loaders: add run_romstage() function to bootblock

Provide a common run_romstage() function to be used by
bootblocks to load and run romstage. This is similar to
run_ramstage() in that it provides a single entry point
for doing the necessary work of loading and running romstage.

Change-Id: Ia9643cc091f97a836cf5caefdff8df4a3443df4c
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/8709
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

src/include/program_loading.h

@@ -22,6 +22,12 @@
 #include <stdint.h>
 #include <stddef.h>
 
+/************************
+ *   ROMSTAGE LOADING   *
+ ************************/
+
+/* Run romstage from bootblock. */
+void run_romstage(void);
 
 /************************
  *   RAMSTAGE LOADING   *

src/lib/loaders/Makefile.inc

@@ -17,6 +17,7 @@
 # Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 #
 
+bootblock-y += load_and_run_romstage.c
 romstage-y += cbfs_ramstage_loader.c
 romstage-y += load_and_run_ramstage.c
 ramstage-y += cbfs_payload_loader.c

src/lib/loaders/load_and_run_romstage.c

@@ -0,0 +1,42 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright 2015 Google Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+
+#include <stdlib.h>
+#include <console/console.h>
+#include <arch/stages.h>
+#include <cbfs.h>
+#include <halt.h>
+#include <program_loading.h>
+
+void run_romstage(void)
+{
+	void *entry;
+
+	entry = cbfs_load_stage(CBFS_DEFAULT_MEDIA,
+				CONFIG_CBFS_PREFIX "/romstage");
+
+	if (entry == (void *)-1) {
+		if (IS_ENABLED(CONFIG_BOOTBLOCK_CONSOLE))
+			die("Couldn't load romstage.\n");
+		halt();
+	}
+
+	stage_exit(entry);
+}