Re: [PATCH v5] Add multicolor support to BlinkM LED driver

From: Joseph Strauss
Date: Wed Feb 14 2024 - 12:40:51 EST

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On 24/01/25 01:22PM, Lee Jones wrote:
> On Sun, 14 Jan 2024, Joseph Strauss wrote:
>
> > Add 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. The struct led_classdev
> > for the regular sysfs classes remain. The blinkm_probe function checks
> > CONFIG_LEDS_BLINKM_MULTICOLOR to decide whether to load the seperate
> > sysfs classes or the single multicolor one, but never both. 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.
> >
> > All of the feedback has been much appreciated. Thanks!
>
> This needs to go below the '---'.
>
> So you've had feedback but no positive reviews resulting in a *-by?
Correct, I've received feedback, but no positive reviews.
>
> Have you Cc:ed all of your reviewers in this version?
>
> > Signed-off-by: Joseph Strauss <jstrauss@xxxxxxxxxxx>
> > ---
> > 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()
> > Changes in v3:
> > - Add CONFIG_LEDS_BLINKM_MULTICOLOR to check whether to use multicolor
> > funcitonality
> > - Extend well-known-leds.txt to include standard names for RGB and indicator
> > LEDS
> > - Change name of Blinkm sysfs class according to well-known-leds.txt
> > - Simplify struct blinkm_led and struct blinkm_data
> > - Remove magic numbers
> > - Fix formatting errors
> > - Remove unrelated changes
> > Changes in v4:
> > - Fix indentation
> > - Add default case to switch statement
> > Changes in v5:
> > - Fix warnings related to snprintf on s390 architecture, reported by
> > 0-DAY CI Kernel Test Service
> >
> > Documentation/leds/leds-blinkm.rst | 27 ++-
> > Documentation/leds/well-known-leds.txt | 8 +
> > drivers/leds/Kconfig | 8 +
> > drivers/leds/leds-blinkm.c | 217 +++++++++++++++++--------
> > 4 files changed, 185 insertions(+), 75 deletions(-)
>
> Looking pretty good. Just a couple of minor nits.
>
> > diff --git a/Documentation/leds/leds-blinkm.rst b/Documentation/leds/leds-blinkm.rst
> > index c74b5bc877b1..16883c2a9a99 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>:rgb:indicator
> > +
> > + $ ls -h /sys/class/leds/blinkm-1-9:rgb:indicator
>
> The `-h` is superfluous, no?
The current leds-blinkm.rst documentation file uses `ls -h` in several
other places, so I continued the pattern. But it does seem superfluous.
Would it be better to remove the `-h` only from the line I added, or the
other instances as well?
>
> > + 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::
>
> :: ?
I used :: here because I thought a shell command should be shown as
code in the documentation.
>
> > +
> > + $ 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.
>
> So what's the difference between brightness and intensity?
Documentation/leds/leds-class-multicolor.rst describes the
multi_intensity file as controlling the hue of the LED, whereas the
brightness file controls the lightness. I could change my documentation
to say "The overall lightness of the color that you choose..." to
clarify that.
>
> > +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 +97,7 @@ E.g.::
> >
> >
> >
> > -as of 6/2012
> > +as of 01/2024
> >
> > dl9pf <at> gmx <dot> de
> > +jstrauss <at> mailbox <dot> org
> > diff --git a/Documentation/leds/well-known-leds.txt b/Documentation/leds/well-known-leds.txt
> > index 2160382c86be..2ac4eaed1454 100644
> > --- a/Documentation/leds/well-known-leds.txt
> > +++ b/Documentation/leds/well-known-leds.txt
> > @@ -70,3 +70,11 @@ Good: "platform:*:charging" (allwinner sun50i)
> > * Screen
> >
> > Good: ":backlight" (Motorola Droid 4)
> > +
> > +* Indicators
> > +
> > +Good: ":indicator" (Blinkm)
> > +
> > +* RGB
> > +
> > +Good: ":rgb" (Blinkm)
> > diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
> > index 499d0f215a8b..f38d786f9a89 100644
> > --- a/drivers/leds/Kconfig
> > +++ b/drivers/leds/Kconfig
> > @@ -736,6 +736,14 @@ config LEDS_BLINKM
> > This option enables support for the BlinkM RGB LED connected
> > through I2C. Say Y to enable support for the BlinkM LED.
> >
> > +config LEDS_BLINKM_MULTICOLOR
> > + bool "Enable multicolor support for BlinkM I2C RGB LED"
> > + depends on LEDS_BLINKM
> > + depends on LEDS_CLASS_MULTICOLOR
> > + help
> > + This option enables multicolor sysfs class support for BlinkM LED and
> > + disables the older, separated sysfs interface
> > +
> > config LEDS_POWERNV
> > tristate "LED support for PowerNV Platform"
> > depends on LEDS_CLASS
> > diff --git a/drivers/leds/leds-blinkm.c b/drivers/leds/leds-blinkm.c
> > index e19cc8a7b7ca..d6ce2cccb816 100644
> > --- a/drivers/leds/leds-blinkm.c
> > +++ b/drivers/leds/leds-blinkm.c
> > @@ -2,6 +2,7 @@
> > /*
> > * leds-blinkm.c
> > * (c) Jan-Simon Möller (dl9pf@xxxxxx)
> > + * (c) Joseph Strauss (jstrauss@xxxxxxxxxxx)
> > */
> >
> > #include <linux/module.h>
> > @@ -15,6 +16,10 @@
> > #include <linux/pm_runtime.h>
> > #include <linux/leds.h>
> > #include <linux/delay.h>
> > +#include <linux/led-class-multicolor.h>
> > +#include <linux/kconfig.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 +27,24 @@ 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;
> > + /* used when multicolor support is disabled */
>
> There's a syntax for either/or in structs. Isn't it 'union'?
>
> Can/does that apply here?
Yes, I think that would be applicable. led_cdev and mcled_cdev are used
in two seperate cases.
>
> > 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 led_cdev_to_blmled(c) container_of(c, struct blinkm_led, 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 blinkm_leds[NUM_LEDS];
> > +
> > /* used for "blinkm" sysfs interface */
> > u8 red; /* color red */
> > u8 green; /* color green */
> > @@ -419,11 +429,29 @@ 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 = lcdev_to_mccdev(led_cdev);
> > + struct blinkm_led *led = mcled_cdev_to_led(mcled_cdev);
> > + struct blinkm_data *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);
> > +
> > + 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 = led_cdev_to_blmled(led_cdev);
> > struct blinkm_data *data = i2c_get_clientdata(led->i2c_client);
> >
> > switch (color) {
> > @@ -569,7 +597,11 @@ 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 +612,12 @@ 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;
> > @@ -598,81 +636,118 @@ static int blinkm_probe(struct i2c_client *client,
> > goto exit;
> > }
> >
> > - for (i = 0; i < 3; 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;
> > - 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 =
> > - blinkm_led_red_set;
> > - err = led_classdev_register(&client->dev,
> > - &led[i]->led_cdev);
> > - if (err < 0) {
> > - dev_err(&client->dev,
> > - "couldn't register LED %s\n",
> > - led[i]->led_cdev.name);
> > - goto failred;
> > - }
> > - break;
> > - case GREEN:
> > - snprintf(blinkm_led_name, sizeof(blinkm_led_name),
> > - "blinkm-%d-%d-green",
> > - client->adapter->nr,
> > - client->addr);
> > - led[i]->led_cdev.name = blinkm_led_name;
> > - led[i]->led_cdev.brightness_set_blocking =
> > - blinkm_led_green_set;
> > - err = led_classdev_register(&client->dev,
> > - &led[i]->led_cdev);
> > - if (err < 0) {
> > - dev_err(&client->dev,
> > - "couldn't register LED %s\n",
> > - led[i]->led_cdev.name);
> > - goto failgreen;
> > - }
> > - break;
> > - case BLUE:
> > - snprintf(blinkm_led_name, sizeof(blinkm_led_name),
> > - "blinkm-%d-%d-blue",
> > - client->adapter->nr,
> > - client->addr);
> > - led[i]->led_cdev.name = blinkm_led_name;
> > - led[i]->led_cdev.brightness_set_blocking =
> > - blinkm_led_blue_set;
> > - err = led_classdev_register(&client->dev,
> > - &led[i]->led_cdev);
> > - if (err < 0) {
> > - dev_err(&client->dev,
> > - "couldn't register LED %s\n",
> > - led[i]->led_cdev.name);
> > - goto failblue;
> > - }
> > - break;
> > - } /* end switch */
> > - } /* end for */
> > -
> > - /* Initialize the blinkm */
> > + if (!IS_ENABLED(CONFIG_LEDS_BLINKM_MULTICOLOR)) {
> > + /* Register red, green, and blue sysfs classes */
> > + for (i = 0; i < NUM_LEDS; i++) {
>
> *Even* more indentation!
>
> Probably worth moving the whole section into a function at this point.
Yes, I think you are right. Thank you for the review.
>
> > + /* RED = 0, GREEN = 1, BLUE = 2 */
> > + leds[i] = &data->blinkm_leds[i];
> > + leds[i]->i2c_client = client;
> > + leds[i]->id = i;
> > + leds[i]->led_cdev.max_brightness = 255;
> > + leds[i]->led_cdev.flags = LED_CORE_SUSPENDRESUME;
> > + switch (i) {
> > + case RED:
> > + scnprintf(blinkm_led_name, sizeof(blinkm_led_name),
> > + "blinkm-%d-%d-red",
> > + client->adapter->nr,
> > + client->addr);
> > + leds[i]->led_cdev.name = blinkm_led_name;
> > + leds[i]->led_cdev.brightness_set_blocking =
> > + blinkm_led_red_set;
> > + err = led_classdev_register(&client->dev,
> > + &leds[i]->led_cdev);
> > + if (err < 0) {
> > + dev_err(&client->dev,
> > + "couldn't register LED %s\n",
> > + leds[i]->led_cdev.name);
> > + goto failred;
> > + }
> > + break;
> > + case GREEN:
> > + scnprintf(blinkm_led_name, sizeof(blinkm_led_name),
> > + "blinkm-%d-%d-green",
> > + client->adapter->nr,
> > + client->addr);
> > + leds[i]->led_cdev.name = blinkm_led_name;
> > + leds[i]->led_cdev.brightness_set_blocking =
> > + blinkm_led_green_set;
> > + err = led_classdev_register(&client->dev,
> > + &leds[i]->led_cdev);
> > + if (err < 0) {
> > + dev_err(&client->dev,
> > + "couldn't register LED %s\n",
> > + leds[i]->led_cdev.name);
> > + goto failgreen;
> > + }
> > + break;
> > + case BLUE:
> > + scnprintf(blinkm_led_name, sizeof(blinkm_led_name),
> > + "blinkm-%d-%d-blue",
> > + client->adapter->nr,
> > + client->addr);
> > + leds[i]->led_cdev.name = blinkm_led_name;
> > + leds[i]->led_cdev.brightness_set_blocking =
> > + blinkm_led_blue_set;
> > + err = led_classdev_register(&client->dev,
> > + &leds[i]->led_cdev);
> > + if (err < 0) {
> > + dev_err(&client->dev,
> > + "couldn't register LED %s\n",
> > + leds[i]->led_cdev.name);
> > + goto failblue;
> > + }
> > + break;
> > + default:
> > + break;
> > + } /* end switch */
> > + } /* end for */
> > + } else {
> > + /* Register multicolor sysfs class */
> > + /* The first element of leds is used for multicolor facilities */
> > + mc_led = &data->blinkm_leds[RED];
> > + mc_led->i2c_client = client;
> > +
> > + mc_led_info[RED].color_index = LED_COLOR_ID_RED;
> > + mc_led_info[GREEN].color_index = LED_COLOR_ID_GREEN;
> > + mc_led_info[BLUE].color_index = LED_COLOR_ID_BLUE;
> > +
> > + mc_led->mcled_cdev.subled_info = mc_led_info;
> > + mc_led->mcled_cdev.num_colors = NUM_LEDS;
> > + mc_led->mcled_cdev.led_cdev.brightness = 255;
> > + mc_led->mcled_cdev.led_cdev.max_brightness = 255;
> > + mc_led->mcled_cdev.led_cdev.flags = LED_CORE_SUSPENDRESUME;
> > +
> > + scnprintf(blinkm_led_name, sizeof(blinkm_led_name),
> > + "blinkm-%d-%d:rgb:indicator",
> > + client->adapter->nr,
> > + client->addr);
> > + mc_led->mcled_cdev.led_cdev.name = blinkm_led_name;
> > + mc_led->mcled_cdev.led_cdev.brightness_set_blocking = blinkm_set_mc_brightness;
> > +
> > + 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;
> > + }
> > + }
> > +
> > blinkm_init_hw(client);
> >
> > return 0;
> >
> > +failmulti:
> > + led_classdev_unregister(&leds[BLUE]->led_cdev);
> > +
> > failblue:
> > - led_classdev_unregister(&led[GREEN]->led_cdev);
> > + led_classdev_unregister(&leds[GREEN]->led_cdev);
> >
> > failgreen:
> > - led_classdev_unregister(&led[RED]->led_cdev);
> > + led_classdev_unregister(&leds[RED]->led_cdev);
> >
> > failred:
> > sysfs_remove_group(&client->dev.kobj, &blinkm_group);
> > +
> > exit:
> > return err;
> > }
> > @@ -684,7 +759,7 @@ static void blinkm_remove(struct i2c_client *client)
> > int i;
> >
> > /* make sure no workqueue entries are pending */
> > - for (i = 0; i < 3; i++)
> > + for (i = 0; i < NUM_LEDS; i++)
> > led_classdev_unregister(&data->blinkm_leds[i].led_cdev);
> >
> > /* reset rgb */
> > @@ -741,6 +816,6 @@ static struct i2c_driver blinkm_driver = {
> > module_i2c_driver(blinkm_driver);
> >
> > MODULE_AUTHOR("Jan-Simon Moeller <dl9pf@xxxxxx>");
> > +MODULE_AUTHOR("Joseph Strauss <jstrauss@xxxxxxxxxxx>");
> > MODULE_DESCRIPTION("BlinkM RGB LED driver");
> > MODULE_LICENSE("GPL");
> > -
> > --
> > 2.42.0
> >
>
> --
> 1)
> Lee Jones [李琼斯]

Joseph Strauss

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