Message-ID: <6f08905e-c420-c227-88bc-6370ec7cb27f@gmail.com>
Date:   Sat, 2 Sep 2017 16:36:00 +0200
From:   Jacek Anaszewski <jacek.anaszewski@...il.com>
To:     Pavel Machek <pavel@....cz>, hkallweit1@...il.com
Cc:     linux-kernel@...r.kernel.org, linux-leds@...r.kernel.org
Subject: Re: RGB support prototype

Hi Pavel,

Thanks for your work. Few comments below.

On 08/31/2017 11:33 AM, Pavel Machek wrote:
> Hi!
> 
>>>> We could even export (read-only) hue/saturation for single-color LEDs...
>>>
>>> Related patches from Heiner Kallweit are still sitting on devel branch
>>> of linux-leds.git:
>>>
>>> https://git.kernel.org/pub/scm/linux/kernel/git/j.anaszewski/linux-leds.git/log/?h=devel
>>>
>>> Possibly it can serve as a basis for further development.
>>
>>> I liked that approach because it was compatible with monochrome
>>> LEDs and triggers.
>>
>> Yeah, I like that. I don't like the implementation and the sysfs
>> interface.
>>
>> Let me try and see if I can turn them into something better...
>>
>> I'm using full 32-bits for parameters; that should give us enough
>> precision. In particular, 32-bits is important for "brightness"; I
>> already have light that goes from .1lm to 1000lm -- which is more than
>> 8-bits can handle.
>>
>> lp5523 conversion... is a very quick hack.
> 
> And here's a better version. I'll still need to adjust white to be
> white... but I guess that would need to be done with any solution.
> 
> I've checked, and triggers seem to work as expected (and I can select
> a color for them).
> 
> Signed-off-by: Pavel Machek <pavel@....cz>
> 
> diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
> index 594b24d..bad8a6e 100644
> --- a/drivers/leds/Kconfig
> +++ b/drivers/leds/Kconfig
> @@ -19,6 +19,14 @@ config LEDS_CLASS
>  	  This option enables the led sysfs class in /sys/class/leds.  You'll
>  	  need this to do anything useful with LEDs.  If unsure, say N.
>  
> +config LEDS_CLASS_RGB
> +	bool "LED RGB Class Support"
> +	depends on LEDS_CLASS
> +	help
> +	  This option enables support for RGB LED devices.
> +	  Sysfs attribute brightness is interpreted as a HSV color value.
> +	  For details see Documentation/leds/leds-class.txt.
> +
>  config LEDS_CLASS_FLASH
>  	tristate "LED Flash Class Support"
>  	depends on LEDS_CLASS
> @@ -38,6 +46,10 @@ config LEDS_BRIGHTNESS_HW_CHANGED
>  
>  	  See Documentation/ABI/testing/sysfs-class-led for details.
>  
> +if LEDS_CLASS_RGB
> +comment "RGB LED drivers"
> +endif # LEDS_CLASS_RGB
> +
>  comment "LED drivers"
>  
>  config LEDS_88PM860X
> diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
> index 909dae6..d5b5e76 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-$(CONFIG_LEDS_CLASS_RGB)	+= led-rgb-core.o
>  obj-$(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 b0e2d55..0bd68a4 100644
> --- a/drivers/leds/led-class.c
> +++ b/drivers/leds/led-class.c
> @@ -65,6 +65,83 @@ static ssize_t brightness_store(struct device *dev,
>  }
>  static DEVICE_ATTR_RW(brightness);
>  
> +static ssize_t saturation_show(struct device *dev,
> +		struct device_attribute *attr, char *buf)
> +{
> +	struct led_classdev *led_cdev = dev_get_drvdata(dev);
> +
> +	/* no lock needed for this */
> +	led_update_brightness(led_cdev);

We will need to update documentation of brightness_get to
require updating hue and saturation for RGB LED drivers.

Also hue and saturation attributes will need related ABI
documentation entries. From what I see you're proposing
that hue and sat would be written to the device on the
occasion of brightness setting, right? We're tossing this
responsibility to to drivers, without exposing an API for
it, so it would have to be highlighted.

> +
> +	return sprintf(buf, "%u\n", led_cdev->saturation);
> +}
> +
> +static ssize_t saturation_store(struct device *dev,
> +		struct device_attribute *attr, const char *buf, size_t size)
> +{
> +	struct led_classdev *led_cdev = dev_get_drvdata(dev);
> +	unsigned long state;
> +	ssize_t ret;
> +
> +	mutex_lock(&led_cdev->led_access);
> +
> +	if (led_sysfs_is_disabled(led_cdev)) {
> +		ret = -EBUSY;
> +		goto unlock;
> +	}
> +
> +	ret = kstrtoul(buf, 10, &state);
> +	if (ret)
> +		goto unlock;
> +
> +	led_cdev->saturation = state;
> +
> +	ret = size;
> +unlock:
> +	mutex_unlock(&led_cdev->led_access);
> +	return ret;
> +}
> +static DEVICE_ATTR_RW(saturation);
> +
> +static ssize_t hue_show(struct device *dev,
> +		struct device_attribute *attr, char *buf)
> +{
> +	struct led_classdev *led_cdev = dev_get_drvdata(dev);
> +
> +	/* no lock needed for this */
> +	led_update_brightness(led_cdev);
> +
> +	return sprintf(buf, "%u\n", led_cdev->hue);
> +}
> +
> +static ssize_t hue_store(struct device *dev,
> +		struct device_attribute *attr, const char *buf, size_t size)
> +{
> +	struct led_classdev *led_cdev = dev_get_drvdata(dev);
> +	unsigned long state;
> +	ssize_t ret;
> +
> +	mutex_lock(&led_cdev->led_access);
> +
> +	if (led_sysfs_is_disabled(led_cdev)) {
> +		ret = -EBUSY;
> +		goto unlock;
> +	}
> +
> +	ret = kstrtoul(buf, 10, &state);
> +	if (ret)
> +		goto unlock;
> +
> +	led_cdev->hue = state;
> +
> +	ret = size;
> +unlock:
> +	mutex_unlock(&led_cdev->led_access);
> +	return ret;
> +}
> +static DEVICE_ATTR_RW(hue);
> +
> +
>  static ssize_t max_brightness_show(struct device *dev,
>  		struct device_attribute *attr, char *buf)
>  {
> @@ -88,6 +165,8 @@ static const struct attribute_group led_trigger_group = {
>  static struct attribute *led_class_attrs[] = {
>  	&dev_attr_brightness.attr,
>  	&dev_attr_max_brightness.attr,
> +	&dev_attr_hue.attr,
> +	&dev_attr_saturation.attr,
>  	NULL,
>  };
>  
> diff --git a/drivers/leds/led-rgb-core.c b/drivers/leds/led-rgb-core.c
> new file mode 100644
> index 0000000..3733032
> --- /dev/null
> +++ b/drivers/leds/led-rgb-core.c
> @@ -0,0 +1,64 @@
> +/*
> + * LED RGB Class Support
> + *
> + * Author: Heiner Kallweit <hkallweit1@...il.com>
> + *
> + * 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"
> +
> +struct led_rgb led_hsv_to_rgb(struct led_hsv hsv)
> +{
> +	unsigned int h = hsv.hue >> 24;
> +	unsigned int s = hsv.saturation >> 24;
> +	unsigned int v = hsv.value >> 24;
> +	unsigned int f, p, q, t, r, g, b;
> +	struct led_rgb res;
> +
> +	if (!v) {
> +		res.red = 0;
> +		res.green = 0;
> +		res.blue = 0;
> +		return res;
> +	}
> +	if (!s) {
> +		res.red = v << 24;
> +		res.green = v << 24;
> +		res.blue = v << 24;

Why the shifting?

> +		return res;
> +	}
> +
> +	f = DIV_ROUND_CLOSEST((h % 42) * 255, 42);
> +	p = v - DIV_ROUND_CLOSEST(s * v, 255);
> +	q = v - DIV_ROUND_CLOSEST(f * s * v, 255 * 255);
> +	t = v - DIV_ROUND_CLOSEST((255 - f) * s * v, 255 * 255);
> +
> +	switch (h / 42) {
> +	case 0:
> +		r = v; g = t; b = p; break;
> +	case 1:
> +		r = q; g = v; b = p; break;
> +	case 2:
> +		r = p; g = v; b = t; break;
> +	case 3:
> +		r = p; g = q; b = v; break;
> +	case 4:
> +		r = t; g = p; b = v; break;
> +	case 5:
> +		r = v; g = p; b = q; break;
> +	}
> +
> +	printk("hsv_to: h %5d, s %5d, v %5d -> %5d, %5d, %5d\n",
> +	       h*390, s*390, v*390, r*390, g*390, b*390);
> +	
> +	res.red = r << 24;
> +	res.green = g << 24;
> +	res.blue = b << 24;
> +	return res;
> +}
> +EXPORT_SYMBOL_GPL(led_hsv_to_rgb);
> diff --git a/drivers/leds/leds-lp5523.c b/drivers/leds/leds-lp5523.c
> index 924e50a..3244c24 100644
> --- a/drivers/leds/leds-lp5523.c
> +++ b/drivers/leds/leds-lp5523.c
> @@ -802,6 +802,26 @@ static ssize_t store_master_fader_leds(struct device *dev,
>  	return ret;
>  }
>  
> +int lp5523_rgb_brightness(struct lp55xx_led *led, struct led_rgb r)
> +{
> +	struct lp55xx_chip *chip = led->chip;
> +	int ret;
> +
> +	mutex_lock(&chip->lock);
> +	r.red >>= 24;
> +	r.green >>= 24;
> +	r.blue >>= 24;	
> +	printk("RGB brightness %d %d %d\n", r.red, r.green, r.blue);
> +	ret = lp55xx_write(chip, LP5523_REG_LED_PWM_BASE + led->chan_nr, r.red);
> +	if (!ret)
> +		lp55xx_write(chip, LP5523_REG_LED_PWM_BASE + led->chan_nr - 1, r.green);
> +	if (!ret)
> +		lp55xx_write(chip, LP5523_REG_LED_PWM_BASE + led->chan_nr - 2, r.blue);
> +	mutex_unlock(&chip->lock);
> +	return ret;
> +
> +}
> +
>  static int lp5523_led_brightness(struct lp55xx_led *led)
>  {
>  	struct lp55xx_chip *chip = led->chip;
> diff --git a/drivers/leds/leds-lp55xx-common.c b/drivers/leds/leds-lp55xx-common.c
> index 5377f22..16e65dc 100644
> --- a/drivers/leds/leds-lp55xx-common.c
> +++ b/drivers/leds/leds-lp55xx-common.c
> @@ -134,6 +134,8 @@ static struct attribute *lp55xx_led_attrs[] = {
>  };
>  ATTRIBUTE_GROUPS(lp55xx_led);
>  
> +extern int lp5523_rgb_brightness(struct lp55xx_led *led, struct led_rgb r);
> +
>  static int lp55xx_set_brightness(struct led_classdev *cdev,
>  			     enum led_brightness brightness)
>  {
> @@ -141,6 +143,18 @@ static int lp55xx_set_brightness(struct led_classdev *cdev,
>  	struct lp55xx_device_config *cfg = led->chip->cfg;
>  
>  	led->brightness = (u8)brightness;
> +
> +	if (led->chan_nr == 6) {
> +		struct led_rgb r;
> +		struct led_hsv hsv;
> +
> +		printk("RGB set request: %d %d %d\n", cdev->brightness, cdev->hue >> 24, cdev->saturation >> 24);
> +		hsv.value = brightness << 24;
> +		hsv.hue = cdev->hue;
> +		hsv.saturation = cdev->saturation;
> +		r = led_hsv_to_rgb(hsv);
> +		return lp5523_rgb_brightness(led, r);
> +	}
>  	return cfg->brightness_fn(led);
>  }
>  
> @@ -176,6 +190,8 @@ static int lp55xx_init_led(struct lp55xx_led *led,
>  	led->cdev.brightness_set_blocking = lp55xx_set_brightness;
>  	led->cdev.groups = lp55xx_led_groups;
>  
> +	printk("Led %d name %s\n", chan, pdata->led_config[chan].name);
> +
>  	if (pdata->led_config[chan].name) {
>  		led->cdev.name = pdata->led_config[chan].name;
>  	} else {
> diff --git a/include/linux/leds.h b/include/linux/leds.h
> index 64c56d4..bd0ae46 100644
> --- a/include/linux/leds.h
> +++ b/include/linux/leds.h
> @@ -37,6 +37,8 @@ struct led_classdev {
>  	const char		*name;
>  	enum led_brightness	 brightness;
>  	enum led_brightness	 max_brightness;
> +	int			 hue;
> +	int			 saturation;
>  	int			 flags;
>  
>  	/* Lower 16 bits reflect status */
> @@ -49,6 +51,7 @@ struct led_classdev {
>  #define LED_HW_PLUGGABLE	(1 << 19)
>  #define LED_PANIC_INDICATOR	(1 << 20)
>  #define LED_BRIGHT_HW_CHANGED	(1 << 21)
> +#define LED_DEV_CAP_RGB		(1 << 24)
>  
>  	/* set_brightness_work / blink_timer flags, atomic, private. */
>  	unsigned long		work_flags;
> @@ -238,6 +241,26 @@ static inline bool led_sysfs_is_disabled(struct led_classdev *led_cdev)
>  	return led_cdev->flags & LED_SYSFS_DISABLE;
>  }
>  
> +struct led_hsv {
> +	u32 hue;
> +	u32 saturation;
> +	u32 value;
> +};
> +
> +struct led_rgb {
> +	u32 red;
> +	u32 green;
> +	u32 blue;
> +};
> +
> +/**
> + * led_hsv_to_rgb - convert a hsv color value to rgb color model
> + * @hsv: the hsv value to convert
> + *
> + * Returns: the resulting rgb value
> + */
> +struct led_rgb led_hsv_to_rgb(struct led_hsv hsv);
> +
>  /*
>   * LED Triggers
>   */
> 
> 

-- 
Best regards,
Jacek Anaszewski

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