backlight" LED class device in sysfs. Signed-off-by: Simon Que <sque@chromium.org> Signed-off-by: Duncan Laurie <dlaurie@chromium.org> Tested-by: Evan McClain <aeroevan@gmail.com> Signed-off-by: Dmitry Torokhov <dtor@chromium.org> Signed-off-by: Olof Johansson <olof@lixom.net>
123 lines
3.4 KiB
C
123 lines
3.4 KiB
C
/*
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* Keyboard backlight LED driver for Chrome OS.
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*
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* Copyright (C) 2012 Google, Inc.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#include <linux/acpi.h>
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#include <linux/leds.h>
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#include <linux/delay.h>
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#include <linux/err.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/platform_device.h>
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#include <linux/slab.h>
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/* Keyboard LED ACPI Device must be defined in firmware */
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#define ACPI_KEYBOARD_BACKLIGHT_DEVICE "\\_SB.KBLT"
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#define ACPI_KEYBOARD_BACKLIGHT_READ ACPI_KEYBOARD_BACKLIGHT_DEVICE ".KBQC"
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#define ACPI_KEYBOARD_BACKLIGHT_WRITE ACPI_KEYBOARD_BACKLIGHT_DEVICE ".KBCM"
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#define ACPI_KEYBOARD_BACKLIGHT_MAX 100
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static void keyboard_led_set_brightness(struct led_classdev *cdev,
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enum led_brightness brightness)
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{
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union acpi_object param;
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struct acpi_object_list input;
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acpi_status status;
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param.type = ACPI_TYPE_INTEGER;
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param.integer.value = brightness;
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input.count = 1;
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input.pointer = ¶m;
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status = acpi_evaluate_object(NULL, ACPI_KEYBOARD_BACKLIGHT_WRITE,
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&input, NULL);
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if (ACPI_FAILURE(status))
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dev_err(cdev->dev, "Error setting keyboard LED value: %d\n",
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status);
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}
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static enum led_brightness
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keyboard_led_get_brightness(struct led_classdev *cdev)
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{
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unsigned long long brightness;
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acpi_status status;
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status = acpi_evaluate_integer(NULL, ACPI_KEYBOARD_BACKLIGHT_READ,
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NULL, &brightness);
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if (ACPI_FAILURE(status)) {
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dev_err(cdev->dev, "Error getting keyboard LED value: %d\n",
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status);
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return -EIO;
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}
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return brightness;
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}
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static int keyboard_led_probe(struct platform_device *pdev)
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{
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struct led_classdev *cdev;
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acpi_handle handle;
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acpi_status status;
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int error;
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/* Look for the keyboard LED ACPI Device */
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status = acpi_get_handle(ACPI_ROOT_OBJECT,
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ACPI_KEYBOARD_BACKLIGHT_DEVICE,
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&handle);
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if (ACPI_FAILURE(status)) {
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dev_err(&pdev->dev, "Unable to find ACPI device %s: %d\n",
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ACPI_KEYBOARD_BACKLIGHT_DEVICE, status);
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return -ENXIO;
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}
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cdev = devm_kzalloc(&pdev->dev, sizeof(*cdev), GFP_KERNEL);
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if (!cdev)
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return -ENOMEM;
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cdev->name = "chromeos::kbd_backlight";
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cdev->max_brightness = ACPI_KEYBOARD_BACKLIGHT_MAX;
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cdev->flags |= LED_CORE_SUSPENDRESUME;
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cdev->brightness_set = keyboard_led_set_brightness;
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cdev->brightness_get = keyboard_led_get_brightness;
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error = devm_led_classdev_register(&pdev->dev, cdev);
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if (error)
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return error;
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return 0;
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}
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static const struct acpi_device_id keyboard_led_id[] = {
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{ "GOOG0002", 0 },
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{ }
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};
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MODULE_DEVICE_TABLE(acpi, keyboard_led_id);
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static struct platform_driver keyboard_led_driver = {
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.driver = {
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.name = "chromeos-keyboard-leds",
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.acpi_match_table = ACPI_PTR(keyboard_led_id),
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},
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.probe = keyboard_led_probe,
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};
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module_platform_driver(keyboard_led_driver);
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MODULE_AUTHOR("Simon Que <sque@chromium.org>");
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MODULE_DESCRIPTION("ChromeOS Keyboard backlight LED Driver");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("platform:chromeos-keyboard-leds");
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