On 2021-11-16 11:35, Jean-Philippe Brucker wrote:
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.
Ha, I'd also resurrected this and was planning to post it at some point this week[0] - you should have said :)
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".
Actually it only needs a general MMU-600 compatible, since once you know it's an Arm Ltd. implementation, you can assume the pattern for the IMP_DEF ID registers to figure out the rest.
Robin. [0] https://gitlab.arm.com/linux-arm/linux-rm/-/commits/smmu-pmcg
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
