Date:   Wed, 25 Sep 2019 23:12:10 +0200
From:   Jacek Anaszewski <jacek.anaszewski@...il.com>
To:     Dan Murphy <dmurphy@...com>, pavel@....cz
Cc:     linux-leds@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v9 05/15] leds: multicolor: Introduce a multicolor class
 definition

Dan,

On 9/25/19 7:46 PM, Dan Murphy wrote:
> 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@...com>
> ---
>  drivers/leds/Kconfig                 |  10 ++
>  drivers/leds/Makefile                |   1 +
>  drivers/leds/led-class-multicolor.c  | 220 +++++++++++++++++++++++++++
>  include/linux/led-class-multicolor.h |  74 +++++++++
>  4 files changed, 305 insertions(+)
>  create mode 100644 drivers/leds/led-class-multicolor.c
>  create mode 100644 include/linux/led-class-multicolor.h
> 
> diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
> index 6e7703fd03d0..cfb1ebb6517f 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..25371bd9a860
> --- /dev/null
> +++ b/drivers/leds/led-class-multicolor.c
> @@ -0,0 +1,220 @@
> +// 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"
> +
> +void led_mc_calc_brightness(struct led_classdev_mc *mcled_cdev,
> +			    enum led_brightness brightness,
> +			    int brightness_val[])
> +{
> +	struct led_mc_color_entry *priv;
> +	int i = 0;
> +
> +	list_for_each_entry(priv, &mcled_cdev->color_list, list) {

I think we should have some way to let the caller know exact mapping
of brightness_val to color_id. Possibly LED mc core should provide
a helper to get color_id by color entry index.

But this remark is actually more relevant to the place of calling.
I'll try to propose something there.

And regarding brightness_val name - how about:

s/brightness_val/brightness_component/ ?


> +		brightness_val[i] = brightness *
> +				    priv->intensity / priv->max_intensity;
> +		i++;
> +	}
> +}
> +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, int color_index)
> +{
> +	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 = 644;

Proper octal value should begin with 0.
But please use combinations of dedicated S_I* definitions
from include/uapi/linux/stat.h.

> +	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 = 444;
> +	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, color_index = 0;
> +
> +	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,
> +							color_index);

color_index is now unused AFAICS.

> +			if (ret)
> +				break;
> +
> +			color_index++;
> +		}
> +	}
> +
> +	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);

Why devm_* versions are missing now?

> +
> +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);
> +
> +MODULE_AUTHOR("Dan Murphy <dmurphy@...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..280ba5a614b4
> --- /dev/null
> +++ b/include/linux/led-class-multicolor.h
> @@ -0,0 +1,74 @@
> +/* 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_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);
> +}
> +
> +/**
> + * 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);
> +
> +#define led_classdev_multicolor_register(parent, mcled_cdev)		\
> +	led_classdev_multicolor_register_ext(parent, mcled_cdev, NULL)

Please turn it into inline.

> +
> +/**
> + * 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 */
> +void led_mc_calc_brightness(struct led_classdev_mc *mcled_cdev,
> +			    enum led_brightness brightness,
> +			    int brightness_val[]);
> +
> +#endif	/* __LINUX_MULTICOLOR_LEDS_H_INCLUDED */
> 

-- 
Best regards,
Jacek Anaszewski

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