Message-ID: <20230315161614.GC9667@google.com>
Date:   Wed, 15 Mar 2023 16:16:14 +0000
From:   Lee Jones <lee@...nel.org>
To:     Joseph Strauss <jstrauss@...lbox.org>
Cc:     pavel@....cz, jansimon.moeller@....de, conor@...nel.org,
        christophe.jaillet@...adoo.fr, linux-leds@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] Add multicolor support to BlinkM LED driver

On Tue, 27 Dec 2022, Joseph Strauss wrote:

> Added multicolor support to the BlinkM driver, making it easier to
> control from userspace. The BlinkM LED is a programmable RGB LED. The
> driver currently supports only the regular LED sysfs class, resulting in
> the creation of three distinct classes, one for red, green, and blue.
> The user then has to input three values into the three seperate
> brightness files within those classes. The multicolor LED framework
> makes the device easier to control with the multi_intensity file: the
> user can input three values at once to form a color, while still
> controlling the lightness with the brightness file.
>
> The main struct blinkm_led has changed slightly. A struct
> led_classdev_mc has been added to represent the multicolor sysfs class,
> and an additional struct led_classdev pointer has been added for
> convenience, which points to the struct led_classdev within struct
> led_classdev_mc. The struct led_classdev for the regular sysfs classes
> remain. Additionally, a field representing the multicolor LED has been
> added to the struct blinkm_data, seperate from the blinkm_leds[3] array.
>
> In the blinkm_probe function, the multicolor LED class is registered
> after the regular LED classes. The blinkm_set_mc_brightness() function
> had to be added to calculate the three color components and then set the
> fields of the blinkm_data structure accordingly.
>
> Signed-off-by: Joseph Strauss <jstrauss@...lbox.org>
> ---
> Changes in v2:
> - Replaced instances of the constant 3 with NUM_LEDS, where applicable
> - Fixed formatting errors
> - Replaced loop inside of blinkm_set_mc_brightness() with equivalent
>   statements
> - Changed id of multicolor class from 4 to 3
> - Replaced call to devm_kmalloc_array() with devm_kcalloc()
>
>  Documentation/leds/leds-blinkm.rst |  26 +++++-
>  drivers/leds/Kconfig               |   1 +
>  drivers/leds/leds-blinkm.c         | 143 +++++++++++++++++++++++------
>  3 files changed, 137 insertions(+), 33 deletions(-)
>
> diff --git a/Documentation/leds/leds-blinkm.rst b/Documentation/leds/leds-blinkm.rst
> index c74b5bc877b1..542a35432c57 100644
> --- a/Documentation/leds/leds-blinkm.rst
> +++ b/Documentation/leds/leds-blinkm.rst
> @@ -13,9 +13,27 @@ The device accepts RGB and HSB color values through separate commands.
>  Also you can store blinking sequences as "scripts" in
>  the controller and run them. Also fading is an option.
>
> -The interface this driver provides is 2-fold:
> +The interface this driver provides is 3-fold:
>
> -a) LED class interface for use with triggers
> +a) LED multicolor class interface for use with triggers
> +#######################################################
> +
> +The registration follows the scheme::
> +
> +  blinkm-<i2c-bus-nr>-<i2c-device-nr>-multi
> +
> +  $ ls -h /sys/class/leds/blinkm-1-9-multi
> +  brightness  device  max_brightness  multi_index  multi_intensity  power  subsystem  trigger  uevent
> +
> +The order in which to write the intensity values can be found in multi_index.
> +Exactly three values between 0 and 255 must be written to multi_intensity to change the color::
> +
> +  $ echo 255 100 50 > multi_intensity
> +
> +The overall brightness of the color that you choose can also be changed by
> +writing a value between 0 and 255 to the brightness file.
> +
> +b) LED class interface for use with triggers
>  ############################################
>
>  The registration follows the scheme::
> @@ -50,7 +68,7 @@ E.g.::
>    $
>
>
> -b) Sysfs group to control rgb, fade, hsb, scripts ...
> +c) Sysfs group to control rgb, fade, hsb, scripts ...
>  #####################################################
>
>  This extended interface is available as folder blinkm
> @@ -79,6 +97,6 @@ E.g.::
>
>
>
> -as of 6/2012
> +as of 12/2022
>
>  dl9pf <at> gmx <dot> de
> diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
> index 499d0f215a8b..8ec06f1f60af 100644
> --- a/drivers/leds/Kconfig
> +++ b/drivers/leds/Kconfig
> @@ -731,6 +731,7 @@ comment "LED driver for blink(1) USB RGB LED is under Special HID drivers (HID_T
>  config LEDS_BLINKM
>  	tristate "LED support for the BlinkM I2C RGB LED"
>  	depends on LEDS_CLASS
> +    depends on LEDS_CLASS_MULTICOLOR

Indentation?

>  	depends on I2C
>  	help
>  	  This option enables support for the BlinkM RGB LED connected
> diff --git a/drivers/leds/leds-blinkm.c b/drivers/leds/leds-blinkm.c
> index 3fb6a2fdaefa..252b20da7137 100644
> --- a/drivers/leds/leds-blinkm.c
> +++ b/drivers/leds/leds-blinkm.c
> @@ -15,6 +15,9 @@
>  #include <linux/pm_runtime.h>
>  #include <linux/leds.h>
>  #include <linux/delay.h>
> +#include <linux/led-class-multicolor.h>
> +
> +#define NUM_LEDS 3
>
>  /* Addresses to scan - BlinkM is on 0x09 by default*/
>  static const unsigned short normal_i2c[] = { 0x09, I2C_CLIENT_END };
> @@ -22,19 +25,26 @@ static const unsigned short normal_i2c[] = { 0x09, I2C_CLIENT_END };
>  static int blinkm_transfer_hw(struct i2c_client *client, int cmd);
>  static int blinkm_test_run(struct i2c_client *client);
>
> +/* Contains data structures for both the color-seperated sysfs classes, and the new multicolor class */
>  struct blinkm_led {
>  	struct i2c_client *i2c_client;
> -	struct led_classdev led_cdev;
> +	struct led_classdev monochrome_led_cdev;
> +	/* points to struct led_classdev inside of struct led_classdev_mc */

You mean mcled_cdev (1 line below) or something different?

If the former, why not just use mcled_cdev directly?

> +	struct led_classdev *led_cdev;
> +	struct led_classdev_mc mcled_cdev;
>  	int id;
>  };
>
> -#define cdev_to_blmled(c)          container_of(c, struct blinkm_led, led_cdev)
> +#define monochrome_led_cdev_to_blmled(c)	container_of(c, struct blinkm_led, monochrome_led_cdev)
> +#define mcled_cdev_to_led(c)				container_of(c, struct blinkm_led, mcled_cdev)
>
>  struct blinkm_data {
>  	struct i2c_client *i2c_client;
>  	struct mutex update_lock;
>  	/* used for led class interface */
> -	struct blinkm_led blinkm_leds[3];
> +	struct blinkm_led mc_blinkm_led;
> +	struct blinkm_led blinkm_leds[NUM_LEDS];

Why not just use the first element in the mc case?

>  	/* used for "blinkm" sysfs interface */
>  	u8 red;			/* color red */
>  	u8 green;		/* color green */
> @@ -419,11 +429,36 @@ static int blinkm_transfer_hw(struct i2c_client *client, int cmd)
>  	return 0;
>  }
>
> +static int blinkm_set_mc_brightness(struct led_classdev *led_cdev,
> +				 enum led_brightness value)
> +{
> +	struct led_classdev_mc *mcled_cdev;
> +	struct blinkm_led *led;
> +	struct blinkm_data *data;
> +
> +	mcled_cdev = lcdev_to_mccdev(led_cdev);
> +	led = mcled_cdev_to_led(mcled_cdev);

Do these 2 on the declaration lines.

> +	data = i2c_get_clientdata(led->i2c_client);
> +
> +	led_mc_calc_color_components(mcled_cdev, value);
> +
> +	data->next_red = (u8) mcled_cdev->subled_info[RED].brightness;
> +	data->next_green = (u8) mcled_cdev->subled_info[GREEN].brightness;
> +	data->next_blue = (u8) mcled_cdev->subled_info[BLUE].brightness;
> +
> +	blinkm_transfer_hw(led->i2c_client, BLM_GO_RGB);

'\n'

> +	dev_dbg(&led->i2c_client->dev,
> +			"# DONE # next_red = %d, next_green = %d, next_blue = %d\n",
> +			data->next_red, data->next_green,
> +			data->next_blue);

Please consider how useful this really is and delete it if possible.

> +	return 0;
> +}
> +
>  static int blinkm_led_common_set(struct led_classdev *led_cdev,
>  				 enum led_brightness value, int color)
>  {
>  	/* led_brightness is 0, 127 or 255 - we just use it here as-is */
> -	struct blinkm_led *led = cdev_to_blmled(led_cdev);
> +	struct blinkm_led *led = monochrome_led_cdev_to_blmled(led_cdev);
>  	struct blinkm_data *data = i2c_get_clientdata(led->i2c_client);
>
>  	switch (color) {
> @@ -480,8 +515,9 @@ static int blinkm_led_blue_set(struct led_classdev *led_cdev,
>
>  static void blinkm_init_hw(struct i2c_client *client)
>  {
> -	blinkm_transfer_hw(client, BLM_STOP_SCRIPT);
> -	blinkm_transfer_hw(client, BLM_GO_RGB);
> +	int ret;
> +	ret = blinkm_transfer_hw(client, BLM_STOP_SCRIPT);
> +	ret = blinkm_transfer_hw(client, BLM_GO_RGB);

This is an unused variable, no?

Did you build with W=1?

>  }
>
>  static int blinkm_test_run(struct i2c_client *client)
> @@ -569,7 +605,11 @@ static int blinkm_probe(struct i2c_client *client,
>  			const struct i2c_device_id *id)
>  {
>  	struct blinkm_data *data;
> -	struct blinkm_led *led[3];
> +	/* For multicolor support */
> +	struct blinkm_led *mc_led;
> +	struct mc_subled *mc_led_info;
> +	/* 3 seperate classes for red, green, and blue respectively */
> +	struct blinkm_led *leds[NUM_LEDS];
>  	int err, i;
>  	char blinkm_led_name[28];
>
> @@ -580,6 +620,12 @@ static int blinkm_probe(struct i2c_client *client,
>  		goto exit;
>  	}
>
> +	mc_led_info = devm_kcalloc(&client->dev, NUM_LEDS, sizeof(*mc_led_info),
> +					GFP_KERNEL);
> +	if (!mc_led_info) {
> +		err = -ENOMEM;
> +		goto exit;
> +	}
>  	data->i2c_addr = 0x08;
>  	/* i2c addr  - use fake addr of 0x08 initially (real is 0x09) */
>  	data->fw_ver = 0xfe;
> @@ -598,28 +644,30 @@ static int blinkm_probe(struct i2c_client *client,
>  		goto exit;
>  	}
>
> -	for (i = 0; i < 3; i++) {
> +
> +	/* Register red, green, and blue sysfs classes */
> +	for (i = 0; i < NUM_LEDS; i++) {
>  		/* RED = 0, GREEN = 1, BLUE = 2 */
> -		led[i] = &data->blinkm_leds[i];
> -		led[i]->i2c_client = client;
> -		led[i]->id = i;
> -		led[i]->led_cdev.max_brightness = 255;
> -		led[i]->led_cdev.flags = LED_CORE_SUSPENDRESUME;
> +		leds[i] = &data->blinkm_leds[i];
> +		leds[i]->i2c_client = client;
> +		leds[i]->id = i;
> +		leds[i]->monochrome_led_cdev.max_brightness = 255;
> +		leds[i]->monochrome_led_cdev.flags = LED_CORE_SUSPENDRESUME;
>  		switch (i) {
>  		case RED:
>  			snprintf(blinkm_led_name, sizeof(blinkm_led_name),
>  					 "blinkm-%d-%d-red",
>  					 client->adapter->nr,
>  					 client->addr);
> -			led[i]->led_cdev.name = blinkm_led_name;
> -			led[i]->led_cdev.brightness_set_blocking =
> +			leds[i]->monochrome_led_cdev.name = blinkm_led_name;
> +			leds[i]->monochrome_led_cdev.brightness_set_blocking =
>  							blinkm_led_red_set;
>  			err = led_classdev_register(&client->dev,
> -						    &led[i]->led_cdev);
> +						    &leds[i]->monochrome_led_cdev);
>  			if (err < 0) {
>  				dev_err(&client->dev,
>  					"couldn't register LED %s\n",
> -					led[i]->led_cdev.name);
> +					leds[i]->monochrome_led_cdev.name);
>  				goto failred;
>  			}
>  			break;
> @@ -628,15 +676,15 @@ static int blinkm_probe(struct i2c_client *client,
>  					 "blinkm-%d-%d-green",
>  					 client->adapter->nr,
>  					 client->addr);
> -			led[i]->led_cdev.name = blinkm_led_name;
> -			led[i]->led_cdev.brightness_set_blocking =
> +			leds[i]->monochrome_led_cdev.name = blinkm_led_name;
> +			leds[i]->monochrome_led_cdev.brightness_set_blocking =
>  							blinkm_led_green_set;
>  			err = led_classdev_register(&client->dev,
> -						    &led[i]->led_cdev);
> +						    &leds[i]->monochrome_led_cdev);
>  			if (err < 0) {
>  				dev_err(&client->dev,
>  					"couldn't register LED %s\n",
> -					led[i]->led_cdev.name);
> +					leds[i]->monochrome_led_cdev.name);
>  				goto failgreen;
>  			}
>  			break;
> @@ -645,34 +693,70 @@ static int blinkm_probe(struct i2c_client *client,
>  					 "blinkm-%d-%d-blue",
>  					 client->adapter->nr,
>  					 client->addr);
> -			led[i]->led_cdev.name = blinkm_led_name;
> -			led[i]->led_cdev.brightness_set_blocking =
> +			leds[i]->monochrome_led_cdev.name = blinkm_led_name;
> +			leds[i]->monochrome_led_cdev.brightness_set_blocking =
>  							blinkm_led_blue_set;
>  			err = led_classdev_register(&client->dev,
> -						    &led[i]->led_cdev);
> +						    &leds[i]->monochrome_led_cdev);
>  			if (err < 0) {
>  				dev_err(&client->dev,
>  					"couldn't register LED %s\n",
> -					led[i]->led_cdev.name);
> +					leds[i]->monochrome_led_cdev.name);
>  				goto failblue;
>  			}
>  			break;
>  		}		/* end switch */
>  	}			/* end for */
>
> +	/* Register multicolor sysfs class */
> +	mc_led = &data->mc_blinkm_led;
> +	mc_led->i2c_client = client;
> +	mc_led->id = 3;

NUM_LEDS?

> +	mc_led_info[0].color_index = LED_COLOR_ID_RED;

These magic numbers should be defined.

> +	mc_led_info[0].channel = 0;

Are these channel numbers arbitrary?

> +	mc_led_info[1].color_index = LED_COLOR_ID_GREEN;
> +	mc_led_info[1].channel = 1;
> +	mc_led_info[2].color_index = LED_COLOR_ID_BLUE;
> +	mc_led_info[2].channel = 2;
> +	mc_led->mcled_cdev.subled_info = mc_led_info;
> +	mc_led->mcled_cdev.num_colors = NUM_LEDS;
> +
> +	mc_led->led_cdev = &mc_led->mcled_cdev.led_cdev;
> +	mc_led->led_cdev->brightness = 255;
> +	mc_led->led_cdev->max_brightness = 255;
> +	mc_led->led_cdev->flags = LED_CORE_SUSPENDRESUME;
> +	snprintf(blinkm_led_name, sizeof(blinkm_led_name),
> +		 "blinkm-%d-%d-multi",
> +		 client->adapter->nr,
> +		 client->addr);
> +	mc_led->led_cdev->name = blinkm_led_name;
> +	mc_led->led_cdev->brightness_set_blocking =
> +					blinkm_set_mc_brightness;

100-chars.

> +	err = led_classdev_multicolor_register(&client->dev, &mc_led->mcled_cdev);
> +	if (err < 0) {
> +		dev_err(&client->dev, "couldn't register LED %s\n",
> +				mc_led->led_cdev->name);
> +		goto failmulti;
> +	}

'\n'

>  	/* Initialize the blinkm */

This comment is superfluous.

>  	blinkm_init_hw(client);
>
>  	return 0;
>
> +failmulti:
> +	led_classdev_unregister(&leds[BLUE]->monochrome_led_cdev);
> +
>  failblue:
> -	led_classdev_unregister(&led[GREEN]->led_cdev);
> +	led_classdev_unregister(&leds[GREEN]->monochrome_led_cdev);
>
>  failgreen:
> -	led_classdev_unregister(&led[RED]->led_cdev);
> +	led_classdev_unregister(&leds[RED]->monochrome_led_cdev);
>
>  failred:
>  	sysfs_remove_group(&client->dev.kobj, &blinkm_group);
> +
>  exit:

If you want to submit a patch to get rid of this exit label ...

>  	return err;
>  }
> @@ -684,8 +768,9 @@ static void blinkm_remove(struct i2c_client *client)
>  	int i;
>
>  	/* make sure no workqueue entries are pending */
> -	for (i = 0; i < 3; i++)
> -		led_classdev_unregister(&data->blinkm_leds[i].led_cdev);
> +	led_classdev_unregister(&data->mc_blinkm_led.mcled_cdev.led_cdev);
> +	for (i = 0; i < NUM_LEDS; i++)
> +		led_classdev_unregister(&data->blinkm_leds[i].monochrome_led_cdev);
>
>  	/* reset rgb */
>  	data->next_red = 0x00;
> --
> 2.38.1
>

--
Lee Jones [李琼斯]

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