[PATCH 0/2] perf/smmuv3: Support devicetree

[Jean-Philippe Brucker]

Add devicetree binding for the SMMUv3 PMU, called Performance Monitoring
Counter Group (PMCG) in the spec. Each SMMUv3 implementation can have
multiple independent PMCGs, for example one for the Translation Control
Unit (TCU) and one per Translation Buffer Unit (TBU).

I previously sent the binding as reply to Jay Chen's thread implementing
device tree support [1]. This posting addresses the comments from that
thread.

Patch 1 adds two compatible strings. "arm,smmu-v3-pmcg" is common to all
PMCGs. "hisilicon,smmu-v3-pmcg-hip08" allows to support the same quirk
as IORT for that implementation (see patch 2). We'll probably want to
also introduce compatible strings for each implementation that has
additional perf events. For example the MMU-600 implementation has
different events for TCU and TBU PMCGs [2], but both components have the
same device IDs. So the driver could differentiate them if they had two
distinct compatible strings such as "arm,mmu-600-pmcg-tbu" and
"arm,mmu-600-pmcg-tcu".

The series doesn't deal with this because for testing I use a software
model which only implements architected events. I do not include DTS
change for that platform because enabling PMCGs requires an additional
model option. See my branch smmu/pmu-dt [3] for details.

[1] https://lore.kernel.org/all/20200707150114.GC159413@myrica/
[2] https://developer.arm.com/documentation/100310/0202/Functional-description/Operation/Performance-Monitoring-Unit
[3] https://jpbrucker.net/git/linux/log/?h=smmu/pmu-dt

Jean-Philippe Brucker (2):
  dt-bindings: Add Arm SMMUv3 PMCG binding
  perf/smmuv3: Add devicetree support

 .../bindings/iommu/arm,smmu-v3-pmcg.yaml      | 67 +++++++++++++++++++
 drivers/perf/arm_smmuv3_pmu.c                 | 25 ++++++-
 2 files changed, 90 insertions(+), 2 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/iommu/arm,smmu-v3-pmcg.yaml

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2.33.1