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From:   Jacek Anaszewski <jacek.anaszewski@gmail.com>
Subject: Re: [PATCH v4 6/9] leds: multicolor: Introduce a multicolor class
 definition
To:     Dan Murphy <dmurphy@ti.com>, pavel@ucw.cz
Cc:     linux-leds@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20190725182818.29556-1-dmurphy@ti.com>
 <20190725182818.29556-7-dmurphy@ti.com>
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Message-ID: <fa74cc04-61fc-161f-2ce1-6de5921fce2f@gmail.com>
Date:   Mon, 29 Jul 2019 22:50:01 +0200
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Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Dan,

On 7/25/19 8:28 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@ti.com>
> ---
>  drivers/leds/Kconfig                 |  10 +
>  drivers/leds/Makefile                |   1 +
>  drivers/leds/led-class-multicolor.c  | 402 +++++++++++++++++++++++++++
>  include/linux/led-class-multicolor.h |  96 +++++++
>  4 files changed, 509 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 f7a3dd7ecf3d..7f780d5b8490 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

s/Class/class/

I'll need to fix it in LED flash class entry too.

> +	  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..123443e6d3eb
> --- /dev/null
> +++ b/drivers/leds/led-class-multicolor.c
> @@ -0,0 +1,402 @@
> +// 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 {
> +	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;
> +	enum led_brightness new_intensity;
> +
> +	struct list_head list;
> +
> +	int color_id;
> +	int color_index;

We need to differentiate both more meaningfully.
Maybe led_color_id and cluster_color_id?

> +};
> +static int calculate_brightness(int brightness, int intensity, int max_intensity)

How about led_mc_calculate_brightness ?

> +{
> +	if (brightness && intensity && max_intensity)
> +		return brightness * intensity / max_intensity;
> +
> +	return LED_OFF;
> +}
> +
> +void set_cluster_brightness(struct led_classdev_mc *mcled_cdev,
> +			    enum led_brightness brightness, int adj_value[])

s/set_cluster/led_mc_set_cluster/

And I think adj_value is not telling too much. How about:

s/adj_value/color_intensity/

> +{
> +	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] = calculate_brightness(brightness, priv->intensity,
> +						    priv->max_intensity);
> +		i++;
> +	}
> +
> +	data->cluster_brightness = brightness;

This property duplicates brightness stored in struct led_classdev and
thus it is redundant.

> +}
> +
> +void get_cluster_brightness(struct led_classdev_mc *mcled_cdev,
> +				  int brightness_val[])

s/get_cluster/led_mc_get_cluster/

s/brightness_val/color_intensity/

> +{
> +	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->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;
> +	const struct led_multicolor_ops *ops = mcled_cdev->ops;
> +	struct led_classdev_mc_priv *priv;
> +	unsigned int value[LED_COLOR_ID_MAX];
> +	int adj_brightness;
> +	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) {

Shouldn't we return error if i != mcled_cdev->num_leds - 1 ?
How can we know which color the value will be for if there is less
values passed than the total number of colors in the cluster?

> +		for (; i < LED_COLOR_ID_MAX; i++)
> +			value[i] = 0;

What use case is it for?

> +	}
> +
> +	list_for_each_entry(priv, &data->color_list, list) {
> +		if (data->cluster_brightness) {
> +			adj_brightness = calculate_brightness(data->cluster_brightness,
> +							      value[priv->color_index],
> +							     priv->max_intensity);
> +			ret = ops->set_color_brightness(priv->mcled_cdev,
> +							priv->color_id,
> +							adj_brightness);
> +			if (ret < 0)
> +				goto done;
> +		}
> +
> +		priv->intensity = value[priv->color_index];
> +	}

Here we could use just brightness_set op as a single call. We should
always write all colors as a result of write to color_mix anyway.

> +
> +done:
> +	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 *led_cdev = priv->mcled_cdev->led_cdev;
> +	struct led_multicolor_ops *ops = priv->mcled_cdev->ops;
> +	unsigned int adj_value;
> +	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;
> +	}

We don't fail in this case in LED class, so let's proceed in the same
way here:

priv->intensity = min(value, priv->max_brightness);

> +
> +	priv->new_intensity = value;
> +
> +	if (data->cluster_brightness) {
> +		adj_value = calculate_brightness(data->cluster_brightness,
> +					priv->new_intensity,
> +					priv->max_intensity);
> +		ret = ops->set_color_brightness(priv->mcled_cdev,
> +						priv->color_id, adj_value);
> +		if (ret < 0) {
> +			priv->new_intensity = priv->intensity;

This is unnecessary complication. Just write the calculated iout
intensity.

We need to highlight it in the documentation that exact requested color
intensity values are written to the hardware only when
brightness == max_brightness.

> +			goto unlock;
> +		}
> +	}
> +
> +	priv->intensity = priv->new_intensity;
> +	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->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->color_id = color_id;
> +	mc_priv->mcled_cdev = mcled_cdev;
> +
> +	data->led_kobj = kobject_create_and_add(led_colors[color_id],
> +						data->color_kobj);

You should not use kobject API in the drivers. See [0].

> +	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_index = 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);
> +	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_multicolor_ops *ops;
> +	struct led_classdev_mc_data *data;
> +	int ret;
> +
> +	if (!mcled_cdev)
> +		return -EINVAL;
> +
> +	ops = mcled_cdev->ops;
> +	if (!ops || !ops->set_color_brightness)
> +		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@ti.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..082883606246
> --- /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;
> +
> +	u32 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 set_cluster_brightness(struct led_classdev_mc *mcled_cdev,
> +			    enum led_brightness brightness,
> +			    int adj_value[]);
> +
> +/* Read current cluster brightness */
> +extern void get_cluster_brightness(struct led_classdev_mc *mcled_cdev,
> +				   int brightness_val[]);
> +
> +#endif	/* __LINUX_MULTICOLOR_LEDS_H_INCLUDED */
> 

I'll review remaining patches (drivers) next time.

[0] https://lore.kernel.org/linux-leds/20160825124948.GA15567@kroah.com/

-- 
Best regards,
Jacek Anaszewski