[S] Change in coreboot[main]: soc/intel/common/gpio: add function to lock GPIO configuration

[Hannah Williams (Code Review)]

Attention is currently required from: Bora Guvendik, Cliff Huang, Jérémy Compostella, Pranava Y N, Subrata Banik.

Hannah Williams has posted comments on this change by Cliff Huang. ( https://review.coreboot.org/c/coreboot/+/84901?usp=email )

Change subject: soc/intel/common/gpio: add function to lock GPIO configuration
......................................................................

Patch Set 3:

(1 comment)

File src/soc/intel/common/block/gpio/gpio.c:

https://review.coreboot.org/c/coreboot/+/84901/comment/6e85fa9b_10e25677?usp... :
PS3, Line 485: /* Clear lock for the exception PADs */
> > The thing is that we don't enable lock in our MB gpio.c and fw_config. […]

Hi Subrata, This is a TODO to a TODO. This GPIO locking proposal was Cliff's solution to task#9 in 357011633#comment16. For JTAG in particular you need to go the route of disabling in mfit - see 302226565.
However, having common code to lock all GPIO configs in Coreboot seems to be a solution that people can use if needed, especially for security reasons. 
Maybe this locking can be turned off for debug builds because it will prevent someone who wants to tune a config value. 
The reason for adding exception list for locking is because we have seen one case  where config was changed from asl before sleep and switched back on wake.