soc/intel/cannonlake: Disable RTC write protect

The cannonlake FSP enables PchLockDownRtcMemoryLock by default, but we
need this memory to be writable.  We normally over-ride this in the
SoC chip init code, so we'll do the same on cannonlake.

TEST=Filled /dev/nvram with 0xff and 0x00 bytes to verify we can flip
all the bits.

Change-Id: I7cdd4abc2b3795d7dd82236fbe3c112428ee882b
Signed-off-by: Caveh Jalali <>
Tested-by: build bot (Jenkins) <>
Reviewed-by: Vincent Palatin <>
diff --git a/src/soc/intel/cannonlake/chip.c b/src/soc/intel/cannonlake/chip.c
index 2187f90..ca2f9a3 100644
--- a/src/soc/intel/cannonlake/chip.c
+++ b/src/soc/intel/cannonlake/chip.c
@@ -200,6 +200,9 @@
+	/* Unlock upper 8 bytes of RTC RAM */
+	params->PchLockDownRtcMemoryLock = 0;
 	/* SATA */
 	params->SataEnable = config->SataEnable;
 	params->SataMode = config->SataMode;