This register isn't used in coreboot and isn't defined in the Picasso
PPR #55570 Rev 3.18.
To enter a lower C-state, a read request to a special IO port is done.
The base address of this group of IO ports is configured in
set_cstate_io_addr via the MSR_CSTATE_ADDRESS and that read won't leave
the CPU. IIRC trying to put the MMIO mapping for entering the lower
C-states into the _CST package didn't work as expected when it was tried
on I think Cezanne.
Signed-off-by: Felix Held <felix-coreboot@felixheld.de>
Change-Id: Ib189993879feaa0a22f6810c4bd5c1a0bc8c5a27
Reviewed-on: https://review.coreboot.org/c/coreboot/+/72497
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Martin Roth <martin.roth@amd.corp-partner.google.com>
a7b922fd74