mb/google/guybrush: Override SPI Fast speeds

Add support to override SPI fast speeds based on board version from both
bootblock and verstage. Overrides apply for Guybrush only and SPI speed
is overridden from 66 MHz to 100 MHz starting board version 4. This will
help to improve the boot time on board version by ~60 ms and still allow
the old boards to boot with 66 MHz.

BUG=b:199779306
TEST=Build and boot to OS in Guybrush. Perform S5->S0, G3->S0, warm
reset and suspend/resume cycles for 50 iterations each.

Signed-off-by: Karthikeyan Ramasubramanian <kramasub@google.com>
Change-Id: I5bf03ab8772f27aca346589e9c5662caf014d0d2
Reviewed-on: https://review.coreboot.org/c/coreboot/+/58117
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>
Reviewed-by: Raul Rangel <rrangel@chromium.org>

src/mainboard/google/guybrush/Kconfig

@@ -111,6 +111,22 @@ config NORMAL_READ_SPI_SPEED
 config ALT_SPI_SPEED
 	default 0	# 66MHz
 
+config OVERRIDE_EFS_SPI_SPEED
+	int
+	default 3 if EM100
+	default 4	# 100MHz
+	help
+	  Override EFS SPI Speed Configuration to be applied based on certain
+	  board version.
+
+config OVERRIDE_EFS_SPI_SPEED_MIN_BOARD
+	hex
+	default 0x4 if BOARD_GOOGLE_GUYBRUSH
+	default 0xffffffff
+	help
+	  Minimum board version starting which the Override EFS SPI Speed
+	  configuration has to be applied.
+
 endif # !EM100
 
 config VARIANT_DIR

src/mainboard/google/guybrush/Makefile.inc

@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0-or-later
 
 bootblock-y += bootblock.c
+bootblock-$(CONFIG_CHROMEOS) += chromeos.c
 
 ifneq ($(wildcard $(MAINBOARD_BLOBS_DIR)/APCB_CZN_D4.bin),)
 $(info APCB sources present.)

src/mainboard/google/guybrush/chromeos.c

@@ -1,5 +1,6 @@
 /* SPDX-License-Identifier: GPL-2.0-or-later */
 
+#include <amdblocks/spi.h>
 #include <baseboard/gpio.h>
 #include <boardid.h>
 #include <boot/coreboot_tables.h>
@@ -36,3 +37,11 @@ int get_ec_is_trusted(void)
 	/* EC is trusted if not in RW. */
 	return !gpio_get(GPIO_EC_IN_RW);
 }
+
+void mainboard_spi_fast_speed_override(uint8_t *fast_speed)
+{
+	uint32_t board_ver = board_id();
+
+	if (board_ver >= CONFIG_OVERRIDE_EFS_SPI_SPEED_MIN_BOARD)
+		*fast_speed = CONFIG_OVERRIDE_EFS_SPI_SPEED;
+}