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 <dmurphy@xxxxxx> --- Documentation/leds/leds-class-multicolor.txt | 152 +++++++++++++++++++ 1 file changed, 152 insertions(+) create mode 100644 Documentation/leds/leds-class-multicolor.txt diff --git a/Documentation/leds/leds-class-multicolor.txt b/Documentation/leds/leds-class-multicolor.txt new file mode 100644 index 000000000000..01175288502e --- /dev/null +++ b/Documentation/leds/leds-class-multicolor.txt @@ -0,0 +1,152 @@ + +Multi Color LED handling under Linux +================================================= + +Author: Dan Murphy <dmurphy@xxxxxx> + +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.txt within this +documentation directory. + +Each colored LED is given its own directory. These directories can be, but not +limited to red, green, blue, white, amber, yellow and violet. 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. + +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 "0x80 0x00 0x80" > 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 exampe blue is at ID 0 and amber ID is 1 so the user would write +echo "<blue> <amber>" > color_mix + +echo "0x38 0x80" > 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 neccesary 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 + + -- 2.22.0.214.g8dca754b1e
