fmap: Introduce new function to derive fmap name from offset/size

vboot passes around the offset and size of the region to use in later stages.
To assign more meaning to this pair, provide a function that returns the
fmap area name if there's a precise match (and an error otherwise).

Change-Id: I5724b860271025c8cb8b390ecbd33352ea779660
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Reviewed-on: http://review.coreboot.org/10865
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/include/fmap.h

@@ -21,6 +21,7 @@
 #define _FMAP_H_
 
 #include <region.h>
+#include <fmap_serialized.h>
 
 /* Locate the named area in the fmap and fill in a region device representing
  * that area. The region is a sub-region of the readonly boot media. Return
@@ -32,4 +33,8 @@ int fmap_locate_area_as_rdev(const char *name, struct region_device *area);
  * < 0 on error. */
 int fmap_locate_area(const char *name, struct region *r);
 
+/* Find fmap area name by offset and size.
+ * Return 0 on success, < 0 on error. */
+int fmap_find_region_name(const struct region * const ar,
+	char name[FMAP_STRLEN]);
 #endif