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LED

.. kernel-doc:: include/led.h
   :doc: Overview


.. kernel-doc:: include/led.h
   :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 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).

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.

TBD : Describe older board dependent macros similar to what is done for

TBD : Describe general support via asm/status_led.h