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Message-ID: <ebb4927c-2194-4224-b8f0-274a181b2bcd@ixit.cz>
Date: Tue, 19 Dec 2023 21:26:57 +0100
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Subject: Re: [PATCH v5] dt-bindings: iommu: Convert msm,iommu-v0 to yaml
To: Robin Murphy <robin.murphy@arm.com>, Joerg Roedel <joro@8bytes.org>,
 Will Deacon <will@kernel.org>, Rob Herring <robh+dt@kernel.org>,
 Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
 Conor Dooley <conor+dt@kernel.org>, Andy Gross <agross@kernel.org>,
 Bjorn Andersson <andersson@kernel.org>,
 Konrad Dybcio <konrad.dybcio@linaro.org>
Cc: iommu@lists.linux.dev, devicetree@vger.kernel.org,
 linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org
References: <20231216002242.112310-2-david@ixit.cz>
 <ab6a34c7-a0f9-4263-a6ea-08026e2bade9@arm.com>
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From: David Heidelberg <david@ixit.cz>
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On 19/12/2023 16:25, Robin Murphy wrote:
> On 2023-12-16 12:22 am, David Heidelberg wrote:
>> Convert Qualcomm IOMMU v0 implementation to yaml format.
>>
>> Signed-off-by: David Heidelberg <david@ixit.cz>
>> ---
>> v5:
>>   - updated example (thx @Konrad)
>>   - ordering of requirements + dropped > and | and reformatted (thx 
>> @Konrad)
>> v4:
>>   - renamed to qcom,apq8064-iommu as Rob requested
>>   - changed title to Qualcomm APQ8064 IOMMU
>>   - dropped quotes around URLs
>>   - dropped mdp node
>>   - dropped unused mdp_port0 label
>>
>> v3:
>>   - I kept the name as -v0, since we have other binding -v1 and it look
>>     good, I can change thou in v4 if requested.
>>   - dropped non-existent smmu_clk part (and adjusted example, which was
>>     using it)
>>   - dropped iommu description
>>   - moved iommu-cells description to the property #iommu-cells
>>
>> v2:
>>   - fix wrong path in binding $id
>>   - comment qcom,mdp4 node example (we don't want to validate it yet)
>>
>>   .../bindings/iommu/msm,iommu-v0.txt           | 64 ---------------
>>   .../bindings/iommu/qcom,apq8064-iommu.yaml    | 82 +++++++++++++++++++
>>   2 files changed, 82 insertions(+), 64 deletions(-)
>>   delete mode 100644 
>> Documentation/devicetree/bindings/iommu/msm,iommu-v0.txt
>>   create mode 100644 
>> Documentation/devicetree/bindings/iommu/qcom,apq8064-iommu.yaml
>>
>> diff --git a/Documentation/devicetree/bindings/iommu/msm,iommu-v0.txt 
>> b/Documentation/devicetree/bindings/iommu/msm,iommu-v0.txt
>> deleted file mode 100644
>> index 20236385f26e..000000000000
>> --- a/Documentation/devicetree/bindings/iommu/msm,iommu-v0.txt
>> +++ /dev/null
>> @@ -1,64 +0,0 @@
>> -* QCOM IOMMU
>> -
>> -The MSM IOMMU is an implementation compatible with the ARM VMSA short
>> -descriptor page tables. It provides address translation for bus 
>> masters outside
>> -of the CPU, each connected to the IOMMU through a port called 
>> micro-TLB.
>> -
>> -Required Properties:
>> -
>> -  - compatible: Must contain "qcom,apq8064-iommu".
>> -  - reg: Base address and size of the IOMMU registers.
>> -  - interrupts: Specifiers for the MMU fault interrupts. For 
>> instances that
>> -    support secure mode two interrupts must be specified, for 
>> non-secure and
>> -    secure mode, in that order. For instances that don't support 
>> secure mode a
>> -    single interrupt must be specified.
>> -  - #iommu-cells: The number of cells needed to specify the stream 
>> id. This
>> -          is always 1.
>> -  - qcom,ncb:      The total number of context banks in the IOMMU.
>> -  - clocks    : List of clocks to be used during SMMU register 
>> access. See
>> - Documentation/devicetree/bindings/clock/clock-bindings.txt
>> -          for information about the format. For each clock specified
>> -          here, there must be a corresponding entry in clock-names
>> -          (see below).
>> -
>> -  - clock-names    : List of clock names corresponding to the clocks 
>> specified in
>> -          the "clocks" property (above).
>> -          Should be "smmu_pclk" for specifying the interface clock
>> -          required for iommu's register accesses.
>> -          Should be "smmu_clk" for specifying the functional clock
>> -          required by iommu for bus accesses.
>> -
>> -Each bus master connected to an IOMMU must reference the IOMMU in 
>> its device
>> -node with the following property:
>> -
>> -  - iommus: A reference to the IOMMU in multiple cells. The first 
>> cell is a
>> -        phandle to the IOMMU and the second cell is the stream id.
>> -        A single master device can be connected to more than one iommu
>> -        and multiple contexts in each of the iommu. So multiple entries
>> -        are required to list all the iommus and the stream ids that the
>> -        master is connected to.
>> -
>> -Example: mdp iommu and its bus master
>> -
>> -                mdp_port0: iommu@7500000 {
>> -            compatible = "qcom,apq8064-iommu";
>> -            #iommu-cells = <1>;
>> -            clock-names =
>> -                "smmu_pclk",
>> -                "smmu_clk";
>> -            clocks =
>> -                <&mmcc SMMU_AHB_CLK>,
>> -                <&mmcc MDP_AXI_CLK>;
>> -            reg = <0x07500000 0x100000>;
>> -            interrupts =
>> -                <GIC_SPI 63 0>,
>> -                <GIC_SPI 64 0>;
>> -            qcom,ncb = <2>;
>> -        };
>> -
>> -        mdp: qcom,mdp@5100000 {
>> -            compatible = "qcom,mdp";
>> -            ...
>> -            iommus = <&mdp_port0 0
>> -                  &mdp_port0 2>;
>> -        };
>> diff --git 
>> a/Documentation/devicetree/bindings/iommu/qcom,apq8064-iommu.yaml 
>> b/Documentation/devicetree/bindings/iommu/qcom,apq8064-iommu.yaml
>> new file mode 100644
>> index 000000000000..5af59305d277
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/iommu/qcom,apq8064-iommu.yaml
>> @@ -0,0 +1,82 @@
>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>> +%YAML 1.2
>> +---
>> +
>> +$id: http://devicetree.org/schemas/iommu/qcom,apq8064-iommu.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: Qualcomm APQ8064 IOMMU
>> +
>> +maintainers:
>> +  - Will Deacon <will@kernel.org>
>> +
>> +description:
>> +  The MSM IOMMU is an implementation compatible with the ARM VMSA short
>> +  descriptor page tables. It provides address translation for bus 
>> masters
>> +  outside of the CPU, each connected to the IOMMU through a port 
>> called micro-TLB.
>> +
>> +properties:
>> +  compatible:
>> +    const: qcom,apq8064-iommu
>> +
>> +  clocks:
>> +    items:
>> +      - description: interface clock for register accesses
>> +      - description: functional clock for bus accesses
>> +
>> +  clock-names:
>> +    items:
>> +      - const: smmu_pclk
>> +      - const: iommu_clk
>> +
>> +  reg:
>> +    maxItems: 1
>> +
>> +  interrupts:
>> +    description: Specifiers for the MMU fault interrupts.
>> +    minItems: 1
>> +    items:
>> +      - description: non-secure mode interrupt
>> +      - description: secure mode interrupt (for instances which 
>> supports it)
>> +
>> +  "#iommu-cells":
>> +    const: 1
>> +    description:
>> +      The first cell is a phandle to the IOMMU and the second cell
>> +      is the stream id.
>> +      A single master device can be connected to more than one iommu
>> +      and multiple contexts in each of the iommu.
>> +      So multiple entries are required to list all the iommus and
>> +      the stream ids that the master is connected to.
>
> This seems pretty confusing since it's the description for some other 
> property, not this one. FWIW I'd just put this as something like "Each 
> IOMMU specifier describes a single Stream ID.", and if you think it's 
> really worth calling out that clients can have multiple IOMMU 
> specifiers, I'd stick that in the overall description.
>
> Thanks,
> Robin.

Good catch, I must do wrong copy-paste here. I would think that the 
description you wrote is good enough and I can drop the rest :) Sending v6.

Thanks
David

>
>> +
>> +  qcom,ncb:
>> +    $ref: /schemas/types.yaml#/definitions/uint32
>> +    description: The total number of context banks in the IOMMU.
>> +
>> +required:
>> +  - reg
>> +  - interrupts
>> +  - clocks
>> +  - clock-names
>> +  - qcom,ncb
>> +
>> +additionalProperties: false
>> +
>> +examples:
>> +  - |
>> +    #include <dt-bindings/clock/qcom,mmcc-msm8960.h>
>> +    #include <dt-bindings/interrupt-controller/irq.h>
>> +    #include <dt-bindings/interrupt-controller/arm-gic.h>
>> +
>> +    iommu@7500000 {
>> +            compatible = "qcom,apq8064-iommu";
>> +            reg = <0x07500000 0x100000>;
>> +            interrupts = <GIC_SPI 63 IRQ_TYPE_LEVEL_HIGH>,
>> +                         <GIC_SPI 64 IRQ_TYPE_LEVEL_HIGH>;
>> +            clocks = <&clk SMMU_AHB_CLK>,
>> +                     <&clk MDP_AXI_CLK>;
>> +            clock-names = "smmu_pclk",
>> +                          "iommu_clk";
>> +            #iommu-cells = <1>;
>> +            qcom,ncb = <2>;
>> +    };

-- 
David Heidelberg