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doc: move legacy API documented in README.LED to doc/api/led.rst

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This moves the content of the legacy LED API from doc/READ.LED to
doc/api/led.rst, applying minimal cosmetic changes to "nicely" integrate
it with the current docs and adding a small introduction to the legacy
API section.

Signed-off-by: Quentin Schulz <quentin.schulz@cherry.de>
This commit is contained in:
Quentin Schulz
2025-12-03 11:03:45 -06:00
committed by Tom Rini
parent 29a7fe55c5
commit e8bc141923
2 changed files with 88 additions and 78 deletions
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doc/README.LED
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@@ -1,77 +0,0 @@
Status LED
========================================
This README describes the status LED API.
The API is defined by the include file include/status_led.h
The first step is to enable CONFIG_LED_STATUS in menuconfig:
> Device Drivers > LED Support.
If the LED support is only for specific board, enable
CONFIG_LED_STATUS_BOARD_SPECIFIC in the menuconfig.
Status LEDS 0 to 5 are enabled by the following configurations at menuconfig:
CONFIG_STATUS_LED0, CONFIG_STATUS_LED1, ... CONFIG_STATUS_LED5
The following should be configured for each of the enabled LEDs:
CONFIG_STATUS_LED_BIT<n>
CONFIG_STATUS_LED_STATE<n>
CONFIG_STATUS_LED_FREQ<n>
Where <n> is an integer 1 through 5 (empty for 0).
CONFIG_STATUS_LED_BIT is passed into the __led_* functions to identify which LED
is being acted on. As such, the value choose must be unique with with respect to
the other CONFIG_STATUS_LED_BIT's. Mapping the value to a physical LED is the
reponsiblity of the __led_* function.
CONFIG_STATUS_LED_STATE is the initial state of the LED. It should be set to one
of these values: CONFIG_LED_STATUS_OFF or CONFIG_LED_STATUS_ON.
CONFIG_STATUS_LED_FREQ determines the LED blink frequency.
Values range from 2 to 10.
Some other LED macros
---------------------
CONFIG_STATUS_LED_BOOT is the LED to light when the board is booting.
This must be a valid LED number (0-5).
CONFIG_STATUS_LED_RED is the red LED. It is used to signal errors. This must be
a valid LED number (0-5). Other similar color LED's macros are
CONFIG_STATUS_LED_GREEN, CONFIG_STATUS_LED_YELLOW and CONFIG_STATUS_LED_BLUE.
General LED functions
---------------------
The following functions should be defined:
__led_init is called once to initialize the LED to CONFIG_STATUS_LED_STATE.
One time start up code should be placed here.
__led_set is called to change the state of the LED.
__led_toggle is called to toggle the current state of the LED.
Colour LED
========================================
Colour LED's are at present only used by ARM.
The functions names explain their purpose.
coloured_LED_init
red_LED_on
red_LED_off
green_LED_on
green_LED_off
yellow_LED_on
yellow_LED_off
blue_LED_on
blue_LED_off
These are weakly defined in arch/arm/lib/board.c to noops. Where applicable, define
these functions in the board specific source.
TBD : Describe older board dependent macros similar to what is done for
TBD : Describe general support via asm/status_led.h
doc/api/led.rst
+88 -1
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@@ -7,4 +7,91 @@ LED
:doc: Overview
.. kernel-doc:: include/led.h
:internal:
:internal:
Legacy LED
==========
Please use the new LED API as defined above. This section is only for reference
for currently supported devices and to aid for migration to the new API.
Status LED
----------
This README describes the status LED API.
The API is defined by the include file include/status_led.h
The first step is to enable CONFIG_LED_STATUS in menuconfig::
> Device Drivers > LED Support.
If the LED support is only for specific board, enable
CONFIG_LED_STATUS_BOARD_SPECIFIC in the menuconfig.
Status LEDS 0 to 5 are enabled by the following configurations at menuconfig:
CONFIG_STATUS_LED0, CONFIG_STATUS_LED1, ... CONFIG_STATUS_LED5
The following should be configured for each of the enabled LEDs:
- CONFIG_STATUS_LED_BIT<n>
- CONFIG_STATUS_LED_STATE<n>
- CONFIG_STATUS_LED_FREQ<n>
Where <n> is an integer 1 through 5 (empty for 0).
CONFIG_STATUS_LED_BIT is passed into the __led_* functions to identify which LED
is being acted on. As such, the value choose must be unique with with respect to
the other CONFIG_STATUS_LED_BIT's. Mapping the value to a physical LED is the
reponsiblity of the __led_* function.
CONFIG_STATUS_LED_STATE is the initial state of the LED. It should be set to one
of these values: CONFIG_LED_STATUS_OFF or CONFIG_LED_STATUS_ON.
CONFIG_STATUS_LED_FREQ determines the LED blink frequency.
Values range from 2 to 10.
Some other LED macros
~~~~~~~~~~~~~~~~~~~~~
CONFIG_STATUS_LED_BOOT is the LED to light when the board is booting.
This must be a valid LED number (0-5).
CONFIG_STATUS_LED_RED is the red LED. It is used to signal errors. This must be
a valid LED number (0-5). Other similar color LED's macros are
CONFIG_STATUS_LED_GREEN, CONFIG_STATUS_LED_YELLOW and CONFIG_STATUS_LED_BLUE.
General LED functions
~~~~~~~~~~~~~~~~~~~~~
The following functions should be defined:
__led_init is called once to initialize the LED to CONFIG_STATUS_LED_STATE.
One time start up code should be placed here.
__led_set is called to change the state of the LED.
__led_toggle is called to toggle the current state of the LED.
Colour LED
----------
Colour LED's are at present only used by ARM.
The functions names explain their purpose.
- coloured_LED_init
- red_LED_on
- red_LED_off
- green_LED_on
- green_LED_off
- yellow_LED_on
- yellow_LED_off
- blue_LED_on
- blue_LED_off
These are weakly defined in arch/arm/lib/board.c to noops. Where applicable, define
these functions in the board specific source.
TBD : Describe older board dependent macros similar to what is done for
TBD : Describe general support via asm/status_led.h