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leds: pwm: Add optional GPIO enable pin support

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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: LI 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: Lee Jones <lee@kernel.org>
This commit is contained in:
LI Qingwu 2025-11-17 05:45:09 +00:00 • committed by Lee Jones
parent d7dca03a48
commit bb64206276
1 changed files with 19 additions and 0 deletions
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19
drivers/leds/leds-pwm.c
View file

@ -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",