acpi-cpufreq: Add support for modern AMD CPUs

The programming model for P-states on modern AMD CPUs is very similar to
that of Intel and VIA. It makes sense to consolidate this support into one
driver rather than duplicating functionality between two of them. This
patch adds support for AMDs with hardware P-state control to acpi-cpufreq.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Andre Przywara <andre.przywara@amd.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
acpi-cpufreq: Add quirk to disable _PSD usage on all AMD CPUs

To workaround some Windows specific behavior, the ACPI _PSD table
on AMD desktop boards advertises all cores as dependent, meaning
that they all can only use the same P-state. acpi-cpufreq strictly
obeys this description, instantiating one CPU only and symlinking
the others. But the hardware can have distinct frequencies for each
core and powernow-k8 did it that way.
So, in order to use the hardware to its full potential and keep the
original powernow-k8 behavior, lets override the _PSD table setting
on AMD hardware.
We use the siblings table, as it matches the current hardware
behavior.

Signed-off-by: Andre Przywara <andre.przywara@amd.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
cpufreq: Add warning message to powernow-k8

cpufreq modules are often loaded from init scripts that assume that
all recent AMD systems will use powernow-k8.
To inform the user of the change of support and ease the transition
to acpi-cpufreq, emit a warning message.

Signed-off-by: Andre Przywara <andre.przywara@amd.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
powernow-k8: delay info messages until initialization has succeeded

powernow-k8 is quite prematurely crying Hooray and outputs diagnostic
messages, although the actual initialization can still fail.
Since now we may have acpi-cpufreq already loaded, we move the
messages at the end of the init routine to avoid confusing output
if the loading of powernow-k8 should not succeed.

Signed-off-by: Andre Przywara <andre.przywara@amd.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
ACPI: Add fixups for AMD P-state figures

Some AMD systems may round the frequencies in ACPI tables to 100MHz
boundaries. We can obtain the real frequencies from MSRs, so add a quirk
to fix these frequencies up on AMD systems.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Andre Przywara <andre.przywara@amd.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
acpi-cpufreq: Add support for disabling dynamic overclocking

One feature present in powernow-k8 that isn't present in acpi-cpufreq
is support for enabling or disabling AMD's core performance boost
technology. This patch adds support to acpi-cpufreq, but also
includes support for Intel's dynamic acceleration.

The original boost disabling sysfs file was per CPU, but acted
globally. Also the naming (cpb) was at least not intuitive.
So lets introduce a single file simply called "boost", which sits
once in /sys/devices/system/cpu/cpufreq.
This should be the only way of using this feature, so add
documentation about the rationale and the usage.

A following patch will re-introduce the cpb knob for compatibility
reasons on AMD CPUs.

Per-CPU boost switching is possible, but not trivial and is thus
postponed to a later patch series.

Signed-off-by: Andre Przywara <andre.przywara@amd.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
acpi-cpufreq: Add compatibility for legacy AMD cpb sysfs knob

The powernow-k8 driver supported a sysfs knob called "cpb", which was
instantiated per CPU, but actually acted globally for the whole
system. To keep some compatibility with this feature, we re-introduce
this behavior here, but:
a) only enable it on AMD CPUs and
b) protect it with a Kconfig switch

I'd like to consider this feature obsolete. Lets keep it around for
some kernel versions and then phase it out.

Signed-off-by: Andre Przywara <andre.przywara@amd.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
cpufreq: Remove support for hardware P-state chips from powernow-k8

These chips are now supported by acpi-cpufreq, so we can delete all the
code handling them.

Andre: Tighten the deprecation warning message. Trigger load of
acpi-cpufreq and let the load of the module finally fail.
This avoids the problem of users ending up without any cpufreq support
after the transition.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Andre Przywara <andre.przywara@amd.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>