Subject: Re: [PATCH v3 2/3] dt-bindings: iommu: add DART iommu bindings

From: Rob Herring <[email-masked]>
Date: Thu, 10 Jun 2021 11:52:44 -0500

On Thu, Jun 03, 2021 at 10:50:02AM +0200, Sven Peter wrote:
> DART (Device Address Resolution Table) is the iommu found on Apple
> ARM SoCs such as the M1.
> 
> Signed-off-by: Sven Peter <[email-masked]>
> ---
>  .../devicetree/bindings/iommu/apple,dart.yaml | 81 +++++++++++++++++++
>  MAINTAINERS                                   |  6 ++
>  2 files changed, 87 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iommu/apple,dart.yaml
> 
> diff --git a/Documentation/devicetree/bindings/iommu/apple,dart.yaml b/Documentation/devicetree/bindings/iommu/apple,dart.yaml
> new file mode 100644
> index 000000000000..db21ca07d121
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iommu/apple,dart.yaml
> @@ -0,0 +1,81 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/iommu/apple,dart.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Apple DART IOMMU
> +
> +maintainers:
> +  - Sven Peter <[email-masked]>
> +
> +description: |+
> +  Apple SoCs may contain an implementation of their Device Address
> +  Resolution Table which provides a mandatory layer of address
> +  translations for various masters.
> +
> +  Each DART instance is capable of handling up to 16 different streams
> +  with individual pagetables and page-level read/write protection flags.
> +
> +  This DART IOMMU also raises interrupts in response to various
> +  fault conditions.
> +
> +properties:
> +  compatible:
> +    const: apple,t8103-dart
> +
> +  reg:
> +    maxItems: 1
> +
> +  interrupts:
> +    maxItems: 1
> +
> +  clocks:
> +    description:
> +      Reference to the gate clock phandle if required for this IOMMU.
> +      Optional since not all IOMMUs are attached to a clock gate.
> +
> +  '#iommu-cells':
> +    const: 1
> +    description:
> +      Has to be one. The single cell describes the stream id emitted by
> +      a master to the IOMMU.
> +
> +required:
> +  - compatible
> +  - reg
> +  - '#iommu-cells'
> +  - interrupts
> +
> +additionalProperties: false
> +
> +examples:
> +  - |+
> +    dart1: iommu@82f80000 {
> +      compatible = "apple,t8103-dart";
> +      reg = <0x82f80000 0x4000>;
> +      interrupts = <1 781 4>;
> +      #iommu-cells = <1>;
> +    };
> +
> +    master1 {
> +      iommus = <&{/dart1} 0>;

/dart1 is a path, but 'dart1' is a label. You need '&dart1' (or 
'&{/iommu@82f80000}' but that doesn't really work here because the 
examples get prefixed with /example-n/...)

With that fixed,

Reviewed-by: Rob Herring <[email-masked]>

> +    };
> +
> +  - |+
> +    dart2a: iommu@82f00000 {
> +      compatible = "apple,t8103-dart";
> +      reg = <0x82f00000 0x4000>;
> +      interrupts = <1 781 4>;
> +      #iommu-cells = <1>;
> +    };
> +    dart2b: iommu@82f80000 {
> +      compatible = "apple,t8103-dart";
> +      reg = <0x82f80000 0x4000>;
> +      interrupts = <1 781 4>;
> +      #iommu-cells = <1>;
> +    };
> +
> +    master2 {
> +      iommus = <&{/dart2a} 0>, <&{/dart2b} 1>;
> +    };
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 673cadd5107a..4373d63f9ccf 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -1240,6 +1240,12 @@ L:	[email-masked]
>  S:	Odd fixes
>  F:	drivers/input/mouse/bcm5974.c
>  
> +APPLE DART IOMMU DRIVER
> +M:	Sven Peter <[email-masked]>
> +L:	[email-masked]
> +S:	Maintained
> +F:	Documentation/devicetree/bindings/iommu/apple,dart.yaml
> +
>  APPLE SMC DRIVER
>  M:	Henrik Rydberg <[email-masked]>
>  L:	[email-masked]
> -- 
> 2.25.1

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