Re: [PATCH v6 5/7] leds: Add driver for ASUS Transformer LEDs

[Lee Jones]

On Sat, 02 May 2026, Svyatoslav Ryhel wrote:

> From: Michał Mirosław <mirq-linux@xxxxxxxxxxxx>
> 
> ASUS Transformer tablets have a green and an amber LED on both the Pad
> and the Dock. If both LEDs are enabled simultaneously, the emitted light
> will be yellow.
> 
> Co-developed-by: Svyatoslav Ryhel <clamor95@xxxxxxxxx>
> Signed-off-by: Svyatoslav Ryhel <clamor95@xxxxxxxxx>
> Signed-off-by: Michał Mirosław <mirq-linux@xxxxxxxxxxxx>
> ---
>  drivers/leds/Kconfig                    | 11 ++++
>  drivers/leds/Makefile                   |  1 +
>  drivers/leds/leds-asus-transformer-ec.c | 79 +++++++++++++++++++++++++
>  3 files changed, 91 insertions(+)
>  create mode 100644 drivers/leds/leds-asus-transformer-ec.c
> 
> diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
> index f4a0a3c8c870..f637d23400a8 100644
> --- a/drivers/leds/Kconfig
> +++ b/drivers/leds/Kconfig
> @@ -120,6 +120,17 @@ config LEDS_OSRAM_AMS_AS3668
>  	  To compile this driver as a module, choose M here: the module
>  	  will be called leds-as3668.
>  
> +config LEDS_ASUS_TRANSFORMER_EC
> +	tristate "LED Support for Asus Transformer charging LED"
> +	depends on LEDS_CLASS
> +	depends on MFD_ASUS_TRANSFORMER_EC
> +	help
> +	  This option enables support for charging indicator on
> +	  Asus Transformer's Pad and it's Dock.
> +
> +	  To compile this driver as a module, choose M here: the module
> +	  will be called leds-asus-transformer-ec.
> +
>  config LEDS_AW200XX
>  	tristate "LED support for Awinic AW20036/AW20054/AW20072/AW20108"
>  	depends on LEDS_CLASS
> diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
> index 8fdb45d5b439..d5395c3f1124 100644
> --- a/drivers/leds/Makefile
> +++ b/drivers/leds/Makefile
> @@ -16,6 +16,7 @@ obj-$(CONFIG_LEDS_AN30259A)		+= leds-an30259a.o
>  obj-$(CONFIG_LEDS_APU)			+= leds-apu.o
>  obj-$(CONFIG_LEDS_ARIEL)		+= leds-ariel.o
>  obj-$(CONFIG_LEDS_AS3668)		+= leds-as3668.o
> +obj-$(CONFIG_LEDS_ASUS_TRANSFORMER_EC)	+= leds-asus-transformer-ec.o
>  obj-$(CONFIG_LEDS_AW200XX)		+= leds-aw200xx.o
>  obj-$(CONFIG_LEDS_AW2013)		+= leds-aw2013.o
>  obj-$(CONFIG_LEDS_BCM6328)		+= leds-bcm6328.o
> diff --git a/drivers/leds/leds-asus-transformer-ec.c b/drivers/leds/leds-asus-transformer-ec.c
> new file mode 100644
> index 000000000000..3186038e3be7
> --- /dev/null
> +++ b/drivers/leds/leds-asus-transformer-ec.c
> @@ -0,0 +1,79 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +
> +#include <linux/err.h>
> +#include <linux/leds.h>
> +#include <linux/mfd/asus-transformer-ec.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +
> +static void asus_ec_led_set_brightness_amber(struct led_classdev *led,
> +					     enum led_brightness brightness)
> +{
> +	const struct asusec_info *ec = dev_get_drvdata(led->dev->parent);
> +
> +	if (brightness)
> +		asus_ec_set_ctl_bits(ec, ASUSEC_CTL_LED_AMBER);

Why not Regmap?

> +	else
> +		asus_ec_clear_ctl_bits(ec, ASUSEC_CTL_LED_AMBER);
> +}
> +
> +static void asus_ec_led_set_brightness_green(struct led_classdev *led,
> +					     enum led_brightness brightness)
> +{
> +	const struct asusec_info *ec = dev_get_drvdata(led->dev->parent);
> +
> +	if (brightness)
> +		asus_ec_set_ctl_bits(ec, ASUSEC_CTL_LED_GREEN);
> +	else
> +		asus_ec_clear_ctl_bits(ec, ASUSEC_CTL_LED_GREEN);
> +}

These are identical bar one variable.


> +static int asus_ec_led_probe(struct platform_device *pdev)
> +{
> +	struct asusec_info *ec = cell_to_ec(pdev);
> +	struct device *dev = &pdev->dev;
> +	struct led_classdev *amber_led, *green_led;
> +	int ret;
> +
> +	platform_set_drvdata(pdev, ec);

This appears to be unused.

> +	amber_led = devm_kzalloc(dev, sizeof(*amber_led), GFP_KERNEL);
> +	if (!amber_led)
> +		return -ENOMEM;
> +
> +	amber_led->name = devm_kasprintf(dev, GFP_KERNEL, "%s::amber", ec->name);
> +	amber_led->max_brightness = 1;
> +	amber_led->flags = LED_CORE_SUSPENDRESUME | LED_RETAIN_AT_SHUTDOWN;
> +	amber_led->brightness_set = asus_ec_led_set_brightness_amber;
> +
> +	ret = devm_led_classdev_register(dev, amber_led);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "failed to register amber LED\n");
> +
> +	green_led = devm_kzalloc(dev, sizeof(*green_led), GFP_KERNEL);
> +	if (!green_led)
> +		return -ENOMEM;
> +
> +	green_led->name = devm_kasprintf(dev, GFP_KERNEL, "%s::green", ec->name);
> +	green_led->max_brightness = 1;
> +	green_led->flags = LED_CORE_SUSPENDRESUME | LED_RETAIN_AT_SHUTDOWN;
> +	green_led->brightness_set = asus_ec_led_set_brightness_green;
> +
> +	ret = devm_led_classdev_register(dev, green_led);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "failed to register green LED\n");

Imagine instead of 2 LEDs, you had 20.  Would you copy and paste this 20
times?  Please re-author this as though there were many more so it
remains efficient and scaleable.

> +	return 0;
> +}
> +
> +static struct platform_driver asus_ec_led_driver = {
> +	.driver.name = "asus-transformer-ec-led",
> +	.probe = asus_ec_led_probe,
> +};
> +module_platform_driver(asus_ec_led_driver);
> +
> +MODULE_AUTHOR("Michał Mirosław <mirq-linux@xxxxxxxxxxxx>");
> +MODULE_AUTHOR("Svyatoslav Ryhel <clamor95@xxxxxxxxx>");
> +MODULE_DESCRIPTION("ASUS Transformer's charging LED driver");
> +MODULE_LICENSE("GPL");
> -- 
> 2.51.0
> 
> 

-- 
Lee Jones