Add a documentation of LED Multicolor LED class specific
sysfs attributes.
Signed-off-by: Dan Murphy <[email protected]>
---
v4 - Add LED class parent brightness definition to the text - https://lore.kernel.org/patchwork/patch/1078398/
.../ABI/testing/sysfs-class-led-multicolor | 74 +++++++++++++++++++
1 file changed, 74 insertions(+)
create mode 100644 Documentation/ABI/testing/sysfs-class-led-multicolor
diff --git a/Documentation/ABI/testing/sysfs-class-led-multicolor b/Documentation/ABI/testing/sysfs-class-led-multicolor
new file mode 100644
index 000000000000..ec2b6ac63ecc
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-led-multicolor
@@ -0,0 +1,74 @@
+What: /sys/class/leds/<led>/brightness
+Date: April 2019
+KernelVersion: 5.2
+Contact: Dan Murphy <[email protected]>
+Description: read/write
+ The multicolor class will redirect the device drivers call back
+ function for brightness control to the multicolor class
+ brightness control function.
+
+ Writing to this file will update all LEDs within the group to a
+ calculated percentage of what each color LED in the group is set
+ to. Please refer to the leds-class-multicolor.txt in the
+ Documentation directory for a complete description.
+
+ The value of the color is from 0 to
+ /sys/class/leds/<led>/max_brightness.
+
+What: /sys/class/leds/<led>/colors/sync_enable
+Date: April 2019
+KernelVersion: 5.2
+Contact: Dan Murphy <[email protected]>
+Description: read/write
+ Writing a 1 to this file will enable the synchronization of all
+ the defined color LEDs within the LED node. Brightness values
+ for each LED will be stored and written when sync is set to 1.
+ Writing a 0 to this file will disable syncing and allow
+ individual control of the LEDs brightness settings.
+
+What: /sys/class/leds/<led>/colors/sync
+Date: April 2019
+KernelVersion: 5.2
+Contact: Dan Murphy <[email protected]>
+Description: write only
+ Writing a 1 to this file while sync_enable is set to 1 will
+ write the current brightness values to all defined LEDs within
+ the LED node. All LEDs defined will be configured based
+ on the brightness that has been requested.
+
+ If sync_enable is set to 0 then writing a 1 to sync has no
+ affect on the LEDs.
+
+What: /sys/class/leds/<led>/colors/<led_color>/brightness
+Date: April 2019
+KernelVersion: 5.2
+Contact: Dan Murphy <[email protected]>
+Description: read/write
+ The led_color directory is dynamically created based on the
+ colors defined by the registrar of the class.
+ The led_color can be but not limited to red, green, blue,
+ white, amber, yellow and violet. Drivers can also declare a
+ LED color for presentation. There is one directory per color
+ presented. The brightness file is created under each
+ led_color directory and controls the individual LED color
+ setting.
+
+ If sync is enabled then writing the brightness value of the LED
+ is deferred until a 1 is written to
+ /sys/class/leds/<led>/color/sync. If syncing is
+ disabled then the LED brightness value will be written
+ immediately to the LED driver.
+
+ The value of the color is from 0 to
+ /sys/class/leds/<led>/colors/<led_color>/max_brightness.
+
+What: /sys/class/leds/<led>/colors/<led_color>/max_brightness
+Date: April 2019
+KernelVersion: 5.2
+Contact: Dan Murphy <[email protected]>
+Description: read only
+ Maximum brightness level for the LED color, default is
+ 255 (LED_FULL).
+
+ If the LED does not support different brightness levels, this
+ should be 1.
--
2.21.0.5.gaeb582a983
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 <[email protected]>
---
v4 - Add LED class parent brightness description - https://lore.kernel.org/patchwork/patch/1078398/
Documentation/leds/leds-class-multicolor.txt | 159 +++++++++++++++++++
1 file changed, 159 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..c8658a068361
--- /dev/null
+++ b/Documentation/leds/leds-class-multicolor.txt
@@ -0,0 +1,159 @@
+
+Multi Color LED handling under Linux
+=================================================
+
+Author: Dan Murphy <[email protected]>
+
+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
+
+Multicolor Class Brightness Control
+-----------------------------------
+The multicolor class will redirect the device drivers call back
+function for brightness control to the multicolor class brightness
+control function.
+
+The brightness level for each LED is calculated based on the color LED
+brightness setting divided by the color LED max brightness setting multiplied by
+the requested value.
+
+led_brightness = requested_value*(led_color_brightness/led_color_max_brightness)
+
+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/brightness
+echo 43 > /sys/class/leds/rgb:grouped_leds/green/brightness
+echo 226 > /sys/class/leds/rgb:grouped_leds/blue/brightness
+
+red -
+ brightness = 138
+ max_brightness = 255
+green -
+ brightness = 43
+ max_brightness = 255
+blue -
+ brightness = 226
+ max_brightness = 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
+
+
--
2.21.0.5.gaeb582a983
Hi Dan,
On 5/30/19 8:16 PM, Dan Murphy wrote:
[...]
> +Multicolor Class Brightness Control
> +-----------------------------------
> +The multicolor class will redirect the device drivers call back
> +function for brightness control to the multicolor class brightness
> +control function.
> +
> +The brightness level for each LED is calculated based on the color LED
> +brightness setting divided by the color LED max brightness setting multiplied by
> +the requested value.
> +
> +led_brightness = requested_value*(led_color_brightness/led_color_max_brightness)
> +
> +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/brightness
> +echo 43 > /sys/class/leds/rgb:grouped_leds/green/brightness
> +echo 226 > /sys/class/leds/rgb:grouped_leds/blue/brightness
> +
> +red -
> + brightness = 138
> + max_brightness = 255
> +green -
> + brightness = 43
> + max_brightness = 255
> +blue -
> + brightness = 226
> + max_brightness = 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.
I've tested this algorithm with python script and at least on my LED
monitor it works as expected. Attached is the script I've come up with.
> +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
> +
> +
>
--
Best regards,
Jacek Anaszewski