Re: [PATCH v10 04/16] leds: multicolor: Introduce a multicolor class definition

[Jacek Anaszewski <jacek.anaszewski@gmail.com>]

Dan,

Thank you for the update.

On 10/1/19 4:56 PM, Dan Murphy wrote:
> Introduce a multicolor class that groups colored LEDs
> within a LED node.
> 
> The multi color class groups monochrome LEDs and allows controlling two
> aspects of the final combined color: hue and lightness. The former is
> controlled via <color>_intensity files and the latter is controlled
> via brightness file.
> 
> Signed-off-by: Dan Murphy <dmurphy@ti.com>
> ---
>  .../ABI/testing/sysfs-class-led-multicolor    |  35 +++
>  Documentation/leds/index.rst                  |   1 +
>  Documentation/leds/leds-class-multicolor.rst  |  96 +++++++
>  drivers/leds/Kconfig                          |  10 +
>  drivers/leds/Makefile                         |   1 +
>  drivers/leds/led-class-multicolor.c           | 268 ++++++++++++++++++
>  include/linux/led-class-multicolor.h          |  88 ++++++
>  7 files changed, 499 insertions(+)
>  create mode 100644 Documentation/ABI/testing/sysfs-class-led-multicolor
>  create mode 100644 Documentation/leds/leds-class-multicolor.rst
>  create mode 100644 drivers/leds/led-class-multicolor.c
>  create mode 100644 include/linux/led-class-multicolor.h
> 
> diff --git a/Documentation/ABI/testing/sysfs-class-led-multicolor b/Documentation/ABI/testing/sysfs-class-led-multicolor
> new file mode 100644
> index 000000000000..65cb43de26e6
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-class-led-multicolor
> @@ -0,0 +1,35 @@
> +What:		/sys/class/leds/<led>/brightness
> +Date:		Sept 2019
> +KernelVersion:	5.5
> +Contact:	Dan Murphy <dmurphy@ti.com>
> +Description:	read/write
> +		Writing to this file will update all LEDs within the group to a
> +		calculated percentage of what each color LED intensity is set
> +		to. The percentage is calculated via the equation below:
> +
> +		led_brightness = brightness * <color>_intensity/<color>_max_intensity
> +
> +		For additional details please refer to
> +		Documentation/leds/leds-class-multicolor.rst.
> +
> +		The value of the color is from 0 to
> +		/sys/class/leds/<led>/max_brightness.
> +
> +What:		/sys/class/leds/<led>/colors/<color>_intensity
> +Date:		Sept 2019
> +KernelVersion:	5.5
> +Contact:	Dan Murphy <dmurphy@ti.com>
> +Description:	read/write
> +		The <color>_intensity file is created based on the color
> +		defined by the registrar of the class.
> +		There is one file per color presented.
> +
> +		The value of the color is from 0 to
> +		/sys/class/leds/<led>/colors/<color>_max_intensity.
> +
> +What:		/sys/class/leds/<led>/colors/<color>_max_intensity
> +Date:		Sept 2019
> +KernelVersion:	5.5
> +Contact:	Dan Murphy <dmurphy@ti.com>
> +Description:	read only
> +		Maximum intensity level for the LED color.
> diff --git a/Documentation/leds/index.rst b/Documentation/leds/index.rst
> index 060f4e485897..bc70c6aa7138 100644
> --- a/Documentation/leds/index.rst
> +++ b/Documentation/leds/index.rst
> @@ -9,6 +9,7 @@ LEDs
>  
>     leds-class
>     leds-class-flash
> +   leds-class-multicolor
>     ledtrig-oneshot
>     ledtrig-transient
>     ledtrig-usbport
> diff --git a/Documentation/leds/leds-class-multicolor.rst b/Documentation/leds/leds-class-multicolor.rst
> new file mode 100644
> index 000000000000..87a1588d7619
> --- /dev/null
> +++ b/Documentation/leds/leds-class-multicolor.rst
> @@ -0,0 +1,96 @@
> +====================================
> +Multi Color LED handling under Linux
> +====================================
> +
> +Description
> +===========
> +The multi color class groups monochrome LEDs and allows controlling two
> +aspects of the final combined color: hue and lightness. The former is
> +controlled via <color>_intensity files and the latter is controlled
> +via brightness file.
> +
> +For more details on hue and lightness notions please refer to
> +https://en.wikipedia.org/wiki/CIECAM02.
> +
> +Note that intensity files only cache the written value and the actual
> +change of hardware state occurs upon writing brightness file. This
> +allows for changing many factors of the perceived color in a virtually
> +unnoticeable way for the human observer.
> +
> +Multicolor Class Control
> +========================
> +The multicolor class presents the LED groups under a directory called "colors".
> +This directory is a child under the LED parent node created by the led_class
> +framework.  The led_class framework is documented in led-class.rst within this
> +documentation directory.
> +
> +Each colored LED will have two files created under the colors directory
> +<color>_intensity and <color>_max_intensity. These files will contain
> +one of LED_COLOR_ID_* definitions from the header
> +include/dt-bindings/leds/common.h.
> +
> +Directory Layout Example
> +========================
> +root:/sys/class/leds/rgb:grouped_leds# ls -lR colors/
> +-rw-rwxr-- 1 root root 4096 Jul 7 03:10 red_max_intensity
> +--w--wx-w- 1 root root 4096 Jul 7 03:10 red_intensity
> +-rw-rwxr-- 1 root root 4096 Jul 7 03:10 green_max_intensity
> +--w--wx-w- 1 root root 4096 Jul 7 03:10 green_intensity
> +-rw-rwxr-- 1 root root 4096 Jul 7 03:10 blue_max_intensity
> +--w--wx-w- 1 root root 4096 Jul 7 03:10 blue_intensity

Now when you have fixed file permissions in LED mc core the
'ls -l' should report them correctly, so this needs to be
updated.

[...]
> +int devm_led_classdev_multicolor_register(struct device *parent,
> +					  struct led_classdev_mc *mcled_cdev)
> +{
> +	struct led_classdev_mc **dr;
> +	int ret;
> +
> +	dr = devres_alloc(devm_led_classdev_multicolor_release,
> +			  sizeof(*dr), GFP_KERNEL);
> +	if (!dr)
> +		return -ENOMEM;
> +
> +	ret = led_classdev_multicolor_register(parent, mcled_cdev);
> +	if (ret) {
> +		devres_free(dr);
> +		return ret;
> +	}
> +
> +	*dr = mcled_cdev;
> +	devres_add(parent, dr);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(devm_led_classdev_multicolor_register);
> +
> +static int devm_led_classdev_multicolor_match(struct device *dev,
> +					      void *res, void *data)
> +{
> +	struct mcled_cdev **p = res;

s/mcled_cdev/led_classdev_mc/

> +
> +	if (WARN_ON(!p || !*p))
> +		return 0;
> +
> +	return *p == data;
> +}
> +
[...]
-- 
Best regards,
Jacek Anaszewski