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 | 99 ++++++++++++++++++++ 1 file changed, 99 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..edbb8139e514 --- /dev/null +++ b/Documentation/leds/leds-class-multicolor.txt @@ -0,0 +1,99 @@ + +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 brightness 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 brightness and max_brightness files are presented for each LED. + +Under the "colors" directory there are two files created: "sync" and +"sync_enable". The sync_enable file controls whether the LED brightness +value is set real time or if the LED brightness value setting is deferred until +the "sync" file is written. If sync_enable is set then writing to each LED +"brightness" file will store the brightness value. Once the "sync" file is +written then each LED color defined in the node will write the brightness of +the LED in the device driver. + +If "sync_enable" is not set then writing the brightness value of the LED to the +device driver is done immediately. Writing the "sync" file has no affect. + +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 +--w------- 1 root root 4096 Jun 28 20:21 sync +-rw------- 1 root root 4096 Jun 28 20:22 sync_enable + +colors/blue: +-rw------- 1 root root 4096 Jun 28 20:21 brightness +-r-------- 1 root root 4096 Jun 28 20:27 max_brightness + +colors/green: +-rw------- 1 root root 4096 Jun 28 20:22 brightness +-r-------- 1 root root 4096 Jun 28 20:27 max_brightness + +colors/red: +-rw------- 1 root root 4096 Jun 28 20:21 brightness +-r-------- 1 root root 4096 Jun 28 20:27 max_brightness + +Example of Writing LEDs with Sync Enabled +----------------------------------------- +Below the red, green and blue LEDs are set to corresponding values. These +values are stored and not written until the sync file is written. + +cd /sys/class/leds/rgb:grouped_leds/colors + +echo 1 > sync_enable + +echo 100 > red/brightness +echo 80 > green/brightness +echo 180 > blue/brightness + +* LED device driver has not been updated and the LED states have not changed. +* Writing the LED brightness files again will only change the stored value and +* not the device driver value. + +echo 1 > sync + +* LED device driver has been updated; the LEDs should present the brightness +* levels that have been set. Since sync_enable is still enabled writing to the +* LED brightness files will not change the current brightnesses. + +Example of Writing LEDs with Sync Disabled +------------------------------------------ +Below the values of each LED are written to the device driver immediately upon +request. + +cd /sys/class/leds/rgb:grouped_leds/colors + +echo 0 > sync_enable + +echo 100 > red/brightness // Red LED should be on with the current brightness +echo 80 > green/brightness // Green LED should be on with the current brightness +echo 180 > blue/brightness // Blue LED should be on with the current brightness +. +. +. +echo 0 > green/brightness // Green LED should be off -- 2.21.0.5.gaeb582a983
