linux-kernel - [PATCH V1 2/2] leds: pwm: Add optional GPIO enable pin support

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Message-ID: <20250702043537.220478-2-Qing-wu.Li@leica-geosystems.com.cn>
Date: Wed,  2 Jul 2025 12:35:37 +0800
From: LI Qingwu <Qing-wu.Li@...ca-geosystems.com.cn>
To: lee@...nel.org,
	pavel@...nel.org,
	robh@...nel.org,
	krzk+dt@...nel.org,
	conor+dt@...nel.org,
	linux-leds@...r.kernel.org,
	devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Qing-wu.Li@...ca-geosystems.com.cn
Cc: bsp-development.geo@...ca-geosystems.com
Subject: [PATCH V1 2/2] leds: pwm: Add optional GPIO enable pin support

add support for optional GPIO-based enable pin control to PWM LED driver.
some PWM LED chips have a dedicated enable GPIO. This commit adds the
support to specify such GPIO, activating the pin when LED brightness
is non-zero and deactivating it when off.

Signed-off-by: LI Qingwu <Qing-wu.Li@...ca-geosystems.com.cn>
---
 drivers/leds/leds-pwm.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/leds/leds-pwm.c b/drivers/leds/leds-pwm.c
index c73134e7b9514..2b8d746d9d7f4 100644
--- a/drivers/leds/leds-pwm.c
+++ b/drivers/leds/leds-pwm.c
@@ -17,6 +17,7 @@
 #include <linux/err.h>
 #include <linux/pwm.h>
 #include <linux/slab.h>
+#include <linux/gpio/consumer.h>
 
 struct led_pwm {
 	const char	*name;
@@ -29,6 +30,7 @@ struct led_pwm_data {
 	struct led_classdev	cdev;
 	struct pwm_device	*pwm;
 	struct pwm_state	pwmstate;
+	struct gpio_desc	*enable_gpio;
 	unsigned int		active_low;
 };
 
@@ -51,6 +53,9 @@ 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_OFF ? 0 : 1);
+
 	led_dat->pwmstate.duty_cycle = duty;
 	/*
 	 * Disabling a PWM doesn't guarantee that it emits the inactive level.
@@ -132,6 +137,11 @@ static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv,
 		break;
 	}
 
+	led_data->enable_gpio =
+		devm_fwnode_gpiod_get(dev, fwnode, "enable", GPIOD_ASIS, NULL);
+	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