linux-kernel - Re: [PATCH v2 2/4] dt-bindings: remoteproc: Add compatibility for TEE support

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Message-ID: <32b5b04b-c644-43d0-b190-4200f0e92979@foss.st.com>
Date: Tue, 13 Feb 2024 16:38:11 +0100
From: Arnaud POULIQUEN <arnaud.pouliquen@...s.st.com>
To: Rob Herring <robh@...nel.org>
CC: Bjorn Andersson <andersson@...nel.org>,
        Mathieu Poirier
	<mathieu.poirier@...aro.org>,
        Jens Wiklander <jens.wiklander@...aro.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley
	<conor+dt@...nel.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-remoteproc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <op-tee@...ts.trustedfirmware.org>, <devicetree@...r.kernel.org>
Subject: Re: [PATCH v2 2/4] dt-bindings: remoteproc: Add compatibility for TEE
 support

Hello Rob,

On 1/30/24 18:51, Rob Herring wrote:
> On Thu, Jan 18, 2024 at 11:04:31AM +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).
>> For instance, 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@...s.st.com>
>> ---
>> V1 to V2 updates
>> - update "st,stm32mp1-m4" compatible description to generalize
>> - remove the 'reset-names' requirement in one conditional branch, as the
>>   property is already part of the condition test.
>> ---
>>  .../bindings/remoteproc/st,stm32-rproc.yaml   | 52 +++++++++++++++----
>>  1 file changed, 43 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..6af821b15736 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 non-secure context
>> +      Use "st,stm32mp1-m4-tee" for the Cortex-M4 coprocessor management by secure context
>>  
>>    reg:
>>      description:
>> @@ -142,21 +147,40 @@ 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
> 
> Note that this is true when 'reset-names' is not present. If that is not 
> desired, then you need 'required: [reset-names]'. Not really a new issue 
> though.
> 

Yes that corresponds to my expectation, for compatibility with legacy DT.
If the hold_boot reset was not used, reset-names was not mandatory
I will add the 'required: [reset-names]' in the else

Thanks,
Arnaud

>> +      then:
>> +        required:
>> +          - st,syscfg-holdboot
>> +          - resets
>> +      else:
>> +        properties:
>> +          st,syscfg-holdboot: false
>> +        required:
>> +          - resets
> 
> 'resets' is always required within the outer 'then' schema, so you can 
> move this up a level.
> 
>> +
>> +  - 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 +212,15 @@ examples:
>>        st,syscfg-rsc-tbl = <&tamp 0x144 0xFFFFFFFF>;
>>        st,syscfg-m4-state = <&tamp 0x148 0xFFFFFFFF>;
>>      };
>> +  - |
>> +    #include <dt-bindings/reset/stm32mp1-resets.h>
>> +    m4@...00000 {
>> +      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
>>