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leds: multicolor: Introduce a multicolor class definition
Introduce a multicolor class that groups colored LEDs within a LED node. 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 intensity file and the latter is controlled via brightness file. Signed-off-by: Dan Murphy <dmurphy@ti.com> Acked-by: Jacek Anaszewski <jacek.anaszewski@gmail.com> Signed-off-by: Pavel Machek <pavel@ucw.cz> [squashed leds: multicolor: Fix camel case in documentation in]
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‎Documentation/ABI/testing/sysfs-class-led-multicolor‎

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What: /sys/class/leds/<led>/brightness
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Date: March 2020
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KernelVersion: 5.9
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Contact: Dan Murphy <dmurphy@ti.com>
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Description: read/write
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Writing to this file will update all LEDs within the group to a
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calculated percentage of what each color LED intensity is set
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to. The percentage is calculated for each grouped LED via the
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equation below:
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led_brightness = brightness * multi_intensity/max_brightness
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For additional details please refer to
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Documentation/leds/leds-class-multicolor.rst.
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The value of the LED is from 0 to
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/sys/class/leds/<led>/max_brightness.
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What: /sys/class/leds/<led>/multi_index
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Date: March 2020
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KernelVersion: 5.9
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Contact: Dan Murphy <dmurphy@ti.com>
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Description: read
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The multi_index array, when read, will output the LED colors
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as an array of strings as they are indexed in the
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multi_intensity file.
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What: /sys/class/leds/<led>/multi_intensity
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Date: March 2020
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KernelVersion: 5.9
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Contact: Dan Murphy <dmurphy@ti.com>
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Description: read/write
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This file contains array of integers. Order of components is
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described by the multi_index array. The maximum intensity should
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not exceed /sys/class/leds/<led>/max_brightness.

‎Documentation/leds/index.rst‎

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99

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leds-class
1111
leds-class-flash
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leds-class-multicolor
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ledtrig-oneshot
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ledtrig-transient
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ledtrig-usbport

‎Documentation/leds/leds-class-multicolor.rst‎

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

‎drivers/leds/Kconfig‎

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for the flash related features of a LED device. It can be built
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as a module.
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config LEDS_CLASS_MULTICOLOR
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tristate "LED Multicolor Class Support"
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depends on LEDS_CLASS
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help
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This option enables the multicolor LED sysfs class in /sys/class/leds.
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It wraps LED class and adds multicolor LED specific sysfs attributes
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and kernel internal API to it. You'll need this to provide support
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for multicolor LEDs that are grouped together. This class is not
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intended for single color LEDs. It can be built as a module.
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config LEDS_BRIGHTNESS_HW_CHANGED
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bool "LED Class brightness_hw_changed attribute support"
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depends on LEDS_CLASS

‎drivers/leds/Makefile‎

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obj-$(CONFIG_NEW_LEDS) += led-core.o
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obj-$(CONFIG_LEDS_CLASS) += led-class.o
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obj-$(CONFIG_LEDS_CLASS_FLASH) += led-class-flash.o
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obj-$(CONFIG_LEDS_CLASS_MULTICOLOR) += led-class-multicolor.o
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obj-$(CONFIG_LEDS_TRIGGERS) += led-triggers.o
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# LED Platform Drivers (keep this sorted, M-| sort)

‎drivers/leds/led-class-multicolor.c‎

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// SPDX-License-Identifier: GPL-2.0
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// LED Multicolor class interface
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// Copyright (C) 2019-20 Texas Instruments Incorporated - http://www.ti.com/
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// Author: Dan Murphy <dmurphy@ti.com>
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#include <linux/device.h>
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#include <linux/init.h>
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#include <linux/led-class-multicolor.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/uaccess.h>
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#include "leds.h"
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int led_mc_calc_color_components(struct led_classdev_mc *mcled_cdev,
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enum led_brightness brightness)
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{
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struct led_classdev *led_cdev = &mcled_cdev->led_cdev;
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int i;
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for (i = 0; i < mcled_cdev->num_colors; i++)
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mcled_cdev->subled_info[i].brightness = brightness *
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mcled_cdev->subled_info[i].intensity /
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led_cdev->max_brightness;
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return 0;
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}
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EXPORT_SYMBOL_GPL(led_mc_calc_color_components);
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static ssize_t multi_intensity_store(struct device *dev,
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struct device_attribute *intensity_attr,
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const char *buf, size_t size)
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{
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struct led_classdev *led_cdev = dev_get_drvdata(dev);
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struct led_classdev_mc *mcled_cdev = lcdev_to_mccdev(led_cdev);
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int nrchars, offset = 0;
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int intensity_value[LED_COLOR_ID_MAX];
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int i;
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ssize_t ret;
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mutex_lock(&led_cdev->led_access);
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for (i = 0; i < mcled_cdev->num_colors; i++) {
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ret = sscanf(buf + offset, "%i%n",
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&intensity_value[i], &nrchars);
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if (ret != 1) {
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ret = -EINVAL;
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goto err_out;
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}
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offset += nrchars;
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}
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offset++;
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if (offset < size) {
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ret = -EINVAL;
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goto err_out;
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}
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for (i = 0; i < mcled_cdev->num_colors; i++)
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mcled_cdev->subled_info[i].intensity = intensity_value[i];
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led_set_brightness(led_cdev, led_cdev->brightness);
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ret = size;
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err_out:
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mutex_unlock(&led_cdev->led_access);
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return ret;
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}
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static ssize_t multi_intensity_show(struct device *dev,
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struct device_attribute *intensity_attr,
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char *buf)
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{
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struct led_classdev *led_cdev = dev_get_drvdata(dev);
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struct led_classdev_mc *mcled_cdev = lcdev_to_mccdev(led_cdev);
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int len = 0;
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int i;
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for (i = 0; i < mcled_cdev->num_colors; i++) {
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len += sprintf(buf + len, "%d",
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mcled_cdev->subled_info[i].intensity);
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if (i < mcled_cdev->num_colors - 1)
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len += sprintf(buf + len, " ");
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}
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buf[len++] = '\n';
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return len;
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}
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static DEVICE_ATTR_RW(multi_intensity);
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static ssize_t multi_index_show(struct device *dev,
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struct device_attribute *multi_index_attr,
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char *buf)
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{
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struct led_classdev *led_cdev = dev_get_drvdata(dev);
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struct led_classdev_mc *mcled_cdev = lcdev_to_mccdev(led_cdev);
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int len = 0;
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int index;
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int i;
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for (i = 0; i < mcled_cdev->num_colors; i++) {
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index = mcled_cdev->subled_info[i].color_index;
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len += sprintf(buf + len, "%s", led_colors[index]);
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if (i < mcled_cdev->num_colors - 1)
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len += sprintf(buf + len, " ");
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}
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buf[len++] = '\n';
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return len;
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}
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static DEVICE_ATTR_RO(multi_index);
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static struct attribute *led_multicolor_attrs[] = {
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&dev_attr_multi_intensity.attr,
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&dev_attr_multi_index.attr,
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NULL,
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};
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ATTRIBUTE_GROUPS(led_multicolor);
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int led_classdev_multicolor_register_ext(struct device *parent,
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struct led_classdev_mc *mcled_cdev,
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struct led_init_data *init_data)
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{
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struct led_classdev *led_cdev;
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if (!mcled_cdev)
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return -EINVAL;
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if (mcled_cdev->num_colors <= 0)
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return -EINVAL;
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if (mcled_cdev->num_colors > LED_COLOR_ID_MAX)
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return -EINVAL;
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led_cdev = &mcled_cdev->led_cdev;
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mcled_cdev->led_cdev.groups = led_multicolor_groups;
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return led_classdev_register_ext(parent, led_cdev, init_data);
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}
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EXPORT_SYMBOL_GPL(led_classdev_multicolor_register_ext);
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void led_classdev_multicolor_unregister(struct led_classdev_mc *mcled_cdev)
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{
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if (!mcled_cdev)
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return;
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led_classdev_unregister(&mcled_cdev->led_cdev);
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}
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EXPORT_SYMBOL_GPL(led_classdev_multicolor_unregister);
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static void devm_led_classdev_multicolor_release(struct device *dev, void *res)
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{
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led_classdev_multicolor_unregister(*(struct led_classdev_mc **)res);
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}
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int devm_led_classdev_multicolor_register_ext(struct device *parent,
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struct led_classdev_mc *mcled_cdev,
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struct led_init_data *init_data)
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{
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struct led_classdev_mc **dr;
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int ret;
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dr = devres_alloc(devm_led_classdev_multicolor_release,
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sizeof(*dr), GFP_KERNEL);
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if (!dr)
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return -ENOMEM;
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ret = led_classdev_multicolor_register_ext(parent, mcled_cdev,
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init_data);
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if (ret) {
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devres_free(dr);
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return ret;
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}
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*dr = mcled_cdev;
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devres_add(parent, dr);
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return 0;
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}
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EXPORT_SYMBOL_GPL(devm_led_classdev_multicolor_register_ext);
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static int devm_led_classdev_multicolor_match(struct device *dev,
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void *res, void *data)
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{
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struct led_classdev_mc **p = res;
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if (WARN_ON(!p || !*p))
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return 0;
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return *p == data;
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}
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void devm_led_classdev_multicolor_unregister(struct device *dev,
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struct led_classdev_mc *mcled_cdev)
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{
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WARN_ON(devres_release(dev,
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devm_led_classdev_multicolor_release,
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devm_led_classdev_multicolor_match, mcled_cdev));
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}
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EXPORT_SYMBOL_GPL(devm_led_classdev_multicolor_unregister);
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MODULE_AUTHOR("Dan Murphy <dmurphy@ti.com>");
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MODULE_DESCRIPTION("Multicolor LED class interface");
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MODULE_LICENSE("GPL v2");

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