samus: Add support for asserting RTCRST

EVT boards will have RTCRST connected to PCH that we can use
to clear RTC backed state in the PCH when power sequencing fails.

For now this is hooked into two places:

1) keyboard initiated hard reset will pulse RTCRST before sequencing
2) if sequencing out of S5 fails becauase SLP_S5 does not deassert
within 4 seconds then RTCRST will be asserted and the system will
try to power up again

TEST=emerge-samus chromeos-ec, not used until EVT
Case #1 is easy to test by checking EC console after refresh+power,
Case #2 is harder to test without EVT hardware so I used a different
signal to pretend that SLP_S5 was not deasserting in order to verify
that the system will go to G3, RTCRST will be asserted, and it will
try to power up again.

Change-Id: I66279dc21fcfe320c1bfc8c7e9ba6b93b87572cb
Signed-off-by: Duncan Laurie <>
Reviewed-by: Alec Berg <>
1 file changed