Commit bb642062 authored by LI Qingwu's avatar LI Qingwu Committed by Lee Jones
Browse files

leds: pwm: Add optional GPIO enable pin support 



Add support for optional GPIO-based enable pin control to PWM LED driver.
Some PWM LED driver chips like TPS92380 and LT3743 require a separate
enable signal in addition to PWM control. Implement support for such
GPIO control through the "enable-gpios" device tree property, activating
the pin when LED brightness is non-zero and deactivating it when off.

Tested on i.MX8MP EVK with TPS92380 LED driver chip

Signed-off-by: default avatarLI Qingwu <Qing-wu.Li@leica-geosystems.com.cn>
Link: https://patch.msgid.link/20251117054511.730246-2-Qing-wu.Li@leica-geosystems.com.cn


Signed-off-by: default avatarLee Jones <lee@kernel.org>
parent d7dca03a

drivers/leds/leds-pwm.c

+19 −0
Original line number Diff line number Diff line
@@ -9,6 +9,7 @@ 
 * based on leds-gpio.c by Raphael Assenat <raph@8d.com>

 */



#include <linux/gpio/consumer.h>

#include <linux/module.h>

#include <linux/kernel.h>

#include <linux/platform_device.h>
@@ -26,6 +27,7 @@ struct led_pwm { 
};



struct led_pwm_data {

	struct gpio_desc	*enable_gpio;

	struct led_classdev	cdev;

	struct pwm_device	*pwm;

	struct pwm_state	pwmstate;
@@ -51,6 +53,8 @@ static int led_pwm_set(struct led_classdev *led_cdev, 
	if (led_dat->active_low)

		duty = led_dat->pwmstate.period - duty;



	gpiod_set_value_cansleep(led_dat->enable_gpio, !!brightness);



	led_dat->pwmstate.duty_cycle = duty;

	/*

	 * Disabling a PWM doesn't guarantee that it emits the inactive level.
@@ -132,6 +136,21 @@ static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv, 
		break;

	}



	/*

	 * Claim the GPIO as GPIOD_ASIS and set the value

	 * later on to honor the different default states

	 */

	led_data->enable_gpio = devm_fwnode_gpiod_get(dev, fwnode, "enable", GPIOD_ASIS, NULL);

	if (IS_ERR(led_data->enable_gpio)) {

		if (PTR_ERR(led_data->enable_gpio) == -ENOENT)

			/* Enable GPIO is optional */

			led_data->enable_gpio = NULL;

		else

			return PTR_ERR(led_data->enable_gpio);

	}



	gpiod_direction_output(led_data->enable_gpio, !!led_data->cdev.brightness);



	ret = devm_led_classdev_register_ext(dev, &led_data->cdev, &init_data);

	if (ret) {

		dev_err(dev, "failed to register PWM led for %s: %d\n",