[PATCH v4 9/9] doc: convert README.LED to .rst documentation

Thu Jun 20 19:11:45 CEST 2024

On 6/20/24 06:37, Christian Marangi wrote:
> On Thu, Jun 20, 2024 at 08:13:34AM +0200, Heinrich Schuchardt wrote:
>> On 6/20/24 01:03, Christian Marangi wrote:
>>> Convert README.LED to .rst documentation and include all the relevant
>>> documentation in the status_led.h.
>>>
>>> Signed-off-by: Christian Marangi <ansuelsmth at gmail.com>
>>> ---
>>>    doc/README.LED         |  77 --------------
>>>    doc/api/index.rst      |   1 +
>>>    doc/api/status_led.rst |  35 +++++++
>>>    include/status_led.h   | 224 ++++++++++++++++++++++++++++++++++++++++-
>>>    4 files changed, 256 insertions(+), 81 deletions(-)
>>>    delete mode 100644 doc/README.LED
>>>    create mode 100644 doc/api/status_led.rst
>>>
>>> diff --git a/doc/README.LED b/doc/README.LED
>>> deleted file mode 100644
>>> index c21c9d53ec3..00000000000
>>> --- a/doc/README.LED
>>> +++ /dev/null
>>> @@ -1,77 +0,0 @@
>>> -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
>>> diff --git a/doc/api/index.rst b/doc/api/index.rst
>>> index 51b2013af36..d40e90801d1 100644
>>> --- a/doc/api/index.rst
>>> +++ b/doc/api/index.rst
>>> @@ -22,6 +22,7 @@ U-Boot API documentation
>>>       rng
>>>       sandbox
>>>       serial
>>> +   status_led
>>>       sysreset
>>>       timer
>>>       unicode
>>> diff --git a/doc/api/status_led.rst b/doc/api/status_led.rst
>>> new file mode 100644
>>> index 00000000000..44bbea47157
>>> --- /dev/null
>>> +++ b/doc/api/status_led.rst
>>> @@ -0,0 +1,35 @@
>>> +.. SPDX-License-Identifier: GPL-2.0+
>>> +
>>> +Status LED
>>> +==========
>>> +
>>> +.. kernel-doc:: include/status_led.h
>>> +   :doc: Overview
>>> +
>>> +CONFIG_STATUS_LED Description
>>> +-----------------------------
>>> +
>>> +.. kernel-doc:: include/status_led.h
>>> +   :doc: CONFIG Description
>>> +
>>> +Special Status LED Configs
>>> +--------------------------
>>> +.. kernel-doc:: include/status_led.h
>>> +   :doc: LED Status Config
>>> +
>>> +Colour Status LED Configs
>>> +-------------------------
>>> +.. kernel-doc:: include/status_led.h
>>> +   :doc: LED Colour Config
>>> +
>>> +Required API
>>> +------------
>>> +
>>> +.. kernel-doc:: include/status_led.h
>>> +   :doc: Required API
>>> +
>>> +Status LED API
>>> +--------------
>>> +
>>> +.. kernel-doc:: include/status_led.h
>>> +   :internal:
>>> diff --git a/include/status_led.h b/include/status_led.h
>>> index 7de40551621..6893d1d68e0 100644
>>> --- a/include/status_led.h
>>> +++ b/include/status_led.h
>>> @@ -4,18 +4,102 @@
>>>     * Wolfgang Denk, DENX Software Engineering, wd at denx.de.
>>>     */
>>>
>>> -/*
>>> - * The purpose of this code is to signal the operational status of a
>>> +/**
>>> + * DOC: Overview
>>> + *
>>> + * Status LED is a Low-Level way to handle LEDs to signal state of the
>>
>> Status LEDs can be used to signal the operational status of a
>>
>>> + * bootloader, for example boot progress, file transfer fail, activity
>>> + * of some sort like tftp transfer, mtd write/erase.
>>
>> for example boot progress, file transfer failure, or ongoing activity
>> like tftp transfer or mtd write/erase.
>>
>>> + *
>>> + * The original usage these API were to signal the operational status of a
>>
>> One usage of this API is signalling the operational status ...
>>
>>>     * target which usually boots over the network; while running in
>>>     * PCBoot, a status LED is blinking. As soon as a valid BOOTP reply
>>
>> What does "PCBoot" refer to? Do you mean U-Boot?
>>
>>>     * message has been received, the LED is turned off. The Linux
>>>     * kernel, once it is running, will start blinking the LED again,
>>>     * with another frequency.
>>> + *
>>> + * Status LED require support Low Level and the board to implement
>>
>>
>>
>>> + * the specific functions to correctly works.
>>>     */
>>>
>>>    #ifndef _STATUS_LED_H_
>>>    #define	_STATUS_LED_H_
>>>
>>> +/**
>>> + * DOC: CONFIG Description
>>
>> DOC: Configuration
>>
>>> + *
>>> + * Enable `CONFIG_LED_STATUS` to support the Status LED under
>>> + * > Device Drivers > LED Support.
>>> + *
>>> + * The Status LED can be defined in various ways, but most of the time,
>>> + * specific functions will need to be defined in the board file.
>>> + * If this is the case, enable `CONFIG_LED_STATUS_BOARD_SPECIFIC`.
>>
>> CONFIG_LED_STATUS_BOARD_SPECIFIC is not used in any defconfig.
>>
>> GPIO is the typical case and board-specific the exception.
>>
>>> + *
>>> + * If the LEDs are GPIO-driven, you can use the GPIO wrapper driver
>>> + * instead of defining specific board functions.
>>> + * If this is the case, enable `CONFIG_LED_STATUS_GPIO`.
>>> + * (Note that `CONFIG_LED_STATUS_BOARD_SPECIFIC` is also required.)
>>> + *
>>> + * The Status LED allows defining up to six different LEDs, from 0 to 5,
>>> + * with the following configurations:
>>> + * `CONFIG_STATUS_LED`, `CONFIG_STATUS_LED1`, ..., `CONFIG_STATUS_LED5`.
>>> + *
>>> + * For each LED, the following options are required:
>>> + *  * `CONFIG_STATUS_LED_BIT<n>`
>>> + *  * `CONFIG_STATUS_LED_STATE<n>`
>>> + *  * `CONFIG_STATUS_LED_FREQ<n>`
>>> + *
>>> + * Where `<n>` is an integer from 1 through 5. (Note that LED 0 doesn't have the
>>> + * integer suffix.)
>>> + *
>>> + * `CONFIG_STATUS_LED_BIT` is passed into the `__led_*` functions to identify
>>> + * which LED is being acted on. The value is opaque, meaning it depends on how
>>> + * the low-level API handles this value. It can be an ID to reference the LED
>>> + * internally, or in the case of the GPIO wrapper, it's the GPIO number of the LED.
>>> + * Mapping the value to a physical LED is the responsibility of the `__led_*` function.
>>> + *
>>> + * `CONFIG_STATUS_LED_STATE` sets 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.
>>> + */
>>> +/**
>>> + * DOC: LED Status Config
>>> + *
>>> + * The Status LED uses two special configurations for common operations:
>>> + *
>>> + *   * CONFIG_STATUS_LED_BOOT is the LED that lights up when the board is booting.
>>> + *   * CONFIG_STATUS_LED_ACTIVITY is the LED that lights and blinks during activity
>>> + *     (e.g., file transfer, flash write).
>>> + *
>>> + * The values set in these configurations refer to the LED ID previously set.
>>> + *
>>> + * - ``CONFIG_STATUS_LED_RED=0`` will refer to the option ``CONFIG_STATUS_LED_BIT``.
>>> + * - ``CONFIG_STATUS_LED_RED=1`` will refer to the option ``CONFIG_STATUS_LED_BIT1``.
>>> + * - ``CONFIG_STATUS_LED_RED=2`` will refer to the option ``CONFIG_STATUS_LED_BIT2``.
>>> + * - ...
>>> + */
>>> +/**
>>> + * DOC: LED Colour Config
>>> + *
>>> + * The Status LED exposes specific configurations for LEDs of different colors.
>>> + *
>>> + * The values set in these configurations refer to the LED ID previously set.
>>> + *
>>> + * - ``CONFIG_STATUS_LED_RED=0`` will refer to the option ``CONFIG_STATUS_LED_BIT``.
>>> + * - ``CONFIG_STATUS_LED_RED=1`` will refer to the option ``CONFIG_STATUS_LED_BIT1``.
>>> + * - ``CONFIG_STATUS_LED_RED=2`` will refer to the option ``CONFIG_STATUS_LED_BIT2``.
>>> + * - ...
>>> + *
>>> + * Supported colors are:
>>> + *   * red
>>> + *   * green
>>> + *   * yellow
>>> + *   * blue
>>> + *   * white
>>> + */
>>> +
>>>    #ifdef CONFIG_LED_STATUS
>>>
>>>    #define LED_STATUS_PERIOD	(CONFIG_SYS_HZ / CONFIG_LED_STATUS_FREQ)
>>> @@ -35,11 +119,49 @@
>>>    #define LED_STATUS_PERIOD5	(CONFIG_SYS_HZ / CONFIG_LED_STATUS_FREQ5)
>>>    #endif /* CONFIG_LED_STATUS5 */
>>>
>>> +/**
>>> + * void status_led_init - Init the Status LED with all the required structs.
>>> + */
>>>    void status_led_init(void);
>>> +/**
>>> + * void status_led_tick - Blink each LED that is currently set in blinking
>>> + *   mode
>>> + * @timestamp: currently unused
>>> + */
>>>    void status_led_tick(unsigned long timestamp);
>>> +/**
>>> + * void status_led_set - Set the LED ID passed as first arg to the mode set
>>> + * @led: reference to the Status LED ID
>>> + * @state: state to set the LED to
>>> + *
>>> + * Modes for state arE:
>>> + *   * CONFIG_LED_STATUS_OFF (LED off)
>>> + *   * CONFIG_LED_STATUS_ON (LED on)
>>> + *   * CONFIG_LED_STATUS_BLINK (LED initially on, expected to blink)
>>> + */
>>>    void status_led_set(int led, int state);
>>> +/**
>>> + * void status_led_toggle - toggle the LED ID
>>> + * @led: reference to the Status LED ID
>>> + *
>>> + * Toggle the LED ID passed as first arg. If it's ON became OFF, if it's
>>> + * OFF became ON.
>>> + */
>>>    void status_led_toggle(int led);
>>> +/**
>>> + * void status_led_activity_start - start a LED activity
>>> + * @led: reference to the Status LED ID
>>> + *
>>> + * Set the Status LED ON and start the Cyclic to make the LED blink at
>>> + * the configured freq.
>>> + */
>>>    void status_led_activity_start(int led);
>>> +/**
>>> + * void status_led_activity_stop - stop a LED activity
>>> + * @led: reference to the Status LED ID
>>> + *
>>> + * Stop and free the Cyclic and turn the LED OFF.
>>
>> 'Cyclic' is and adjective and cannot stand alone. Do you mean:
>>
>> Stop and free the cyclic function and turn off the LED.
>>
>>> + */
>>>    void status_led_activity_stop(int led);
>>>
>>>    /*****  MVS v1  **********************************************************/
>>
>> We don't have 'config MVS' in any Kconfig. Please remove the dead code.
>>
>>> @@ -62,9 +184,61 @@ void status_led_activity_stop(int led);
>>>    /* led_id_t is unsigned long mask */
>>>    typedef unsigned long led_id_t;
>>>
>>> +/**
>>> + * DOC: Required API
>>> + *
>>> + * The Status LED requires the following API functions to operate correctly
>>
>> The following functions are implemented by the GPIO LED driver. If using
>> CONFIG_LED_STATUS_BOARD_SPECIFIC=y, they have to be implemented by the
>> board code.
>>
>
> Well CONFIG_LED_STATUS_BOARD_SPECIFIC is mandatory for these function to
> be exporsed. GPIO is just a way to provide these function using the GPIO
> common implementation. Maybe I will make it more clear but it should be
> also written at the start of the DOC.

The Linux kernel defines LEDs in the device-tree including labels. Why
do we need CONFIG_LED_STATUS_BOARD_SPECIFIC at all?

Shouldn't we eliminate all the legacy code like cmd/legacy_led.c instead
of enhancing it?

Best regards

Heinrich

>
>>> + * and compile:
>>> + *
>>> + * - ``__led_toggle``: Low-level function to toggle the LED at the specified
>>> + *   mask.
>>> + * - ``__led_init``: Initializes the Status LED, sets up required tables, and
>>> + *   configures registers.
>>> + * - ``__led_set``: Low-level function to set the state of the LED at the
>>> + *   specified mask.
>>> + * - ``__led_blink``: Low-level function to set the LED to blink at the
>>> + *   specified frequency.
>>> + *
>>> + * The Status LED also provides optional functions to control colored LEDs.
>>
>> Do you mean
>>
>> Controlling colored LEDs requires the additional functions see :doc:
>> `Coloured LED API`.
>>
>>> + * Each supported LED color has corresponding ``_on`` and ``_off`` functions.
>>> + *
>>> + * There is also support for ``coloured_LED_init`` for LEDs that provide
>>> + * multiple colors. (Currently, this is only used by ARM.)
>>
>> We have hundreds of ARM based boards. Could you be a bit more specific,
>> please.
>>
>
> Well the only one used is the RED colour and it's in arm/lib/crt0.S in
> the ASM code.
>
>>> + *
>>> + * Each function is weakly defined and should be implemented in the
>>> + * board-specific source file. (This does not apply to the GPIO LED wrapper.)
>>> + */
>>> +/**
>>> + * void __led_toggle - toggle LED at @mask
>>> + * @mask: opaque value to reference the LED
>>> + *
>>> + * Low-Level function to toggle the LED at mask.
>>> + */
>>>    extern void __led_toggle (led_id_t mask);
>>> +/**
>>> + * void __led_init - Init the LED at @mask
>>> + * @mask: opaque value to reference the LED
>>> + * @state: starting state of the LED
>>> + *
>>> + * Init the Status LED, init required tables, setup regs...
>>> + */
>>>    extern void __led_init (led_id_t mask, int state);
>>> +/**
>>> + * void __led_set - Set the LED at @mask
>>> + * @mask: opaque value to reference the LED
>>> + * @state: state to set the LED to
>>> + *
>>> + * Init the Status LED, init required tables, setup regs...
>>> + */
>>>    extern void __led_set (led_id_t mask, int state);
>>> +/**
>>> + * void __led_blink - Set the LED at @mask to HW blink
>>> + * @mask: opaque value to reference the LED
>>> + * @freq: freq to make the LED blink at
>>> + *
>>> + * Low-Level function to set the LED at HW blink by the
>>> + * passed freq.
>>> + */
>>>    void __led_blink(led_id_t mask, int freq);
>>>    #else
>>>    # error Status LED configuration missing
>>> @@ -77,20 +251,62 @@ void __led_blink(led_id_t mask, int freq);
>>>
>>>    #endif	/* CONFIG_LED_STATUS	*/
>>>
>>> -/*
>>> - * Coloured LEDs API
>>> +/**
>>> + * DOC: Coloured LED API
>>> + *
>>> + * Status LED expose optional functions to control coloured LED.
>>
>> The status LED API uses optional functions ...
>>
>>> + * Each LED color supported expose _on and _off function.
>>> + *
>>> + * There is also support for coloured_LED_init for LED that provide
>>> + * multiple colours. (currently only used by ARM)
>>
>> No clue why you refer to ARM. I found only the following files that
>> providing board specific implementations:
>>
>
> Another case of arm/lib/crt0.S
>
> These confusing thing are picked from the old txt just to not drop info
> and try to do a 1:1 conversion.
>
>> board/beagle/beagle/led.c
>> board/siemens/corvus/board.c
>>
>> Best regards
>>
>> Heinrich
>>
>>> + *
>>> + * Each function is weakly defined and should be defined in the board
>>> + * specific source. (doesn't apply for GPIO LED wrapper)
>>>     */
>>>    #ifndef	__ASSEMBLY__
>>> +/**
>>> + * void coloured_LED_init - Init multi colour LED
>>> + */
>>>    void coloured_LED_init(void);
>>> +/**
>>> + * void red_led_on - Turn LED Red on
>>> + */
>>>    void red_led_on(void);
>>> +/**
>>> + * void red_led_off - Turn LED Red off
>>> + */
>>>    void red_led_off(void);
>>> +/**
>>> + * void green_led_on - Turn LED Green on
>>> + */
>>>    void green_led_on(void);
>>> +/**
>>> + * void green_led_off - Turn LED Green off
>>> + */
>>>    void green_led_off(void);
>>> +/**
>>> + * void yellow_led_on - Turn LED Yellow on
>>> + */
>>>    void yellow_led_on(void);
>>> +/**
>>> + * void yellow_led_off - Turn LED Yellow off
>>> + */
>>>    void yellow_led_off(void);
>>> +/**
>>> + * void blue_led_on - Turn LED Blue on
>>> + */
>>>    void blue_led_on(void);
>>> +/**
>>> + * void blue_led_off - Turn LED Blue off
>>> + */
>>>    void blue_led_off(void);
>>> +/**
>>> + * void white_led_on - Turn LED White on
>>> + */
>>>    void white_led_on(void);
>>> +/**
>>> + * void white_led_off - Turn LED White off
>>> + */
>>>    void white_led_off(void);
>>>    #else
>>>    	.extern LED_init
>>
>