Re: [PATCH v7 1/5] leds: core: add generic support for RGB LED's

[Jacek Anaszewski]

Hi Heiner,

Thanks for the updated set. I've renamed the feature to RGB LED class
and pushed out to devel branch of linux-leds.git. It will sit there
till the end of the upcoming merge window. There have been some
uncertainties raised related to overloading brightness syntax. so let's
better have it in linux-next through the whole next development cycle
for the people to comment on.

Thanks,
Jacek Anaszewski

On 03/04/2016 10:09 PM, Heiner Kallweit wrote:
> Add generic support for RGB 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 <hkallweit1@xxxxxxxxx>
> ---
> 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
> v5:
> - change "RGB Color LED" to "RGB LED" in Kconfig
> - move definition of LED_HUE_SAT_MASK to drivers/leds/leds.h
> - rename LED_DEV_CAP_HSV to LED_DEV_CAP_RGB
> v6:
> - no change
> v7:
> - removed "Color" from RGB Color LED in commit message and title
> - don't include linux/kernel.h in led-rgb-core.c
> - keep definition of LED_DEV_CAP_[] flags together
> ---
>   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 | 39 +++++++++++++++++++++++++++++++++++++++
>   drivers/leds/leds.h         | 18 ++++++++++++++++++
>   include/linux/leds.h        | 11 ++++++++++-
>   7 files changed, 91 insertions(+), 10 deletions(-)
>   create mode 100644 drivers/leds/led-rgb-core.c
>
> diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
> index 7f940c2..5b1c852 100644
> --- a/drivers/leds/Kconfig
> +++ b/drivers/leds/Kconfig
> @@ -13,6 +13,13 @@ menuconfig NEW_LEDS
>
>   if NEW_LEDS
>
> +config LEDS_RGB
> +	bool "RGB LED Support"
> +	help
> +	 This option enables support for RGB Color LED devices.
> +	 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 LED drivers"
> +endif # LEDS_RGB
> +
>   comment "LED drivers"
>
>   config LEDS_88PM860X
> diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
> index e9d5309..cc3676f 100644
> --- a/drivers/leds/Makefile
> +++ b/drivers/leds/Makefile
> @@ -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
> diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
> index aa84e5b..007a5b3 100644
> --- a/drivers/leds/led-class.c
> +++ b/drivers/leds/led-class.c
> @@ -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);
>
> diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c
> index 3495d5d..e75b0c8 100644
> --- a/drivers/leds/led-core.c
> +++ b/drivers/leds/led-core.c
> @@ -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;
> diff --git a/drivers/leds/led-rgb-core.c b/drivers/leds/led-rgb-core.c
> new file mode 100644
> index 0000000..cbd8b35
> --- /dev/null
> +++ b/drivers/leds/led-rgb-core.c
> @@ -0,0 +1,39 @@
> +/*
> + * LED Class Color Support
> + *
> + * Author: Heiner Kallweit <hkallweit1@xxxxxxxxx>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + */
> +
> +#include <linux/leds.h>
> +#include "leds.h"
> +
> +/*
> + * 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_RGB)
> +		brightness = led_rgb_adjust_hue_sat(led_cdev, value);
> +
> +	return brightness |
> +	       min(value & LED_BRIGHTNESS_MASK, led_cdev->max_brightness);
> +}
> diff --git a/drivers/leds/leds.h b/drivers/leds/leds.h
> index db3f20d..b853f54 100644
> --- a/drivers/leds/leds.h
> +++ b/drivers/leds/leds.h
> @@ -16,17 +16,35 @@
>   #include <linux/rwsem.h>
>   #include <linux/leds.h>
>
> +#define LED_BRIGHTNESS_MASK	0x000000ff
> +#define LED_HUE_SAT_MASK	0x00ffff00
> +
>   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;
> diff --git a/include/linux/leds.h b/include/linux/leds.h
> index f203a8f..58e8299 100644
> --- a/include/linux/leds.h
> +++ b/include/linux/leds.h
> @@ -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;
> @@ -49,7 +57,8 @@ struct led_classdev {
>   #define LED_BLINK_DISABLE	(1 << 21)
>   #define LED_SYSFS_DISABLE	(1 << 22)
>   #define LED_DEV_CAP_FLASH	(1 << 23)
> -#define LED_HW_PLUGGABLE	(1 << 24)
> +#define LED_DEV_CAP_RGB		(1 << 24)
> +#define LED_HW_PLUGGABLE	(1 << 25)
>
>   	/* Set LED brightness level
>   	 * Must not sleep. Use brightness_set_blocking for drivers


--
Best regards,
Jacek Anaszewski