[PATCH v2 1/2] dt-bindings: rng: mtk-rng: add SMC-based TRNG variants

[Krzysztof Kozlowski]

On Thu, Apr 02, 2026 at 01:37:02AM +0100, Daniel Golle wrote:
> Add compatible strings for MediaTek SoCs where the hardware random number
> generator is accessed via a vendor-defined Secure Monitor Call (SMC)
> rather than direct MMIO register access:
> 
>   - mediatek,mt7981-rng
>   - mediatek,mt7987-rng
>   - mediatek,mt7988-rng
> 
> These variants require no reg, clocks, or clock-names properties since
> the RNG hardware is managed by ARM Trusted Firmware-A.
> 
> Relax the $nodename pattern to also allow 'rng' in addition to the
> existing 'rng at ...' pattern.
> 
> Add a second example showing the minimal SMC variant binding.
> 
> Signed-off-by: Daniel Golle <daniel at makrotopia.org>
> ---
> v2: express compatibilities with fallback
> 
>  .../devicetree/bindings/rng/mtk-rng.yaml      | 28 ++++++++++++++++---
>  1 file changed, 24 insertions(+), 4 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/rng/mtk-rng.yaml b/Documentation/devicetree/bindings/rng/mtk-rng.yaml
> index 7e8dc62e5d3a6..34648b53d14c6 100644
> --- a/Documentation/devicetree/bindings/rng/mtk-rng.yaml
> +++ b/Documentation/devicetree/bindings/rng/mtk-rng.yaml
> @@ -11,12 +11,13 @@ maintainers:
>  
>  properties:
>    $nodename:
> -    pattern: "^rng@[0-9a-f]+$"
> +    pattern: "^rng(@[0-9a-f]+)?$"
>  
>    compatible:
>      oneOf:
>        - enum:
>            - mediatek,mt7623-rng
> +          - mediatek,mt7981-rng
>        - items:
>            - enum:
>                - mediatek,mt7622-rng
> @@ -25,6 +26,11 @@ properties:
>                - mediatek,mt8365-rng
>                - mediatek,mt8516-rng
>            - const: mediatek,mt7623-rng
> +      - items:
> +          - enum:
> +              - mediatek,mt7987-rng
> +              - mediatek,mt7988-rng
> +          - const: mediatek,mt7981-rng
>  
>    reg:
>      maxItems: 1
> @@ -38,9 +44,19 @@ properties:
>  
>  required:
>    - compatible
> -  - reg
> -  - clocks
> -  - clock-names
> +
> +allOf:
> +  - if:
> +      properties:
> +        compatible:
> +          not:

As requested last time - drop

> +            contains:
> +              const: mediatek,mt7981-rng
> +    then:

missing constraints for mediatek,mt7981-rng. So does it have IO space
and clocks or not?

> +      required:
> +        - reg
> +        - clocks
> +        - clock-names
>  
>  additionalProperties: false
>  
> @@ -53,3 +69,7 @@ examples:
>              clocks = <&infracfg CLK_INFRA_TRNG>;
>              clock-names = "rng";
>      };
> +  - |
> +    rng {
> +            compatible = "mediatek,mt7981-rng";

No improvements.

Also, make the example complete since binding claims you have clocks and
reg.

I am not sure it should be even same file, but if you are making it same
file, then make it correct.

Best regards,
Krzysztof