mb/google/rex: Use gpio padbased table override

In order to improve gpio merge mechanism. Change iteration override
to padbased table override. And the following patch will change fw
config override with ramstage gpio table override.

Port of commit 7aef2b1294 ("mb/google/nissa: Apply gpio padbased
 table override")

BUG=none
TEST=Verify devbeep at depthcharge console

Signed-off-by: Kapil Porwal <kapilporwal@google.com>
Change-Id: I2ee86bbec7d25a35d726f29ad79891f1054bf52c
Reviewed-on: https://review.coreboot.org/c/coreboot/+/73182
Reviewed-by: Subrata Banik <subratabanik@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Eric Lai <eric_lai@quanta.corp-partner.google.com>

src/mainboard/google/rex/mainboard.c

@@ -8,16 +8,28 @@
 #include <drivers/wwan/fm/chip.h>
 #include <ec/ec.h>
 #include <fw_config.h>
+#include <stdlib.h>
 #include <vendorcode/google/chromeos/chromeos.h>
 
 WEAK_DEV_PTR(rp6_wwan);
 
+void __weak fw_config_gpio_padbased_override(struct pad_config *padbased_table)
+{
+	/* default implementation does nothing */
+}
+
 static void mainboard_init(void *chip_info)
 {
-	const struct pad_config *pads;
-	size_t num;
-	pads = variant_gpio_table(&num);
-	gpio_configure_pads(pads, num);
+	struct pad_config *padbased_table;
+	const struct pad_config *base_pads;
+	size_t base_num;
+
+	padbased_table = new_padbased_table();
+	base_pads = variant_gpio_table(&base_num);
+	gpio_padbased_override(padbased_table, base_pads, base_num);
+	fw_config_gpio_padbased_override(padbased_table);
+	gpio_configure_pads_with_padbased(padbased_table);
+	free(padbased_table);
 }
 
 void __weak variant_generate_s0ix_hook(enum s0ix_entry entry)

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

@@ -15,6 +15,7 @@
 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);
+void fw_config_gpio_padbased_override(struct pad_config *padbased_table);
 
 const struct mb_cfg *variant_memory_params(void);
 void variant_get_spd_info(struct mem_spd *spd_info);