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Date: Tue, 16 Jan 2024 13:21:45 -0600
From: Rob Herring <robh@kernel.org>
To: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
Cc: Bjorn Andersson <andersson@kernel.org>,
	Mathieu Poirier <mathieu.poirier@linaro.org>,
	Jens Wiklander <jens.wiklander@linaro.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Conor Dooley <conor+dt@kernel.org>,
	linux-stm32@st-md-mailman.stormreply.com,
	linux-arm-kernel@lists.infradead.org,
	linux-remoteproc@vger.kernel.org, linux-kernel@vger.kernel.org,
	op-tee@lists.trustedfirmware.org, devicetree@vger.kernel.org
Subject: Re: [PATCH 2/4] dt-bindings: remoteproc: add compatibility for TEE
 support
Message-ID: <20240116192145.GA265232-robh@kernel.org>
References: <20240115135249.296822-1-arnaud.pouliquen@foss.st.com>
 <20240115135249.296822-3-arnaud.pouliquen@foss.st.com>
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In-Reply-To: <20240115135249.296822-3-arnaud.pouliquen@foss.st.com>

On Mon, Jan 15, 2024 at 02:52:47PM +0100, Arnaud Pouliquen wrote:
> The "st,stm32mp1-m4-tee" compatible is utilized in a system configuration
> where the Cortex-M4 firmware is loaded by the Trusted execution Environment
> (TEE).
> This compatible is used in both the Linux and OP-TEE device-tree.
> - In OP-TEE, a node is defined in the device tree with the
>   st,stm32mp1-m4-tee to support signed remoteproc firmware.
>   Based on DT properties, OP-TEE authenticates, loads, starts, and stops
>   the firmware.
> - On Linux, when the compatibility is set, the Cortex-M resets should not
>   be declared in the device tree.
> 
> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
> ---
>  .../bindings/remoteproc/st,stm32-rproc.yaml   | 53 +++++++++++++++----
>  1 file changed, 44 insertions(+), 9 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/remoteproc/st,stm32-rproc.yaml b/Documentation/devicetree/bindings/remoteproc/st,stm32-rproc.yaml
> index 370af61d8f28..9fdfa30eff20 100644
> --- a/Documentation/devicetree/bindings/remoteproc/st,stm32-rproc.yaml
> +++ b/Documentation/devicetree/bindings/remoteproc/st,stm32-rproc.yaml
> @@ -16,7 +16,12 @@ maintainers:
>  
>  properties:
>    compatible:
> -    const: st,stm32mp1-m4
> +    enum:
> +      - st,stm32mp1-m4
> +      - st,stm32mp1-m4-tee
> +    description:
> +      Use "st,stm32mp1-m4" for the Cortex-M4 coprocessor management by Linux

What if other OSs want to manage the M4?

> +      Use "st,stm32mp1-m4-tee" for the Cortex-M4 coprocessor management by secure context
>  
>    reg:
>      description:
> @@ -142,21 +147,41 @@ properties:
>  required:
>    - compatible
>    - reg
> -  - resets
>  
>  allOf:
>    - if:
>        properties:
> -        reset-names:
> -          not:
> -            contains:
> -              const: hold_boot
> +        compatible:
> +          contains:
> +            const: st,stm32mp1-m4
> +    then:
> +      if:
> +        properties:
> +          reset-names:
> +            not:
> +              contains:
> +                const: hold_boot
> +      then:
> +        required:
> +          - st,syscfg-holdboot
> +          - resets
> +      else:
> +        properties:
> +          st,syscfg-holdboot: false
> +        required:
> +          - reset-names

Looks like a new required property.

> +          - resets
> +
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            const: st,stm32mp1-m4-tee
>      then:
> -      required:
> -        - st,syscfg-holdboot
> -    else:
>        properties:
>          st,syscfg-holdboot: false
> +        reset-names: false
> +        resets: false
>  
>  additionalProperties: false
>  
> @@ -188,5 +213,15 @@ examples:
>        st,syscfg-rsc-tbl = <&tamp 0x144 0xFFFFFFFF>;
>        st,syscfg-m4-state = <&tamp 0x148 0xFFFFFFFF>;
>      };
> +  - |
> +    #include <dt-bindings/reset/stm32mp1-resets.h>
> +    m4@10000000 {
> +      compatible = "st,stm32mp1-m4-tee";
> +      reg = <0x10000000 0x40000>,
> +            <0x30000000 0x40000>,
> +            <0x38000000 0x10000>;
> +      st,syscfg-rsc-tbl = <&tamp 0x144 0xFFFFFFFF>;
> +      st,syscfg-m4-state = <&tamp 0x148 0xFFFFFFFF>;
> +    };
>  
>  ...
> -- 
> 2.25.1
>