[PATCH 1/2] dt-bindings: Add Arm SMMUv3 PMCG binding

[Rob Herring]

On Tue, Nov 16, 2021 at 5:52 AM Jean-Philippe Brucker
<jean-philippe at linaro.org> wrote:
>
> Add binding for the Arm SMMUv3 PMU. Each node represents a PMCG, and is
> placed as a sibling node of the SMMU. Although the PMCGs registers may
> be within the SMMU MMIO region, they are separate devices, and there can
> be multiple PMCG devices for each SMMU (for example one for the TCU and
> one for each TBU).
>
> Signed-off-by: Jean-Philippe Brucker <jean-philippe at linaro.org>
> ---
>  .../bindings/iommu/arm,smmu-v3-pmcg.yaml      | 67 +++++++++++++++++++
>  1 file changed, 67 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iommu/arm,smmu-v3-pmcg.yaml
>
> diff --git a/Documentation/devicetree/bindings/iommu/arm,smmu-v3-pmcg.yaml b/Documentation/devicetree/bindings/iommu/arm,smmu-v3-pmcg.yaml
> new file mode 100644
> index 000000000000..a893e071fdb4
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iommu/arm,smmu-v3-pmcg.yaml
> @@ -0,0 +1,67 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/iommu/arm,smmu-v3-pmcg.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Arm SMMUv3 Performance Monitor Counter Group
> +
> +maintainers:
> +  - Will Deacon <will at kernel.org>
> +  - Robin Murphy <Robin.Murphy at arm.com>
> +
> +description: |+

Don't need '|+' if no formatting to preserve.

> +  An SMMUv3 may have several Performance Monitor Counter Group (PMCG).
> +  They are standalone performance monitoring units that support both
> +  architected and IMPLEMENTATION DEFINED event counters.

Humm, I don't know that I agree they are standalone. They could be I
guess, but looking at the MMU-600 spec the PMCG looks like it's just a
subset of registers in a larger block. This seems similar to MPAM
(which I'm working on a binding for) where it's just a register map
and interrupts, but every other possible resource is unspecified by
the architecture.

The simplest change from this would be just specifying that the PMCG
is child node(s) of whatever it is part of. The extreme would be this
is all part of the SMMU binding (i.e. reg entry X is PMCG registers,
interrupts entry Y is pmu irq).

> +
> +properties:
> +  $nodename:
> +    pattern: "^pmu@[0-9a-f]*"

s/*/+/

Need at least 1 digit.

> +  compatible:
> +    oneOf:
> +      - items:
> +        - enum:
> +          - hisilicon,smmu-v3-pmcg-hip08
> +        - const: arm,smmu-v3-pmcg
> +      - const: arm,smmu-v3-pmcg
> +
> +  reg:
> +    description: |
> +      Base addresses of the PMCG registers. Either a single address for Page 0
> +      or an additional address for Page 1, where some registers can be
> +      relocated with SMMU_PMCG_CFGR.RELOC_CTRS.
> +    minItems: 1
> +    maxItems: 2
> +
> +  interrupts:
> +    maxItems: 1
> +
> +  msi-parent: true
> +
> +required:
> +  - compatible
> +  - reg
> +
> +additionalProperties: false
> +
> +examples:
> +  - |+
> +    #include <dt-bindings/interrupt-controller/arm-gic.h>
> +    #include <dt-bindings/interrupt-controller/irq.h>
> +
> +    pmu at 2b420000 {
> +            compatible = "arm,smmu-v3-pmcg";
> +            reg = <0 0x2b420000 0 0x1000>,
> +                  <0 0x2b430000 0 0x1000>;
> +            interrupts = <GIC_SPI 80 IRQ_TYPE_EDGE_RISING>;
> +            msi-parent = <&its 0xff0000>;
> +    };
> +
> +    pmu at 2b440000 {
> +            compatible = "arm,smmu-v3-pmcg";
> +            reg = <0 0x2b440000 0 0x1000>,
> +                  <0 0x2b450000 0 0x1000>;
> +            interrupts = <GIC_SPI 81 IRQ_TYPE_EDGE_RISING>;
> +            msi-parent = <&its 0xff0000>;
> +    };
> --
> 2.33.1
>