[PATCH v18 4/4] leds: multicolor: Introduce a multicolor class definition
From: Dan Murphy
Date: Tue Mar 24 2020 - 14:20:48 EST
Introduce a multicolor class that groups colored LEDs
within a LED node.
The multi color class groups monochrome LEDs and allows controlling two
aspects of the final combined color: hue and lightness. The former is
controlled via color_intensity files and the latter is controlled
via brightness file.
CC: Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Dan Murphy <dmurphy@xxxxxx>
---
A design alternative to having files that having multiple values written to a
single file is here:
https://lore.kernel.org/patchwork/patch/1186194/
.../ABI/testing/sysfs-class-led-multicolor | 51 ++++
Documentation/leds/index.rst | 1 +
Documentation/leds/leds-class-multicolor.rst | 110 +++++++++
drivers/leds/Kconfig | 10 +
drivers/leds/Makefile | 1 +
drivers/leds/led-class-multicolor.c | 224 ++++++++++++++++++
include/linux/led-class-multicolor.h | 124 ++++++++++
7 files changed, 521 insertions(+)
create mode 100644 Documentation/ABI/testing/sysfs-class-led-multicolor
create mode 100644 Documentation/leds/leds-class-multicolor.rst
create mode 100644 drivers/leds/led-class-multicolor.c
create mode 100644 include/linux/led-class-multicolor.h
diff --git a/Documentation/ABI/testing/sysfs-class-led-multicolor b/Documentation/ABI/testing/sysfs-class-led-multicolor
new file mode 100644
index 000000000000..a93772212c21
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-led-multicolor
@@ -0,0 +1,51 @@
+What: /sys/class/leds/<led>/brightness
+Date: March 2020
+KernelVersion: 5.8
+Contact: Dan Murphy <dmurphy@xxxxxx>
+Description: read/write
+ Writing to this file will update all LEDs within the group to a
+ calculated percentage of what each color LED intensity is set
+ to. The percentage is calculated for each grouped LED via the
+ equation below:
+
+ led_brightness = brightness * <color>_intensity/<color>_max_intensity
+
+ For additional details please refer to
+ Documentation/leds/leds-class-multicolor.rst.
+
+ The value of the color is from 0 to
+ /sys/class/leds/<led>/max_brightness.
+
+What: /sys/class/leds/<led>/color_index
+Date: March 2020
+KernelVersion: 5.8
+Contact: Dan Murphy <dmurphy@xxxxxx>
+Description: read
+ The color_index array, when read, will output the LED colors
+ by name as they are indexed in the color_intensity array.
+
+What: /sys/class/leds/<led>/num_color_leds
+Date: March 2020
+KernelVersion: 5.8
+Contact: Dan Murphy <dmurphy@xxxxxx>
+Description: read
+ The num_color_leds indicates the number of LEDs defined in the
+ color_intensity, color_max_intensity and color_index arrays.
+
+What: /sys/class/leds/<led>/color_max_intensity
+Date: March 2020
+KernelVersion: 5.8
+Contact: Dan Murphy <dmurphy@xxxxxx>
+Description: read
+ Maximum intensity level for the LED color within the array.
+ The max intensities for each color must be entered based on the
+ color_index array.
+
+What: /sys/class/leds/<led>/color_intensity
+Date: March 2020
+KernelVersion: 5.8
+Contact: Dan Murphy <dmurphy@xxxxxx>
+Description: read/write
+ Intensity level for the LED color within the array.
+ The intensities for each color must be entered based on the
+ color_index array.
diff --git a/Documentation/leds/index.rst b/Documentation/leds/index.rst
index 060f4e485897..bc70c6aa7138 100644
--- a/Documentation/leds/index.rst
+++ b/Documentation/leds/index.rst
@@ -9,6 +9,7 @@ LEDs
leds-class
leds-class-flash
+ leds-class-multicolor
ledtrig-oneshot
ledtrig-transient
ledtrig-usbport
diff --git a/Documentation/leds/leds-class-multicolor.rst b/Documentation/leds/leds-class-multicolor.rst
new file mode 100644
index 000000000000..902a281a44d4
--- /dev/null
+++ b/Documentation/leds/leds-class-multicolor.rst
@@ -0,0 +1,110 @@
+====================================
+Multi Color LED handling under Linux
+====================================
+
+Description
+===========
+The multi color class groups monochrome LEDs and allows controlling two
+aspects of the final combined color: hue and lightness. The former is
+controlled via the color_intensity array file and the latter is controlled
+via brightness file.
+
+For more details on hue and lightness notions please refer to
+https://en.wikipedia.org/wiki/CIECAM02.
+
+Note that intensity file only caches the written values and the actual
+change of hardware state occurs upon writing brightness file. This
+allows for changing many factors of the perceived color in a virtually
+unnoticeable way for the human observer.
+
+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 color_* files. The order of the
+colors are arbitrary the color_index file can be read to determine the color
+to index value.
+
+The color_index file is an array that contains the string list of the colors as
+they are defined in each color_* array file.
+
+The color_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.
+
+The color_max_intensity is an array that can be read to indicate each color LED
+maximum intensity value.
+
+The num_color_leds file returns the total number of color LEDs that are
+presented in each color_* array.
+
+Directory Layout Example
+========================
+root:/sys/class/leds/multicolor:grouped_leds# 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 color_index
+-rw-r--r-- 1 root root 4096 Oct 19 16:16 color_intensity
+-r--r--r-- 1 root root 4096 Oct 19 16:16 color_max_intensity
+-r--r--r-- 1 root root 4096 Oct 19 16:16 num_color_leds
+
+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 brightness.
+
+led_brightness = brightness * color_intensity/color_max_intensity
+
+It is important to note that for each LED within the cluster the
+color_max_intensity value should be the same. This will help maintain a
+consistent hue across brightness levels.
+
+Example:
+A user first writes the color LEDs intensity file with the brightness levels
+that for each LED that is necessary to achieve a blueish violet output from a
+RGB LED group.
+
+cat /sys/class/leds/multicolor:grouped_leds/color_index
+green blue red
+
+echo 43 226 138 > /sys/class/leds/multicolor:grouped_leds/color_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/multicolor:grouped_leds/max_brightness
+255
+echo 128 > /sys/class/leds/multicolor: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/multicolor:grouped_leds/max_brightness
+255
+
+echo 128 > /sys/class/leds/multicolor:grouped_leds/brightness
+
+cat /sys/class/leds/multicolor:grouped_leds/brightness
+128
diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
index d82f1dea3711..37dcdb06a29b 100644
--- a/drivers/leds/Kconfig
+++ b/drivers/leds/Kconfig
@@ -30,6 +30,16 @@ config LEDS_CLASS_FLASH
for the flash related features of a LED device. It can be built
as a module.
+config LEDS_CLASS_MULTI_COLOR
+ tristate "LED Mulit Color LED Class Support"
+ depends on LEDS_CLASS
+ help
+ This option enables the multicolor LED sysfs class in /sys/class/leds.
+ It wraps LED class and adds multicolor LED specific sysfs attributes
+ and kernel internal API to it. You'll need this to provide support
+ for multicolor LEDs that are grouped together. This class is not
+ intended for single color LEDs. It can be built as a module.
+
config LEDS_BRIGHTNESS_HW_CHANGED
bool "LED Class brightness_hw_changed attribute support"
depends on LEDS_CLASS
diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
index d7e1107753fb..310b5518783a 100644
--- a/drivers/leds/Makefile
+++ b/drivers/leds/Makefile
@@ -4,6 +4,7 @@
obj-$(CONFIG_NEW_LEDS) += led-core.o
obj-$(CONFIG_LEDS_CLASS) += led-class.o
obj-$(CONFIG_LEDS_CLASS_FLASH) += led-class-flash.o
+obj-$(CONFIG_LEDS_CLASS_MULTI_COLOR) += led-class-multicolor.o
obj-$(CONFIG_LEDS_TRIGGERS) += led-triggers.o
# LED Platform Drivers
diff --git a/drivers/leds/led-class-multicolor.c b/drivers/leds/led-class-multicolor.c
new file mode 100644
index 000000000000..0dbafede6e58
--- /dev/null
+++ b/drivers/leds/led-class-multicolor.c
@@ -0,0 +1,224 @@
+// SPDX-License-Identifier: GPL-2.0
+// LED Multi Color class interface
+// Copyright (C) 2019 Texas Instruments Incorporated - http://www.ti.com/
+
+#include <linux/device.h>
+#include <linux/init.h>
+#include <linux/led-class-multicolor.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+
+#include "leds.h"
+
+int led_mc_calc_color_components(struct led_classdev_mc *mcled_cdev,
+ enum led_brightness brightness)
+{
+ int i;
+
+ for (i = 0; i < mcled_cdev->num_colors; i++)
+ mcled_cdev->color_brightness[i] = brightness *
+ mcled_cdev->color_led_intensity[i] /
+ mcled_cdev->color_led_max_intensity[i];
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(led_mc_calc_color_components);
+
+static ssize_t color_intensity_store(struct device *dev,
+ struct device_attribute *intensity_attr,
+ const char *buf, size_t size)
+{
+ struct led_classdev *led_cdev = dev_get_drvdata(dev);
+ struct led_classdev_mc *priv = lcdev_to_mccdev(led_cdev);
+ int nrchars, offset = 0;
+ int intensity_value[LED_COLOR_ID_MAX];
+ int i;
+ ssize_t ret;
+
+ mutex_lock(&led_cdev->led_access);
+
+ for (i = 0; i < priv->num_colors; i++) {
+ ret = sscanf(buf + offset, "%i%n",
+ &intensity_value[i], &nrchars);
+ if (ret != 1) {
+ dev_err(led_cdev->dev,
+ "Incorrect number of LEDs expected %i values intensity was not applied\n",
+ priv->num_colors);
+ goto err_out;
+ }
+ offset += nrchars;
+ }
+
+ memcpy(&priv->color_led_intensity, intensity_value,
+ sizeof(intensity_value));
+err_out:
+ ret = size;
+ mutex_unlock(&led_cdev->led_access);
+ return ret;
+}
+
+static ssize_t color_intensity_show(struct device *dev,
+ struct device_attribute *intensity_attr,
+ char *buf)
+{
+ struct led_classdev *led_cdev = dev_get_drvdata(dev);
+ struct led_classdev_mc *priv = lcdev_to_mccdev(led_cdev);
+ int len = 0;
+ int i;
+
+ for (i = 0; i < priv->num_colors; i++)
+ len += sprintf(buf + len, "%d ", priv->color_led_intensity[i]);
+
+ len += sprintf(buf + len, "%s", "\n");
+
+ return len;
+}
+static DEVICE_ATTR_RW(color_intensity);
+
+static ssize_t color_index_show(struct device *dev,
+ struct device_attribute *color_index_attr,
+ char *buf)
+{
+ struct led_classdev *led_cdev = dev_get_drvdata(dev);
+ struct led_classdev_mc *priv = lcdev_to_mccdev(led_cdev);
+ int len = 0;
+ int i;
+
+ for (i = 0; i < priv->num_colors; i++)
+ len += sprintf(buf + len, "%s ", priv->color_index[i]);
+
+ len += sprintf(buf + len, "%s", "\n");
+
+ return len;
+}
+static DEVICE_ATTR_RO(color_index);
+
+static ssize_t color_max_intensity_show(struct device *dev,
+ struct device_attribute *max_intensity_attr,
+ char *buf)
+{
+ struct led_classdev *led_cdev = dev_get_drvdata(dev);
+ struct led_classdev_mc *priv = lcdev_to_mccdev(led_cdev);
+ int len = 0;
+ int i;
+
+ for (i = 0; i < priv->num_colors; i++)
+ len += sprintf(buf + len, "%d ",
+ priv->color_led_max_intensity[i]);
+
+ len += sprintf(buf + len, "%s", "\n");
+
+ return len;
+}
+static DEVICE_ATTR_RO(color_max_intensity);
+
+static ssize_t num_color_leds_show(struct device *dev,
+ struct device_attribute *max_intensity_attr,
+ char *buf)
+{
+ struct led_classdev *led_cdev = dev_get_drvdata(dev);
+ struct led_classdev_mc *priv = lcdev_to_mccdev(led_cdev);
+
+ return sprintf(buf, "%d\n", priv->num_colors);
+}
+static DEVICE_ATTR_RO(num_color_leds);
+
+static struct attribute *led_multicolor_attrs[] = {
+ &dev_attr_color_intensity.attr,
+ &dev_attr_color_index.attr,
+ &dev_attr_color_max_intensity.attr,
+ &dev_attr_num_color_leds.attr,
+ NULL,
+};
+ATTRIBUTE_GROUPS(led_multicolor);
+
+int led_classdev_multicolor_register_ext(struct device *parent,
+ struct led_classdev_mc *mcled_cdev,
+ struct led_init_data *init_data)
+{
+ struct led_classdev *led_cdev;
+ int i;
+
+ if (!mcled_cdev)
+ return -EINVAL;
+
+ if (!mcled_cdev->num_colors)
+ return -EINVAL;
+
+ led_cdev = &mcled_cdev->led_cdev;
+
+ mcled_cdev->led_cdev.groups = led_multicolor_groups;
+
+ for (i = 0; i <= mcled_cdev->num_colors; i++)
+ if (!mcled_cdev->color_led_max_intensity[i])
+ mcled_cdev->color_led_max_intensity[i] = LED_FULL;
+
+ return led_classdev_register_ext(parent, &mcled_cdev->led_cdev,
+ init_data);
+}
+EXPORT_SYMBOL_GPL(led_classdev_multicolor_register_ext);
+
+void led_classdev_multicolor_unregister(struct led_classdev_mc *mcled_cdev)
+{
+ if (!mcled_cdev)
+ return;
+
+ led_classdev_unregister(&mcled_cdev->led_cdev);
+}
+EXPORT_SYMBOL_GPL(led_classdev_multicolor_unregister);
+
+static void devm_led_classdev_multicolor_release(struct device *dev, void *res)
+{
+ led_classdev_multicolor_unregister(*(struct led_classdev_mc **)res);
+}
+
+int devm_led_classdev_multicolor_register_ext(struct device *parent,
+ struct led_classdev_mc *mcled_cdev,
+ struct led_init_data *init_data)
+{
+ struct led_classdev_mc **dr;
+ int ret;
+
+ dr = devres_alloc(devm_led_classdev_multicolor_release,
+ sizeof(*dr), GFP_KERNEL);
+ if (!dr)
+ return -ENOMEM;
+
+ ret = led_classdev_multicolor_register_ext(parent, mcled_cdev,
+ init_data);
+ if (ret) {
+ devres_free(dr);
+ return ret;
+ }
+
+ *dr = mcled_cdev;
+ devres_add(parent, dr);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(devm_led_classdev_multicolor_register_ext);
+
+static int devm_led_classdev_multicolor_match(struct device *dev,
+ void *res, void *data)
+{
+ struct led_classdev_mc **p = res;
+
+ if (WARN_ON(!p || !*p))
+ return 0;
+
+ return *p == data;
+}
+
+void devm_led_classdev_multicolor_unregister(struct device *dev,
+ struct led_classdev_mc *mcled_cdev)
+{
+ WARN_ON(devres_release(dev,
+ devm_led_classdev_multicolor_release,
+ devm_led_classdev_multicolor_match, mcled_cdev));
+}
+EXPORT_SYMBOL_GPL(devm_led_classdev_multicolor_unregister);
+
+MODULE_AUTHOR("Dan Murphy <dmurphy@xxxxxx>");
+MODULE_DESCRIPTION("Multi Color LED class interface");
+MODULE_LICENSE("GPL v2");
diff --git a/include/linux/led-class-multicolor.h b/include/linux/led-class-multicolor.h
new file mode 100644
index 000000000000..bfbde2e98340
--- /dev/null
+++ b/include/linux/led-class-multicolor.h
@@ -0,0 +1,124 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* LED Multicolor class interface
+ * Copyright (C) 2019 Texas Instruments Incorporated - http://www.ti.com/
+ */
+
+#ifndef __LINUX_MULTICOLOR_LEDS_H_INCLUDED
+#define __LINUX_MULTICOLOR_LEDS_H_INCLUDED
+
+#include <linux/leds.h>
+#include <dt-bindings/leds/common.h>
+
+struct led_classdev_mc {
+ /* led class device */
+ struct led_classdev led_cdev;
+
+ struct device_attribute color_max_intensity_attr;
+ struct device_attribute color_intensity_attr;
+ struct device_attribute color_index_attr;
+
+ int color_brightness[LED_COLOR_ID_MAX];
+
+ int color_led_intensity[LED_COLOR_ID_MAX];
+ int color_led_max_intensity[LED_COLOR_ID_MAX];
+ const char *color_index[LED_COLOR_ID_MAX];
+
+ int num_colors;
+};
+
+static inline struct led_classdev_mc *lcdev_to_mccdev(
+ struct led_classdev *led_cdev)
+{
+ return container_of(led_cdev, struct led_classdev_mc, led_cdev);
+}
+
+#if IS_ENABLED(CONFIG_LEDS_CLASS_MULTI_COLOR)
+/**
+ * led_classdev_multicolor_register_ext - register a new object of led_classdev
+ * class with support for multicolor LEDs
+ * @parent: the multicolor LED to register
+ * @mcled_cdev: the led_classdev_mc structure for this device
+ * @init_data: the LED class Multi color device initialization data
+ *
+ * Returns: 0 on success or negative error value on failure
+ */
+int led_classdev_multicolor_register_ext(struct device *parent,
+ struct led_classdev_mc *mcled_cdev,
+ struct led_init_data *init_data);
+
+static inline int led_classdev_multicolor_register(struct device *parent,
+ struct led_classdev_mc *mcled_cdev)
+{
+ return led_classdev_multicolor_register_ext(parent, mcled_cdev, NULL);
+}
+
+/**
+ * led_classdev_multicolor_unregister - unregisters an object of led_classdev
+ * class with support for multicolor LEDs
+ * @mcled_cdev: the multicolor LED to unregister
+ *
+ * Unregister a previously registered via led_classdev_multicolor_register
+ * object
+ */
+void led_classdev_multicolor_unregister(struct led_classdev_mc *mcled_cdev);
+
+/* Calculate brightness for the monochrome LED cluster */
+int led_mc_calc_color_components(struct led_classdev_mc *mcled_cdev,
+ enum led_brightness brightness);
+
+int devm_led_classdev_multicolor_register_ext(struct device *parent,
+ struct led_classdev_mc *mcled_cdev,
+ struct led_init_data *init_data);
+
+static inline int devm_led_classdev_multicolor_register(struct device *parent,
+ struct led_classdev_mc *mcled_cdev)
+{
+ return devm_led_classdev_multicolor_register_ext(parent, mcled_cdev,
+ NULL);
+}
+
+void devm_led_classdev_multicolor_unregister(struct device *parent,
+ struct led_classdev_mc *mcled_cdev);
+#else
+
+static inline int led_classdev_multicolor_register_ext(struct device *parent,
+ struct led_classdev_mc *mcled_cdev,
+ struct led_init_data *init_data)
+{
+ return -EINVAL;
+}
+
+static inline int led_classdev_multicolor_register(struct device *parent,
+ struct led_classdev_mc *mcled_cdev)
+{
+ return led_classdev_multicolor_register_ext(parent, mcled_cdev, NULL);
+}
+
+static inline void led_classdev_multicolor_unregister(struct led_classdev_mc *mcled_cdev) {};
+static inline int led_mc_calc_color_components(struct led_classdev_mc *mcled_cdev,
+ enum led_brightness brightness,
+ struct led_mc_color_conversion color_components[])
+{
+ return -EINVAL;
+}
+
+static inline int devm_led_classdev_multicolor_register_ext(struct device *parent,
+ struct led_classdev_mc *mcled_cdev,
+ struct led_init_data *init_data)
+{
+ return -EINVAL;
+}
+
+static inline int devm_led_classdev_multicolor_register(struct device *parent,
+ struct led_classdev_mc *mcled_cdev)
+{
+ return devm_led_classdev_multicolor_register_ext(parent, mcled_cdev,
+ NULL);
+}
+
+static inline void devm_led_classdev_multicolor_unregister(struct device *parent,
+ struct led_classdev_mc *mcled_cdev)
+{};
+
+#endif /* IS_ENABLED(CONFIG_LEDS_CLASS_MULTI_COLOR) */
+#endif /* __LINUX_MULTICOLOR_LEDS_H_INCLUDED */
--
2.25.1