MFC r303891, r303892:
sys: replace comma with semicolon when pertinent.

Uses of commas instead of a semicolons can easily go undetected. The comma
can serve as a statement separator but this shouldn't be abused when
statements are meant to be standalone.

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Use ACPI-supplied CPU frequencies instead of estimated ones as we are about
to use other values from the same table anyway.

MFC after: 3 days

Introduce the new kernel sub-tree x86 which should contain all the code
shared and generalized between our current amd64, i386 and pc98.

This is just an initial step that should lead to a more complete effort.
For the moment, a very simple porting of cpufreq modules, BIOS calls and
the whole MD specific ISA bus part is added to the sub-tree but ideally
a lot of code might be added and more shared support should grow.

Sponsored by: Sandvine Incorporated
Reviewed by: emaste, kib, jhb, imp
Discussed on: arch
MFC: 3 weeks

Remove an unused variable.

Found with: Coverity Prevent(tm)
CID: 3677

Do not use PowerNow! if FID or VID is missing.

Use power management information for AMD CPUs from identcpu.c.

Fail detach if cpufreq_unregister() fails.

MFC after: 1 week

Attach the cpufreq child devices with specific orders to enforce relative
priority of some of the drivers that manage the same state (e.g. ichss0
vs est0). Specifically, powernow, est, and p4tcc are added at order 10,
ichss at order 20, and smist at order 30. Previously, some laptops were
seeing both ichss0 and est0 attaching and stomping on each other.

XXX: This isn't quite ideal, but works with the existing hacks, I think
what we really want instead is a single "speedstep0" device for CPUs
that the ichss, est, and smist drivers probe (but with differing
priorities).

MFC after: 1 week

o introduce a flags 'errata' for HW bugs onto the softc.
o remove errata_a0 and introduce the corresponding flags into 'errata'.
o introduce a new errata for K8, namely some platform might set the
PENDING_BIT but aren't able to unset it, also don't loop forever
waiting PENDING_BIT being cleared.
o try to introduce a workaround for the PENDING_BIT stuck problem,
o support now half multipliers for K8.

Tested by: Abdullah Al-Marrie

Approved by: njl

Since DELAY() was moved, most <machine/clock.h> #includes have been
unnecessary.

Remove check of numpst to allow more K8 variants to attach. The other
checks, including cpuid_is_k7(), will catch CPUs that really don't support
this method.

Submitted by: Bruno Ducrot
Tested by: Jari Kirma (kirma cs.hut.fi)

Add the powernow driver, which handles AMD Mobile Athlon PowerNow! (k7)
and AMD Cool&Quiet PowerNow! (k8) cpufreq control. This driver is enabled
for both i386 and amd64 architectures. It has both acpi and legacy BIOS
attachments. Thanks to Bruno Ducrot for writing this driver and Jung-uk
Kim for testing.

Submitted by: Bruno Ducrot (ducrot:poupinou.org)