linux-kernel - [PATCH v2 0/6] Add support for Translation Buffer Units

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Message-ID: <20231118042730.2799-1-quic_c_gdjako@quicinc.com>
Date:   Fri, 17 Nov 2023 20:27:24 -0800
From:   Georgi Djakov <quic_c_gdjako@...cinc.com>
To:     <robh+dt@...nel.org>, <krzysztof.kozlowski+dt@...aro.org>,
        <conor+dt@...nel.org>, <will@...nel.org>, <robin.murphy@....com>,
        <joro@...tes.org>
CC:     <devicetree@...r.kernel.org>, <andersson@...nel.org>,
        <konrad.dybcio@...aro.org>, <linux-arm-kernel@...ts.infradead.org>,
        <iommu@...ts.linux.dev>, <linux-kernel@...r.kernel.org>,
        <linux-arm-msm@...r.kernel.org>, <quic_cgoldswo@...cinc.com>,
        <quic_sukadev@...cinc.com>, <quic_pdaly@...cinc.com>,
        <quic_sudaraja@...cinc.com>, <djakov@...nel.org>
Subject: [PATCH v2 0/6] Add support for Translation Buffer Units

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@quicinc.com

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