New patch to review for coreboot: reef: tune tpm i2c frequency to 400kHz

[Aaron Durbin]

Aaron Durbin ([e-mail]) just uploaded a new patch set to gerrit, which you can find at https://review.coreboot.org/17214

-gerrit

commit f91099801a38aa2ba32b45d0b34586e38897c50e
Author: Aaron Durbin 
Date:   Thu Nov 3 08:34:23 2016 -0500

reef: tune tpm i2c frequency to 400kHz

This brings the frequency down to 400kHz which is spec for
    fast i2c.

BUG=chrome-os-partner:58889

Change-Id: I8689a062b5457aa431eaa7fb688a7170dad83fcf
    Signed-off-by: Aaron Durbin 
---
 src/mainboard/google/reef/variants/baseboard/devicetree.cb | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/src/mainboard/google/reef/variants/baseboard/devicetree.cb b/src/mainboard/google/reef/variants/baseboard/devicetree.cb
index 30d61f6..559b007 100644
--- a/src/mainboard/google/reef/variants/baseboard/devicetree.cb
+++ b/src/mainboard/google/reef/variants/baseboard/devicetree.cb
@@ -71,8 +71,18 @@ chip soc/intel/apollolake
    register "gpe0_dw2" = "PMC_GPE_N_63_32"
    register "gpe0_dw3" = "PMC_GPE_SW_31_0"

-	# Enable I2C2 bus early for TPM access
-	register "i2c[2].early_init" = "1"
+	# Enable I2C2 bus early for TPM access and configure as 400kHz
+	# with manually tuned values.
+	register "i2c[2]" = "{
+		.early_init = 1,
+		.speed = I2C_SPEED_FAST,
+		.speed_config[0] = {
+			.speed = I2C_SPEED_FAST,
+			.scl_lcnt = 0xd0,
+			.scl_hcnt = 0x68,
+			.sda_hold = 0x27,
+		}
+	}"

# Minimum SLP S3 assertion width 28ms.
    register "slp_s3_assertion_width_usecs" = "28000"