coreboot: infrastructure for different ramstage loaders

There are 2 methods currently available in coreboot to load
ramstage from romstage: cbfs and vboot. The vboot path had
to be explicitly enabled and code needed to be added to
each chipset to support both. Additionally, many of the paths
were duplicated between the two. An additional complication
is the presence of having a relocatable ramstage which creates
another path with duplication.

To rectify this situation provide a common API through the
use of a callback to load the ramstage. The rest of the
existing logic to handle all the various cases is put in
a common place.

Change-Id: I5268ce70686cc0d121161a775c3a86ea38a4d8ae
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/5087
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>

src/include/cbfs.h

@@ -83,6 +83,10 @@ void selfboot(void *entry);
 /* Defined in individual arch / board implementation. */
 int init_default_cbfs_media(struct cbfs_media *media);
 
+#if defined(__PRE_RAM__)
+struct romstage_handoff;
+struct cbmem_entry;
+
 #if CONFIG_RELOCATABLE_RAMSTAGE && defined(__PRE_RAM__)
 /* The cache_loaded_ramstage() and load_cached_ramstage() functions are defined
  * to be weak so that board and chipset code may override them. Their job is to
@@ -90,9 +94,6 @@ int init_default_cbfs_media(struct cbfs_media *media);
  * relocated ramstage is saved using the cbmem infrastructure. These
  * functions are only valid during romstage. */
 
-struct romstage_handoff;
-struct cbmem_entry;
-
 /* The implementer of cache_loaded_ramstage() may use the romstage_handoff
  * structure to store information, but note that the handoff variable can be
  * NULL. The ramstage cbmem_entry represents the region occupied by the loaded
@@ -105,7 +106,22 @@ cache_loaded_ramstage(struct romstage_handoff *handoff,
 void * __attribute__((weak))
 load_cached_ramstage(struct romstage_handoff *handoff,
                      const struct cbmem_entry *ramstage);
+#else  /* CONFIG_RELOCATABLE_RAMSTAGE */
+
+static inline void cache_loaded_ramstage(struct romstage_handoff *handoff,
+			const struct cbmem_entry *ramstage, void *entry_point)
+{
+}
+
+static inline void *
+load_cached_ramstage(struct romstage_handoff *handoff,
+			const struct cbmem_entry *ramstage)
+{
+	return NULL;
+}
+
 #endif /* CONFIG_RELOCATABLE_RAMSTAGE */
+#endif /* defined(__PRE_RAM__) */
 
 #endif