diff --git a/scripts/dtc/srcpos.h b/scripts/dtc/srcpos.h
index ce980ca..93a2712 100644
--- a/scripts/dtc/srcpos.h
+++ b/scripts/dtc/srcpos.h
@@ -33,10 +33,39 @@
 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;
@@ -84,4 +113,6 @@
 extern void srcpos_warn(struct srcpos *pos, char const *, ...)
      __attribute__((format(printf, 2, 3)));
 
+extern void srcpos_set_line(char *f, int l);
+
 #endif /* _SRCPOS_H_ */