Re: [PATCH v14 4/4] iommu/arm-smmu: Add support for qcom,smmu-v2 variant

Robin Murphy
2018-08-22T15:27:04Z

On 27/07/18 08:02, Vivek Gautam wrote:
> qcom,smmu-v2 is an arm,smmu-v2 implementation with specific
> clock and power requirements. This smmu core is used with
> multiple masters on msm8996, viz. mdss, video, etc.
> Add bindings for the same.
>
> Signed-off-by: Vivek Gautam <vivek.gautam-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>
> Reviewed-by: Rob Herring <robh-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
> Reviewed-by: Tomasz Figa <tfiga-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
> ---
>
> Change since v13:
> - No change.
>
> .../devicetree/bindings/iommu/arm,smmu.txt | 42 ++++++++++++++++++++++
> drivers/iommu/arm-smmu.c | 13 +++++++
> 2 files changed, 55 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/iommu/arm,smmu.txt b/Documentation/devicetree/bindings/iommu/arm,smmu.txt
> index 8a6ffce12af5..7c71a6ed465a 100644
> --- a/Documentation/devicetree/bindings/iommu/arm,smmu.txt
> +++ b/Documentation/devicetree/bindings/iommu/arm,smmu.txt
> @@ -17,10 +17,19 @@ conditions.
> "arm,mmu-401"
> "arm,mmu-500"
> "cavium,smmu-v2"
> + "qcom,<soc>-smmu-v2", "qcom,smmu-v2"
>
> depending on the particular implementation and/or the
> version of the architecture implemented.
>
> + A number of Qcom SoCs use qcom,smmu-v2 version of the IP.
> + "qcom,<soc>-smmu-v2" represents a soc specific compatible
> + string that should be present along with the "qcom,smmu-v2"
> + to facilitate SoC specific clocks/power connections and to
> + address specific bug fixes.

As demonstrated in the GPU thread, this proves a bit too vague for a
useful binding. Provided Qcom folks can reach a consensus on what a
given SoC is actually called, I'd rather just unambiguously list
whatever sets of fully-defined strings we need.

Robin.

> + An example string would be -
> + "qcom,msm8996-smmu-v2", "qcom,smmu-v2".
> +
> - reg : Base address and size of the SMMU.
>
> - #global-interrupts : The number of global interrupts exposed by the
> @@ -71,6 +80,22 @@ conditions.
> or using stream matching with #iommu-cells = <2>, and
> may be ignored if present in such cases.
>
> +- clock-names: List of the names of clocks input to the device. The
> + required list depends on particular implementation and
> + is as follows:
> + - for "qcom,smmu-v2":
> + - "bus": clock required for downstream bus access and
> + for the smmu ptw,
> + - "iface": clock required to access smmu's registers
> + through the TCU's programming interface.
> + - unspecified for other implementations.
> +
> +- clocks: Specifiers for all clocks listed in the clock-names property,
> + as per generic clock bindings.
> +
> +- power-domains: Specifiers for power domains required to be powered on for
> + the SMMU to operate, as per generic power domain bindings.
> +
> ** Deprecated properties:
>
> - mmu-masters (deprecated in favour of the generic "iommus" binding) :
> @@ -137,3 +162,20 @@ conditions.
> iommu-map = <0 &smmu3 0 0x400>;
> ...
> };
> +
> + /* Qcom's arm,smmu-v2 implementation */
> + smmu4: iommu {
> + compatible = "qcom,msm8996-smmu-v2", "qcom,smmu-v2";
> + reg = <0xd00000 0x10000>;
> +
> + #global-interrupts = <1>;
> + interrupts = <GIC_SPI 73 IRQ_TYPE_LEVEL_HIGH>,
> + <GIC_SPI 320 IRQ_TYPE_LEVEL_HIGH>,
> + <GIC_SPI 321 IRQ_TYPE_LEVEL_HIGH>;
> + #iommu-cells = <1>;
> + power-domains = <&mmcc MDSS_GDSC>;
> +
> + clocks = <&mmcc SMMU_MDP_AXI_CLK>,
> + <&mmcc SMMU_MDP_AHB_CLK>;
> + clock-names = "bus", "iface";
> + };
> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
> index e558abf1ecfc..2b4edba188a5 100644
> --- a/drivers/iommu/arm-smmu.c
> +++ b/drivers/iommu/arm-smmu.c
> @@ -119,6 +119,7 @@ enum arm_smmu_implementation {
> GENERIC_SMMU,
> ARM_MMU500,
> CAVIUM_SMMUV2,
> + QCOM_SMMUV2,
> };
>
> struct arm_smmu_s2cr {
> @@ -1971,6 +1972,17 @@ ARM_SMMU_MATCH_DATA(arm_mmu401, ARM_SMMU_V1_64K, GENERIC_SMMU);
> ARM_SMMU_MATCH_DATA(arm_mmu500, ARM_SMMU_V2, ARM_MMU500);
> ARM_SMMU_MATCH_DATA(cavium_smmuv2, ARM_SMMU_V2, CAVIUM_SMMUV2);
>
> +static const char * const qcom_smmuv2_clks[] = {
> + "bus", "iface",
> +};
> +
> +static const struct arm_smmu_match_data qcom_smmuv2 = {
> + .version = ARM_SMMU_V2,
> + .model = QCOM_SMMUV2,
> + .clks = qcom_smmuv2_clks,
> + .num_clks = ARRAY_SIZE(qcom_smmuv2_clks),
> +};
> +
> static const struct of_device_id arm_smmu_of_match[] = {
> { .compatible = "arm,smmu-v1", .data = &smmu_generic_v1 },
> { .compatible = "arm,smmu-v2", .data = &smmu_generic_v2 },
> @@ -1978,6 +1990,7 @@ static const struct of_device_id arm_smmu_of_match[] = {
> { .compatible = "arm,mmu-401", .data = &arm_mmu401 },
> { .compatible = "arm,mmu-500", .data = &arm_mmu500 },
> { .compatible = "cavium,smmu-v2", .data = &cavium_smmuv2 },
> + { .compatible = "qcom,smmu-v2", .data = &qcom_smmuv2 },
> { },
> };
> MODULE_DEVICE_TABLE(of, arm_smmu_of_match);
>