Re: [PATCH 05/11] dt-bindings: document the Qualcomm TEE Shared Memory Bridge

[Konrad Dybcio]

On 29.08.2023 10:02, Krzysztof Kozlowski wrote:
> On 28/08/2023 21:25, Bartosz Golaszewski wrote:
>> Add Device Tree bindings for Qualcomm TEE Shared Memory Brige - a
>> mechanism that allows sharing memory buffers between trustzone and the
>> kernel.
> 
> Subject prefix:
> dt-bindings: firmware:
> 
> 
> 
>>
>> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>
>> ---
>>  .../bindings/firmware/qcom,shm-bridge.yaml    | 36 +++++++++++++++++++
>>  1 file changed, 36 insertions(+)
>>  create mode 100644 Documentation/devicetree/bindings/firmware/qcom,shm-bridge.yaml
>>
>> diff --git a/Documentation/devicetree/bindings/firmware/qcom,shm-bridge.yaml b/Documentation/devicetree/bindings/firmware/qcom,shm-bridge.yaml
>> new file mode 100644
>> index 000000000000..f660962b7b86
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/firmware/qcom,shm-bridge.yaml
>> @@ -0,0 +1,36 @@
>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/firmware/qcom,shm-bridge.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: QCOM Shared Memory Bridge
>> +
>> +description: |
> 
> Do not need '|' unless you need to preserve formatting.
> 
>> +  Qualcomm TEE Shared Memory Bridge allows sharing limited areas of kernel's
>> +  virtual memory with the trustzone in order to avoid mapping the entire RAM.
>> +
>> +maintainers:
>> +  - Bjorn Andersson <andersson@xxxxxxxxxx>
>> +  - Konrad Dybcio <konrad.dybcio@xxxxxxxxxx>
>> +  - Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>
>> +
>> +properties:
>> +  compatible:
>> +    items:
>> +      - enum:
>> +          - qcom,shm-bridge-sa8775p
>> +          - qcom,shm-bridge-sm8150
>> +          - qcom,shm-bridge-sm8450
>> +      - const: qcom,shm-bridge
>> +
> 
> Looks quite empty... Why this cannot be part of qcom,scm? IOW, why do
> you need new binding if you do not have any resources here and the block
> is essentially feature of qcom,scm firmware?
Since it's "discoverable" (via retval of an scm call), I'd second the
idea of probing this from within the SCM driver.

Konrad