[v3,03/13] dt-bindings: serial: Add compatible for Renesas RZ/T2H SoC in sci

Document RZ/T2H (a.k.a r9a09g077) in SCI binding.

Signed-off-by: Thierry Bultel <thierry.bultel.yh@bp.renesas.com>
Reviewed-by: Paul Barker <paul.barker.ct@bp.renesas.com>
---
 .../bindings/serial/renesas,sci.yaml          | 64 ++++++++++++-------
 1 file changed, 40 insertions(+), 24 deletions(-)

On Wed, Feb 26, 2025 at 02:09:22PM +0100, Thierry Bultel wrote:
> Document RZ/T2H (a.k.a r9a09g077) in SCI binding.
> 
> Signed-off-by: Thierry Bultel <thierry.bultel.yh@bp.renesas.com>
> Reviewed-by: Paul Barker <paul.barker.ct@bp.renesas.com>
> ---
>  .../bindings/serial/renesas,sci.yaml          | 64 ++++++++++++-------
>  1 file changed, 40 insertions(+), 24 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/serial/renesas,sci.yaml b/Documentation/devicetree/bindings/serial/renesas,sci.yaml
> index 64d3db6e54e5..2c4080283963 100644
> --- a/Documentation/devicetree/bindings/serial/renesas,sci.yaml
> +++ b/Documentation/devicetree/bindings/serial/renesas,sci.yaml
> @@ -9,9 +9,6 @@ title: Renesas Serial Communication Interface
>  maintainers:
>    - Geert Uytterhoeven <geert+renesas@glider.be>
>  
> -allOf:
> -  - $ref: serial.yaml#
> -
>  properties:
>    compatible:
>      oneOf:
> @@ -22,6 +19,8 @@ properties:
>                - renesas,r9a07g054-sci     # RZ/V2L
>            - const: renesas,sci            # generic SCI compatible UART
>  
> +      - const: renesas,r9a09g077-sci      # RZ/T2H
> +

Perhaps explain in the commit msg why the 'renesas,sci' is not 
applicable for this chip.

>        - items:
>            - const: renesas,sci            # generic SCI compatible UART
>  
> @@ -54,8 +53,6 @@ properties:
>          - fck # UART functional clock
>          - sck # optional external clock input
>  
> -  uart-has-rtscts: false
> -
>  required:
>    - compatible
>    - reg
> @@ -63,25 +60,44 @@ required:
>    - clocks
>    - clock-names
>  
> -if:
> -  properties:
> -    compatible:
> -      contains:
> -        enum:
> -          - renesas,r9a07g043-sci
> -          - renesas,r9a07g044-sci
> -          - renesas,r9a07g054-sci
> -then:
> -  properties:
> -    resets:
> -      maxItems: 1
> -
> -    power-domains:
> -      maxItems: 1
> -
> -  required:
> -    - resets
> -    - power-domains
> +allOf:
> +  - $ref: serial.yaml#
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            const: renesas,r9a09g077-sci
> +    then:
> +      properties:
> +        uart-has-rtscts: true

Drop. It is already allowed.

> +        power-domains:
> +          maxItems: 1
> +      required:
> +        - power-domains
> +
> +    else:
> +      properties:
> +        uart-has-rtscts: false
> +
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            enum:
> +              - renesas,r9a07g043-sci
> +              - renesas,r9a07g044-sci
> +              - renesas,r9a07g054-sci
> +    then:
> +      properties:
> +        resets:
> +          maxItems: 1
> +
> +        power-domains:
> +          maxItems: 1
> +
> +      required:
> +        - resets
> +        - power-domains
>  
>  unevaluatedProperties: false
>  
> -- 
> 2.43.0
>

Hi Rob,
thanks for you review

> -----Original Message-----
> From: Rob Herring <robh@kernel.org>
> Sent: lundi 3 mars 2025 14:36
> To: Thierry Bultel <thierry.bultel.yh@bp.renesas.com>
> Cc: thierry.bultel@linatsea.fr; linux-renesas-soc@vger.kernel.org;
> geert@linux-m68k.org; Paul Barker <paul.barker.ct@bp.renesas.com>; Geert
> Uytterhoeven <geert+renesas@glider.be>; linux-kernel@vger.kernel.org;
> linux-serial@vger.kernel.org; devicetree@vger.kernel.org
> Subject: Re: [PATCH v3 03/13] dt-bindings: serial: Add compatible for
> Renesas RZ/T2H SoC in sci
> 
> On Wed, Feb 26, 2025 at 02:09:22PM +0100, Thierry Bultel wrote:
> > Document RZ/T2H (a.k.a r9a09g077) in SCI binding.
> >
> > Signed-off-by: Thierry Bultel <thierry.bultel.yh@bp.renesas.com>
> > Reviewed-by: Paul Barker <paul.barker.ct@bp.renesas.com>
> > ---
> >  .../bindings/serial/renesas,sci.yaml          | 64 ++++++++++++-------
> >  1 file changed, 40 insertions(+), 24 deletions(-)
> >
> > diff --git a/Documentation/devicetree/bindings/serial/renesas,sci.yaml
> > b/Documentation/devicetree/bindings/serial/renesas,sci.yaml
> > index 64d3db6e54e5..2c4080283963 100644
> > --- a/Documentation/devicetree/bindings/serial/renesas,sci.yaml
> > +++ b/Documentation/devicetree/bindings/serial/renesas,sci.yaml
> > @@ -9,9 +9,6 @@ title: Renesas Serial Communication Interface
> >  maintainers:
> >    - Geert Uytterhoeven <geert+renesas@glider.be>
> >
> > -allOf:
> > -  - $ref: serial.yaml#
> > -
> >  properties:
> >    compatible:
> >      oneOf:
> > @@ -22,6 +19,8 @@ properties:
> >                - renesas,r9a07g054-sci     # RZ/V2L
> >            - const: renesas,sci            # generic SCI compatible UART
> >
> > +      - const: renesas,r9a09g077-sci      # RZ/T2H
> > +
> 
> Perhaps explain in the commit msg why the 'renesas,sci' is not applicable
> for this chip.


Would something like that be explicit enough ? 

"The SCI of RZ/T2H SoC (a.k.a r9a09g077), as a lot
of similarities with other Renesas SoCs like G2L, G3S and V2L,
but a different set of registers, that moreover are 32 bits instead
of 16 bits. 
This is why the 'renesas,sci' fallback does not apply for it".

Thanks !
Thierry

Hi Thierry,

On Mon, 3 Mar 2025 at 16:10, Thierry Bultel
<thierry.bultel.yh@bp.renesas.com> wrote:
> > -----Original Message-----
> > From: Rob Herring <robh@kernel.org>
> > Sent: lundi 3 mars 2025 14:36
> > To: Thierry Bultel <thierry.bultel.yh@bp.renesas.com>
> > Cc: thierry.bultel@linatsea.fr; linux-renesas-soc@vger.kernel.org;
> > geert@linux-m68k.org; Paul Barker <paul.barker.ct@bp.renesas.com>; Geert
> > Uytterhoeven <geert+renesas@glider.be>; linux-kernel@vger.kernel.org;
> > linux-serial@vger.kernel.org; devicetree@vger.kernel.org
> > Subject: Re: [PATCH v3 03/13] dt-bindings: serial: Add compatible for
> > Renesas RZ/T2H SoC in sci
> >
> > On Wed, Feb 26, 2025 at 02:09:22PM +0100, Thierry Bultel wrote:
> > > Document RZ/T2H (a.k.a r9a09g077) in SCI binding.
> > >
> > > Signed-off-by: Thierry Bultel <thierry.bultel.yh@bp.renesas.com>
> > > Reviewed-by: Paul Barker <paul.barker.ct@bp.renesas.com>
> > > ---
> > >  .../bindings/serial/renesas,sci.yaml          | 64 ++++++++++++-------
> > >  1 file changed, 40 insertions(+), 24 deletions(-)
> > >
> > > diff --git a/Documentation/devicetree/bindings/serial/renesas,sci.yaml
> > > b/Documentation/devicetree/bindings/serial/renesas,sci.yaml
> > > index 64d3db6e54e5..2c4080283963 100644
> > > --- a/Documentation/devicetree/bindings/serial/renesas,sci.yaml
> > > +++ b/Documentation/devicetree/bindings/serial/renesas,sci.yaml
> > > @@ -9,9 +9,6 @@ title: Renesas Serial Communication Interface
> > >  maintainers:
> > >    - Geert Uytterhoeven <geert+renesas@glider.be>
> > >
> > > -allOf:
> > > -  - $ref: serial.yaml#
> > > -
> > >  properties:
> > >    compatible:
> > >      oneOf:
> > > @@ -22,6 +19,8 @@ properties:
> > >                - renesas,r9a07g054-sci     # RZ/V2L
> > >            - const: renesas,sci            # generic SCI compatible UART
> > >
> > > +      - const: renesas,r9a09g077-sci      # RZ/T2H
> > > +
> >
> > Perhaps explain in the commit msg why the 'renesas,sci' is not applicable
> > for this chip.
>
> Would something like that be explicit enough ?
>
> "The SCI of RZ/T2H SoC (a.k.a r9a09g077), as a lot
> of similarities with other Renesas SoCs like G2L, G3S and V2L,
> but a different set of registers, that moreover are 32 bits instead
> of 16 bits.
> This is why the 'renesas,sci' fallback does not apply for it".

FTR, the registers being 32-bit instead of 8/16-bit wide is the least of
your problems... If it was just a SCI with 32-bit registers, you could
use "reg-io-width = <4>;" and "reg-shift = <2>;", and add support for
the latter to the driver (it already uses regshift on non-DT SuperH).

Gr{oetje,eeting}s,

                        Geert