Change in coreboot[master]: mb/google/poppy: Add late_gpio support

[Caveh Jalali (Code Review)]

Hello Shelley Chen, build bot (Jenkins), Furquan Shaikh, Tim Wawrzynczak, Nick Vaccaro,

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

https://review.coreboot.org/c/coreboot/+/46619

to look at the new patch set (#3).

Change subject: mb/google/poppy: Add late_gpio support
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mb/google/poppy: Add late_gpio support

This adds support for configuring GPIOs late in the boot process. When
GPIOs are used for reset sequencing, long delays may be necessary.  We
can achieve these long delays by adding a step to control GPIOs just
before we hand off to a payload. On an m3 atlas, this provides about a
320ms delay between the romstage GPIO initialization and the late
stage GPIO initialization. For reference, the delay between romstage
GPIO initialization and the main GPIO initialization is about 170ms.

BRANCH=atlas
BUG=b:168757348
TEST=tested with patch stack to verify that we successfully reset the
    bluetooth chip.

Change-Id: I847f90275740ca825e4c93e6b8d5650143228476
Signed-off-by: Caveh Jalali 
---
M src/mainboard/google/poppy/variants/baseboard/gpio.c
M src/mainboard/google/poppy/variants/baseboard/include/baseboard/variants.h
2 files changed, 19 insertions(+), 0 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/19/46619/3