Adding upstream version 6.1.76.upstream/6.1.76upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 86 insertions, 0 deletions

diff --git a/Documentation/leds/leds-class-multicolor.rst b/Documentation/leds/leds-class-multicolor.rst
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+.. SPDX-License-Identifier: GPL-2.0
+
+====================================
+Multicolor LED handling under Linux
+====================================
+
+Description
+===========
+The multicolor class groups monochrome LEDs and allows controlling two
+aspects of the final combined color: hue and lightness. The former is
+controlled via the multi_intensity array file and the latter is controlled
+via brightness file.
+
+Multicolor Class Control
+========================
+The multicolor class presents files that groups the colors as indexes in an
+array.  These files are children 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 be indexed under the multi_* files. The order of the
+colors will be arbitrary. The multi_index file can be read to determine the
+color name to indexed value.
+
+The multi_index file is an array that contains the string list of the colors as
+they are defined in each multi_* array file.
+
+The multi_intensity is an array that can be read or written to for the
+individual color intensities.  All elements within this array must be written in
+order for the color LED intensities to be updated.
+
+Directory Layout Example
+========================
+root:/sys/class/leds/multicolor:status# ls -lR
+-rw-r--r--    1 root     root          4096 Oct 19 16:16 brightness
+-r--r--r--    1 root     root          4096 Oct 19 16:16 max_brightness
+-r--r--r--    1 root     root          4096 Oct 19 16:16 multi_index
+-rw-r--r--    1 root     root          4096 Oct 19 16:16 multi_intensity
+
+Multicolor Class Brightness Control
+===================================
+The brightness level for each LED is calculated based on the color LED
+intensity setting divided by the global max_brightness setting multiplied by
+the requested brightness.
+
+led_brightness = brightness * multi_intensity/max_brightness
+
+Example:
+A user first writes the multi_intensity file with the brightness levels
+for each LED that are necessary to achieve a certain color output from a
+multicolor LED group.
+
+cat /sys/class/leds/multicolor:status/multi_index
+green blue red
+
+echo 43 226 138 > /sys/class/leds/multicolor:status/multi_intensity
+
+red -
+	intensity = 138
+	max_brightness = 255
+green -
+	intensity = 43
+	max_brightness = 255
+blue -
+	intensity = 226
+	max_brightness = 255
+
+The user can control the brightness of that multicolor LED group by writing the
+global 'brightness' control.  Assuming a 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 global brightness file then the values written to each LED will be
+adjusted base on this value.
+
+cat /sys/class/leds/multicolor:status/max_brightness
+255
+echo 128 > /sys/class/leds/multicolor:status/brightness
+
+adjusted_red_value = 128 * 138/255 = 69
+adjusted_green_value = 128 * 43/255 = 21
+adjusted_blue_value = 128 * 226/255 = 113
+
+Reading the global brightness file will return the current brightness value of
+the color LED group.
+
+cat /sys/class/leds/multicolor:status/brightness
+128