leds: core: add generic support for RGB Color LED's

Add generic support for RGB Color LED's.

Basic idea is to use enum led_brightness also for the hue and saturation color components.This allows to implement the color extension w/o changes to struct led_classdev.

Select LEDS_RGB to enable building drivers using the RGB extension.

Flag LED_SET_HUE_SAT allows to specify that hue / saturation should be overridden even if the provided values are zero.

Some examples for writing values to /sys/class/leds/<xx>/brightness:
(now also hex notation can be used)

255 -> set full brightness and keep existing color if set
0 -> switch LED off but keep existing color so that it can be restored
if the LED is switched on again later
0x1000000 -> switch LED off and set also hue and saturation to 0 0x00ffff -> set full brightness, full saturation and set hue to 0 (red)

Signed-off-by Heiner Kallweit <[email protected]>

Hi Heiner,

I don't see [PATCH v4 2/4]. Have you sent it?

Quoted 15 lines

Add generic support for RGB Color LED's.

Basic idea is to use enum led_brightness also for the hue and saturation color components.This allows to implement the color extension w/o changes to struct led_classdev.

Select LEDS_RGB to enable building drivers using the RGB extension.

Flag LED_SET_HUE_SAT allows to specify that hue / saturation should be overridden even if the provided values are zero.

Some examples for writing values to /sys/class/leds/<xx>/brightness:
(now also hex notation can be used)

Quoted 7 lines

255 -> set full brightness and keep existing color if set
0 -> switch LED off but keep existing color so that it can be restored
if the LED is switched on again later
0x1000000 -> switch LED off and set also hue and saturation to 0 0x00ffff -> set full brightness, full saturation and set hue to 0 (red)

Signed-off-by Heiner Kallweit <[email protected]>

[...]

--
Best regards,
Jacek Anaszewski

Quoted 4 lines · Jacek Anaszewski

Hi Heiner,

I don't see [PATCH v4 2/4]. Have you sent it?

Patch 2 of series wasn't changed since v3. Therefore I didn't resend it. Do you prefer to always get the full series even if particular patches weren't changed?

Quoted 23 lines · Heiner Kallweit

Quoted 22 lines

Add generic support for RGB Color LED's.

Basic idea is to use enum led_brightness also for the hue and saturation color components.This allows to implement the color extension w/o changes to struct led_classdev.

Select LEDS_RGB to enable building drivers using the RGB extension.

Flag LED_SET_HUE_SAT allows to specify that hue / saturation should be overridden even if the provided values are zero.

Some examples for writing values to /sys/class/leds/<xx>/brightness:
(now also hex notation can be used)

255 -> set full brightness and keep existing color if set
0 -> switch LED off but keep existing color so that it can be restored
if the LED is switched on again later
0x1000000 -> switch LED off and set also hue and saturation to 0 0x00ffff -> set full brightness, full saturation and set hue to 0 (red)

Signed-off-by Heiner Kallweit <[email protected]>

Quoted 9 lines

Quoted 4 lines · Jacek Anaszewski

Hi Heiner,

I don't see [PATCH v4 2/4]. Have you sent it?

Patch 2 of series wasn't changed since v3. Therefore I didn't resend it. Do you prefer to always get the full series even if particular patches weren't changed?

You set the total number of patches in the patch set to 4, so not having one of the patches in the middle looks odd. Yes, for better readability and consistency I prefer to include all patches to the set even if there are no difference in comparison to the previous version.

Of course, if only one of e.g. five patches is to be modified then sending the only one suffices, let's just use common sense.

Note, that I don't expect that you sent the missing one now.

Quoted 23 lines

Quoted 23 lines · Heiner Kallweit

Quoted 22 lines

Add generic support for RGB Color LED's.

Basic idea is to use enum led_brightness also for the hue and saturation color components.This allows to implement the color extension w/o changes to struct led_classdev.

Select LEDS_RGB to enable building drivers using the RGB extension.

Flag LED_SET_HUE_SAT allows to specify that hue / saturation should be overridden even if the provided values are zero.

Some examples for writing values to /sys/class/leds/<xx>/brightness:
(now also hex notation can be used)

255 -> set full brightness and keep existing color if set
0 -> switch LED off but keep existing color so that it can be restored
if the LED is switched on again later
0x1000000 -> switch LED off and set also hue and saturation to 0 0x00ffff -> set full brightness, full saturation and set hue to 0 (red)

Signed-off-by Heiner Kallweit <[email protected]>

Add generic support for RGB Color LED's.

Basic idea is to use enum led_brightness also for the hue and saturation color components.This allows to implement the color extension w/o changes to struct led_classdev.

Select LEDS_RGB to enable building drivers using the RGB extension.

Flag LED_SET_HUE_SAT allows to specify that hue / saturation should be overridden even if the provided values are zero.

Some examples for writing values to /sys/class/leds/<xx>/brightness:
(now also hex notation can be used)

255 -> set full brightness and keep existing color if set
0 -> switch LED off but keep existing color so that it can be restored
if the LED is switched on again later
0x1000000 -> switch LED off and set also hue and saturation to 0 0x00ffff -> set full brightness, full saturation and set hue to 0 (red)

Signed-off-by Heiner Kallweit <[email protected]>

---
v2:
- move extension-specific code into a separate source file and introduce config symbol LEDS_HSV for it
- create separate patch for the extension to sysfs
- use variable name led_cdev as in the rest if the core
- rename to_hsv to led_validate_brightness
- rename LED_BRIGHTNESS_SET_COLOR to LED_SET_HSV
- introduce helper is_off for checking whether V part
of a HSV value is zero
v3:
- change Kconfig to use depend instead of select, add help message, and change config symbol to LEDS_COLOR
- change LED core object file name in Makefile
- rename flag LED_SET_HSV to LED_SET_COLOR
- rename is_off to led_is_off
- rename led_validate-brightness to led_confine_brightness
- rename variable in led_confine_brightness
- add dummy enum led_brightness value to enforce 32bit enum
- rename led-hsv-core.c to led-color-core.c
- move check of provided brightness value to led_confine_brightness v4:
- change config symbol name to LEDS_RGB
- change name of new file to led-rgb-core.c
- factor out part of led_confine_brightness
- change led_is_off to __is_set_brightness
- in led_set_software_blink pass led_cdev->max_brightness instead of LED_FULL
- rename LED_SET_COLOR to LED_SET_HUE_SAT

---
  drivers/leds/Kconfig        | 11 +++++++++++
  drivers/leds/Makefile       |  4 +++-
  drivers/leds/led-class.c    |  2 +-
  drivers/leds/led-core.c     | 16 +++++++++-------
  drivers/leds/led-rgb-core.c | 42 ++++++++++++++++++++++++++++++++++++++++++
  drivers/leds/leds.h         | 17 +++++++++++++++++
  include/linux/leds.h        |  9 +++++++++
  7 files changed, 92 insertions(+), 9 deletions(-)

create mode 100644 drivers/leds/led-rgb-core.c

drivers/leds/Kconfig +0 -0

index 7f940c2..4a4f1b2 100644

drivers/leds/Kconfig +7 -0

+	 Sysfs attribute brightness is interpreted as a HSV color value.
+	 For details see Documentation/leds/leds-class.txt.
+
  config LEDS_CLASS
  	tristate "LED Class Support"
  	help

@@ -29,6 +36,10 @@ config LEDS_CLASS_FLASH
  	  for the flash related features of a LED device. It can be built
  	  as a module.
 
+if LEDS_RGB
+comment "RGB Color LED drivers"
+endif # LEDS_RGB
+
  comment "LED drivers"
 
  config LEDS_88PM860X

drivers/leds/Makefile +3 -1

index e9d5309..cc3676f 100644
@@ -1,6 +1,8 @@
 
  # LED Core
-obj-$(CONFIG_NEW_LEDS)			+= led-core.o
+obj-$(CONFIG_NEW_LEDS)			+= led-core-objs.o
+led-core-objs-y				:= led-core.o
+led-core-objs-$(CONFIG_LEDS_RGB)	+= led-rgb-core.o
  obj-$(CONFIG_LEDS_CLASS)		+= led-class.o
  obj-$(CONFIG_LEDS_CLASS_FLASH)		+= led-class-flash.o
  obj-$(CONFIG_LEDS_TRIGGERS)		+= led-triggers.o

drivers/leds/led-class.c +1 -1

index aa84e5b..007a5b3 100644
@@ -53,7 +53,7 @@ static ssize_t brightness_store(struct device *dev,
  	if (ret)
  		goto unlock;
 
-	if (state == LED_OFF)
+	if (!__is_brightness_set(state))
  		led_trigger_remove(led_cdev);
  	led_set_brightness(led_cdev, state);
 

drivers/leds/led-core.c +9 -7

index 3495d5d..e75b0c8 100644
@@ -62,7 +62,7 @@ static void led_timer_function(unsigned long data)
  	}
 
  	brightness = led_get_brightness(led_cdev);
-	if (!brightness) {
+	if (!__is_brightness_set(brightness)) {
  		/* Time to switch the LED on. */
  		brightness = led_cdev->blink_brightness;
  		delay = led_cdev->blink_delay_on;

@@ -133,8 +133,9 @@ static void led_set_software_blink(struct led_classdev *led_cdev,
  	if (current_brightness)
  		led_cdev->blink_brightness = current_brightness;
  	if (!led_cdev->blink_brightness)
-		led_cdev->blink_brightness = led_cdev->max_brightness;
-
+		led_cdev->blink_brightness =
+				led_confine_brightness(led_cdev,
+						led_cdev->max_brightness);
  	led_cdev->blink_delay_on = delay_on;
  	led_cdev->blink_delay_off = delay_off;
 

@@ -235,12 +236,13 @@ void led_set_brightness(struct led_classdev *led_cdev,
  		 * work queue task to avoid problems in case we are called
  		 * from hard irq context.
  		 */
-		if (brightness == LED_OFF) {
+		if (!__is_brightness_set(brightness)) {
  			led_cdev->flags |= LED_BLINK_DISABLE;
  			schedule_work(&led_cdev->set_brightness_work);
  		} else {
  			led_cdev->flags |= LED_BLINK_BRIGHTNESS_CHANGE;
-			led_cdev->blink_brightness = brightness;
+			led_cdev->blink_brightness =
+				led_confine_brightness(led_cdev, brightness);
  		}
  		return;
  	}

@@ -265,7 +267,7 @@ EXPORT_SYMBOL_GPL(led_set_brightness_nopm);
  void led_set_brightness_nosleep(struct led_classdev *led_cdev,
  				enum led_brightness value)
  {
-	led_cdev->brightness = min(value, led_cdev->max_brightness);
+	led_cdev->brightness = led_confine_brightness(led_cdev, value);
 
  	if (led_cdev->flags & LED_SUSPENDED)
  		return;

@@ -280,7 +282,7 @@ int led_set_brightness_sync(struct led_classdev *led_cdev,
  	if (led_cdev->blink_delay_on || led_cdev->blink_delay_off)
  		return -EBUSY;
 
-	led_cdev->brightness = min(value, led_cdev->max_brightness);
+	led_cdev->brightness = led_confine_brightness(led_cdev, value);
 
  	if (led_cdev->flags & LED_SUSPENDED)
  		return 0;

drivers/leds/led-rgb-core.c new file +6 -0

new file mode 100644
index 0000000..b81daeb
@@ -0,0 +1,42 @@
+/*
+ * LED Class Color Support
+ *
+ * Author: Heiner Kallweit <[email protected]>
+ *
+ * This program is free software; you can redistribute it and/or modify

drivers/leds/led-rgb-core.c new file +26 -0

+
+/*
+ * The color extension handles RGB LEDs but uses a HSV color model internally.
+ * led_rgb_adjust_hue_sat sets hue and saturation part of the HSV color value.
+ */
+static enum led_brightness led_rgb_adjust_hue_sat(struct led_classdev *led_cdev,
+						  enum led_brightness value)
+{
+	/* LED_SET_HUE_SAT sets hue and saturation even if both are zero */
+	if (value & LED_SET_HUE_SAT || value > LED_FULL)
+		return value & LED_HUE_SAT_MASK;
+	else
+		return led_cdev->brightness & ~LED_BRIGHTNESS_MASK;
+}
+
+enum led_brightness led_confine_brightness(struct led_classdev *led_cdev,
+					   enum led_brightness value)
+{
+	enum led_brightness brightness = 0;
+
+	if (led_cdev->flags & LED_DEV_CAP_HSV)
+		brightness = led_rgb_adjust_hue_sat(led_cdev, value);
+
+	return brightness |
+	       min(value & LED_BRIGHTNESS_MASK, led_cdev->max_brightness);
+}

drivers/leds/leds.h +17 -0

index db3f20d..f3a8ed5 100644
@@ -16,17 +16,34 @@
  #include <linux/rwsem.h>
  #include <linux/leds.h>
 
+#define LED_BRIGHTNESS_MASK	0x000000ff
+
  static inline int led_get_brightness(struct led_classdev *led_cdev)
  {
  	return led_cdev->brightness;
  }
 
+static inline bool __is_brightness_set(enum led_brightness brightness)
+{
+	return (brightness & LED_BRIGHTNESS_MASK) != LED_OFF;
+}
+
  void led_init_core(struct led_classdev *led_cdev);
  void led_stop_software_blink(struct led_classdev *led_cdev);
  void led_set_brightness_nopm(struct led_classdev *led_cdev,
  				enum led_brightness value);
  void led_set_brightness_nosleep(struct led_classdev *led_cdev,
  				enum led_brightness value);
+#if IS_ENABLED(CONFIG_LEDS_RGB)
+enum led_brightness led_confine_brightness(struct led_classdev *led_cdev,
+					   enum led_brightness value);
+#else
+static inline enum led_brightness led_confine_brightness(
+		struct led_classdev *led_cdev, enum led_brightness value)
+{
+	return min(value, led_cdev->max_brightness);
+}
+#endif
 
  extern struct rw_semaphore leds_list_lock;
  extern struct list_head leds_list;

include/linux/leds.h +9 -0

index f203a8f..1e98b2e 100644
@@ -29,8 +29,16 @@ enum led_brightness {
  	LED_OFF		= 0,
  	LED_HALF	= 127,
  	LED_FULL	= 255,
+	/*
+	 * dummy enum value to make gcc use a 32 bit type for the enum
+	 * even if compiled with -fshort-enums. This is needed for
+	 * the enum to store hsv values.
+	 */
+	LED_LEVEL_DUMMY	= 0xffffffff,
  };
 
+#define LED_SET_HUE_SAT		BIT(24)
+
  struct led_classdev {
  	const char		*name;
  	enum led_brightness	 brightness;

@@ -50,6 +58,7 @@ struct led_classdev {
  #define LED_SYSFS_DISABLE	(1 << 22)
  #define LED_DEV_CAP_FLASH	(1 << 23)
  #define LED_HW_PLUGGABLE	(1 << 24)
+#define LED_DEV_CAP_HSV		(1 << 25)
 
  	/* Set LED brightness level
  	 * Must not sleep. Use brightness_set_blocking for drivers