mb/google/rex: Add entry stubs of each stage

Add entry point stubs of each stage for Rex. More functionalities will
be added later.

BUG=b:224325352
TEST=util/abuild/abuild -p none -t google/rex -a -c max

Signed-off-by: Eric Lai <eric_lai@quanta.corp-partner.google.com>
Change-Id: I2310e58ab92bdb0ce86a9f7284cc0b3e04a2889f
Reviewed-on: https://review.coreboot.org/c/coreboot/+/64591
Reviewed-by: Tarun Tuli <taruntuli@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/google/rex/Makefile.inc

@@ -0,0 +1,10 @@
+bootblock-y += bootblock.c
+
+romstage-y += romstage.c
+
+ramstage-y += mainboard.c
+
+subdirs-y += variants/baseboard/$(BASEBOARD_DIR)
+
+CPPFLAGS_common += -I$(src)/mainboard/$(MAINBOARDDIR)/variants/baseboard/include
+CPPFLAGS_common += -I$(src)/mainboard/$(MAINBOARDDIR)/variants/baseboard/$(BASEBOARD_DIR)/include

src/mainboard/google/rex/bootblock.c

@@ -0,0 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include <bootblock_common.h>
+
+void bootblock_mainboard_init(void)
+{
+	/* TODO: Perform mainboard initialization */
+}

src/mainboard/google/rex/mainboard.c

@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include <device/device.h>
+
+static void mainboard_init(void *chip_info)
+{
+	/* TODO: Perform mainboard initialization */
+}
+
+static void mainboard_enable(struct device *dev)
+{
+	/* TODO: Enable mainboard */
+}
+
+struct chip_operations mainboard_ops = {
+	.init = mainboard_init,
+	.enable_dev = mainboard_enable,
+};

src/mainboard/google/rex/romstage.c

@@ -0,0 +1,9 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include <fsp/api.h>
+#include <soc/romstage.h>
+
+void mainboard_memory_init_params(FSPM_UPD *memupd)
+{
+	/* TODO : Fill FSP-M memory params */
+}

src/mainboard/google/rex/variants/baseboard/include/baseboard/variants.h

@@ -0,0 +1,9 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#ifndef __BASEBOARD_VARIANTS_H__
+#define __BASEBOARD_VARIANTS_H__
+
+#include <soc/gpio.h>
+#include <stdint.h>
+
+#endif /*__BASEBOARD_VARIANTS_H__ */

src/mainboard/google/rex/variants/baseboard/rex/include/baseboard/gpio.h

@@ -0,0 +1,9 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#ifndef __BASEBOARD_GPIO_H__
+#define __BASEBOARD_GPIO_H__
+
+#include <soc/gpe.h>
+#include <soc/gpio.h>
+
+#endif /* __BASEBOARD_GPIO_H__ */