Re: [PATCH 09/12] dt-bindings: arm: fsl: Add msi-map device-tree binding for fsl-mc bus

[Rob Herring <robh+dt@kernel.org>]

On Thu, May 21, 2020 at 7:00 AM Lorenzo Pieralisi
<lorenzo.pieralisi@arm.com> wrote:
>
> From: Laurentiu Tudor <laurentiu.tudor@nxp.com>
>
> The existing bindings cannot be used to specify the relationship
> between fsl-mc devices and GIC ITSes.
>
> Add a generic binding for mapping fsl-mc devices to GIC ITSes, using
> msi-map property.
>
> Signed-off-by: Laurentiu Tudor <laurentiu.tudor@nxp.com>
> Cc: Rob Herring <robh+dt@kernel.org>
> ---
>  .../devicetree/bindings/misc/fsl,qoriq-mc.txt | 30 +++++++++++++++++--
>  1 file changed, 27 insertions(+), 3 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/misc/fsl,qoriq-mc.txt b/Documentation/devicetree/bindings/misc/fsl,qoriq-mc.txt
> index 9134e9bcca56..b0813b2d0493 100644
> --- a/Documentation/devicetree/bindings/misc/fsl,qoriq-mc.txt
> +++ b/Documentation/devicetree/bindings/misc/fsl,qoriq-mc.txt
> @@ -18,9 +18,9 @@ same hardware "isolation context" and a 10-bit value called an ICID
>  the requester.
>
>  The generic 'iommus' property is insufficient to describe the relationship
> -between ICIDs and IOMMUs, so an iommu-map property is used to define
> -the set of possible ICIDs under a root DPRC and how they map to
> -an IOMMU.
> +between ICIDs and IOMMUs, so the iommu-map and msi-map properties are used
> +to define the set of possible ICIDs under a root DPRC and how they map to
> +an IOMMU and a GIC ITS respectively.
>
>  For generic IOMMU bindings, see
>  Documentation/devicetree/bindings/iommu/iommu.txt.
> @@ -28,6 +28,9 @@ Documentation/devicetree/bindings/iommu/iommu.txt.
>  For arm-smmu binding, see:
>  Documentation/devicetree/bindings/iommu/arm,smmu.yaml.
>
> +For GICv3 and GIC ITS bindings, see:
> +Documentation/devicetree/bindings/interrupt-controller/arm,gic-v3.yaml.
> +
>  Required properties:
>
>      - compatible
> @@ -119,6 +122,15 @@ Optional properties:
>    associated with the listed IOMMU, with the iommu-specifier
>    (i - icid-base + iommu-base).
>
> +- msi-map: Maps an ICID to a GIC ITS and associated iommu-specifier
> +  data.
> +
> +  The property is an arbitrary number of tuples of
> +  (icid-base,iommu,iommu-base,length).

I'm confused because the example has GIC ITS phandle, not an IOMMU.

What is an iommu-base?

> +
> +  Any ICID in the interval [icid-base, icid-base + length) is
> +  associated with the listed GIC ITS, with the iommu-specifier
> +  (i - icid-base + iommu-base).
>  Example:
>
>          smmu: iommu@5000000 {
> @@ -128,6 +140,16 @@ Example:
>                 ...
>          };
>
> +       gic: interrupt-controller@6000000 {
> +               compatible = "arm,gic-v3";
> +               ...
> +               its: gic-its@6020000 {
> +                       compatible = "arm,gic-v3-its";
> +                       msi-controller;
> +                       ...
> +               };
> +       };
> +
>          fsl_mc: fsl-mc@80c000000 {
>                  compatible = "fsl,qoriq-mc";
>                  reg = <0x00000008 0x0c000000 0 0x40>,    /* MC portal base */
> @@ -135,6 +157,8 @@ Example:
>                  msi-parent = <&its>;
>                  /* define map for ICIDs 23-64 */
>                  iommu-map = <23 &smmu 23 41>;
> +                /* define msi map for ICIDs 23-64 */
> +                msi-map = <23 &its 23 41>;

Seeing 23 twice is odd. The numbers to the right of 'its' should be an
ITS number space.

>                  #address-cells = <3>;
>                  #size-cells = <1>;
>
> --
> 2.26.1
>