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

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 <[email protected]>

1 files changed, 88 insertions, 1 deletions

diff --git a/doc/api/led.rst b/doc/api/led.rst
index e52e350d1bb..661d1379620 100644
--- a/doc/api/led.rst
+++ b/doc/api/led.rst
@@ -7,4 +7,91 @@ LED
    :doc: Overview
 
 .. kernel-doc:: include/led.h
-   :internal:
\ No newline at end of file
+   :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