cbfstool: Use cbfs_image API for "create" command.

Usage Changes: To support platforms with different memory layout, "create" takes
two extra optional parameters:

    "-b": base address (or offset) for bootblock. When omitted, put bootblock in
          end of ROM (x86  style).
    "-H": header offset. When omitted, put header right before bootblock,
          and update a top-aligned virtual address reference in end of ROM.

  Example: (can be found in ARM MAkefile):
    cbfstool coreboot.rom create -m armv7 -s 4096K -B bootblock.bin \
             -a 64 -b 0x0000 -H 0x2040 -o 0x5000

Verified to boot on ARM (Snow) and X86 (QEMU).

Change-Id: Ida2a9e32f9a459787b577db5e6581550d9d7017b
Signed-off-by: Hung-Te Lin <hungte@chromium.org>
Reviewed-on: http://review.coreboot.org/2214
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

util/cbfstool/cbfs_image.h

@@ -22,6 +22,8 @@
 #include "common.h"
 #include "cbfs.h"
 
+#define IS_TOP_ALIGNED_ADDRESS(x)	((uint32_t)(x) > 0x80000000)
+
 /* CBFS image processing */
 
 struct cbfs_image {
@@ -29,6 +31,20 @@ struct cbfs_image {
 	struct cbfs_header *header;
 };
 
+/* Creates an empty CBFS image by given size, and description to its content
+ * (bootblock, align, header location, starting offset of CBFS entries.
+ * The output image will contain a valid cbfs_header, with one cbfs_file
+ * entry with type CBFS_COMPONENT_NULL, with max available size.
+ * Returns 0 on success, otherwise none-zero. */
+int cbfs_image_create(struct cbfs_image *image,
+		      uint32_t arch,
+		      size_t size,
+		      uint32_t align,
+		      struct buffer *bootblock,
+		      int32_t bootblock_offset,
+		      int32_t header_offset,
+		      int32_t entries_offset);
+
 /* Loads a CBFS image from file. Returns 0 on success, otherwise non-zero. */
 int cbfs_image_from_file(struct cbfs_image *image, const char *filename);