Re: [PATCH v4 3/4] dt-bindings: mailbox: add binding for Microchip IPC mailbox controller

[Conor Dooley <conor@kernel.org>]

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On Tue, Nov 26, 2024 at 08:04:38AM +0100, Krzysztof Kozlowski wrote:
> On Mon, Nov 25, 2024 at 05:58:17PM +0000, Valentina Fernandez wrote:
> > +properties:
> > +  compatible:
> > +    oneOf:
> > +      - description:
> > +          Intended for use by software running in supervisor privileged
> > +          mode (s-mode). This SBI interface is compatible with the Mi-V
> > +          Inter-hart Communication (IHC) IP.
> > +        const: microchip,sbi-ipc
> > +
> > +      - description:
> > +          Intended for use by the SBI implementation in machine mode
> > +          (m-mode), this compatible string is for the MIV_IHC Soft-IP.
> > +        const: microchip,miv-ihc-rtl-v2

> > +allOf:
> > +  - if:
> > +      properties:
> > +        compatible:
> > +          contains:
> > +            const: microchip,sbi-ipc
> > +    then:
> > +      properties:
> > +        reg: false
> 
> What does this mean in reality? Device does not have IO address space?
> Then it is completely different programming model, isn't it?

Ye, different programming models. Two compatibles for the same hardware,
but one represents the m-mode/firmware programming model that has MMIO
access and is the SBI implementation and the other the s-mode/OS
programming model that uses ecalls provided by the SBI implementation.

> > +        microchip,ihc-chan-disabled-mask: false
> > +    else:
> > +      required:
> > +        - reg
> > +        - microchip,ihc-chan-disabled-mask


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