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doc: introduce led.rst documentation

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Introduce simple led.rst documentation to document all the additional
Kconfig and the current limitation of LED_BLINK and GPIO software blink.

Also add missing definition for sw_blink in led_uc_plat struct.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
This commit is contained in:
Christian Marangi 2024-10-01 14:24:42 +02:00 • committed by Tom Rini
parent 990f726ce7
commit 051c448c8b
3 changed files with 52 additions and 0 deletions
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1
doc/api/index.rst
View file

@ -14,6 +14,7 @@ U-Boot API documentation
event
getopt
interrupt
led
linker_lists
lmb
logging

10
doc/api/led.rst Normal file
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@ -0,0 +1,10 @@
.. SPDX-License-Identifier: GPL-2.0+
LED
===
.. kernel-doc:: include/led.h
:doc: Overview
.. kernel-doc:: include/led.h
:internal:

41
include/led.h
View file

@ -11,6 +11,46 @@
#include <cyclic.h>
#include <dm/ofnode.h>
/**
* DOC: Overview
*
* Generic LED API provided when a supported compatible is defined in DeviceTree.
*
* To enable support for LEDs, enable the `CONFIG_LED` Kconfig option.
*
* The most common implementation is for GPIO-connected LEDs. If using GPIO-connected LEDs,
* enable the `LED_GPIO` Kconfig option.
*
* `LED_BLINK` support requires LED driver support and is therefore optional. If LED blink
* functionality is needed, enable the `LED_BLINK` Kconfig option. If LED driver doesn't
* support HW Blink, SW Blink can be used with the Cyclic framework by enabling the
* CONFIG_LED_SW_BLINK.
*
* Boot and Activity LEDs are also supported. These LEDs can signal various system operations
* during runtime, such as boot initialization, file transfers, and flash write/erase operations.
*
* To enable a Boot LED, enable `CONFIG_LED_BOOT` and define in `/options/u-boot` root node the
* property `boot-led`. This will enable the specified LED to blink and turn ON when
* the bootloader initializes correctly.
*
* To enable an Activity LED, enable `CONFIG_LED_ACTIVITY` and define in `/options/u-boot` root
* node the property `activity-led`.
* This will enable the specified LED to blink and turn ON during file transfers or flash
* write/erase operations.
*
* Both Boot and Activity LEDs provide a simple API to turn the LED ON or OFF:
* `led_boot_on()`, `led_boot_off()`, `led_activity_on()`, and `led_activity_off()`.
*
* Both configurations can optionally define a `boot/activity-led-period` property
* if `CONFIG_LED_BLINK` or `CONFIG_LED_SW_BLINK` is enabled for LED blink operations, which
* is usually used by the Activity LED. If not defined the default value of 250 (ms) is used.
*
* When `CONFIG_LED_BLINK` or `CONFIG_LED_SW_BLINK` is enabled, additional APIs are exposed:
* `led_boot_blink()` and `led_activity_blink()`. Note that if `CONFIG_LED_BLINK` or
* `CONFIG_LED_SW_BLINK` is disabled, these APIs will behave like the `led_boot_on()` and
* `led_activity_on()` APIs, respectively.
*/
struct udevice;
enum led_state_t {
@ -41,6 +81,7 @@ struct led_sw_blink {
*
* @label: LED label
* @default_state: LED default state
* @sw_blink: LED software blink struct
*/
struct led_uc_plat {
const char *label;