romstage_handoff: provide common logic for setup

The romstage_handoff structure can be utilized from different components
of the romstage -- some in the chipset code, some in coreboot's core
libarary. To ensure that all users handle initialization of a newly
added romstage_handoff structure properly, provide a common function to
handle structure initialization.

Change-Id: I3998c6bb228255f4fd93d27812cf749560b06e61
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/2795
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

src/include/romstage_handoff.h

@@ -20,6 +20,8 @@
 #define ROMSTAGE_HANDOFF_H
 
 #include <stdint.h>
+#include <string.h>
+#include <cbmem.h>
 
 /* It is the chipset's responsbility for maintaining the integrity of this
  * structure in CBMEM. For instance, if chipset code adds this structure
@@ -31,5 +33,30 @@ struct romstage_handoff {
 	uint32_t reserve_size;
 };
 
+#if defined(__PRE_RAM__)
+/* The romstage_handoff_find_or_add() function provides the necessary logic
+ * for initializng the romstage_handoff structure in cbmem. Different components
+ * of the romstage may be responsible for setting up different fields. Therefore
+ * that same logic flow should be used for allocating and initializing the
+ * structure. A newly allocated structure will be memset to 0. */
+static inline struct romstage_handoff *romstage_handoff_find_or_add(void)
+{
+	struct romstage_handoff *handoff;
+
+	/* cbmem_add() first does a find and uses the old location before the
+	 * real add. However, it is important to know when the structure is not
+	 * found so it can be initialized to 0. */
+	handoff = cbmem_find(CBMEM_ID_ROMSTAGE_INFO);
+
+	if (handoff == NULL) {
+		handoff = cbmem_add(CBMEM_ID_ROMSTAGE_INFO, sizeof(*handoff));
+		if (handoff != NULL)
+			memset(handoff, 0, sizeof(*handoff));
+	}
+
+	return handoff;
+}
+#endif
+
 #endif /* ROMSTAGE_HANDOFF_H */
 

src/lib/cbfs.c

@@ -161,7 +161,7 @@ void * cbfs_load_stage(struct cbfs_media *media, const char *name)
 	if (rmodule_load(ramstage_loc, &ramstage))
 		return (void *) -1;
 
-	handoff = cbmem_add(CBMEM_ID_ROMSTAGE_INFO, sizeof(*handoff));
+	handoff = romstage_handoff_find_or_add();
 	if (handoff) {
 		handoff->reserve_base = (uint32_t)ramstage_base;
 		handoff->reserve_size = (uint32_t)cbmem_base -