--- /dev/null
+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
projects / karo-tx-uboot.git / blobdiff