dtc: Add -i option to support search paths

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>

1 files changed, 29 insertions, 0 deletions

diff --git a/srcpos.h b/srcpos.h
index ce980ca..5617916 100644
--- a/srcpos.h
+++ b/srcpos.h
@@ -33,10 +33,39 @@ struct srcfile_state {
 extern FILE *depfile; /* = NULL */
 extern struct srcfile_state *current_srcfile; /* = NULL */
 
+/**
+ * Open a source file.
+ *
+ * If the source file is a relative pathname, then it is searched for in the
+ * current directory (the directory of the last source file read) and after
+ * that in the search path.
+ *
+ * We work through the search path in order from the first path specified to
+ * the last.
+ *
+ * If the file is not found, then this function does not return, but calls
+ * die().
+ *
+ * @param fname		Filename to search
+ * @param fullnamep	If non-NULL, it is set to the allocated filename of the
+ *			file that was opened. The caller is then responsible
+ *			for freeing the pointer.
+ * @return pointer to opened FILE
+ */
 FILE *srcfile_relative_open(const char *fname, char **fullnamep);
+
 void srcfile_push(const char *fname);
 int srcfile_pop(void);
 
+/**
+ * Add a new directory to the search path for input files
+ *
+ * The new path is added at the end of the list.
+ *
+ * @param dirname	Directory to add
+ */
+void srcfile_add_search_path(const char *dirname);
+
 struct srcpos {
     int first_line;
     int first_column;