Re: [PATCH v8 1/2] dt-bindings: arm: Add OP-TEE transport for SCMI

[Etienne Carriere <etienne.carriere@linaro.org>]

Hello Ahmad,

On Mon, 28 Feb 2022 at 17:01, Ahmad Fatoum <a.fatoum@pengutronix.de> wrote:
>
> Hello Etienne,
>
> On 28.10.21 16:00, Etienne Carriere wrote:
> > Introduce compatible "linaro,scmi-optee" for SCMI transport channel
> > based on an OP-TEE service invocation. The compatible mandates a
> > channel ID defined with property "linaro,optee-channel-id".
>
> I just found this thread via the compatible in the STM32MP131 patch set:
> https://lore.kernel.org/all/20220225133137.813919-1-gabriel.fernandez@foss.st.com/
>
> Linux doesn't care whether PSCI is provided by TF-A, OP-TEE or something
> else, so there is just the arm,psci* compatible.
>
> What's different about SCMI that this is not possible? Why couldn't the
> existing binding and driver be used to communicate with OP-TEE as secure
> monitor as well?

Compatible "linaro,scmi-optee" denote a alternate SCMI transport to
those already in v5.16.
"arm,psci" defines a mailbox + shmem interface.
"arm,psci
 it uses an optee service as in service


>
> Cheers,
> Ahmad
>
> >
> > Cc: devicetree@vger.kernel.org
> > Cc: Rob Herring <robh+dt@kernel.org>
> > Signed-off-by: Etienne Carriere <etienne.carriere@linaro.org>
> > ---
> > Changes since v6:
> >  - Remove maxItems from linaro,optee-channel-id description
> >
> > No change since v5
> >
> > Changes since v4:
> >  - Fix sram node name in DTS example: s/-shm-/-sram-/
> >
> > Changes since v3:
> >  - Add description for linaro,optee-channel-id in patternProperties
> >    specifying protocol can optionaly define a dedicated channel id.
> >  - Fix DTS example (duplicated phandles issue, subnodes ordering)
> >  - Fix typo in DTS example and description comments.
> >
> > Changes since v2:
> >  - Define mandatory property linaro,optee-channel-id
> >  - Rebased on yaml description file
> >
> > Changes since v1:
> >  - Removed modification regarding mboxes property description.
> > ---
> >  .../bindings/firmware/arm,scmi.yaml           | 65 +++++++++++++++++++
> >  1 file changed, 65 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/firmware/arm,scmi.yaml b/Documentation/devicetree/bindings/firmware/arm,scmi.yaml
> > index 5c4c6782e052..eae15df36eef 100644
> > --- a/Documentation/devicetree/bindings/firmware/arm,scmi.yaml
> > +++ b/Documentation/devicetree/bindings/firmware/arm,scmi.yaml
> > @@ -38,6 +38,9 @@ properties:
> >                       The virtio transport only supports a single device.
> >          items:
> >            - const: arm,scmi-virtio
> > +      - description: SCMI compliant firmware with OP-TEE transport
> > +        items:
> > +          - const: linaro,scmi-optee
> >
> >    interrupts:
> >      description:
> > @@ -83,6 +86,11 @@ properties:
> >      description:
> >        SMC id required when using smc or hvc transports
> >
> > +  linaro,optee-channel-id:
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    description:
> > +      Channel specifier required when using OP-TEE transport.
> > +
> >    protocol@11:
> >      type: object
> >      properties:
> > @@ -195,6 +203,12 @@ patternProperties:
> >          minItems: 1
> >          maxItems: 2
> >
> > +      linaro,optee-channel-id:
> > +        $ref: /schemas/types.yaml#/definitions/uint32
> > +        description:
> > +          Channel specifier required when using OP-TEE transport and
> > +          protocol has a dedicated communication channel.
> > +
> >      required:
> >        - reg
> >
> > @@ -226,6 +240,16 @@ else:
> >        - arm,smc-id
> >        - shmem
> >
> > +  else:
> > +    if:
> > +      properties:
> > +        compatible:
> > +          contains:
> > +            const: linaro,scmi-optee
> > +    then:
> > +      required:
> > +        - linaro,optee-channel-id
> > +
> >  examples:
> >    - |
> >      firmware {
> > @@ -340,7 +364,48 @@ examples:
> >                  reg = <0x11>;
> >                  #power-domain-cells = <1>;
> >              };
> > +        };
> > +    };
> > +
> > +  - |
> > +    firmware {
> > +        scmi {
> > +            compatible = "linaro,scmi-optee";
> > +            linaro,optee-channel-id = <0>;
> > +
> > +            #address-cells = <1>;
> > +            #size-cells = <0>;
> > +
> > +            scmi_dvfs1: protocol@13 {
> > +                reg = <0x13>;
> > +                linaro,optee-channel-id = <1>;
> > +                shmem = <&cpu_optee_lpri0>;
> > +                #clock-cells = <1>;
> > +            };
> > +
> > +            scmi_clk0: protocol@14 {
> > +                reg = <0x14>;
> > +                #clock-cells = <1>;
> > +            };
> > +        };
> > +    };
> >
> > +    soc {
> > +        #address-cells = <2>;
> > +        #size-cells = <2>;
> > +
> > +        sram@51000000 {
> > +            compatible = "mmio-sram";
> > +            reg = <0x0 0x51000000 0x0 0x10000>;
> > +
> > +            #address-cells = <1>;
> > +            #size-cells = <1>;
> > +            ranges = <0 0x0 0x51000000 0x10000>;
> > +
> > +            cpu_optee_lpri0: optee-sram-section@0 {
> > +                compatible = "arm,scmi-shmem";
> > +                reg = <0x0 0x80>;
> > +            };
> >          };
> >      };
> >
>
>
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