linux-toradex.git/include/acpi/cppc_acpi.h, branch v6.11-rc6

ACPI: CPPC: Add helper to get the highest performance value

2024-01-31T13:54:50+00:00

Add support for getting the highest performance to the
generic CPPC driver. This enables downstream drivers
such as amd-pstate to discover and use these values.

Refer to Chapter 8.4.6.1.1.1. Highest Performance of ACPI
Specification 6.5 for details on continuous performance control
of CPPC (linked below).

Tested-by: Oleksandr Natalenko 
Reviewed-by: Mario Limonciello 
Reviewed-by: Wyes Karny 
Reviewed-by: Perry Yuan 
Acked-by: Huang Rui 
Signed-off-by: Meng Li 
Link: https://uefi.org/specs/ACPI/6.5/08_Processor_Configuration_and_Control.html?highlight=cppc#highest-performance
[ rjw: Subject and changelog edits ]
Signed-off-by: Rafael J. Wysocki

cpufreq/cppc: Move and rename cppc_cpufreq_{perf_to_khz|khz_to_perf}()

2023-12-23T14:52:35+00:00

Move and rename cppc_cpufreq_perf_to_khz() and cppc_cpufreq_khz_to_perf() to
use them outside cppc_cpufreq in topology_init_cpu_capacity_cppc().

Modify the interface to use struct cppc_perf_caps *caps instead of
struct cppc_cpudata *cpu_data as we only use the fields of cppc_perf_caps.

cppc_cpufreq was converting the lowest and nominal freq from MHz to kHz
before using them. We move this conversion inside cppc_perf_to_khz and
cppc_khz_to_perf to make them generic and usable outside cppc_cpufreq.

No functional change

Signed-off-by: Vincent Guittot 
Signed-off-by: Ingo Molnar 
Tested-by: Pierre Gondois 
Acked-by: Rafael J. Wysocki 
Acked-by: Viresh Kumar 
Link: https://lore.kernel.org/r/20231211104855.558096-6-vincent.guittot@linaro.org

ACPI: CPPC: Add auto select register read/write support

2023-03-17T18:06:23+00:00

For some AMD shared memory based systems, the autonomous selection bit
needed to be set explicitly. Add autonomous selection register related
APIs to acpi driver, which amd_pstate driver uses later.

Acked-by: Huang Rui 
Reviewed-by: Mario Limonciello 
Tested-by: Oleksandr Natalenko 
Signed-off-by: Wyes Karny 
[ rjw: Fixed up kerneldoc comments, white space adjustment, subject edits ]
Signed-off-by: Rafael J. Wysocki

ACPI: CPPC: Add AMD pstate energy performance preference cppc control

2023-02-03T20:59:41+00:00

Add support for setting and querying EPP preferences to the generic
CPPC driver.  This enables downstream drivers such as amd-pstate to discover
and use these values.

Downstream drivers that want to use the new symbols cppc_get_epp_caps
and cppc_set_epp_perf for querying and setting EPP preferences will need
to call cppc_set_epp_perf to enable the EPP function firstly.

Acked-by: Huang Rui 
Reviewed-by: Mario Limonciello 
Reviewed-by: Wyes Karny 
Tested-by: Wyes Karny 
Signed-off-by: Perry Yuan 
Signed-off-by: Rafael J. Wysocki

ACPI: CPPC: Disable FIE if registers in PCC regions

2022-09-24T16:43:46+00:00

PCC regions utilize a mailbox to set/retrieve register values used by
the CPPC code. This is fine as long as the operations are
infrequent. With the FIE code enabled though the overhead can range
from 2-11% of system CPU overhead (ex: as measured by top) on Arm
based machines.

So, before enabling FIE assure none of the registers used by
cppc_get_perf_ctrs() are in the PCC region. Finally, add a module
parameter which can override the PCC region detection at boot or
module reload.

Signed-off-by: Jeremy Linton 
Acked-by: Viresh Kumar 
Reviewed-by: Ionela Voinescu 
Signed-off-by: Rafael J. Wysocki

ACPI: CPPC: Do not prevent CPPC from working in the future

2022-07-26T18:56:49+00:00

There is a problem with the current revision checks in
is_cppc_supported() that they essentially prevent the CPPC support
from working if a new _CPC package format revision being a proper
superset of the v3 and only causing _CPC to return a package with more
entries (while retaining the types and meaning of the entries defined by
the v3) is introduced in the future and used by the platform firmware.

In that case, as long as the number of entries in the _CPC return
package is at least CPPC_V3_NUM_ENT, it should be perfectly fine to
use the v3 support code and disregard the additional package entries
added by the new package format revision.

For this reason, drop is_cppc_supported() altogether, put the revision
checks directly into acpi_cppc_processor_probe() so they are easier to
follow and rework them to take the case mentioned above into account.

Fixes: 4773e77cdc9b ("ACPI / CPPC: Add support for CPPC v3")
Cc: 4.18+  # 4.18+
Signed-off-by: Rafael J. Wysocki

ACPI: CPPC: Don't require _OSC if X86_FEATURE_CPPC is supported

2022-07-05T18:36:11+00:00

commit 72f2ecb7ece7 ("ACPI: bus: Set CPPC _OSC bits for all and
when CPPC_LIB is supported") added support for claiming to
support CPPC in _OSC on non-Intel platforms.

This unfortunately caused a regression on a vartiety of AMD
platforms in the field because a number of AMD platforms don't set
the `_OSC` bit 5 or 6 to indicate CPPC or CPPC v2 support.

As these AMD platforms already claim CPPC support via a dedicated
MSR from `X86_FEATURE_CPPC`, use this enable this feature rather
than requiring the `_OSC` on platforms with a dedicated MSR.

If there is additional breakage on the shared memory designs also
missing this _OSC, additional follow up changes may be needed.

Fixes: 72f2ecb7ece7 ("Set CPPC _OSC bits for all and when CPPC_LIB is supported")
Reported-by: Perry Yuan 
Signed-off-by: Mario Limonciello 
Signed-off-by: Rafael J. Wysocki

cpufreq: CPPC: Enable fast_switch

2022-05-19T17:45:34+00:00

The communication mean of the _CPC desired performance can be
PCC, System Memory, System IO, or Functional Fixed Hardware.

commit b7898fda5bc7 ("cpufreq: Support for fast frequency switching")
fast_switching is 'for switching CPU frequencies from interrupt
context'.
Writes to SystemMemory and SystemIo are fast and suitable this.
This is not the case for PCC and might not be the case for FFH.

Enable fast_switching for the cppc_cpufreq driver in above cases.

Add cppc_allow_fast_switch() to check the desired performance
register address space and set fast_switching accordingly.

Signed-off-by: Pierre Gondois 
Reviewed-by: Sudeep Holla 
Acked-by: Viresh Kumar 
Signed-off-by: Rafael J. Wysocki

ACPI: CPPC: Add CPPC enable register function

2021-12-30T17:51:39+00:00

Add a new function to enable CPPC feature. This function
will write Continuous Performance Control package
EnableRegister field on the processor.

CPPC EnableRegister register described in section 8.4.7.1 of ACPI 6.4:
This element is optional. If supported, contains a resource descriptor
with a single Register() descriptor that describes a register to which
OSPM writes a One to enable CPPC on this processor. Before this register
is set, the processor will be controlled by legacy mechanisms (ACPI
Pstates, firmware, etc.).

This register will be used for AMD processors to enable AMD P-State
function instead of legacy ACPI P-States.

Signed-off-by: Jinzhou Su 
Signed-off-by: Huang Rui 
Signed-off-by: Rafael J. Wysocki

ACPI: CPPC: Introduce cppc_get_nominal_perf()

2021-09-07T19:15:16+00:00

On some systems the nominal_perf value retrieved via CPPC is just
a constant and fetching it doesn't require accessing any registers,
so if it is the only CPPC capability that's needed, it is wasteful
to run cppc_get_perf_caps() in order to get just that value alone,
especially when this is done for CPUs other than the one running
the code.

For this reason, introduce cppc_get_nominal_perf() allowing
nominal_perf to be obtained individually, by generalizing the
existing cppc_get_desired_perf() (and renaming it) so it can be
used to retrieve any specific CPPC capability value.

While at it, clean up the cppc_get_desired_perf() kerneldoc comment
a bit.

Signed-off-by: Rafael J. Wysocki