Change in coreboot[master]: trogdor: Add fingerprint power sequencing

[Julius Werner (Code Review)]

Attention is currently required from: Julius Werner, mturney mturney.
Hello Shelley Chen, build bot (Jenkins), Alexandru Stan, mturney mturney,

I'd like you to reexamine a change. Please visit

https://review.coreboot.org/c/coreboot/+/50504

to look at the new patch set (#2).

Change subject: trogdor: Add fingerprint power sequencing
......................................................................

trogdor: Add fingerprint power sequencing

Some Trogdor variants will include a fingerprint sensor, so this patch
adds support for its power sequencing. There is a requirement that the
fingerprint power needs to be *off* for at least 200ms, and when it is
turned back on it needs to stabilize for at least 3.5ms before taking
the FPMCU out of reset. We meet these timing requirements by splitting
the sequence across bootblock, romstage and ramstage. On current Trogdor
boards we measured <end of bootblock> to <end of romstage> at ~430ms and
<end of romstage> to <start of ramstage> at 12ms, so we easily meet the
required numbers this way.

BRANCH=trogdor
BUG=b:170284663

Signed-off-by: Julius Werner 
Change-Id: Iccd77e6e1c378110fca2b2b7ff1f534fce54f8ea
---
M src/mainboard/google/trogdor/Kconfig
M src/mainboard/google/trogdor/board.h
M src/mainboard/google/trogdor/chromeos.c
M src/mainboard/google/trogdor/mainboard.c
M src/mainboard/google/trogdor/romstage.c
5 files changed, 36 insertions(+), 0 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/04/50504/2