Re: [PATCH] platform/chrome: Add Chrome OS keyboard backlight LEDs support

From: Guenter Roeck
Date: Fri Mar 04 2016 - 20:50:15 EST

On Fri, Mar 4, 2016 at 5:23 PM, Dmitry Torokhov
<dmitry.torokhov@xxxxxxxxx> wrote:
> 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@xxxxxxxxxxxx>
> Signed-off-by: Duncan Laurie <dlaurie@xxxxxxxxxxxx>
> Signed-off-by: Dmitry Torokhov <dtor@xxxxxxxxxxxx>
> ---
>
> Changes form previous submission:
>
> - moved from drivers/leds to drivers/platform/chrome
> - added method to retrieve brightness from ACPI
> - renamed to cros_kbd_led_backlight
> - config option renamed to CROS_KBD_LED_BACKLIGHT
> - no longer setting initial brightness to max brightness (although on
> Pixel 1 - Link - ACPI initially reports 100 as brightness anyway)
>
> I ran this on Pixel 1; Evan, could you give it a spin on your Pixel 2?
>
> Thanks!
>
> drivers/platform/chrome/Kconfig | 10 ++
> drivers/platform/chrome/Makefile | 15 +--
> drivers/platform/chrome/cros_kbd_led_backlight.c | 123 +++++++++++++++++++++++
> 3 files changed, 141 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/platform/chrome/Kconfig b/drivers/platform/chrome/Kconfig
> index d03df4a..76bdae1 100644
> --- a/drivers/platform/chrome/Kconfig
> +++ b/drivers/platform/chrome/Kconfig
> @@ -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
> diff --git a/drivers/platform/chrome/Makefile b/drivers/platform/chrome/Makefile
> index bc498bd..4f34627 100644
> --- a/drivers/platform/chrome/Makefile
> +++ b/drivers/platform/chrome/Makefile
> @@ -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
> diff --git a/drivers/platform/chrome/cros_kbd_led_backlight.c b/drivers/platform/chrome/cros_kbd_led_backlight.c
> new file mode 100644
> index 0000000..55477d7
> --- /dev/null
> +++ b/drivers/platform/chrome/cros_kbd_led_backlight.c
> @@ -0,0 +1,123 @@
> +/*
> + * 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;
> +
> + platform_set_drvdata(pdev, cdev);

Is this needed ?

Thanks,
Guenter

> + 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@xxxxxxxxxxxx>");
> +MODULE_DESCRIPTION("ChromeOS Keyboard backlight LED Driver");
> +MODULE_LICENSE("GPL");
> +MODULE_ALIAS("platform:chromeos-keyboard-leds");
> --
> 2.7.0.rc3.207.g0ac5344
>
>
> --
> Dmitry