Simon Glass 00caae6d47 env: Rename getenv/_f() to env_get() 6 年之前
..
Kconfig 4db98d3d92 kconfig: Add API kconfig file 7 年之前
Makefile 7c60423106 api: Add FreeBSD API support for MIPS platforms 8 年之前
README d3a6532cbe Coding Style cleanup; update CHANGELOG 16 年之前
api.c 00caae6d47 env: Rename getenv/_f() to env_get() 6 年之前
api_display.c 1a4596601f Add GPL-2.0+ SPDX-License-Identifier to source files 11 年之前
api_net.c 211815784c api: Disable api_net when DM is used 7 年之前
api_platform-arm.c 1a4596601f Add GPL-2.0+ SPDX-License-Identifier to source files 11 年之前
api_platform-mips.c 7c60423106 api: Add FreeBSD API support for MIPS platforms 8 年之前
api_platform-powerpc.c 907208c452 powerpc: Partialy restore core of mpc8xx 6 年之前
api_private.h 1a4596601f Add GPL-2.0+ SPDX-License-Identifier to source files 11 年之前
api_storage.c 10e40d54b3 Kconfig: Add CONFIG_SATA to enable SATA 6 年之前

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