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u-boot/api
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Heinrich Schuchardt fef0f1cc38 api: move API related config options into submenu 
Kconfig settings that are related to the API for standalone applications
should be in the API sub-menu and not on the top level.

CONFIG_STANDALONE_LOAD_ADDR is only relevant if standalone example
applications are built.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
2023-03-30 15:09:58 -04:00
..
api_display.c api: Drop LCD implementation 2022-10-30 20:07:16 +01:00
api_net.c SPDX: Convert all of our single license tags to Linux Kernel style 2018-05-07 09:34:12 -04:00
api_platform-arm.c SPDX: Convert all of our single license tags to Linux Kernel style 2018-05-07 09:34:12 -04:00
api_platform-mips.c global: Move from bi_memstart/memsize -> gd->ram_base/ram_size 2020-08-26 09:19:34 +02:00
api_platform-powerpc.c global: Move from bi_memstart/memsize -> gd->ram_base/ram_size 2020-08-26 09:19:34 +02:00
api_private.h common: board_r: Drop initr_api wrapper 2021-01-15 14:36:12 -05:00
api_storage.c Convert CONFIG_SYS_MMC_MAX_DEVICE to Kconfig 2022-11-10 10:08:55 -05:00
api.c common: board_r: Drop initr_api wrapper 2021-01-15 14:36:12 -05:00
Kconfig api: move API related config options into submenu 2023-03-30 15:09:58 -04:00
Makefile SPDX: Convert all of our single license tags to Linux Kernel style 2018-05-07 09:34:12 -04:00
README Coding Style cleanup; update CHANGELOG 2008-01-10 00:55:14 +01:00

README 

U-Boot machine/arch independent API for external apps
=====================================================

1.  Main assumptions

  - there is a single entry point (syscall) to the API

  - per current design the syscall is a C-callable function in the U-Boot
    text, which might evolve into a real syscall using machine exception trap
    once this initial version proves functional

  - the consumer app is responsible for producing appropriate context (call
    number and arguments)

  - upon entry, the syscall dispatches the call to other (existing) U-Boot
    functional areas like networking or storage operations

  - consumer application will recognize the API is available by searching
    a specified (assumed by convention) range of address space for the
    signature

  - the U-Boot integral part of the API is meant to be thin and non-intrusive,
    leaving as much processing as possible on the consumer application side,
    for example it doesn't keep states, but relies on hints from the app and
    so on

  - optional (CONFIG_API)


2. Calls

  - console related (getc, putc, tstc etc.)
  - system (reset, platform info)
  - time (delay, current)
  - env vars (enumerate all, get, set)
  - devices (enumerate all, open, close, read, write); currently two classes
    of devices are recognized and supported: network and storage (ide, scsi,
    usb etc.)


3. Structure overview

  - core API, integral part of U-Boot, mandatory
    - implements the single entry point (mimics UNIX syscall)

  - glue
    - entry point at the consumer side, allows to make syscall, mandatory
      part

    - helper conveniency wrappers so that consumer app does not have to use
      the syscall directly, but in a more friendly manner (a la libc calls),
      optional part

  - consumer application
    - calls directly, or leverages the provided glue mid-layer