[coreboot-gerrit] Change in coreboot[master]: Add console deinit API, use in SMM handler

[Johnny Lin (Code Review)]

Attention is currently required from: Nico Huber, Jonathan Zhang, Paul Menzel, Christian Walter, Rocky Phagura, Angel Pons, Arthur Heymans, Kyösti Mälkki, Deomid "rojer" Ryabkov.
Johnny Lin has uploaded a new patch set (#11) to the change originally created by Deomid "rojer" Ryabkov. ( https://review.coreboot.org/c/coreboot/+/56386 )

Change subject: Add console deinit API, use in SMM handler
......................................................................

Add console deinit API, use in SMM handler

SMM handler should return shared hardware to the state it was at the time
of the SMI call. When CONFIG_DEBUG_SMI is enabled SMM handler performs
console hardware initialization that may interfere with OS.

Specifically, this has been observed with SMM handler output to UART
on an OCP Delta Lake server: uart8250_init disables interrupts because it
uses polling but the Linux kernel (5.6) uses interrupts. As a result, SMI
call leaves interrupts disabled and causes OS console I/O issues.

For 8250, we save all the registers we touch in init and restore them in
deinit. Other deinit functions are provided as stubs only due to lack of
hardware for testing but should probably be looked into as well.

Signed-off-by: Deomid "rojer" Ryabkov 
Change-Id: Ia5e51f385f83cb998c244ca1d1ffc10339d3a714
---
M src/console/console.c
M src/console/init.c
M src/cpu/x86/smm/smm_module_handler.c
M src/drivers/uart/pl011.c
M src/drivers/uart/sifive.c
M src/drivers/uart/uart8250io.c
M src/drivers/uart/uart8250mem.c
M src/include/console/cbmem_console.h
M src/include/console/console.h
M src/include/console/flash.h
M src/include/console/ne2k.h
M src/include/console/qemu_debugcon.h
M src/include/console/spi.h
M src/include/console/spkmodem.h
M src/include/console/streams.h
M src/include/console/system76_ec.h
M src/include/console/uart.h
M src/include/console/usb.h
18 files changed, 126 insertions(+), 2 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/86/56386/11