[PATCH] led: led_pwm: Add a driver for LEDs connected to PWM

[Simon Glass]

Hi Ivan,

On Sun, 27 Feb 2022 at 11:16, Ivan Vozvakhov <i.vozvakhov at corp.mail.ru> wrote:
>
> From: Ivan Vozvakhov <i.vozvakhov at vk.team>
>
> Add a driver which allows to use of LEDs connected
> to PWM (Linux compatible).
> MAINTAINERS: add i.vozvakhov as a maintainer of leds-pwm
> (required during new functionality adding).
>
> Signed-off-by: Ivan Vozvakhov <i.vozvakhov at vk.team>
> Signed-off-by: Ivan Vozvakhov <i.vozvakhov at corp.mail.ru>
> ---
>
>  MAINTAINERS                                |   6 +
>  doc/device-tree-bindings/leds/leds-pwm.txt |  47 +++++
>  drivers/led/Kconfig                        |   6 +
>  drivers/led/Makefile                       |   1 +
>  drivers/led/led_pwm.c                      | 189 +++++++++++++++++++++
>  5 files changed, 249 insertions(+)
>  create mode 100644 doc/device-tree-bindings/leds/leds-pwm.txt
>  create mode 100644 drivers/led/led_pwm.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index fb171e0c68..2e8f8cdada 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -869,6 +869,12 @@ F: doc/README.kwbimage
>  F:     doc/kwboot.1
>  F:     tools/kwb*
>
> +LED
> +M:     Ivan Vozvakhov <i.vozvakhov at vk.team>
> +S:     Supported
> +F:     doc/device-tree-bindings/leds/leds-pwm.txt
> +F:     drivers/led/led_pwm.c
> +
>  LOGGING
>  M:     Simon Glass <sjg at chromium.org>
>  S:     Maintained
> diff --git a/doc/device-tree-bindings/leds/leds-pwm.txt b/doc/device-tree-bindings/leds/leds-pwm.txt
> new file mode 100644
> index 0000000000..186e8a848f
> --- /dev/null
> +++ b/doc/device-tree-bindings/leds/leds-pwm.txt
> @@ -0,0 +1,47 @@
> +LEDs connected to PWM (Linux compatible)
> +
> +Required properties:
> +- compatible : should be "pwm-leds".
> +
> +Each LED is represented as a sub-node of the pwm-leds device.  Each
> +node's name represents the name of the corresponding LED.
> +
> +LED sub-node properties:
> +- pwms :  (required) LED pwm channel, see "pwms property" in
> +  doc/device-tree-bindings/pwm/pwm.txt
> +- label :  (optional) LED label, see "label property" in
> +  doc/device-tree-bindings/led/common.txt
> +- max-brightness :  (optional, unsigned, default 255) Maximum brightness possible
> +  for the LED
> +- active-low :  (optional, boolean, default false) For PWMs where the LED is
> +  wired to supply rather than ground
> +- u-boot,default-brightness :  (optional, unsigned, default 0) Initial state
> +  of pwm-leds
> +
> +Example:
> +
> +leds {
> +    compatible = "pwm-leds";
> +    status = "okay";
> +
> +    blue {
> +        label = "led-blue";
> +        pwms = <&pwm1 0 100000 0>;
> +        max-brightness = <255>;
> +        u-boot,default-brightness = <127>;
> +    };
> +
> +    green {
> +        label = "led-green";
> +        pwms = <&pwm2 0 100000 0>;
> +        max-brightness = <255>;
> +        u-boot,default-brightness = <127>;
> +    };
> +
> +    red {
> +        label = "led-red";
> +        pwms = <&pwm3 0 100000 0>;
> +        max-brightness = <255>;
> +        u-boot,default-brightness = <127>;
> +    };
> +}
> diff --git a/drivers/led/Kconfig b/drivers/led/Kconfig
> index cc87fbf395..48616e2f55 100644
> --- a/drivers/led/Kconfig
> +++ b/drivers/led/Kconfig
> @@ -42,6 +42,12 @@ config LED_CORTINA
>           This option enables support for LEDs connected to the Cortina
>           Access CAxxxx SOCs.
>
> +config LED_PWM
> +       bool "LED PWM"
> +       depends on LED && DM_PWM
> +       help
> +         Enable support for LEDs connected to PWM.
> +         Linux compatible ofdata.
>
>  config LED_BLINK
>         bool "Support LED blinking"
> diff --git a/drivers/led/Makefile b/drivers/led/Makefile
> index 8e3ae7f146..c31a59e1aa 100644
> --- a/drivers/led/Makefile
> +++ b/drivers/led/Makefile
> @@ -7,5 +7,6 @@ obj-y += led-uclass.o
>  obj-$(CONFIG_LED_BCM6328) += led_bcm6328.o
>  obj-$(CONFIG_LED_BCM6358) += led_bcm6358.o
>  obj-$(CONFIG_LED_BCM6858) += led_bcm6858.o
> +obj-$(CONFIG_LED_PWM) += led_pwm.o
>  obj-$(CONFIG_$(SPL_)LED_GPIO) += led_gpio.o
>  obj-$(CONFIG_LED_CORTINA) += led_cortina.o
> diff --git a/drivers/led/led_pwm.c b/drivers/led/led_pwm.c
> new file mode 100644
> index 0000000000..d36ce4c0df
> --- /dev/null
> +++ b/drivers/led/led_pwm.c
> @@ -0,0 +1,189 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Copyright (C) 2022 VK
> + * Author: Ivan Vozvakhov <i.vozvakhov at vk.team>
> + */
> +
> +#include <common.h>
> +#include <dm.h>
> +#include <errno.h>
> +#include <led.h>
> +#include <malloc.h>
> +#include <dm/lists.h>
> +#include <pwm.h>
> +
> +#define LEDS_PWM_DRIVER_NAME   "led_pwm"
> +

Please add a proper struct comment describing these values and what
they mean...e.g. if polarity is true, what does that mean?

> +struct led_pwm_priv {
> +       struct udevice *pwm;
> +       uint active_low;        /* polarity */
> +       uint period;    /* period_ns */
> +       uint duty;
> +       uint channel;
> +       bool enabled;
> +       bool polarity;
> +};
> +

[..]

Regards,
Simon