arch/x86: Add a common romstage entry

It might be possible to have this used for more than x86, but that
will be for a later commit.

Change-Id: I4968364a95b5c69c21d3915d302d23e6f1ca182f
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/55067
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Elyes Haouas <ehaouas@noos.fr>

src/arch/x86/Makefile.inc

@@ -159,6 +159,7 @@ endif # CONFIG_ARCH_VERSTAGE_X86_32 / CONFIG_ARCH_VERSTAGE_X86_64
 ifeq ($(CONFIG_ARCH_ROMSTAGE_X86_32)$(CONFIG_ARCH_ROMSTAGE_X86_64),y)
 
 romstage-y += assembly_entry.S
+romstage-y += romstage.c
 romstage-y += boot.c
 romstage-$(CONFIG_DEBUG_HW_BREAKPOINTS_IN_ALL_STAGES) += breakpoint.c
 romstage-y += post.c

src/arch/x86/romstage.c

@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <arch/cpu.h>
+#include <console/console.h>
+#include <timestamp.h>
+#include <romstage_common.h>
+
+asmlinkage void car_stage_entry(void)
+{
+	timestamp_add_now(TS_ROMSTAGE_START);
+
+	/* Assumes the hardware was set up during the bootblock */
+	console_init();
+
+	romstage_main();
+}