Re: [PATCH 4/4] dt-bindings: firmware: Add Qualcomm UEFI Secure Application client

[Sudeep Holla <sudeep.holla@arm.com>]

On Sun, Jul 24, 2022 at 12:49:49AM +0200, Maximilian Luz wrote:
> Add bindings for the Qualcomm Trusted Execution Environment (TrEE) UEFI
> Secure application (uefisecapp) client.
> 
> Signed-off-by: Maximilian Luz <luzmaximilian@gmail.com>
> ---
>  .../firmware/qcom,tee-uefisecapp.yaml         | 38 +++++++++++++++++++
>  MAINTAINERS                                   |  1 +
>  2 files changed, 39 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/firmware/qcom,tee-uefisecapp.yaml
> 
> diff --git a/Documentation/devicetree/bindings/firmware/qcom,tee-uefisecapp.yaml b/Documentation/devicetree/bindings/firmware/qcom,tee-uefisecapp.yaml
> new file mode 100644
> index 000000000000..9e5de1005d5c
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/firmware/qcom,tee-uefisecapp.yaml
> @@ -0,0 +1,38 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/soc/qcom/qcom,rpmh-rsc.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Qualcomm Trusted Execution Environment UEFI Secure Application
> +
> +maintainers:
> +  - Maximilian Luz <luzmaximilian@gmail.com>
> +
> +description: |
> +  Various Qualcomm SoCs do not allow direct access to UEFI variables. Instead,
> +  these need to be accessed via the UEFI Secure Application (uefisecapp),
> +  residing in the Trusted Execution Environment (TrEE). These bindings mark the
> +  presence of uefisecapp and allow the respective client driver to load and
> +  install efivar operations, providing the kernel with access to UEFI
> +  variables.
> +
> +properties:
> +  compatible:
> +    const: qcom,tee-uefisecapp
> +
> +required:
> +  - compatible
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    firmware {
> +        scm {
> +            compatible = "qcom,scm-sc8180x", "qcom,scm";
> +        };
> +        tee-uefisecapp {
> +            compatible = "qcom,tee-uefisecapp";
> +        };

Do you expect some issues using the scm driver APIs without the
any additions in the DT ? I mean can't you auto-discover by using the
APIs. I haven't looked at the driver or any other patches in the series,
but I would like to know if we can avoid adding any new bindings if it
can be discovered via those SCM driver APIs.

-- 
Regards,
Sudeep