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>

3 files changed, 47 insertions, 0 deletions

diff --git a/src/mainboard/google/rex/variants/baseboard/include/baseboard/variants.h b/src/mainboard/google/rex/variants/baseboard/include/baseboard/variants.h
index d16d3dad53..a2fc805287 100644
--- a/src/mainboard/google/rex/variants/baseboard/include/baseboard/variants.h
+++ b/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__ */
diff --git a/src/mainboard/google/rex/variants/baseboard/rex/Makefile.inc b/src/mainboard/google/rex/variants/baseboard/rex/Makefile.inc
new file mode 100644
index 0000000000..6c29346470
--- /dev/null
+++ b/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
diff --git a/src/mainboard/google/rex/variants/baseboard/rex/gpio.c b/src/mainboard/google/rex/variants/baseboard/rex/gpio.c
new file mode 100644
index 0000000000..d9c31666ae
--- /dev/null
+++ b/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;
+}