mb/google/rex: Add GPIO stubs

Add stubbed out GPIO configuration and perform GPIO initialization
during bootblock, romstage and ramstage.

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: I51426f9557dafc357fc54a971b6f76fac5323e0a
Reviewed-on: https://review.coreboot.org/c/coreboot/+/64593
Reviewed-by: Tarun Tuli <taruntuli@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/google/rex/Kconfig

@@ -31,4 +31,8 @@ config MAINBOARD_FAMILY
 config MAINBOARD_PART_NUMBER
 	default "Rex" if BOARD_GOOGLE_REX0
 
+config VARIANT_DIR
+	string
+	default "rex0" if BOARD_GOOGLE_REX0
+
 endif # BOARD_GOOGLE_REX_COMMON

src/mainboard/google/rex/Makefile.inc

@@ -4,7 +4,12 @@ romstage-y += romstage.c
 
 ramstage-y += mainboard.c
 
+VARIANT_DIR:=$(call strip_quotes,$(CONFIG_VARIANT_DIR))
+BASEBOARD_DIR:=$(call strip_quotes,$(CONFIG_BASEBOARD_DIR))
+
 subdirs-y += variants/baseboard/$(BASEBOARD_DIR)
+subdirs-y += variants/$(VARIANT_DIR)
 
 CPPFLAGS_common += -I$(src)/mainboard/$(MAINBOARDDIR)/variants/baseboard/include
 CPPFLAGS_common += -I$(src)/mainboard/$(MAINBOARDDIR)/variants/baseboard/$(BASEBOARD_DIR)/include
+CPPFLAGS_common += -I$(src)/mainboard/$(MAINBOARDDIR)/variants/$(VARIANT_DIR)/include

src/mainboard/google/rex/bootblock.c

@@ -1,8 +1,13 @@
 /* SPDX-License-Identifier: GPL-2.0-or-later */
 
+#include <baseboard/variants.h>
 #include <bootblock_common.h>
 
 void bootblock_mainboard_init(void)
 {
-	/* TODO: Perform mainboard initialization */
+	const struct pad_config *pads;
+	size_t num;
+
+	pads = variant_early_gpio_table(&num);
+	gpio_configure_pads(pads, num);
 }

src/mainboard/google/rex/mainboard.c

@@ -1,10 +1,14 @@
 /* SPDX-License-Identifier: GPL-2.0-or-later */
 
+#include <baseboard/variants.h>
 #include <device/device.h>
 
 static void mainboard_init(void *chip_info)
 {
-	/* TODO: Perform mainboard initialization */
+	const struct pad_config *pads;
+	size_t num;
+	pads = variant_gpio_table(&num);
+	gpio_configure_pads(pads, num);
 }
 
 static void mainboard_enable(struct device *dev)

src/mainboard/google/rex/romstage.c

@@ -1,9 +1,14 @@
 /* SPDX-License-Identifier: GPL-2.0-or-later */
 
+#include <baseboard/variants.h>
 #include <fsp/api.h>
 #include <soc/romstage.h>
 
 void mainboard_memory_init_params(FSPM_UPD *memupd)
 {
-	/* TODO : Fill FSP-M memory params */
+	const struct pad_config *pads;
+	size_t pads_num;
+
+	pads = variant_romstage_gpio_table(&pads_num);
+	gpio_configure_pads(pads, pads_num);
 }

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

@@ -6,4 +6,12 @@
 #include <soc/gpio.h>
 #include <stdint.h>
 
+/* The next set of functions return the gpio table and fill in the number of entries for
+ * each table.
+ */
+
+const struct pad_config *variant_gpio_table(size_t *num);
+const struct pad_config *variant_early_gpio_table(size_t *num);
+const struct pad_config *variant_romstage_gpio_table(size_t *num);
+
 #endif /*__BASEBOARD_VARIANTS_H__ */

src/mainboard/google/rex/variants/baseboard/rex/Makefile.inc

@@ -0,0 +1,5 @@
+bootblock-y += gpio.c
+
+romstage-y += gpio.c
+
+ramstage-y += gpio.c

src/mainboard/google/rex/variants/baseboard/rex/gpio.c

@@ -0,0 +1,34 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include <baseboard/gpio.h>
+#include <baseboard/variants.h>
+#include <soc/gpio.h>
+
+/* Pad configuration in ramstage */
+static const struct pad_config gpio_table[] = {
+	/* ToDo: Fill gpio configuration */
+};
+
+/* Early pad configuration in bootblock */
+static const struct pad_config early_gpio_table[] = {
+	/* ToDo: Fill early gpio configuration */
+};
+
+const struct pad_config *__weak variant_gpio_table(size_t *num)
+{
+	*num = ARRAY_SIZE(gpio_table);
+	return gpio_table;
+}
+
+const struct pad_config *__weak variant_early_gpio_table(size_t *num)
+{
+	*num = ARRAY_SIZE(early_gpio_table);
+	return early_gpio_table;
+}
+
+/* Create the stub for romstage gpio, typically use for power sequence */
+const struct pad_config *__weak variant_romstage_gpio_table(size_t *num)
+{
+	*num = 0;
+	return NULL;
+}

src/mainboard/google/rex/variants/rex0/include/variant/gpio.h

@@ -0,0 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#ifndef __MAINBOARD_GPIO_H__
+#define __MAINBOARD_GPIO_H__
+
+#include <baseboard/gpio.h>
+
+#endif /* __MAINBOARD_GPIO_H__ */