arm64: topology: read CPPC FFH feedback counters in one operation

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arm64 implements CPPC FFH feedback-counter reads using AMU counters.
Because those counters must be sampled on the target CPU, reading the
delivered and reference counters separately widens the observation window
between them.

Implement the paired FFH feedback-counter read hook on arm64 and sample
both AMU counters together before decoding the requested CPC register
values.

Also factor the FFH bitfield extraction logic into a helper and reuse
it from the existing single-counter FFH read path.

Tested-by: Sumit Gupta <sumitg@nvidia.com>
Reviewed-by: Sumit Gupta <sumitg@nvidia.com>
Tested-by: Vanshidhar Konda <vanshikonda@os.amperecomputing.com>
Reviewed-by: Vanshidhar Konda <vanshikonda@os.amperecomputing.com>
Signed-off-by: Pengjie Zhang <zhangpengjie2@huawei.com>
Tested-by: Jeremy Linton <jeremy.linton@arm.com>
Reviewed-by: Jeremy Linton <jeremy.linton@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>

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Pengjie Zhang 2026-07-08 16:28:18 +08:00 • committed by Will Deacon

parent 9aa7df5205

commit 42971d5329

1 changed files with 84 additions and 8 deletions

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arch/arm64/kernel/topology.c

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