[PATCH v6 0/7] Add support for Translation Buffer Units

[Georgi Djakov <quic_c_gdjako@quicinc.com>]

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.
A common TBU DT schema is added to describe the TBUs.

The Qualcomm SDM845 and SC7280 platforms have an implementation of the
SMMU-500, that has multiple TBUs. A vendor-specific 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.

v6:
- Use SoC-specific compatibles (Krzysztof)
- Use additionalProperties: false (Krzysztof)
- Wrap description text to 80 cols (Krzysztof)

v5: https://lore.kernel.org/r/20240226172218.69486-1-quic_c_gdjako@quicinc.com
- Drop the common TBU bindings and child nodes. These TBU functionalities
  are only Qualcomm specific and not generic. In the unmodified ARM MMU-500
  implementation there are no TBU-specific resources, so just make them
  standalone DT nodes. (Robin)
- The "qcom,stream-id-range" DT property now takes a phandle to the smmu
  and a stream ID range.

v4: https://lore.kernel.org/r/20240201210529.7728-1-quic_c_gdjako@quicinc.com/
- Create a common TBU schema. Move the vendor-specific properties into
  a separate schema that references the common one. (Rob)
- Drop unused DT labels in example, fix regex. (Rob)
- Properly rebase on latest code.

v3: https://lore.kernel.org/r/20231220060236.18600-1-quic_c_gdjako@quicinc.com
- Having a TBU is not Qualcomm specific, so allow having TBU child
  nodes with no specific constraints on properties. For some of the
  vendor compatibles however, add a schema to describe specific
  properties and allow validation. (Rob)
- Drop the useless reg-names DT property on TBUs. (Rob)
- Make the stream-id-range DT property a common one. (Rob)
- Fix the DT example. (Rob)
- Minor fixes on the TBU driver.
- Add support for SC7280 platforms.

v2: https://lore.kernel.org/r/20231118042730.2799-1-quic_c_gdjako@quicinc.com
- 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@quicinc.com

Georgi Djakov (7):
  dt-bindings: iommu: Add Qualcomm TBU
  iommu/arm-smmu-qcom-tbu: 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
  iommu/arm-smmu-qcom: Use the custom fault handler on more platforms
  arm64: dts: qcom: sc7280: Add DT nodes for the TBUs

 .../devicetree/bindings/iommu/qcom,tbu.yaml   |  69 +++
 arch/arm64/boot/dts/qcom/sc7280.dtsi          |  89 ++++
 arch/arm64/boot/dts/qcom/sdm845.dtsi          |  70 +++
 drivers/iommu/Kconfig                         |   9 +
 drivers/iommu/arm/arm-smmu/Makefile           |   1 +
 .../iommu/arm/arm-smmu/arm-smmu-qcom-tbu.c    | 496 ++++++++++++++++++
 drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c    |   8 +
 drivers/iommu/arm/arm-smmu/arm-smmu-qcom.h    |   2 +
 drivers/iommu/arm/arm-smmu/arm-smmu.c         |  12 +-
 drivers/iommu/arm/arm-smmu/arm-smmu.h         |   3 +
 10 files changed, 757 insertions(+), 2 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/iommu/qcom,tbu.yaml
 create mode 100644 drivers/iommu/arm/arm-smmu/arm-smmu-qcom-tbu.c