Change in coreboot[master]: mb/lenovo/x200: Use lower C-states on battery

[Arthur Heymans (Code Review)]

Hello Alexander Couzens, Patrick Rudolph, Duncan Laurie, Paul Menzel, Stefan Reinauer, build bot (Jenkins), Furquan Shaikh,

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

https://review.coreboot.org/c/coreboot/+/22932

to look at the new patch set (#16).

Change subject: mb/lenovo/x200: Use lower C-states on battery
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mb/lenovo/x200: Use lower C-states on battery

This adds an array with C6 as lowest CPU cstate on battery for
thinkpad x200. This is changed when the PNOT method is called which
notifies the CPU to update C- and P-states.

This adds a weak function get_bat_cst_entries which is analogous to
get_cst_entries and expects an implementation in a mainboard specific
code.

For other boards the same C-states are on battery as on AC.

Without thorough testing this seems to shave off something between
~0.5W and ~1W while idle compared to having C3/C4 as the lowest
C-state.

Change-Id: Idf32ee2ac3272fee74ce3b92b2c537cb722991d7
Signed-off-by: Arthur Heymans 
---
M src/arch/x86/include/arch/acpigen.h
M src/cpu/intel/speedstep/acpi.c
M src/mainboard/lenovo/x200/cstates.c
3 files changed, 61 insertions(+), 7 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/32/22932/16