Making cpufreq(9) per cpu

[Martin Husemann <martin%duskware.de@localhost>]

There was a recent discussion on port-sparc64 about the cpufreq(9) interface,
and I noticed it basically is a single, global interface, which stores
a single cookie.

This sounds a bit restrictive; for one it assumes identical cpus and available
frequencies for all cpus (ok, that is not a very far stretch, but we do
have working SMP setups where it would fail - if the affected CPUs would
provide any clock changing features at all).

So wouldn't it be better to add a cpuinfo* to cpufreq_register() and
friends (some already have it), and store the struct cpufreq (not the
pointer to it!) in the MI part of cpuinfo?

Then maybe add the notion of "I am a secondary core and will always have same
frequncy as cpuinfo* other". And of course some way to mark the cpufreq
data as not initialized (that could be just NULL pointers for
cf_{get,set}_freq).

That way ACPI could still do its global thing bound to cpu0 and all others
as "slaves", while on sparc64 we could store the per cpu pci root bridge
softc pointer in the cf_cookie pointer in struct cpufreq.

What do you think?

Martin