[PATCH v11 04/16] leds: multicolor: Introduce a multicolor class definition

Dan Murphy
2019-10-08T20:48:56Z

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.

Signed-off-by: Dan Murphy <dmurphy@ti.com>
---
.../ABI/testing/sysfs-class-led-multicolor | 35 +++
Documentation/leds/index.rst | 1 +
Documentation/leds/leds-class-multicolor.rst | 96 +++++++
drivers/leds/Kconfig | 10 +
drivers/leds/Makefile | 1 +
drivers/leds/led-class-multicolor.c | 271 ++++++++++++++++++
include/linux/led-class-multicolor.h | 143 +++++++++
7 files changed, 557 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..65cb43de26e6
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-led-multicolor
@@ -0,0 +1,35 @@
+What: /sys/class/leds/<led>/brightness
+Date: Sept 2019
+KernelVersion: 5.5
+Contact: Dan Murphy <dmurphy@ti.com>
+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 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>/colors/<color>_intensity
+Date: Sept 2019
+KernelVersion: 5.5
+Contact: Dan Murphy <dmurphy@ti.com>
+Description: read/write
+ The <color>_intensity file is created based on the color
+ defined by the registrar of the class.
+ There is one file per color presented.
+
+ The value of the color is from 0 to
+ /sys/class/leds/<led>/colors/<color>_max_intensity.
+
+What: /sys/class/leds/<led>/colors/<color>_max_intensity
+Date: Sept 2019
+KernelVersion: 5.5
+Contact: Dan Murphy <dmurphy@ti.com>
+Description: read only
+ Maximum intensity level for the LED color.
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..7a695a29377e
--- /dev/null
+++ b/Documentation/leds/leds-class-multicolor.rst
@@ -0,0 +1,96 @@
+====================================
+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 <color>_intensity files 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 files only cache the written value 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 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.rst within this
+documentation directory.
+
+Each colored LED will have two files created under the colors directory
+<color>_intensity and <color>_max_intensity. These files will contain
+one of LED_COLOR_ID_* definitions from the header
+include/dt-bindings/leds/common.h.
+
+Directory Layout Example
+========================
+root:/sys/class/leds/rgb:grouped_leds# ls -lR colors/
+-rw-r--r-- 1 root root 4096 Jul 7 03:10 blue_intensity
+-r--r--r-- 1 root root 4096 Jul 7 03:10 blue_max_intensity
+-rw-r--r-- 1 root root 4096 Jul 7 03:10 green_intensity
+-r--r--r-- 1 root root 4096 Jul 7 03:10 green_max_intensity
+-rw-r--r-- 1 root root 4096 Jul 7 03:10 red_intensity
+-r--r--r-- 1 root root 4096 Jul 7 03:10 red_max_intensity
+
+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
+
+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 necessary to achieve a blueish violet output from the RGB LED group.
+
+echo 138 > /sys/class/leds/rgb:grouped_leds/red_intensity
+echo 43 > /sys/class/leds/rgb:grouped_leds/green_intensity
+echo 226 > /sys/class/leds/rgb:grouped_leds/blue_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/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/brightness
+128
diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
index 4b68520ac251..a1ede89afc9e 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 2da39e896ce8..841038cfe35b 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..89f4bc9e057c
--- /dev/null
+++ b/drivers/leds/led-class-multicolor.c
@@ -0,0 +1,271 @@
+// 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"
+
+#define INTENSITY_NAME "_intensity"
+#define MAX_INTENSITY_NAME "_max_intensity"
+
+int led_mc_calc_brightness(struct led_classdev_mc *mcled_cdev,
+ enum led_brightness brightness,
+ struct led_mc_color_conversion color_component[])
+{
+ struct led_mc_color_entry *priv;
+ int i = 0;
+
+ list_for_each_entry(priv, &mcled_cdev->color_list, list) {
+ color_component[i].color_id = priv->led_color_id;
+ color_component[i].brightness = brightness *
+ priv->intensity / priv->max_intensity;
+ i++;
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(led_mc_calc_brightness);
+
+static ssize_t intensity_store(struct device *dev,
+ struct device_attribute *intensity_attr,
+ const char *buf, size_t size)
+{
+ struct led_mc_color_entry *priv = container_of(intensity_attr,
+ struct led_mc_color_entry,
+ intensity_attr);
+ struct led_classdev *led_cdev = priv->mcled_cdev->led_cdev;
+ unsigned long value;
+ ssize_t ret;
+
+ mutex_lock(&led_cdev->led_access);
+
+ ret = kstrtoul(buf, 10, &value);
+ if (ret)
+ goto unlock;
+
+ if (value > priv->max_intensity) {
+ ret = -EINVAL;
+ goto unlock;
+ }
+
+ priv->intensity = value;
+ ret = size;
+
+unlock:
+ mutex_unlock(&led_cdev->led_access);
+ return ret;
+}
+
+static ssize_t intensity_show(struct device *dev,
+ struct device_attribute *intensity_attr,
+ char *buf)
+{
+ struct led_mc_color_entry *priv = container_of(intensity_attr,
+ struct led_mc_color_entry,
+ intensity_attr);
+
+ return sprintf(buf, "%d\n", priv->intensity);
+}
+
+static ssize_t max_intensity_show(struct device *dev,
+ struct device_attribute *max_intensity_attr,
+ char *buf)
+{
+ struct led_mc_color_entry *priv = container_of(max_intensity_attr,
+ struct led_mc_color_entry,
+ max_intensity_attr);
+
+ return sprintf(buf, "%d\n", priv->max_intensity);
+}
+
+static struct attribute *led_color_attrs[] = {
+ NULL,
+};
+
+static struct attribute_group led_color_group = {
+ .name = "colors",
+ .attrs = led_color_attrs,
+};
+
+static int led_multicolor_init_color(struct led_classdev_mc *mcled_cdev,
+ int color_id)
+{
+ struct led_classdev *led_cdev = mcled_cdev->led_cdev;
+ struct led_mc_color_entry *mc_priv;
+ char *intensity_file_name;
+ char *max_intensity_file_name;
+ size_t len;
+ int ret;
+
+ mc_priv = devm_kzalloc(led_cdev->dev, sizeof(*mc_priv), GFP_KERNEL);
+ if (!mc_priv)
+ return -ENOMEM;
+
+ mc_priv->led_color_id = color_id;
+ mc_priv->mcled_cdev = mcled_cdev;
+
+ sysfs_attr_init(&mc_priv->intensity_attr.attr);
+ len = strlen(led_colors[color_id]) + strlen(INTENSITY_NAME) + 1;
+ intensity_file_name = kzalloc(len, GFP_KERNEL);
+ if (!intensity_file_name)
+ return -ENOMEM;
+
+ snprintf(intensity_file_name, len, "%s%s",
+ led_colors[color_id], INTENSITY_NAME);
+ mc_priv->intensity_attr.attr.name = intensity_file_name;
+ mc_priv->intensity_attr.attr.mode = 0644;
+ mc_priv->intensity_attr.store = intensity_store;
+ mc_priv->intensity_attr.show = intensity_show;
+ ret = sysfs_add_file_to_group(&led_cdev->dev->kobj,
+ &mc_priv->intensity_attr.attr,
+ led_color_group.name);
+ if (ret)
+ goto intensity_err_out;
+
+ sysfs_attr_init(&mc_priv->max_intensity_attr.attr);
+ len = strlen(led_colors[color_id]) + strlen(MAX_INTENSITY_NAME) + 1;
+ max_intensity_file_name = kzalloc(len, GFP_KERNEL);
+ if (!max_intensity_file_name) {
+ ret = -ENOMEM;
+ goto intensity_err_out;
+ }
+
+ snprintf(max_intensity_file_name, len, "%s%s",
+ led_colors[color_id], MAX_INTENSITY_NAME);
+ mc_priv->max_intensity_attr.attr.name = max_intensity_file_name;
+ mc_priv->max_intensity_attr.attr.mode = 0444;
+ mc_priv->max_intensity_attr.show = max_intensity_show;
+ ret = sysfs_add_file_to_group(&led_cdev->dev->kobj,
+ &mc_priv->max_intensity_attr.attr,
+ led_color_group.name);
+ if (ret)
+ goto max_intensity_err_out;
+
+ mc_priv->max_intensity = LED_FULL;
+ list_add_tail(&mc_priv->list, &mcled_cdev->color_list);
+
+max_intensity_err_out:
+ kfree(max_intensity_file_name);
+intensity_err_out:
+ kfree(intensity_file_name);
+ return ret;
+}
+
+static int led_multicolor_init_color_dir(struct led_classdev_mc *mcled_cdev)
+{
+ struct led_classdev *led_cdev = mcled_cdev->led_cdev;
+ int ret;
+ int i;
+
+ ret = sysfs_create_group(&led_cdev->dev->kobj, &led_color_group);
+ if (ret)
+ return ret;
+
+ for (i = 0; i < LED_COLOR_ID_MAX; i++) {
+ if (test_bit(i, &mcled_cdev->available_colors)) {
+ ret = led_multicolor_init_color(mcled_cdev, i);
+ if (ret)
+ break;
+
+ }
+ }
+
+ return ret;
+}
+
+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 ret;
+
+ if (!mcled_cdev)
+ return -EINVAL;
+
+ led_cdev = mcled_cdev->led_cdev;
+ INIT_LIST_HEAD(&mcled_cdev->color_list);
+
+ /* Register led class device */
+ ret = led_classdev_register_ext(parent, led_cdev, init_data);
+ if (ret)
+ return ret;
+
+ return led_multicolor_init_color_dir(mcled_cdev);
+}
+EXPORT_SYMBOL_GPL(led_classdev_multicolor_register_ext);
+
+void led_classdev_multicolor_unregister(struct led_classdev_mc *mcled_cdev)
+{
+ struct led_mc_color_entry *priv, *next;
+
+ if (!mcled_cdev)
+ return;
+
+ list_for_each_entry_safe(priv, next, &mcled_cdev->color_list, list)
+ list_del(&priv->list);
+
+ sysfs_remove_group(&mcled_cdev->led_cdev->dev->kobj, &led_color_group);
+ 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(parent, mcled_cdev);
+ 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@ti.com>");
+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..5d0cdca32223
--- /dev/null
+++ b/include/linux/led-class-multicolor.h
@@ -0,0 +1,143 @@
+/* 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;
+
+struct led_mc_color_conversion {
+ int color_id;
+ int brightness;
+ int output_num;
+};
+
+struct led_mc_color_entry {
+ struct led_classdev_mc *mcled_cdev;
+
+ struct device_attribute max_intensity_attr;
+ struct device_attribute intensity_attr;
+
+ enum led_brightness max_intensity;
+ enum led_brightness intensity;
+
+ struct list_head list;
+
+ int led_color_id;
+};
+
+struct led_classdev_mc {
+ /* led class device */
+ struct led_classdev *led_cdev;
+ struct list_head color_list;
+
+ unsigned long available_colors;
+ int num_leds;
+};
+#ifdef CONFIG_LEDS_CLASS_MULTI_COLOR
+static inline struct led_classdev_mc *lcdev_to_mccdev(
+ struct led_classdev *lcdev)
+{
+ return container_of(lcdev, struct led_classdev_mc, led_cdev);
+}
+
+/**
+ * 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_brightness(struct led_classdev_mc *mcled_cdev,
+ enum led_brightness brightness,
+ struct led_mc_color_conversion color_component[]);
+
+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 struct led_classdev_mc *lcdev_to_mccdev(
+ struct led_classdev *lcdev)
+{
+ return NULL;
+}
+
+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 -EINVAL;
+}
+
+static inline void led_classdev_multicolor_unregister(struct led_classdev_mc *mcled_cdev) {}
+
+static inline int led_mc_calc_brightness(struct led_classdev_mc *mcled_cdev,
+ enum led_brightness brightness,
+ struct led_mc_color_conversion color_component[])
+{
+ 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 -EINVAL;
+}
+
+static inline void devm_led_classdev_multicolor_unregister(struct device *parent,
+ struct led_classdev_mc *mcled_cdev) {}
+
+#endif /* CONFIG_LEDS_CLASS_MULTI_COLOR */
+#endif /* __LINUX_MULTICOLOR_LEDS_H_INCLUDED */
--
2.22.0.214.g8dca754b1e