timestamps: don't drop ramstage timestamps with EARLY_CBMEM_INIT

While running ramstage with the EARLY_CBMEM_INIT config the timestamp
cache was re-initialized and subsequently used. The result was that
the ramstage timestamps would be dropped from cbmem.  The reason
is that the ramstage timestamps perpetually lived in ramstage BSS
never getting sync'd back into cbmem. The fix is to honor the
cache state in ramstage in the timestamp_init() path.

Also, make cache_state a fixed bit width to allow for different
architectures across the pre-ramstage stages.

TEST=Used qemu-armv7 as a test harness with debugging info.

Change-Id: Ibb276e513278e81cb741b1e1f6dbd1e8051cc907
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/10880
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

src/lib/timestamp.c

@@ -34,7 +34,7 @@
 #define MAX_TIMESTAMP_CACHE 16
 
 struct __attribute__((__packed__)) timestamp_cache {
-	int cache_state;
+	uint32_t cache_state;
 	struct timestamp_table table;
 	/* The struct timestamp_table has a 0 length array as its last field.
 	 * The  following 'entries' array serves as the storage space for the
@@ -199,6 +199,13 @@ void timestamp_init(uint64_t base)
 		return;
 	}
 
+	/* In the EARLY_CBMEM_INIT case timestamps could have already been
+	 * recovered. In those circumstances honor the cache which sits in BSS
+	 * as it has already been initialized. */
+	if (ENV_RAMSTAGE &&
+	    ts_cache->cache_state != TIMESTAMP_CACHE_UNINITIALIZED)
+		return;
+
 	timestamp_cache_init(ts_cache, base);
 }