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drivers: led: Provide a software implementation of blink API
The LED blink API is quite useful but this is not supported by all the LED controller. This provides a software implementation of blink that uses a delayable work to blink a LED. To use it, a driver just have to allocate and init a struct for holding blinking led data and to call the software blinking functions. Signed-off-by: Alexandre Bailon <abailon@baylibre.com>
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3 files changed

+150
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‎drivers/led/Kconfig

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

‎drivers/led/led_blink.h

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

‎drivers/led/led_core.c

Lines changed: 106 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -5,8 +5,11 @@
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*/
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#include <zephyr/drivers/led.h>
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#include <zephyr/kernel.h>
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9-
int z_impl_led_on(const struct device *dev, uint32_t led)
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#include "led_blink.h"
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static int led_core_on(const struct device *dev, uint32_t led)
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{
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const struct led_driver_api *api = (const struct led_driver_api *)dev->api;
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@@ -21,7 +24,7 @@ int z_impl_led_on(const struct device *dev, uint32_t led)
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return api->on(dev, led);
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}
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24-
int z_impl_led_off(const struct device *dev, uint32_t led)
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static int led_core_off(const struct device *dev, uint32_t led)
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{
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const struct led_driver_api *api = (const struct led_driver_api *)dev->api;
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@@ -36,10 +39,110 @@ int z_impl_led_off(const struct device *dev, uint32_t led)
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return api->off(dev, led);
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}
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#ifdef CONFIG_LED_BLINK_SOFTWARE
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static void led_blink_software_off(struct k_work *work);
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static struct led_blink_software_data *led_blink_software_get_data(const struct device *dev,
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uint32_t led)
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{
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const struct led_driver_api *api = (const struct led_driver_api *)dev->api;
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if (!api->get_blink_data) {
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return NULL;
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}
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return api->get_blink_data(dev, led);
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}
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static void led_blink_software_on(struct k_work *work)
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{
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struct k_work_delayable *dwork = k_work_delayable_from_work(work);
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struct led_blink_software_data *data =
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CONTAINER_OF(dwork, struct led_blink_software_data, work);
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led_core_on(data->dev, data->led);
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k_work_init_delayable(&data->work, led_blink_software_off);
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k_work_schedule(&data->work, K_MSEC(data->delay_on));
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}
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static void led_blink_software_off(struct k_work *work)
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{
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struct k_work_delayable *dwork = k_work_delayable_from_work(work);
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struct led_blink_software_data *data =
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CONTAINER_OF(dwork, struct led_blink_software_data, work);
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led_core_off(data->dev, data->led);
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k_work_init_delayable(&data->work, led_blink_software_on);
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k_work_schedule(&data->work, K_MSEC(data->delay_off));
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}
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int led_blink_software_start(const struct device *dev, uint32_t led, uint32_t delay_on,
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uint32_t delay_off)
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{
81+
struct led_blink_software_data *data;
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data = led_blink_software_get_data(dev, led);
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if (!data) {
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return -EINVAL;
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}
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if (!delay_on && !delay_off) {
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/* Default 1Hz blinking when delay_on and delay_off are 0 */
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delay_on = 500;
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delay_off = 500;
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} else if (!delay_on) {
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/* Always off */
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led_core_off(dev, led);
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} else if (!delay_off) {
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/* Always on */
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led_core_on(dev, led);
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}
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data->dev = dev;
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data->led = led;
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data->delay_on = delay_on;
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data->delay_off = delay_off;
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k_work_init_delayable(&data->work, led_blink_software_on);
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return k_work_schedule(&data->work, K_NO_WAIT);
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}
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static void led_blink_software_stop(const struct device *dev, uint32_t led)
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{
111+
struct led_blink_software_data *data;
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data = led_blink_software_get_data(dev, led);
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if (data) {
115+
struct k_work_sync sync;
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k_work_cancel_delayable_sync(&data->work, &sync);
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}
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}
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#else
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static inline void led_blink_software_stop(const struct device *dev, uint32_t led)
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{
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}
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#endif /* CONFIG_LED_BLINK_SOFTWARE */
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int z_impl_led_on(const struct device *dev, uint32_t led)
127+
{
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led_blink_software_stop(dev, led);
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return led_core_on(dev, led);
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}
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int z_impl_led_off(const struct device *dev, uint32_t led)
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{
134+
led_blink_software_stop(dev, led);
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return led_core_off(dev, led);
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}
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int z_impl_led_set_brightness(const struct device *dev, uint32_t led, uint8_t value)
40139
{
41140
const struct led_driver_api *api = (const struct led_driver_api *)dev->api;
42141

142+
if (!value) {
143+
led_blink_software_stop(dev, led);
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}
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43146
if (api->set_brightness == NULL) {
44147
if (api->on == NULL || api->off == NULL) {
45148
return -ENOSYS;
@@ -66,7 +169,7 @@ int z_impl_led_blink(const struct device *dev, uint32_t led, uint32_t delay_on,
66169
const struct led_driver_api *api = (const struct led_driver_api *)dev->api;
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68171
if (api->blink == NULL) {
69-
return -ENOSYS;
172+
return led_blink_software_start(dev, led, delay_on, delay_off);
70173
}
71174
return api->blink(dev, led, delay_on, delay_off);
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}

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