Change in coreboot[master]: soc/intel/common: add generic gpio lock mechanism

[Nick Vaccaro (Code Review)]

Attention is currently required from: Bora Guvendik, Caveh Jalali, Selma Bensaid, Maulik V Vaghela, Subrata Banik, Nick Vaccaro, Patrick Rudolph.
Hello Bora Guvendik, build bot (Jenkins), Caveh Jalali, Selma Bensaid, Maulik V Vaghela, Tim Wawrzynczak, Subrata Banik, Patrick Rudolph, Karthik Ramasubramanian,

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

https://review.coreboot.org/c/coreboot/+/58351

to look at the new patch set (#13).

Change subject: soc/intel/common: add generic gpio lock mechanism
......................................................................

soc/intel/common: add generic gpio lock mechanism

For added security, there are some gpios that an SoC will want to lock
once initially configured, such as gpios attached to non-host (x86)
controllers, so that they can't be recofigured at a later point in
time by rogue code.

Likewise, a mainboard may have some gpios connected to secure busses
and/or devices that they want to protect from being changed post
initial configuration.

This change adds a generic gpio locking mechanism that allows the SoC
to export a list of GPIOs to be locked down and allows the mainboard
to export a list of GPIOs that it wants locked down once
initialization is complete.

Use the SOC_INTEL_COMMON_BLOCK_SMM_LOCK_GPIO_PADS Kconfig option to
enable this feature.

BUG=b:201430600
TEST='emerge-brya coreboot chromeos-bootimage', flash and verify
brya0 boots successfully to kernel.

Signed-off-by: Nick Vaccaro 
Change-Id: I42979fb89567d8bcd9392da4fb8c4113ef427b14
---
M src/soc/intel/common/block/gpio/gpio.c
M src/soc/intel/common/block/include/intelblocks/gpio.h
M src/soc/intel/common/block/smm/Kconfig
M src/soc/intel/common/block/smm/smihandler.c
4 files changed, 154 insertions(+), 40 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/51/58351/13