hwpstate: add CPPC support for pstate driver on AMD

[aokblast]

Summary

hwpstate: add CPPC support for pstate driver on AMD

Implement CPPC interface for AMD Pstate Driver.
This feature is only enabled when the CPUID shows it support CPPC.

The CPPC is implemneted by the following steps:

1. Write MSR to enable it.
2. Read capability registert which indicates binary value of levels

about lowest, best energy efficient, guarantee, and max performance.

3. Write request register with epp in energy balanced mode. And let

CPU and firmware to enter autonomous mode.

Also, create a sysctl to allow userspace to change epp value

[aokblast]

Fix errors

[aokblast]

use wildcard to generate correct number of devices

[aokblast]

• atkbd: fix first keystroke force reset

[aokblast]

Reset to the correct version

[aokblast]

Add epp to sysctl

[aokblast]

Use balanced mode as the default epp

[markj]

In general, please include some summary of the code changes in the review description. This makes reviewing easier: I can quickly understand what the change is supposed to do, and then I can compare the code changes with your description to look for discrepancies.

sys/x86/cpufreq/hwpstate_amd.c

236

The sysctl_handle_int() call doesn't need to be inside the sched_bind() section, it should be moved earlier.

494

714

775–792

There should be an extra newline after local variable declarations.

sys/x86/x86/identcpu.c

1694

The AND is redundant. Is there a typo here?

[aokblast]

Fix comments

[aokblast]

fix include order

[aokblast]

move set_autonomous mode into attach

[olce]

I'd like the opportunity to review this (next week).

[aokblast]

In D49587#1160034, @olce wrote:

I'd like the opportunity to review this (next week).

Of course. Not hurry. I just want to make more people engage in:).