u-boot/doc/README.LED
Heiko Schocher 5b8e76c35e powerpc, 8xx: remove support for 8xx
There was for long time no activity in the 8xx area.
We need to go further and convert to Kconfig, but it
turned out, nobody is interested anymore in 8xx,
so remove it (with a heavy heart, knowing that I remove
here the root of U-Boot).

Signed-off-by: Heiko Schocher <hs@denx.de>
2017-06-12 08:37:55 -04:00

77 lines
2.4 KiB
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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