It is often inconvenient to place device tree files in the same directory
as their includes, or to specify the full path to include files.
An example of this is in U-Boot where we have a .dtsi file for each SOC
type, and this is included by the board .dts file. We need to either use
a mechanism like:
/include/ ARCH_CPU_DTS
with sed or cpp to perform the replacement with the correct path, or
we must specify the full path in the file:
/include/ "../../arch/arm/dts/tegra20.dtsi"
The first option is not desirable since it requires anyone compiling the
file to first pre-process it. The second is not desirable since it
introduces a path which is project-specific into a file which is supposed
to be a hardware description. For example Linux and U-Boot are unlikely to
put these include files in the same place.
It is much more convenient to specify the search patch on the command line
as is done with C pre-processors, for example.
Introduce a -i option to add to the list of search paths used to find
source and include files.
We cannot use -I as it is already in use. Other suggestions welcome.
Signed-off-by: Simon Glass <sjg@chromium.org>
