x86: add coreboot table entry for TSC info

The 8254 (Programmable Interrupt Timer) is becoming optional
on x86 platforms -- either from saving power or not including it
at all. To allow a payload to still use a TSC without doing
calibration provide the TSC frequency information in the coreboot
tables. That data is provided by code/logic already employed
by platform. If tsc_freq_mhz() returns 0 or
CONFIG_TSC_CONSTANT_RATE is not selected the coreboot table
record isn't created.

TEST=With all subsequent patches confirmed TSC is picked up in

Change-Id: Iaeadb85c2648587debcf55f4fa5351d0c287e971
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/13670
Tested-by: build bot (Jenkins)
Reviewed-by: Furquan Shaikh <furquan@google.com>
Reviewed-by: Andrey Petrov <andrey.petrov@intel.com>
2 files changed