coreboot rush: Add support for basic romstage

Add basic romstage support for rush. Since, dram init needs to be done before we
can jump to armv8 core, romstage will run on armv4 core as well. Thus,
correcting the compiler selection options.

BUG=None
BRANCH=None
TEST=Compiles successfully for rush. Prints romstage banner and initial printk

Change-Id: Ie3cd290e56a712b07c1503dab199e4e34cec04d2
Signed-off-by: Furquan Shaikh <furquan@google.com>
Reviewed-on: https://chromium-review.googlesource.com/205763
Tested-by: Furquan Shaikh <furquan@chromium.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Tom Warren <twarren@nvidia.com>
Commit-Queue: Aaron Durbin <adurbin@chromium.org>

src/arch/arm/armv4/Makefile.inc

@@ -45,6 +45,7 @@ ifeq ($(CONFIG_ARCH_ROMSTAGE_ARM_V4),y)
 
 romstage-c-ccopts += $(armv4_flags)
 romstage-S-ccopts += $(armv4_flags)
+romstage-y += cache.c
 
 endif
 ################################################################################

src/mainboard/google/rush/romstage.c

@@ -20,11 +20,19 @@
 #include <arch/stages.h>
 #include <cbfs.h>
 #include <console/console.h>
+#include <arch/exception.h>
 
 void main(void)
 {
 	void *entry;
 
+	console_init();
+	exception_init();
+
+	printk(BIOS_INFO, "T132: romstage here\n");
+
+	while (1);
+
         entry = cbfs_load_stage(CBFS_DEFAULT_MEDIA, "fallback/ramstage");
         stage_exit(entry);
 }

src/soc/nvidia/tegra132/Kconfig

@@ -2,12 +2,13 @@ config SOC_NVIDIA_TEGRA132
 	bool
 	default n
 	select ARCH_BOOTBLOCK_ARM_V4
-	select ARCH_ROMSTAGE_ARM_V8_64
+	select ARCH_ROMSTAGE_ARM_V4
 	select ARCH_RAMSTAGE_ARM_V8_64
 	select ARM_LPAE
 	select BOOTBLOCK_CONSOLE
 	select HAVE_UART_SPECIAL
 	select HAVE_UART_MEMORY_MAPPED
+	select EARLY_CONSOLE
 	select ARM_BOOTBLOCK_CUSTOM
 
 if SOC_NVIDIA_TEGRA132