| | 1 | U-Boot machine/arch independent API for external apps |
| | 2 | ===================================================== |
| | 3 | |
| | 4 | 1. Main assumptions |
| | 5 | |
| | 6 | - there is a single entry point (syscall) to the API |
| | 7 | |
| | 8 | - per current design the syscall is a C-callable function in the U-Boot |
| | 9 | text, which might evolve into a real syscall using machine exception trap |
| | 10 | once this initial version proves functional |
| | 11 | |
| | 12 | - the consumer app is responsible for producing appropriate context (call |
| | 13 | number and arguments) |
| | 14 | |
| | 15 | - upon entry, the syscall dispatches the call to other (existing) U-Boot |
| | 16 | functional areas like networking or storage operations |
| | 17 | |
| | 18 | - consumer application will recognize the API is available by searching |
| | 19 | a specified (assumed by convention) range of address space for the |
| | 20 | signature |
| | 21 | |
| | 22 | - the U-Boot integral part of the API is meant to be thin and non-intrusive, |
| | 23 | leaving as much processing as possible on the consumer application side, |
| | 24 | for example it doesn't keep states, but relies on hints from the app and |
| | 25 | so on |
| | 26 | |
| | 27 | - optional (CONFIG_API) |
| | 28 | |
| | 29 | |
| | 30 | 2. Calls |
| | 31 | |
| | 32 | - console related (getc, putc, tstc etc.) |
| | 33 | - system (reset, platform info) |
| | 34 | - time (delay, current) |
| | 35 | - env vars (enumerate all, get, set) |
| | 36 | - devices (enumerate all, open, close, read, write); currently two classes |
| | 37 | of devices are recognized and supported: network and storage (ide, scsi, |
| | 38 | usb etc.) |
| | 39 | |
| | 40 | |
| | 41 | 3. Structure overview |
| | 42 | |
| | 43 | - core API, integral part of U-Boot, mandatory |
| | 44 | - implements the single entry point (mimics UNIX syscall) |
| | 45 | |
| | 46 | - glue |
| | 47 | - entry point at the consumer side, allows to make syscall, mandatory |
| | 48 | part |
| | 49 | |
| | 50 | - helper conveniency wrappers so that consumer app does not have to use |
| | 51 | the syscall directly, but in a more friendly manner (a la libc calls), |
| | 52 | optional part |
| | 53 | |
| | 54 | - consumer application |
| | 55 | - calls directly, or leverages the provided glue mid-layer |
projects / J-u-boot.git / blame_incremental