The TCUs (Translation Control Units) and TBUs (Translation Buffer Units) are key components of the MMU-500. Multiple TBUs are connected to a single TCU over an interconnect. Each TBU contains a TLB that caches page tables. The MMU-500 implements a TBU for each connected master, and the TBU is designed, so that it is local to the master. The Qualcomm SDM845 platform has an implementation of the SMMU-500, that has multiple TBUs. A DT schema is added to describe the resources for each TBU (register space, power-domains, interconnects and clocks). The TBU driver will manage the resources and allow the system to operate the TBUs during a context fault to obtain details by doing s1 inv, software + hardware page table walks etc. This is implemented with ATOS/eCATs as the ATS feature is not supported. Being able to query the TBUs is useful for debugging various hardware/software issues on these platforms. v2: - Improve DT binding description, add full example. (Konrad) - Drop Qcom specific stuff from the generic binding. (Rob) - Unconditionally try to populate subnodes. (Konrad) - Improve TBU driver commit text, remove memory barriers. (Bjorn) - Move TBU stuff into separate file. Make the driver builtin. - TODO: Evaluate whether to keep TBU support as a separate driver or just instantiate things from qcom_smmu_impl_init() v1: https://lore.kernel.org/r/20231019021923.13939-1-quic_c_gdjako@xxxxxxxxxxx Georgi Djakov (6): dt-bindings: iommu: Add Translation Buffer Unit bindings iommu/arm-smmu-qcom: Add support for TBUs iommu/arm-smmu-qcom: Add Qualcomm TBU driver iommu/arm-smmu: Allow using a threaded handler for context interrupts iommu/arm-smmu-qcom: Use a custom context fault handler for sdm845 arm64: dts: qcom: sdm845: Add DT nodes for the TBUs .../devicetree/bindings/iommu/arm,smmu.yaml | 25 + .../bindings/iommu/qcom,qsmmuv500-tbu.yaml | 89 ++++ arch/arm64/boot/dts/qcom/sdm845.dtsi | 82 +++ drivers/iommu/Kconfig | 8 + drivers/iommu/arm/arm-smmu/Makefile | 1 + .../iommu/arm/arm-smmu/arm-smmu-qcom-tbu.c | 504 ++++++++++++++++++ drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 12 + drivers/iommu/arm/arm-smmu/arm-smmu-qcom.h | 6 +- drivers/iommu/arm/arm-smmu/arm-smmu.c | 12 +- drivers/iommu/arm/arm-smmu/arm-smmu.h | 3 + 10 files changed, 739 insertions(+), 3 deletions(-) create mode 100644 Documentation/devicetree/bindings/iommu/qcom,qsmmuv500-tbu.yaml create mode 100644 drivers/iommu/arm/arm-smmu/arm-smmu-qcom-tbu.c
