Add support to get layout from fmap (e.g. coreboot rom)

Flashmap, or simply fmap, is a binary data format for describing
region offsets, sizes, and certain attributes and is widely used by
coreboot. This patch adds support for the fmap data format version 1.1
and adds --fmap and --fmap-file arguments.

Using --fmap will make flashrom to search the ROM content for fmap
data. Using --fmap-file will make flashrom search a supplied file
for fmap data.

An example of how to update the COREBOOT region of a ROM:
flashrom -p programmer --fmap -w coreboot.rom -i COREBOOT
flashrom -p programmer --fmap-file coreboot.rom -w coreboot.rom -i COREBOOT

The fmap functions are mostly copied from cbfstool.

Currently it is made mutually exclusive with other layout options until
we are more clever about this input.

Change-Id: I0e7fad38ed79a84d41358e1f175c36d255786c12
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Signed-off-by: David Hendricks <dhendricks@fb.com>
Reviewed-on: https://review.coreboot.org/23203
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Tested-by: David Hendricks <david.hendricks@gmail.com>
Reviewed-by: Werner Zeh <werner.zeh@siemens.com>
Reviewed-by: Nico Huber <nico.h@gmx.de>
diff --git a/libflashrom.h b/libflashrom.h
index 04907b2..4fbcd35 100644
--- a/libflashrom.h
+++ b/libflashrom.h
@@ -61,8 +61,12 @@
 
 struct flashrom_layout;
 int flashrom_layout_read_from_ifd(struct flashrom_layout **, struct flashrom_flashctx *, const void *dump, size_t len);
+int flashrom_layout_read_fmap_from_rom(struct flashrom_layout **,
+		struct flashrom_flashctx *, off_t offset, size_t length);
+int flashrom_layout_read_fmap_from_buffer(struct flashrom_layout **layout,
+		struct flashrom_flashctx *, const uint8_t *buf, size_t len);
 int flashrom_layout_include_region(struct flashrom_layout *, const char *name);
 void flashrom_layout_release(struct flashrom_layout *);
 void flashrom_layout_set(struct flashrom_flashctx *, const struct flashrom_layout *);
 
-#endif				/* !__LIBFLASHROM_H__ */
\ No newline at end of file
+#endif				/* !__LIBFLASHROM_H__ */