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Date: Fri, 7 Oct 2022 08:46:31 +0200
From: Jean-Jacques Hiblot <jjhiblot@...phandler.com>
To: Jacek Anaszewski <jacek.anaszewski@...il.com>, <pavel@....cz>,
<robh+dt@...nel.org>, <sven.schwermer@...ruptive-technologies.com>,
<krzysztof.kozlowski+dt@...aro.org>
CC: <johan+linaro@...nel.org>, <marijn.suijten@...ainline.org>,
<bjorn.andersson@...aro.org>, <andy.shevchenko@...il.com>,
<linux-leds@...r.kernel.org>, <devicetree@...r.kernel.org>,
<linux-kernel@...r.kernel.org>, <sha@...gutronix.de>
Subject: Re: [RESEND PATCH v3 4/4] leds: Add a multicolor LED driver to group
monochromatic LEDs
On 18/09/2022 16:54, Jacek Anaszewski wrote:
> Hi Jean,
>
> General question to this driver: since it seems that it is allowed to
> have duplicate LEDs of the same color, then it will be impossible to
> distinguish which of the two same colors in multi_index file will refer
> to which physical LED. Are you aware of this shortcoming?
Hi Jacek,
yes I'm aware of this, but I don't think it can be a problem in a real
environment. There will probably few cases were multiple leds of the
same color are used and even fewer were those leds need to be controlled
differently.
>
> Besides that I have two remarks below.
>
> On 9/17/22 10:13, Jean-Jacques Hiblot wrote:
>> By allowing to group multiple monochrome LED into multicolor LEDs,
>> all involved LEDs can be controlled in-sync. This enables using effects
>> using triggers, etc.
>>
>> Signed-off-by: Jean-Jacques Hiblot <jjhiblot@...phandler.com>
>> ---
>> drivers/leds/rgb/Kconfig | 6 +
>> drivers/leds/rgb/Makefile | 1 +
>> drivers/leds/rgb/leds-group-multicolor.c | 153 +++++++++++++++++++++++
>> 3 files changed, 160 insertions(+)
>> create mode 100644 drivers/leds/rgb/leds-group-multicolor.c
>>
>> diff --git a/drivers/leds/rgb/Kconfig b/drivers/leds/rgb/Kconfig
>> index 204cf470beae..c2610c47a82d 100644
>> --- a/drivers/leds/rgb/Kconfig
>> +++ b/drivers/leds/rgb/Kconfig
>> @@ -2,6 +2,12 @@
>> if LEDS_CLASS_MULTICOLOR
>> +config LEDS_GRP_MULTICOLOR
>> + tristate "Multi-color LED grouping support"
>> + help
>> + This option enables support for monochrome LEDs that are
>> + grouped into multicolor LEDs.
>> +
>> config LEDS_PWM_MULTICOLOR
>> tristate "PWM driven multi-color LED Support"
>> depends on PWM
>> diff --git a/drivers/leds/rgb/Makefile b/drivers/leds/rgb/Makefile
>> index 0675bc0f6e18..4de087ad79bc 100644
>> --- a/drivers/leds/rgb/Makefile
>> +++ b/drivers/leds/rgb/Makefile
>> @@ -1,4 +1,5 @@
>> # SPDX-License-Identifier: GPL-2.0
>> +obj-$(CONFIG_LEDS_GRP_MULTICOLOR) += leds-group-multicolor.o
>> obj-$(CONFIG_LEDS_PWM_MULTICOLOR) += leds-pwm-multicolor.o
>> obj-$(CONFIG_LEDS_QCOM_LPG) += leds-qcom-lpg.o
>> diff --git a/drivers/leds/rgb/leds-group-multicolor.c
>> b/drivers/leds/rgb/leds-group-multicolor.c
>> new file mode 100644
>> index 000000000000..61f9e1954fc4
>> --- /dev/null
>> +++ b/drivers/leds/rgb/leds-group-multicolor.c
>> @@ -0,0 +1,153 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + * multi-color LED built with monochromatic LED devices
>> + *
>> + * Copyright 2022 Jean-Jacques Hiblot <jjhiblot@...phandler.com>
>> + */
>> +
>> +#include <linux/err.h>
>> +#include <linux/leds.h>
>> +#include <linux/led-class-multicolor.h>
>> +#include <linux/math.h>
>> +#include <linux/module.h>
>> +#include <linux/mod_devicetable.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/property.h>
>> +
>> +struct led_mcg_priv {
>> + struct led_classdev_mc mc_cdev;
>> + struct led_classdev **monochromatics;
>> +};
>> +
>> +static int led_mcg_set(struct led_classdev *cdev,
>> + enum led_brightness brightness)
>> +{
>> + struct led_classdev_mc *mc_cdev = lcdev_to_mccdev(cdev);
>> + struct led_mcg_priv *priv =
>> + container_of(mc_cdev, struct led_mcg_priv, mc_cdev);
>> + int i;
>> +
>> + led_mc_calc_color_components(mc_cdev, brightness);
>> +
>> + for (i = 0; i < mc_cdev->num_colors; i++) {
>> + struct led_classdev *mono = priv->monochromatics[i];
>> + int actual_led_brightness;
>> +
>> + /*
>> + * Scale the intensity according the max brightness of the
>> + * monochromatic LED
> s/according the/according to the/
>
>> + */
>> + actual_led_brightness = DIV_ROUND_CLOSEST(
>> + mono->max_brightness * mc_cdev->subled_info[i].brightness,
>> + mc_cdev->led_cdev.max_brightness);
>
> How about dropping above usage of led_mc_calc_color_components()
> helper in favour of doing all required calculations here?
> It would be easier for the reader to grasp the idea then.
>
>> +
>> + led_set_brightness(mono, actual_led_brightness);
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static int led_mcg_probe(struct platform_device *pdev)
>> +{
>> + struct device *dev = &pdev->dev;
>> + struct led_init_data init_data = {};
>> + struct led_classdev *cdev;
>> + struct mc_subled *subled;
>> + struct led_mcg_priv *priv;
>> + int i, count, ret;
>> + unsigned int max_brightness;
>> +
>> + priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
>> + if (!priv)
>> + return -ENOMEM;
>> +
>> + count = 0;
>> + max_brightness = 0;
>> + for (;;) {
>> + struct led_classdev *led_cdev;
>> +
>> + led_cdev = devm_of_led_get(dev, count);
>> + if (IS_ERR(led_cdev)) {
>> + /* Reached the end of the list ? */
>> + if (PTR_ERR(led_cdev) == -ENOENT)
>> + break;
>> + return dev_err_probe(dev, PTR_ERR(led_cdev),
>> + "Unable to get led #%d", count);
>> + }
>> + count++;
>> +
>> + priv->monochromatics = devm_krealloc(dev, priv->monochromatics,
>> + count * sizeof(*priv->monochromatics),
>> + GFP_KERNEL);
>> + if (!priv->monochromatics)
>> + return -ENOMEM;
>> +
>> + priv->monochromatics[count - 1] = led_cdev;
>> +
>> + max_brightness = max(max_brightness, led_cdev->max_brightness);
>> + }
>> +
>> + subled = devm_kzalloc(dev, count * sizeof(*subled), GFP_KERNEL);
>> + if (!subled)
>> + return -ENOMEM;
>> + priv->mc_cdev.subled_info = subled;
>> +
>> + for (i = 0; i < count; i++) {
>> + struct led_classdev *led_cdev = priv->monochromatics[i];
>> +
>> + subled[i].color_index = led_cdev->color;
>> + /* configure the LED intensity to its maximum */
>> + subled[i].intensity = max_brightness;
>> + }
>> +
>> + /* init the multicolor's LED class device */
>> + cdev = &priv->mc_cdev.led_cdev;
>> + cdev->flags = LED_CORE_SUSPENDRESUME;
>> + cdev->brightness_set_blocking = led_mcg_set;
>> + cdev->max_brightness = max_brightness;
>> + cdev->color = LED_COLOR_ID_MULTI;
>> + priv->mc_cdev.num_colors = count;
>> +
>> + init_data.fwnode = dev_fwnode(dev);
>> + ret = devm_led_classdev_multicolor_register_ext(dev,
>> &priv->mc_cdev,
>> + &init_data);
>> + if (ret)
>> + return dev_err_probe(dev, ret,
>> + "failed to register multicolor led for %s.\n",
>> + cdev->name);
>> +
>> + ret = led_mcg_set(cdev, cdev->brightness);
>> + if (ret)
>> + return dev_err_probe(dev, ret,
>> + "failed to set led value for %s.",
>> + cdev->name);
>> +
>> + for (i = 0; i < count; i++) {
>> + struct led_classdev *led_cdev = priv->monochromatics[i];
>> +
>> + /* Make the sysfs of the monochromatic LED read-only */
>> + led_cdev->flags |= LED_SYSFS_DISABLE;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static const struct of_device_id of_led_mcg_match[] = {
>> + { .compatible = "leds-group-multicolor" },
>> + {}
>> +};
>> +MODULE_DEVICE_TABLE(of, of_led_mcg_match);
>> +
>> +static struct platform_driver led_mcg_driver = {
>> + .probe = led_mcg_probe,
>> + .driver = {
>> + .name = "leds_group_multicolor",
>> + .of_match_table = of_led_mcg_match,
>> + }
>> +};
>> +module_platform_driver(led_mcg_driver);
>> +
>> +MODULE_AUTHOR("Jean-Jacques Hiblot <jjhiblot@...phandler.com>");
>> +MODULE_DESCRIPTION("multi-color LED group driver");
>> +MODULE_LICENSE("GPL");
>> +MODULE_ALIAS("platform:leds-group-multicolor");
>
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