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Diffstat (limited to 'roms/u-boot/doc/README.LED')
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diff --git a/roms/u-boot/doc/README.LED b/roms/u-boot/doc/README.LED new file mode 100644 index 000000000..c21c9d53e --- /dev/null +++ b/roms/u-boot/doc/README.LED @@ -0,0 +1,77 @@ +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 |