Useful to avoid #ifdef throughout the code that uses the board driver API.

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

This function will be used by the SPL to get the names of images to load
from the FIT. This allows to load different images based on runtime HW
detection.

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

Since there is no canonical "board device" that can be used in board
files, it is difficult to use DM function for board initialization in
these cases.

Hence, add a uclass that implements a simple "board device", which can
hold devices not suitable anywhere else in the device tree, and is also
able to read encoded information, e.g. hard-wired GPIOs on a GPIO
expander, read-only memory ICs, etc. that carry information about the
hardware.

The devices of this uclass expose methods to read generic data types
(integers, strings, booleans) to encode the information provided by the
hardware.

Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Mario Six <mario.six@gdsys.cc>