mb/google/volteer/var/voxel: Add settings for noise mitgation

Enable acoustic noise mitgation for volteer platforms.

BUG=b:179328166
BRANCH=none
TEST= Measure the change in noise level by changing the values
in devicetree.

Signed-off-by: Pan Sheng-Liang <sheng-liang.pan@quanta.corp-partner.google.com>
Change-Id: I279a85c7741094bb7ddf0c1fde74b31189b12171
Reviewed-on: https://review.coreboot.org/c/coreboot/+/50293
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nick Vaccaro <nvaccaro@google.com>
diff --git a/src/mainboard/google/volteer/variants/voxel/overridetree.cb b/src/mainboard/google/volteer/variants/voxel/overridetree.cb
index 879086f..ed90069 100644
--- a/src/mainboard/google/volteer/variants/voxel/overridetree.cb
+++ b/src/mainboard/google/volteer/variants/voxel/overridetree.cb
@@ -19,6 +19,17 @@
 	# Disable SRCCLKREQ1#
 	register "PcieClkSrcUsage[1]" = "PCIE_CLK_NOTUSED"
 
+	# Acoustic settings
+	register "AcousticNoiseMitigation" = "1"
+	register "SlowSlewRate[VR_DOMAIN_IA]" = "SLEW_FAST_8"
+	register "SlowSlewRate[VR_DOMAIN_GT]" = "SLEW_FAST_8"
+	register "SlowSlewRate[VR_DOMAIN_SA]" = "SLEW_FAST_8"
+	register "SlowSlewRate[VR_DOMAIN_VLCC]" = "SLEW_FAST_8"
+	register "FastPkgCRampDisable[VR_DOMAIN_IA]" = "1"
+	register "FastPkgCRampDisable[VR_DOMAIN_GT]" = "1"
+	register "FastPkgCRampDisable[VR_DOMAIN_SA]" = "1"
+	register "FastPkgCRampDisable[VR_DOMAIN_VLCC]" = "1"
+
 	device domain 0 on
 		device ref dptf on
 			chip drivers/intel/dptf