[coreboot-gerrit] Change in coreboot[master]: mb/google/volteer: disable TBT if no USB4 hardware available

[Duncan Laurie (Code Review)]

Duncan Laurie has submitted this change. ( https://review.coreboot.org/c/coreboot/+/45946 )

Change subject: mb/google/volteer: disable TBT if no USB4 hardware available
......................................................................

mb/google/volteer: disable TBT if no USB4 hardware available

Implement mainboard_silicon_init_params() to allow for disabling of
TBT root ports if the device does not have usb4 hardware.

Add code to mainboard_memory_init_params() to disable memory-related
settings associated with TBT in cases where no usb4 is available.

BUG=b:167983038
TEST=none

Change-Id: Iab23c07e15f754ca807f128b9edad7fdc9a44b9d
Signed-off-by: Nick Vaccaro 
Reviewed-on: https://review.coreboot.org/c/coreboot/+/45946
Tested-by: build bot (Jenkins) 
Reviewed-by: Duncan Laurie 
---
M src/mainboard/google/volteer/mainboard.c
M src/mainboard/google/volteer/romstage.c
2 files changed, 23 insertions(+), 0 deletions(-)

Approvals:
  build bot (Jenkins): Verified
  Duncan Laurie: Looks good to me, approved

diff --git a/src/mainboard/google/volteer/mainboard.c b/src/mainboard/google/volteer/mainboard.c
index 23c3e92..1fcd5eb 100644
--- a/src/mainboard/google/volteer/mainboard.c
+++ b/src/mainboard/google/volteer/mainboard.c
@@ -78,6 +78,21 @@
    	override_pads, override_num);
 }

+void mainboard_silicon_init_params(FSP_S_CONFIG *params)
+{
+	bool has_usb4;
+
+	/* If device doesn't have USB4 hardware, disable tbt */
+	has_usb4 = (fw_config_probe(FW_CONFIG(DB_USB, USB4_GEN2)) ||
+	    fw_config_probe(FW_CONFIG(DB_USB, USB4_GEN3)));
+
+	if (!has_usb4)
+		memset(params->ITbtPcieRootPortEn,
+		       0,
+		       ARRAY_SIZE(params->ITbtPcieRootPortEn) *
+		       sizeof(*params->ITbtPcieRootPortEn));
+}
+
 struct chip_operations mainboard_ops = {
    .init = mainboard_chip_init,
    .enable_dev = mainboard_enable,
diff --git a/src/mainboard/google/volteer/romstage.c b/src/mainboard/google/volteer/romstage.c
index 720ab7f..315ec20 100644
--- a/src/mainboard/google/volteer/romstage.c
+++ b/src/mainboard/google/volteer/romstage.c
@@ -27,4 +27,12 @@
    	mem_cfg->PchHdaEnable = 0;

meminit_ddr(mem_cfg, board_cfg, &spd_info, half_populated);
+
+	/* Disable TBT if no USB4 hardware */
+	if (!(fw_config_probe(FW_CONFIG(DB_USB, USB4_GEN2)) ||
+		    fw_config_probe(FW_CONFIG(DB_USB, USB4_GEN3)))) {
+		mem_cfg->TcssDma0En = 0;
+		mem_cfg->TcssItbtPcie0En = 0;
+		mem_cfg->TcssItbtPcie1En = 0;
+	}
 }