broadwell: Add configuration for tuning VR for C-state operations

Add some configuration options that allow tuning the VR for C-state
settings that may be able to reduce noise.

- Add option to enable slow VR ramp rate for C-state exit
- Add variable to configure the minimum C6/C7 voltage

BUG=chrome-os-partner:34771
BRANCH=broadwell
TEST=build and boot on samus

Change-Id: I01445d62fbfcf200b787b924d8d72685819a4715
Signed-off-by: Stefan Reinauer <reinauer@chromium.org>
Original-Commit-Id: ed8f355e60292c82791817ae31bff58ac2390a72
Original-Change-Id: I8af75b69c8b55d3e210170ee96f8e22c2fd76374
Original-Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/241950
Original-Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/9497
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

1 files changed, 22 insertions, 0 deletions

diff --git a/src/soc/intel/broadwell/chip.h b/src/soc/intel/broadwell/chip.h
index 703c865..77c517d 100644
--- a/src/soc/intel/broadwell/chip.h
+++ b/src/soc/intel/broadwell/chip.h
@@ -130,6 +130,28 @@ struct soc_intel_broadwell_config {
 	/* Enable S0iX support */
 	int s0ix_enable;
 
+	/*
+	 * Minimum voltage for C6/C7 state:
+	 * 0x67 = 1.6V (full swing)
+	 *  ...
+	 * 0x79 = 1.7V
+	 *  ...
+	 * 0x83 = 1.8V (no swing)
+	 */
+	int vr_cpu_min_vid;
+
+	/*
+	 * Set slow VR ramp rate on C-state exit:
+	 * 0 = Fast VR ramp rate / 2
+	 * 1 = Fast VR ramp rate / 4
+	 * 2 = Fast VR ramp rate / 8
+	 * 3 = Fast VR ramp rate / 16
+	 */
+	int vr_slow_ramp_rate_set;
+
+	/* Enable slow VR ramp rate */
+	int vr_slow_ramp_rate_enable;
+
 	/* Deep SX enable */
 	int deep_sx_enable_ac;
 	int deep_sx_enable_dc;