Add the support documentation on the multicolor LED framework. This document defines the directores and file generated by the multicolor framework. It also documents usage.
Signed-off-by: Dan Murphy <dmur...@ti.com> --- Documentation/leds/index.rst | 1 + Documentation/leds/leds-class-multicolor.rst | 149 +++++++++++++++++++ 2 files changed, 150 insertions(+) create mode 100644 Documentation/leds/leds-class-multicolor.rst 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..0b40c85f417a --- /dev/null +++ b/Documentation/leds/leds-class-multicolor.rst @@ -0,0 +1,149 @@ +==================================== +Multi Color LED handling under Linux +==================================== + +Description +=========== +There are varying monochrome LED colors available for application. These +LEDs can be used as a single use case LED or can be mixed with other color +LEDs to produce the full spectrum of color. Color LEDs that are grouped +can be presented under a single LED node with individual color control. +The multicolor class groups these LEDs and allows dynamically setting the value +of a single LED or setting the intensity values of the LEDs in the group and +updating the LEDs virtually simultaneously. + +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 is given its own directory. These directories will be one of +LED_COLOR_ID_* definitions from the header include/dt-bindings/leds/common.h. +Under these directories the intensity and max_intensity files are presented for +each LED. + +Directory Layout Example +======================== +root:/sys/class/leds/rgb:grouped_leds# ls -lR colors/ +colors/: +drwxr-xr-x 2 root root 0 Jun 28 20:21 blue +drwxr-xr-x 2 root root 0 Jun 28 20:21 green +drwxr-xr-x 2 root root 0 Jun 28 20:21 red +-rw------- 1 root root 4096 Jun 28 20:21 color_mix + +colors/blue: +-rw------- 1 root root 4096 Jun 28 20:21 intensity +-r-------- 1 root root 4096 Jun 28 20:27 max_intensity +-r-------- 1 root root 4096 Jun 28 20:21 color_id + +colors/green: +-rw------- 1 root root 4096 Jun 28 20:22 intensity +-r-------- 1 root root 4096 Jun 28 20:27 max_intensity +-r-------- 1 root root 4096 Jun 28 20:21 color_id + +colors/red: +-rw------- 1 root root 4096 Jun 28 20:21 intensity +-r-------- 1 root root 4096 Jun 28 20:27 max_intensity +-r-------- 1 root root 4096 Jun 28 20:21 color_id + +Multicolor Color Mixing +======================= +Multicolor monochrome LEDs intensity can be modified and mixed to produce a +varying array of colors. The color_mix file gives the user the ability to write +all the monochrome LEDs registered in the directory with a single call. +To create a specific color from monochrome LEDs the color_mix file needs to be +written with each color's intensity. The order in which the monochrome LEDs +should be written is based on the colors color_id. The LEDs brightness will be +updated on the next call to the parent brightness file. + +For example: +cat /sys/class/leds/rgb:grouped_leds/red/color_id +0 +cat /sys/class/leds/rgb:grouped_leds/green/color_id +1 +cat /sys/class/leds/rgb:grouped_leds/blue/color_id +2 + +red - color_id = 0 +green - color_id = 1 +blue - color_id = 2 + +These id's are the order in which to write the color_mix file. + +echo "<red> <green> <blue>" > color_mix + +echo "80 00 80" > color_mix + +The order of the monochrome LEDs are determined during multicolor class +registration and will not change unless unregistered and re-registered. + +Other example with amber monochrome LED: +blue - color_id = 0 +amber - color_id = 1 + +In this example blue is at ID 0 and amber ID is 1 so the user would write +echo "<blue> <amber>" > color_mix + +echo "38 80" > color_mix + +If a single monochrome LED needs to be modified then the user would write the +colors/<color>/intensity file. + + +Multicolor Class Brightness Control +=================================== +The multiclor class framework will calculate each monochrome LEDs intensity. + +The brightness level for each LED is calculated based on the color LED +intensity setting divided by the color LED max intensity setting multiplied by +the requested value. + +led_brightness = requested_value * led_color_intensity/led_color_max_intensity + +Example: +Three LEDs are present in the group as defined in "Directory Layout Example" +within this document. + +A user first writes the color LED brightness file with the brightness level that +is necessary to achieve a blueish violet output from the RGB LED group. + +echo 138 > /sys/class/leds/rgb:grouped_leds/red/intensity +echo 43 > /sys/class/leds/rgb:grouped_leds/green/intensity +echo 226 > /sys/class/leds/rgb:grouped_leds/blue/intensity + +red - + intensity = 138 + max_intensity = 255 +green - + intensity = 43 + max_intensity = 255 +blue - + intensity = 226 + max_intensity = 255 + +The user can control the brightness of that RGB group by writing the parent +'brightness' control. Assuming a parent max_brightness of 255 the user may want +to dim the LED color group to half. The user would write a value of 128 to the +parent brightness file then the values written to each LED will be adjusted +base on this value + +cat /sys/class/leds/rgb:grouped_leds/max_brightness +255 +echo 128 > /sys/class/leds/rgb:grouped_leds/brightness + +adjusted_red_value = 128 * 138/255 = 69 +adjusted_green_value = 128 * 43/255 = 21 +adjusted_blue_value = 128 * 226/255 = 113 + +Reading the parent brightness file will return the current brightness value of +the color LED group. + +cat /sys/class/leds/rgb:grouped_leds/max_brightness +255 + +echo 128 > /sys/class/leds/rgb:grouped_leds/brightness + +cat /sys/class/leds/rgb:grouped_leds/max_brightness +128 -- 22.214.171.124.g8dca754b1e