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

[Heinrich Schuchardt]

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.

> + * 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.

> + *
> + * 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:

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