mb/google/brya/var/nereid: Configure descriptor for either Type-C or HDMI

Some bytes in the descriptor need to be set differently for Type-C and
HDMI. To allow using a single firmware variant for both cases, update
the descriptor at runtime based on fw_config. This is a temporary
workaround while we find a better solution.

The byte values were determined by changing the following CSE strap and
comparing the generated descriptors:
Type-C: TypeCPort2Config = "No Thunderbolt"
HDMI:   TypeCPort2Config = "DP Fixed Connection"

The default value before updating the descriptor is Type-C, but this was
chosen arbitrarily.

BUG=b:226848617
TEST=Type-C and HDMI both work on nereid with fw_config set correctly.

Change-Id: I2cc230e3bd35816c81989ae7e01df5d2c152062e
Signed-off-by: Reka Norman <rekanorman@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/63366
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Eric Lai <eric_lai@quanta.corp-partner.google.com>
Reviewed-by: Sam McNally <sammc@google.com>

src/mainboard/google/brya/Kconfig.name

@@ -90,6 +90,7 @@ config BOARD_GOOGLE_NIVVIKS
 
 config BOARD_GOOGLE_NEREID
 	bool "->  Nereid"
+	select ALDERLAKE_CONFIGURE_DESCRIPTOR
 	select BOARD_GOOGLE_BASEBOARD_NISSA
 
 config BOARD_GOOGLE_PRIMUS

src/mainboard/google/brya/bootblock.c

@@ -10,3 +10,10 @@ void bootblock_mainboard_early_init(void)
 	pads = variant_early_gpio_table(&num);
 	gpio_configure_pads(pads, num);
 }
+
+void bootblock_mainboard_init(void)
+{
+	variant_update_descriptor();
+}
+
+void __weak variant_update_descriptor(void) {}

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

@@ -34,6 +34,8 @@ void variant_generate_s0ix_hook(enum s0ix_entry);
 /* Modify devictree settings during ramstage */
 void variant_devtree_update(void);
 
+void variant_update_descriptor(void);
+
 struct cpu_power_limits {
 	uint16_t mchid;
 	u8 cpu_tdp;

src/mainboard/google/brya/variants/nereid/Makefile.inc

@@ -1,5 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0-only
 bootblock-y += gpio.c
+bootblock-y += variant.c
 
 romstage-y += gpio.c
 romstage-y += memory.c

src/mainboard/google/brya/variants/nereid/variant.c

@@ -1,7 +1,10 @@
 /* SPDX-License-Identifier: GPL-2.0-or-later */
 
+#include <baseboard/variants.h>
+#include <console/console.h>
 #include <drivers/intel/gma/opregion.h>
 #include <fw_config.h>
+#include <soc/bootblock.h>
 
 const char *mainboard_vbt_filename(void)
 {
@@ -10,3 +13,30 @@ const char *mainboard_vbt_filename(void)
 
 	return "vbt.bin";
 }
+
+void variant_update_descriptor(void)
+{
+	/* TypeCPort2Config = "No Thunderbolt" */
+	struct descriptor_byte typec_bytes[] = {
+		{ 0xc76, 0xb7 },
+		{ 0xc77, 0xb6 },
+		{ 0xc7c, 0xee },
+		{ 0xca0, 0x0c },
+	};
+
+	/* TypeCPort2Config = "DP Fixed Connection" */
+	struct descriptor_byte hdmi_bytes[] = {
+		{ 0xc76, 0x75 },
+		{ 0xc77, 0xc4 },
+		{ 0xc7c, 0x1e },
+		{ 0xca0, 0x0e },
+	};
+
+	if (fw_config_probe(FW_CONFIG(DB_USB, DB_1A_HDMI))) {
+		printk(BIOS_INFO, "Configuring descriptor for HDMI\n");
+		configure_descriptor(hdmi_bytes, ARRAY_SIZE(hdmi_bytes));
+	} else {
+		printk(BIOS_INFO, "Configuring descriptor for Type-C\n");
+		configure_descriptor(typec_bytes, ARRAY_SIZE(typec_bytes));
+	}
+}