[PATCH v17 04/19] leds: multicolor: Introduce a multicolor class definition

[Dan Murphy]

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@xxxxxx>
---
 .../ABI/testing/sysfs-class-led-multicolor    |  36 +++
 Documentation/leds/index.rst                  |   1 +
 Documentation/leds/leds-class-multicolor.rst  | 100 +++++++
 drivers/leds/Kconfig                          |  10 +
 drivers/leds/Makefile                         |   1 +
 drivers/leds/led-class-multicolor.c           | 272 ++++++++++++++++++
 include/linux/led-class-multicolor.h          | 139 +++++++++
 7 files changed, 559 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..3d1f9d726c70
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-led-multicolor
@@ -0,0 +1,36 @@
+What:		/sys/class/leds/<led>/brightness
+Date:		Sept 2019
+KernelVersion:	5.5
+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>/colors/<color>_intensity
+Date:		Sept 2019
+KernelVersion:	5.5
+Contact:	Dan Murphy <dmurphy@xxxxxx>
+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@xxxxxx>
+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..8f7b62dd856e
--- /dev/null
+++ b/Documentation/leds/leds-class-multicolor.rst
@@ -0,0 +1,100 @@
+====================================
+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/multicolor: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
+
+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:
+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..62669c9435c2
--- /dev/null
+++ b/drivers/leds/led-class-multicolor.c
@@ -0,0 +1,272 @@
+// 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_color_components(struct led_classdev_mc *mcled_cdev,
+				 enum led_brightness brightness,
+			      struct led_mc_color_conversion color_components[])
+{
+	struct led_mc_color_entry *priv;
+	int i = 0;
+
+	list_for_each_entry(priv, &mcled_cdev->color_list, list) {
+		color_components[i].color_id = priv->led_color_id;
+		color_components[i].brightness = brightness *
+					  priv->intensity / priv->max_intensity;
+		i++;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(led_mc_calc_color_components);
+
+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_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..94ec5d1ff154
--- /dev/null
+++ b/include/linux/led-class-multicolor.h
@@ -0,0 +1,139 @@
+/* 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;
+};
+
+static inline struct led_classdev_mc *lcdev_to_mccdev(
+						struct led_classdev *lcdev)
+{
+	return container_of(lcdev, 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,
+			     struct led_mc_color_conversion color_components[]);
+
+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 */
-- 
2.22.0.214.g8dca754b1e