linux-kernel - Re: [PATCH v5 1/2] dt-bindings: arm: optee: add interrupt controller properties

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Date:   Tue, 16 May 2023 08:02:28 +0200
From:   Etienne Carriere <etienne.carriere@...aro.org>
To:     linux-kernel@...r.kernel.org
Cc:     devicetree@...r.kernel.org, op-tee@...ts.trustedfirmware.org,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        Jens Wiklander <jens.wiklander@...aro.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Marc Zyngier <maz@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Sumit Garg <sumit.garg@...aro.org>,
        Pascal Paillet <p.paillet@...s.st.com>
Subject: Re: [PATCH v5 1/2] dt-bindings: arm: optee: add interrupt controller properties

Dear all,

On Sat, 6 May 2023 at 09:33, Etienne Carriere
<etienne.carriere@...aro.org> wrote:
>
> Adds an optional interrupt controller property to optee firmware node
> in the DT bindings. Optee driver may embeds an irqchip exposing
> OP-TEE interrupt events notified by the TEE world. Optee registers up
> to 1 interrupt controller and identifies each line with a line
> number from 0 to UINT16_MAX.
>
> The identifiers and meaning of the interrupt line number are specific
> to the platform and shall be found in the OP-TEE platform documentation.
>
> In the example shown in optee DT binding documentation, the platform SCMI
> device controlled by Linux scmi driver uses optee interrupt irq 5 as
> signal to trigger processing of an asynchronous incoming SCMI message
> in the scope of a CPU DVFS control. A platform can have several SCMI
> channels driven this way. Optee irqs also permit small embedded devices
> to share e.g. a gpio expander, a group of wakeup sources, etc... between
> OP-TEE world (for sensitive services) and Linux world (for non-sensitive
> services). The physical controller is driven from the TEE which exposes
> some controls to Linux kernel.
>
> Cc: Jens Wiklander <jens.wiklander@...aro.org>
> Cc: Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>
> Cc: Marc Zyngier <maz@...nel.org>
> Cc: Rob Herring <robh+dt@...nel.org>
> Cc: Sumit Garg <sumit.garg@...aro.org>
> Co-developed-by: Pascal Paillet <p.paillet@...s.st.com>
> Signed-off-by: Pascal Paillet <p.paillet@...s.st.com>
> Signed-off-by: Etienne Carriere <etienne.carriere@...aro.org>
> ---

Any feedback on this change proposal?

Regards,
Etienne

> Changes since v4:
> - Removed empty line between Cc: tags and S-o-b tags.
>
> No changes since v3
>
> Changes since v2:
> - Added a sentence on optee irq line number values and meaning, in
>   DT binding doc and commit message.
> - Updated example in DT binding doc from comment, fixed misplaced
>   interrupt-parent property and removed gic and sram shm nodes.
>
> Changes since v1:
> - Added a description to #interrupt-cells property.
> - Changed of example. Linux wakeup event was subject to discussion and
>   i don't know much about input events in Linux. So move to SCMI.
>   In the example, an SCMI server in OP-TEE world raises optee irq 5
>   so that Linux scmi optee channel &scmi_cpu_dvfs pushed in the incoming
>   SCMI message in the scmi device for liekly later processing in threaded
>   context. The example includes all parties: optee, scmi, sram, gic.
> - Obviously rephrased the commit message.
> ---
>  .../arm/firmware/linaro,optee-tz.yaml         | 38 +++++++++++++++++++
>  1 file changed, 38 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/arm/firmware/linaro,optee-tz.yaml b/Documentation/devicetree/bindings/arm/firmware/linaro,optee-tz.yaml
> index 5d033570b57b..9d9a797a6b2f 100644
> --- a/Documentation/devicetree/bindings/arm/firmware/linaro,optee-tz.yaml
> +++ b/Documentation/devicetree/bindings/arm/firmware/linaro,optee-tz.yaml
> @@ -41,6 +41,16 @@ properties:
>        HVC #0, register assignments
>        register assignments are specified in drivers/tee/optee/optee_smc.h
>
> +  interrupt-controller: true
> +
> +  "#interrupt-cells":
> +    const: 1
> +    description: |
> +      OP-TEE exposes irq for irp chip controllers from OP-TEE world. Each
> +      irq is assigned a single line number identifier used as first argument.
> +      Line number identifiers and their meaning shall be found in the OP-TEE
> +      firmware platform documentation.
> +
>  required:
>    - compatible
>    - method
> @@ -65,3 +75,31 @@ examples:
>              method = "hvc";
>          };
>      };
> +
> +  - |
> +    #include <dt-bindings/interrupt-controller/arm-gic.h>
> +    firmware  {
> +        optee: optee {
> +            compatible = "linaro,optee-tz";
> +            method = "smc";
> +            interrupt-parent = <&gic>;
> +            interrupts = <GIC_SPI 187 IRQ_TYPE_EDGE_RISING>;
> +            interrupt-controller;
> +            #interrupt-cells = <1>;
> +        };
> +
> +        scmi {
> +            compatible = "linaro,scmi-optee";
> +            linaro,optee-channel-id = <0>;
> +            shmem = <&scmi_shm_tx>, <&scmi_shm_rx>;
> +            interrupts-extended = <&optee 5>;
> +            interrupt-names = "a2p";
> +            #address-cells = <1>;
> +            #size-cells = <0>;
> +
> +            scmi_cpu_dvfs: protocol@13 {
> +                reg = <0x13>;
> +                #clock-cells = <1>;
> +            };
> +        };
> +    };
> --
> 2.25.1
>