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To the exception of red_led_on in the arm-specific assembly code, all code interacting with the red status LED was guarded by the CONFIG_LED_STATUS_RED symbol, which is enabled in none of the upstream defconfigs. Since the last board which overrode the weak red_led_on function got migrated to the new LED mechanism, there's also no user of the arm-specific assembly code anymore, therefore it can be removed along the other unreachable code sections. Signed-off-by: Quentin Schulz <quentin.schulz@cherry.de> Reviewed-by: Heiko Schocher <hs@nabladev.com>
74 lines
2.1 KiB
ReStructuredText
74 lines
2.1 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0+
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LED
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===
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.. kernel-doc:: include/led.h
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:doc: Overview
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.. kernel-doc:: include/led.h
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:internal:
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Legacy LED
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==========
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Please use the new LED API as defined above. This section is only for reference
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for currently supported devices and to aid for migration to the new API.
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Status LED
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----------
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This README describes the status LED API.
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The API is defined by the include file include/status_led.h
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The first step is to enable CONFIG_LED_STATUS in menuconfig::
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> Device Drivers > LED Support.
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If the LED support is only for specific board, enable
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CONFIG_LED_STATUS_BOARD_SPECIFIC in the menuconfig.
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Status LEDS 0 to 5 are enabled by the following configurations at menuconfig:
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CONFIG_STATUS_LED0, CONFIG_STATUS_LED1, ... CONFIG_STATUS_LED5
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The following should be configured for each of the enabled LEDs:
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- CONFIG_STATUS_LED_BIT<n>
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- CONFIG_STATUS_LED_STATE<n>
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- CONFIG_STATUS_LED_FREQ<n>
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Where <n> is an integer 1 through 5 (empty for 0).
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CONFIG_STATUS_LED_BIT is passed into the __led_* functions to identify which LED
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is being acted on. As such, the value choose must be unique with respect to
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the other CONFIG_STATUS_LED_BIT's. Mapping the value to a physical LED is the
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reponsiblity of the __led_* function.
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CONFIG_STATUS_LED_STATE is the initial state of the LED. It should be set to one
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of these values: CONFIG_LED_STATUS_OFF or CONFIG_LED_STATUS_ON.
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CONFIG_STATUS_LED_FREQ determines the LED blink frequency.
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Values range from 2 to 10.
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Some other LED macros
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~~~~~~~~~~~~~~~~~~~~~
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CONFIG_STATUS_LED_BOOT is the LED to light when the board is booting.
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This must be a valid LED number (0-5).
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General LED functions
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~~~~~~~~~~~~~~~~~~~~~
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The following functions should be defined:
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__led_init is called once to initialize the LED to CONFIG_STATUS_LED_STATE.
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One time start up code should be placed here.
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__led_set is called to change the state of the LED.
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__led_toggle is called to toggle the current state of the LED.
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TBD : Describe older board dependent macros similar to what is done for
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TBD : Describe general support via asm/status_led.h
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