platform/chrome: Add Chrome OS keyboard backlight LEDs support

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>
This commit is contained in:
Simon Que 2016-03-08 11:12:46 -08:00 committed by Olof Johansson
parent 48b9b6d469
commit 492ef7829d
3 changed files with 140 additions and 7 deletions

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@ -64,4 +64,14 @@ config CROS_EC_PROTO
help
ChromeOS EC communication protocol helpers.
config CROS_KBD_LED_BACKLIGHT
tristate "Backlight LED support for Chrome OS keyboards"
depends on LEDS_CLASS && ACPI
help
This option enables support for the keyboard backlight LEDs on
select Chrome OS systems.
To compile this driver as a module, choose M here: the
module will be called cros_kbd_led_backlight.
endif # CHROMEOS_PLATFORMS

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@ -1,8 +1,9 @@
obj-$(CONFIG_CHROMEOS_LAPTOP) += chromeos_laptop.o
obj-$(CONFIG_CHROMEOS_PSTORE) += chromeos_pstore.o
cros_ec_devs-objs := cros_ec_dev.o cros_ec_sysfs.o \
cros_ec_lightbar.o cros_ec_vbc.o
obj-$(CONFIG_CROS_EC_CHARDEV) += cros_ec_devs.o
obj-$(CONFIG_CROS_EC_LPC) += cros_ec_lpc.o
obj-$(CONFIG_CROS_EC_PROTO) += cros_ec_proto.o
obj-$(CONFIG_CHROMEOS_LAPTOP) += chromeos_laptop.o
obj-$(CONFIG_CHROMEOS_PSTORE) += chromeos_pstore.o
cros_ec_devs-objs := cros_ec_dev.o cros_ec_sysfs.o \
cros_ec_lightbar.o cros_ec_vbc.o
obj-$(CONFIG_CROS_EC_CHARDEV) += cros_ec_devs.o
obj-$(CONFIG_CROS_EC_LPC) += cros_ec_lpc.o
obj-$(CONFIG_CROS_EC_PROTO) += cros_ec_proto.o
obj-$(CONFIG_CROS_KBD_LED_BACKLIGHT) += cros_kbd_led_backlight.o

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@ -0,0 +1,122 @@
/*
* Keyboard backlight LED driver for Chrome OS.
*
* Copyright (C) 2012 Google, Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <linux/acpi.h>
#include <linux/leds.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
/* Keyboard LED ACPI Device must be defined in firmware */
#define ACPI_KEYBOARD_BACKLIGHT_DEVICE "\\_SB.KBLT"
#define ACPI_KEYBOARD_BACKLIGHT_READ ACPI_KEYBOARD_BACKLIGHT_DEVICE ".KBQC"
#define ACPI_KEYBOARD_BACKLIGHT_WRITE ACPI_KEYBOARD_BACKLIGHT_DEVICE ".KBCM"
#define ACPI_KEYBOARD_BACKLIGHT_MAX 100
static void keyboard_led_set_brightness(struct led_classdev *cdev,
enum led_brightness brightness)
{
union acpi_object param;
struct acpi_object_list input;
acpi_status status;
param.type = ACPI_TYPE_INTEGER;
param.integer.value = brightness;
input.count = 1;
input.pointer = &param;
status = acpi_evaluate_object(NULL, ACPI_KEYBOARD_BACKLIGHT_WRITE,
&input, NULL);
if (ACPI_FAILURE(status))
dev_err(cdev->dev, "Error setting keyboard LED value: %d\n",
status);
}
static enum led_brightness
keyboard_led_get_brightness(struct led_classdev *cdev)
{
unsigned long long brightness;
acpi_status status;
status = acpi_evaluate_integer(NULL, ACPI_KEYBOARD_BACKLIGHT_READ,
NULL, &brightness);
if (ACPI_FAILURE(status)) {
dev_err(cdev->dev, "Error getting keyboard LED value: %d\n",
status);
return -EIO;
}
return brightness;
}
static int keyboard_led_probe(struct platform_device *pdev)
{
struct led_classdev *cdev;
acpi_handle handle;
acpi_status status;
int error;
/* Look for the keyboard LED ACPI Device */
status = acpi_get_handle(ACPI_ROOT_OBJECT,
ACPI_KEYBOARD_BACKLIGHT_DEVICE,
&handle);
if (ACPI_FAILURE(status)) {
dev_err(&pdev->dev, "Unable to find ACPI device %s: %d\n",
ACPI_KEYBOARD_BACKLIGHT_DEVICE, status);
return -ENXIO;
}
cdev = devm_kzalloc(&pdev->dev, sizeof(*cdev), GFP_KERNEL);
if (!cdev)
return -ENOMEM;
cdev->name = "chromeos::kbd_backlight";
cdev->max_brightness = ACPI_KEYBOARD_BACKLIGHT_MAX;
cdev->flags |= LED_CORE_SUSPENDRESUME;
cdev->brightness_set = keyboard_led_set_brightness;
cdev->brightness_get = keyboard_led_get_brightness;
error = devm_led_classdev_register(&pdev->dev, cdev);
if (error)
return error;
return 0;
}
static const struct acpi_device_id keyboard_led_id[] = {
{ "GOOG0002", 0 },
{ }
};
MODULE_DEVICE_TABLE(acpi, keyboard_led_id);
static struct platform_driver keyboard_led_driver = {
.driver = {
.name = "chromeos-keyboard-leds",
.acpi_match_table = ACPI_PTR(keyboard_led_id),
},
.probe = keyboard_led_probe,
};
module_platform_driver(keyboard_led_driver);
MODULE_AUTHOR("Simon Que <sque@chromium.org>");
MODULE_DESCRIPTION("ChromeOS Keyboard backlight LED Driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:chromeos-keyboard-leds");