Re: [PATCH v5 1/7] dt-bindings: Arm: Add Firmware Framework for Armv8-A (FF-A) binding

[Sumit Garg <sumit.garg@linaro.org>]

Hi Sudeep,

Apologies for catching up late on this patch-set.

On Thu, 25 Mar 2021 at 20:05, Sudeep Holla <sudeep.holla@arm.com> wrote:
>
> Since the FF-A v1.0 specification doesn't list the UUID of all the
> partitions in the discovery API, we need to specify the UUID of the
> partitions that need to be accessed by drivers within the kernel.
>

Wouldn't we be able to implement auto-discovery of ffa partitions? I
think enumeration of ffa partitions on FFA bus should be quite similar
to enumeration of TAs on TEE bus (see [1]). Otherwise we need to put
these redundant DT entries for every ffa partition which IMHO would
bloat up device trees for every platform.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/tee/optee/device.c#n153

-Sumit

> This binding to provide the list of partitions that kernel drivers
> may need to access.
>
> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
> ---
>  .../devicetree/bindings/arm/arm,ffa.yaml      | 57 +++++++++++++++++++
>  1 file changed, 57 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/arm/arm,ffa.yaml
>
> diff --git a/Documentation/devicetree/bindings/arm/arm,ffa.yaml b/Documentation/devicetree/bindings/arm/arm,ffa.yaml
> new file mode 100644
> index 000000000000..42ed33464ba7
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/arm/arm,ffa.yaml
> @@ -0,0 +1,57 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/arm/arm,ffa.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Arm Firmware Framework for Arm v8-A (in-kernel users)
> +
> +maintainers:
> +  - Sudeep Holla <sudeep.holla@arm.com>
> +
> +description: |
> +  Firmware frameworks implementing partition according to the FF-A
> +  specification defined by ARM document number ARM DEN 0077A ("Arm Firmware
> +  Framework for Arm v8-A") [0], providing services to be used by other
> +  partitions.
> +
> +  [0] https://developer.arm.com/docs/den0077/latest
> +
> +properties:
> +  $nodename:
> +    const: ffa
> +
> +  compatible:
> +    oneOf:
> +      - const: arm,ffa-1.0
> +
> +patternProperties:
> +  "^ffa-partition-[0-9]+$":
> +    type: object
> +    description: One or more child nodes, each describing an FFA partition.
> +    properties:
> +      $nodename:
> +        const: ffa_partition
> +
> +      compatible:
> +        const: arm,ffa-1.0-partition
> +
> +      uuid:
> +        $ref: '/schemas/types.yaml#definitions/string'
> +        description: |
> +          The 128-bit UUID [2] of the service implemented by this partition.
> +
> +          [2] https://tools.ietf.org/html/rfc4122
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    ffa {
> +      compatible = "arm,ffa-1.0";
> +
> +      ffa-partition-0 {
> +        compatible = "arm,ffa-1.0-partition";
> +        uuid = "12345678-9abc-def0-1234-56789abcdef0";
> +      };
> +    };
> --
> 2.25.1
>
>
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