arch/x86: move postcar main logic into C

The console_init(), MTRR printing, and loading ramstage
logic was previously all in assembly. Move that logic
into C code so that future features can more easily be
added into the postcar boot flow.

BUG=chrome-os-partner:57513

Change-Id: I332140f569caf0803570fd635d894295de8c0018
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/16618
Tested-by: build bot (Jenkins)
Reviewed-by: Furquan Shaikh <furquan@google.com>
Reviewed-by: Andrey Petrov <andrey.petrov@intel.com>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
diff --git a/src/arch/x86/Makefile.inc b/src/arch/x86/Makefile.inc
index 38a2a8c..8357588 100644
--- a/src/arch/x86/Makefile.inc
+++ b/src/arch/x86/Makefile.inc
@@ -287,6 +287,7 @@
 postcar-y += memset.c
 postcar-y += memlayout.ld
 postcar-$(CONFIG_X86_TOP4G_BOOTMEDIA_MAP) += mmap_boot.c
+postcar-y += postcar.c
 postcar-$(CONFIG_COLLECT_TIMESTAMPS) += timestamp.c
 
 LDFLAGS_postcar += -Map $(objcbfs)/postcar.map
diff --git a/src/arch/x86/exit_car.S b/src/arch/x86/exit_car.S
index ca9b70e..5c62c92 100644
--- a/src/arch/x86/exit_car.S
+++ b/src/arch/x86/exit_car.S
@@ -26,11 +26,6 @@
 .text
 .global _start
 _start:
-#if IS_ENABLED(CONFIG_POSTCAR_CONSOLE)
-	/* Enable the console */
-	call	console_init
-#endif /* CONFIG_POSTCAR_CONSOLE */
-
 	/* chipset_teardown_car() is expected to disable cache-as-ram. */
 	call	chipset_teardown_car
 
@@ -113,13 +108,8 @@
 	wrmsr
 #endif /* CONFIG_SOC_SETS_MSRS */
 
-	/* Display the MTRRs */
-#if IS_ENABLED(CONFIG_POSTCAR_CONSOLE)
-	call	soc_display_mtrrs
-#endif /* CONFIG_POSTCAR_CONSOLE */
-
-	/* Load and run ramstage. */
-	call	copy_and_run
+	/* Call into main for postcar. */
+	call main
 	/* Should never return. */
 1:
 	jmp	1b
diff --git a/src/arch/x86/postcar.c b/src/arch/x86/postcar.c
new file mode 100644
index 0000000..8c3ea43
--- /dev/null
+++ b/src/arch/x86/postcar.c
@@ -0,0 +1,31 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright 2016 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.
+ */
+
+#include <console/console.h>
+#include <main_decl.h>
+#include <program_loading.h>
+#include <soc/intel/common/util.h>
+
+void main(void)
+{
+	console_init();
+
+	/* Display the MTRRs */
+	if (IS_ENABLED(CONFIG_DISPLAY_MTRRS))
+		soc_display_mtrrs();
+
+	/* Load and run ramstage. */
+	run_ramstage();
+}