Message-ID: <2bfd27cf-6703-48b8-be82-9b36066ef2ed@gmail.com>
Date:   Sun, 15 Sep 2019 18:20:36 +0200
From:   Jacek Anaszewski <jacek.anaszewski@...il.com>
To:     Dan Murphy <dmurphy@...com>, pavel@....cz
Cc:     robh+dt@...nel.org, linux-leds@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 6/9] leds: multicolor: Introduce a multicolor class
 definition

Dan,

On 9/11/19 8:01 PM, Dan Murphy wrote:
> Introduce a multicolor class that groups colored LEDs
> within a LED node.
> 
> The framework allows for dynamically setting individual LEDs
> or setting brightness levels of LEDs and updating them virtually
> simultaneously.
> 
> Signed-off-by: Dan Murphy <dmurphy@...com>
> ---
>  drivers/leds/Kconfig                 |  10 +
>  drivers/leds/Makefile                |   1 +
>  drivers/leds/led-class-multicolor.c  | 387 +++++++++++++++++++++++++++
>  include/linux/led-class-multicolor.h |  96 +++++++
>  4 files changed, 494 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 1988de1d64c0..71e7fd4f6f15 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 41fb073a39c1..897b810257dd 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..c733192b31fa
> --- /dev/null
> +++ b/drivers/leds/led-class-multicolor.c
> @@ -0,0 +1,387 @@
> +// 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"
> +
> +struct led_classdev_mc_priv {

I'd go for some more informative struct name here.
And also this is not going to be main classdev struct
so we can drop that from the name.

struct led_mc_color_entry ?

> +	struct led_classdev_mc *mcled_cdev;
> +
> +	struct device_attribute max_intensity_attr;
> +	struct device_attribute intensity_attr;
> +	struct device_attribute color_index_attr;
> +
> +	enum led_brightness max_intensity;
> +	enum led_brightness intensity;
> +
> +	struct list_head list;
> +
> +	int led_color_id;
> +	int color_seq_pos;
> +};
> +
> +static int led_mc_calculate_brightness(int brightness, int intensity,
> +				       int max_intensity)
> +{
> +	if (brightness && intensity && max_intensity)

This check looks odd. I'd drop it entirely. One thing we could worry
about would be max_intensity == 0 but this should be secured by the
core on registration. Effectively I don't see the need for wrapping
below calculation in a function at all.

> +		return brightness * intensity / max_intensity;
> +
> +	return LED_OFF;
> +}
> +
> +void led_mc_set_cluster_brightness(struct led_classdev_mc *mcled_cdev,


We really don't set cluster brightness but calculate it only here
(we can skip "cluster" as well):

s/led_mc_set_cluster_brightness/led_mc_calc_brightness/

> +			    enum led_brightness brightness, int adj_value[])

s/adj_value/brightness_val/

> +{
> +	struct led_classdev_mc_data *data = mcled_cdev->data;
> +	struct led_classdev_mc_priv *priv;
> +	int i = 0;
> +
> +	list_for_each_entry(priv, &data->color_list, list) {
> +		adj_value[i] = led_mc_calculate_brightness(brightness,
> +							   priv->intensity,
> +							   priv->max_intensity);

brightness_val[i] = brightness * priv->intensity / priv->max_intensity;

> +		i++;
> +	}
> +
> +	data->cluster_brightness = brightness;

Why can't we use led_classdev_mc->led_cdev->brightness for storing
cluster brightness?

> +}
> +
> +void led_mc_get_cluster_brightness(struct led_classdev_mc *mcled_cdev,
> +				  int brightness_val[])
> +{
> +	struct led_classdev_mc_data *data = mcled_cdev->data;
> +	struct led_classdev_mc_priv *priv;
> +	int i = 0;
> +
> +	list_for_each_entry(priv, &data->color_list, list) {
> +		brightness_val[i] = priv->intensity;
> +		i++;
> +	}
> +}
> +
> +static ssize_t color_index_show(struct device *dev,
> +				   struct device_attribute *color_index_attr,
> +				   char *buf)
> +{
> +	struct led_classdev_mc_priv *priv = container_of(color_index_attr,
> +						    struct led_classdev_mc_priv,
> +						      color_index_attr);
> +
> +	return sprintf(buf, "%d\n", priv->led_color_id);
> +}
> +
> +static ssize_t color_mix_store(struct device *dev,
> +				struct device_attribute *color_mix_attr,
> +				const char *buf, size_t size)
> +{
> +	struct led_classdev_mc_data *data = container_of(color_mix_attr,
> +						    struct led_classdev_mc_data,
> +						      color_mix_attr);
> +	struct led_classdev_mc *mcled_cdev = data->mcled_cdev;
> +	struct led_classdev_mc_priv *priv;
> +	unsigned int value[LED_COLOR_ID_MAX];
> +	int nrchars, offset = 0;
> +	unsigned int i;
> +	int ret;
> +
> +	for (i = 0; i < mcled_cdev->num_leds; i++) {
> +		ret = sscanf(buf + offset, "%i%n", &value[i], &nrchars);
> +		if (ret != 1)
> +			break;
> +
> +		offset += nrchars;
> +	}
> +
> +	if (i != mcled_cdev->num_leds) {
> +		dev_err(dev, "Wrong number of LEDs defined %i, need %i\n",
> +			i, mcled_cdev->num_leds);
> +		return -EINVAL;
> +	}
> +
> +	list_for_each_entry(priv, &data->color_list, list) {
> +		priv->intensity = value[priv->color_seq_pos];
> +		if (mcled_cdev->ops) {
> +			ret = mcled_cdev->ops->set_color_brightness(mcled_cdev,
> +							    priv->led_color_id,
> +							    priv->intensity);
> +			if (ret)
> +				goto out;
> +		}
> +	}
> +out:
> +	return size;
> +}
> +
> +static ssize_t intensity_store(struct device *dev,
> +				struct device_attribute *intensity_attr,
> +				const char *buf, size_t size)
> +{
> +	struct led_classdev_mc_priv *priv = container_of(intensity_attr,
> +						    struct led_classdev_mc_priv,
> +						      intensity_attr);
> +	struct led_classdev_mc_data *data = priv->mcled_cdev->data;
> +	struct led_classdev_mc *mcled_cdev = data->mcled_cdev;
> +	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;
> +
> +	if (mcled_cdev->ops) {
> +		ret = mcled_cdev->ops->set_color_brightness(mcled_cdev,
> +							    priv->led_color_id,
> +							    priv->intensity);
> +		if (ret)
> +			goto unlock;
> +	}
> +
> +	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_classdev_mc_priv *priv = container_of(intensity_attr,
> +						    struct led_classdev_mc_priv,
> +						      intensity_attr);
> +	const struct led_multicolor_ops *ops = priv->mcled_cdev->ops;
> +	int value = 0;
> +
> +	if (ops->get_color_brightness) {
> +		value = ops->get_color_brightness(priv->mcled_cdev,
> +						  priv->led_color_id);
> +		priv->intensity = value;
> +	} else {
> +		value = priv->intensity;
> +	}
> +
> +	return sprintf(buf, "%d\n", value);
> +}
> +
> +static ssize_t max_intensity_show(struct device *dev,
> +				   struct device_attribute *max_intensity_attr,
> +				   char *buf)
> +{
> +	struct led_classdev_mc_priv *priv = container_of(max_intensity_attr,
> +						    struct led_classdev_mc_priv,
> +						      max_intensity_attr);
> +
> +	return sprintf(buf, "%d\n", priv->max_intensity);
> +}
> +
> +static int led_multicolor_init_color(struct led_classdev_mc_data *data,
> +				     struct led_classdev_mc *mcled_cdev,
> +				     int color_id, int color_index)
> +{
> +	struct led_classdev *led_cdev = mcled_cdev->led_cdev;
> +	struct led_classdev_mc_priv *mc_priv;
> +	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;
> +
> +	data->led_kobj = kobject_create_and_add(led_colors[color_id],
> +						data->color_kobj);

No change here since previous version? What prevents you from following
what has been done for drivers/usb/core/ledtrig-usbport.c?

Use sysfs_create_group() for creating color dir
and sysfs_add_file_to_group() for adding files to it.


> +	if (!data->led_kobj)
> +		return -EINVAL;
> +
> +	sysfs_attr_init(&mc_priv->intensity_attr.attr);
> +	mc_priv->intensity_attr.attr.name = "intensity";
> +	mc_priv->intensity_attr.attr.mode = S_IRUGO | S_IWUGO;
> +	mc_priv->intensity_attr.store = intensity_store;
> +	mc_priv->intensity_attr.show = intensity_show;
> +	ret = sysfs_create_file(data->led_kobj,
> +				&mc_priv->intensity_attr.attr);
> +	if (ret)
> +		goto err_out;
> +
> +	sysfs_attr_init(&mc_priv->max_intensity_attr.attr);
> +	mc_priv->max_intensity_attr.attr.name = "max_intensity";
> +	mc_priv->max_intensity_attr.attr.mode = S_IRUGO;
> +	mc_priv->max_intensity_attr.show = max_intensity_show;
> +	ret = sysfs_create_file(data->led_kobj,
> +				&mc_priv->max_intensity_attr.attr);
> +	if (ret)
> +		goto err_out;
> +
> +	sysfs_attr_init(&mc_priv->color_index_attr.attr);
> +	mc_priv->color_index_attr.attr.name = "color_id";
> +	mc_priv->color_index_attr.attr.mode = S_IRUGO;
> +	mc_priv->color_index_attr.show = color_index_show;
> +	ret = sysfs_create_file(data->led_kobj,
> +				&mc_priv->color_index_attr.attr);
> +	if (ret)
> +		goto err_out;
> +
> +	mc_priv->max_intensity = LED_FULL;
> +	mc_priv->color_seq_pos = color_index;
> +	list_add_tail(&mc_priv->list, &data->color_list);
> +
> +err_out:
> +	return ret;
> +}
> +
> +static int led_multicolor_init_color_dir(struct led_classdev_mc_data *data,
> +					 struct led_classdev_mc *mcled_cdev)
> +{
> +	struct led_classdev *led_cdev = mcled_cdev->led_cdev;
> +	u32 color_id;
> +	int ret;
> +	int i, j = 0;
> +
> +	data->color_kobj = kobject_create_and_add("colors",
> +						  &led_cdev->dev->kobj);

Again: use sysfs_create_group().

> +	if (!data->color_kobj)
> +		return -EINVAL;
> +
> +	data->mcled_cdev = mcled_cdev;
> +
> +	for (i = 0; i < LED_COLOR_ID_MAX; i++) {
> +		color_id = (mcled_cdev->available_colors & (1 << i));
> +		if (color_id) {
> +			ret = led_multicolor_init_color(data, mcled_cdev, i, j);
> +			if (ret)
> +				break;
> +
> +			j++;
> +		}
> +	}
> +
> +	sysfs_attr_init(&data->color_mix_attr.attr);
> +	data->color_mix_attr.attr.name = "color_mix";
> +	data->color_mix_attr.attr.mode = S_IRUGO | S_IWUGO;
> +	data->color_mix_attr.store = color_mix_store;
> +	ret = sysfs_create_file(data->color_kobj,
> +				&data->color_mix_attr.attr);
> +
> +	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;
> +	struct led_classdev_mc_data *data;
> +	int ret;
> +
> +	if (!mcled_cdev)
> +		return -EINVAL;
> +
> +	data = kzalloc(sizeof(*data), GFP_KERNEL);
> +	if (!data)
> +		return -ENOMEM;
> +
> +	mcled_cdev->data = data;
> +	led_cdev = mcled_cdev->led_cdev;
> +	INIT_LIST_HEAD(&data->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(data, mcled_cdev);
> +}
> +EXPORT_SYMBOL_GPL(led_classdev_multicolor_register_ext);
> +
> +void led_classdev_multicolor_unregister(struct led_classdev_mc *mcled_cdev)
> +{
> +	if (!mcled_cdev)
> +		return;
> +
> +	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);
> +}
> +
> +/**
> + * devm_of_led_classdev_register - resource managed led_classdev_register()
> + *
> + * @parent: parent of LED device
> + * @led_cdev: the led_classdev structure for this device.
> + */
> +int devm_led_classdev_multicolor_register(struct device *parent,
> +					  struct led_classdev_mc *mcled_cdev)
> +{
> +	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(parent, mcled_cdev);
> +	if (ret) {
> +		devres_free(dr);
> +		return ret;
> +	}
> +
> +	*dr = mcled_cdev;
> +	devres_add(parent, dr);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(devm_led_classdev_multicolor_register);
> +
> +static int devm_led_classdev_multicolor_match(struct device *dev,
> +					      void *res, void *data)
> +{
> +	struct mcled_cdev **p = res;
> +
> +	if (WARN_ON(!p || !*p))
> +		return 0;
> +
> +	return *p == data;
> +}
> +
> +/**
> + * devm_led_classdev_multicolor_unregister() - resource managed
> + *					led_classdev_multicolor_unregister()
> + * @parent: The device to unregister.
> + * @mcled_cdev: the led_classdev_mc structure for this device.
> + */
> +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@...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..193ba0e46042
> --- /dev/null
> +++ b/include/linux/led-class-multicolor.h
> @@ -0,0 +1,96 @@
> +/* 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_classdev_mc_data {
> +	struct led_classdev_mc *mcled_cdev;
> +
> +	struct kobject *color_kobj;
> +	struct kobject *led_kobj;
> +
> +	struct device_attribute color_mix_attr;
> +
> +	struct list_head color_list;
> +
> +	enum led_brightness cluster_brightness;
> +};
> +
> +struct led_multicolor_ops {
> +	/* Set brightness for a specific color id */
> +	int (*set_color_brightness)(struct led_classdev_mc *mcled_cdev,
> +				    int color_id, int value);
> +	/* Read current color setting */
> +	int (*get_color_brightness)(struct led_classdev_mc *mcled_cdev,
> +				    int color_id);
> +};
> +
> +struct led_classdev_mc {
> +	/* led class device */
> +	struct led_classdev *led_cdev;
> +
> +	/* multicolor led specific ops */
> +	struct led_multicolor_ops *ops;
> +
> +	struct led_classdev_mc_data *data;
> +
> +	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
> + */
> +extern 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)
> +
> +/**
> + * 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
> + */
> +extern void led_classdev_multicolor_unregister(struct led_classdev_mc *mcled_cdev);
> +
> +extern int devm_led_classdev_multicolor_register(struct device *parent,
> +					struct led_classdev_mc *mcled_cdev);
> +
> +extern void devm_led_classdev_multicolor_unregister(struct device *parent,
> +					   struct led_classdev_mc *mcled_cdev);
> +
> +/* Set brightness for the monochrome LED cluster */
> +extern void led_mc_set_cluster_brightness(struct led_classdev_mc *mcled_cdev,
> +			    enum led_brightness brightness,
> +			    int adj_value[]);
> +
> +/* Read current cluster brightness */
> +extern void led_mc_get_cluster_brightness(struct led_classdev_mc *mcled_cdev,
> +				   int brightness_val[]);
> +
> +#endif	/* __LINUX_MULTICOLOR_LEDS_H_INCLUDED */
> 

-- 
Best regards,
Jacek Anaszewski

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