linux-kernel - Re: [PATCH v3 2/7] dt-bindings: iio: adc: document RZ/T2H and RZ/N2H ADC

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Message-ID: <CAMuHMdWOWMvyGLz8HGEvosrGY070e2Xtm+dFTcd0EDTq+55nmg@mail.gmail.com>
Date: Thu, 2 Oct 2025 14:22:01 +0200
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Cosmin Tanislav <cosmin-gabriel.tanislav.xa@...esas.com>
Cc: Jonathan Cameron <jic23@...nel.org>, David Lechner <dlechner@...libre.com>, 
	Nuno Sá <nuno.sa@...log.com>, 
	Andy Shevchenko <andy@...nel.org>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Geert Uytterhoeven <geert+renesas@...der.be>, Magnus Damm <magnus.damm@...il.com>, 
	linux-iio@...r.kernel.org, linux-renesas-soc@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Conor Dooley <conor.dooley@...rochip.com>
Subject: Re: [PATCH v3 2/7] dt-bindings: iio: adc: document RZ/T2H and RZ/N2H ADC

Hi Cosmin,

On Wed, 1 Oct 2025 at 14:24, Cosmin Tanislav
<cosmin-gabriel.tanislav.xa@...esas.com> wrote:
> Document the A/D 12-Bit successive approximation converters found in the
> Renesas RZ/T2H (R9A09G077) and RZ/N2H (R9A09G087) SoCs.
>
> RZ/T2H has two ADCs with 4 channels and one with 6.
> RZ/N2H has two ADCs with 4 channels and one with 15.
>
> Signed-off-by: Cosmin Tanislav <cosmin-gabriel.tanislav.xa@...esas.com>
> Acked-by: Conor Dooley <conor.dooley@...rochip.com>
> Reviewed-by: Geert Uytterhoeven <geert+renesas@...der.be>

Thanks for your patch!

> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/adc/renesas,r9a09g077-adc.yaml
> @@ -0,0 +1,160 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/iio/adc/renesas,r9a09g077-adc.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Renesas RZ/T2H / RZ/N2H ADC12
> +
> +maintainers:
> +  - Cosmin Tanislav <cosmin-gabriel.tanislav.xa@...esas.com>
> +
> +description: |
> +  A/D Converter block is a successive approximation analog-to-digital converter
> +  with a 12-bit accuracy. Up to 16 analog input channels can be selected.
> +  Conversions can be performed in single or continuous mode. Result of the ADC
> +  is stored in a 16-bit data register corresponding to each channel.
> +
> +properties:
> +  compatible:
> +    enum:
> +      - renesas,r9a09g077-adc # RZ/T2H
> +      - renesas,r9a09g087-adc # RZ/N2H

Given the number of channels is now handled completely through the
number of subnodes, I wonder if this should be changed to:

    oneOf:
      - items:
          - const: renesas,r9a09g087-adc # RZ/N2H
          - const: renesas,r9a09g077-adc # RZ/T2H
      - items:
          - const: renesas,r9a09g077-adc # RZ/T2H

...

> +allOf:
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            const: renesas,r9a09g077-adc
> +    then:
> +      patternProperties:
> +        "^channel@[6-9a-f]$": false
> +        "^channel@[0-5]$":
> +          properties:
> +            reg:
> +              maximum: 5
> +
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            enum:
> +              - renesas,r9a09g087-adc
> +    then:
> +      patternProperties:
> +        "^channel@[f]$": false
> +        "^channel@[0-9a-e]$":
> +          properties:
> +            reg:
> +              maximum: 14

... and the SoC-specific restrictions above dropped?
The number of channels is instance-specific anyway.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds