[PATCH V9 2/3] leds: pwm: Add optional GPIO enable pin support
From: LI Qingwu <hidden>
Date: 2025-11-05 06:50:21
Also in:
linux-leds, lkml
Subsystem:
led subsystem, the rest · Maintainers:
Lee Jones, Pavel Machek, Linus Torvalds
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 <redacted> --- drivers/leds/leds-pwm.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+)
diff --git a/drivers/leds/leds-pwm.c b/drivers/leds/leds-pwm.c
index c73134e7b951..aa9e14d912bf 100644
--- a/drivers/leds/leds-pwm.c
+++ b/drivers/leds/leds-pwm.c@@ -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",
--
2.43.0