drivers: led: Provide a fallback implementation of blink API

drivers/led/CMakeLists.txt

@@ -25,6 +25,8 @@ zephyr_library_sources_ifdef(CONFIG_PCA9633 pca9633.c)
 zephyr_library_sources_ifdef(CONFIG_TLC59108 tlc59108.c)
 # zephyr-keep-sorted-stop
 
+zephyr_library_sources(led_core.c)
+
 zephyr_library_sources_ifdef(CONFIG_LED_SHELL   led_shell.c)
 
 zephyr_library_sources_ifdef(CONFIG_USERSPACE   led_handlers.c)

drivers/led/Kconfig

@@ -26,6 +26,12 @@ config LED_SHELL
 	help
 	  Enable LED shell for testing.
 
+config LED_BLINK_SOFTWARE
+	bool "LED Blink fallback"
+	help
+	  Provides a software implementation of LED blink API.
+	  This could be used when the LED controller doesn't support blinking.
+
 # zephyr-keep-sorted-start
 source "drivers/led/Kconfig.axp192"
 source "drivers/led/Kconfig.dac"

drivers/led/led_blink.h

@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) 2025 BayLibre SAS
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#ifndef ZEPHYR_DRIVERS_LED_LED_BLINK_H_
+#define ZEPHYR_DRIVERS_LED_LED_BLINK_H_
+
+#define LED_BLINK_SOFTWARE_DATA_INIT(node_id) {}
+
+#define LED_BLINK_SOFTWARE_DATA(inst, name) \
+	COND_CODE_1(CONFIG_LED_BLINK_SOFTWARE, ( \
+	.name = (struct led_blink_software_data[]) {\
+		DT_INST_FOREACH_CHILD_SEP(inst, LED_BLINK_SOFTWARE_DATA_INIT, (,)) \
+	},), ())
+
+#ifdef CONFIG_LED_BLINK_SOFTWARE
+struct led_blink_software_data {
+	const struct device *dev;
+	uint32_t led;
+	struct k_work_delayable work;
+	uint32_t delay_on;
+	uint32_t delay_off;
+};
+
+int led_blink_software_start(const struct device *dev, uint32_t led, uint32_t delay_on,
+			     uint32_t delay_off);
+#else
+struct led_blink_software_data;
+static inline int led_blink_software_start(const struct device *dev, uint32_t led,
+					   uint32_t delay_on, uint32_t delay_off)
+{
+	return -ENOSYS;
+}
+#endif
+
+#endif /* ZEPHYR_DRIVERS_LED_LED_BLINK_H_ */

drivers/led/led_core.c

@@ -0,0 +1,175 @@
+/*
+ * Copyright (c) 2025 BayLibre SAS
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr/drivers/led.h>
+#include <zephyr/kernel.h>
+
+#include "led_blink.h"
+
+static int led_core_on(const struct device *dev, uint32_t led)
+{
+	const struct led_driver_api *api = (const struct led_driver_api *)dev->api;
+
+	if (api->set_brightness == NULL && api->on == NULL) {
+		return -ENOSYS;
+	}
+
+	if (api->on == NULL) {
+		return api->set_brightness(dev, led, LED_BRIGHTNESS_MAX);
+	}
+
+	return api->on(dev, led);
+}
+
+static int led_core_off(const struct device *dev, uint32_t led)
+{
+	const struct led_driver_api *api = (const struct led_driver_api *)dev->api;
+
+	if (api->set_brightness == NULL && api->off == NULL) {
+		return -ENOSYS;
+	}
+
+	if (api->off == NULL) {
+		return api->set_brightness(dev, led, 0);
+	}
+
+	return api->off(dev, led);
+}
+
+#ifdef CONFIG_LED_BLINK_SOFTWARE
+static void led_blink_software_off(struct k_work *work);
+static struct led_blink_software_data *led_blink_software_get_data(const struct device *dev,
+								   uint32_t led)
+{
+	const struct led_driver_api *api = (const struct led_driver_api *)dev->api;
+
+	if (!api->get_blink_data) {
+		return NULL;
+	}
+
+	return api->get_blink_data(dev, led);
+}
+
+static void led_blink_software_on(struct k_work *work)
+{
+	struct k_work_delayable *dwork = k_work_delayable_from_work(work);
+	struct led_blink_software_data *data =
+		CONTAINER_OF(dwork, struct led_blink_software_data, work);
+
+	led_core_on(data->dev, data->led);
+	k_work_init_delayable(&data->work, led_blink_software_off);
+	k_work_schedule(&data->work, K_MSEC(data->delay_on));
+}
+
+static void led_blink_software_off(struct k_work *work)
+{
+	struct k_work_delayable *dwork = k_work_delayable_from_work(work);
+	struct led_blink_software_data *data =
+		CONTAINER_OF(dwork, struct led_blink_software_data, work);
+
+	led_core_off(data->dev, data->led);
+	k_work_init_delayable(&data->work, led_blink_software_on);
+	k_work_schedule(&data->work, K_MSEC(data->delay_off));
+}
+
+int led_blink_software_start(const struct device *dev, uint32_t led, uint32_t delay_on,
+			     uint32_t delay_off)
+{
+	struct led_blink_software_data *data;
+
+	data = led_blink_software_get_data(dev, led);
+	if (!data) {
+		return -EINVAL;
+	}
+
+	if (!delay_on && !delay_off) {
+		/* Default 1Hz blinking when delay_on and delay_off are 0 */
+		delay_on = 500;
+		delay_off = 500;
+	} else if (!delay_on) {
+		/* Always off */
+		led_core_off(dev, led);
+	} else if (!delay_off) {
+		/* Always on */
+		led_core_on(dev, led);
+	}
+
+	data->dev = dev;
+	data->led = led;
+	data->delay_on = delay_on;
+	data->delay_off = delay_off;
+
+	k_work_init_delayable(&data->work, led_blink_software_on);
+	return k_work_schedule(&data->work, K_NO_WAIT);
+}
+
+static void led_blink_software_stop(const struct device *dev, uint32_t led)
+{
+	struct led_blink_software_data *data;
+
+	data = led_blink_software_get_data(dev, led);
+	if (data) {
+		struct k_work_sync sync;
+
+		k_work_cancel_delayable_sync(&data->work, &sync);
+	}
+}
+#else
+static inline void led_blink_software_stop(const struct device *dev, uint32_t led)
+{
+}
+#endif /* CONFIG_LED_BLINK_SOFTWARE */
+
+int z_impl_led_on(const struct device *dev, uint32_t led)
+{
+	led_blink_software_stop(dev, led);
+	return led_core_on(dev, led);
+}
+
+int z_impl_led_off(const struct device *dev, uint32_t led)
+{
+	led_blink_software_stop(dev, led);
+	return led_core_off(dev, led);
+}
+
+int z_impl_led_set_brightness(const struct device *dev, uint32_t led, uint8_t value)
+{
+	const struct led_driver_api *api = (const struct led_driver_api *)dev->api;
+
+	if (!value) {
+		led_blink_software_stop(dev, led);
+	}
+
+	if (api->set_brightness == NULL) {
+		if (api->on == NULL || api->off == NULL) {
+			return -ENOSYS;
+		}
+	}
+
+	if (value > LED_BRIGHTNESS_MAX) {
+		return -EINVAL;
+	}
+
+	if (api->set_brightness == NULL) {
+		if (value) {
+			return api->on(dev, led);
+		} else {
+			return api->off(dev, led);
+		}
+	}
+
+	return api->set_brightness(dev, led, value);
+}
+
+int z_impl_led_blink(const struct device *dev, uint32_t led, uint32_t delay_on, uint32_t delay_off)
+{
+	const struct led_driver_api *api = (const struct led_driver_api *)dev->api;
+
+	if (api->blink == NULL) {
+		return led_blink_software_start(dev, led, delay_on, delay_off);
+	}
+	return api->blink(dev, led, delay_on, delay_off);
+}

drivers/led/led_gpio.c

@@ -16,6 +16,8 @@
 #include <zephyr/device.h>
 #include <zephyr/kernel.h>
 
+#include "led_blink.h"
+
 #include <zephyr/logging/log.h>
 LOG_MODULE_REGISTER(led_gpio, CONFIG_LED_LOG_LEVEL);
 
@@ -24,9 +26,28 @@ struct led_gpio_config {
 	const struct gpio_dt_spec *led;
 };
 
-static int led_gpio_set_brightness(const struct device *dev, uint32_t led, uint8_t value)
+struct led_gpio_data {
+#ifdef CONFIG_LED_BLINK_SOFTWARE
+	struct led_blink_software_data *blink_data;
+#endif
+};
+
+#ifdef CONFIG_LED_BLINK_SOFTWARE
+struct led_blink_software_data *led_gpio_blink_data(const struct device *dev, uint32_t led)
 {
+	const struct led_gpio_config *config = dev->config;
+	struct led_gpio_data *data = dev->data;
+
+	if (led >= config->num_leds) {
+		return NULL;
+	}
+
+	return &data->blink_data[led];
+}
+#endif
 
+static int led_gpio_set_brightness(const struct device *dev, uint32_t led, uint8_t value)
+{
 	const struct led_gpio_config *config = dev->config;
 	const struct gpio_dt_spec *led_gpio;
 
@@ -69,6 +90,9 @@ static int led_gpio_init(const struct device *dev)
 
 static DEVICE_API(led, led_gpio_api) = {
 	.set_brightness	= led_gpio_set_brightness,
+#ifdef CONFIG_LED_BLINK_SOFTWARE
+	.get_blink_data	= led_gpio_blink_data,
+#endif
 };
 
 #define LED_GPIO_DEVICE(i)					\
@@ -78,12 +102,17 @@ static const struct gpio_dt_spec gpio_dt_spec_##i[] = {		\
 };								\
 								\
 static const struct led_gpio_config led_gpio_config_##i = {	\
-	.num_leds	= ARRAY_SIZE(gpio_dt_spec_##i),	\
+	.num_leds	= ARRAY_SIZE(gpio_dt_spec_##i),		\
 	.led		= gpio_dt_spec_##i,			\
 };								\
 								\
+static struct led_gpio_data led_gpio_data_##i = {		\
+	LED_BLINK_SOFTWARE_DATA(i, blink_data)			\
+};								\
+								\
 DEVICE_DT_INST_DEFINE(i, &led_gpio_init, NULL,			\
-		      NULL, &led_gpio_config_##i,		\
+				 (&led_gpio_data_##i),		\
+		      &led_gpio_config_##i,			\
 		      POST_KERNEL, CONFIG_LED_INIT_PRIORITY,	\
 		      &led_gpio_api);