Re: [PATCH RFC v2 5/9] dt-bindings: watchdog: renesas,r9a09g057-wdt: Add SYS syscon support

Hi Prabhakar,

On Thu, 2 Jul 2026 at 14:31, Prabhakar <[email protected]> wrote:
> From: Lad Prabhakar <[email protected]>
>
> On the Renesas RZ/T2H SoC, the Watchdog Timer Control Register (WDTDCR)
> resides within the System Controller (SYS) block rather than the WDT
> address space itself.
>
> Previously, this was handled by including a second register range in the
> "reg" property. However, this is architecturally incorrect as the SYS
> block consists of two distinct regions (0x80290000 and 0x81290000) that
> contain registers for multiple peripheral blocks.
>
> Now that the SYS driver provides a unified syscon regmap, introduce the
> "renesas,sys" phandle-array property to allow the WDT driver to
> access its control register via the system controller.
>
> Mark the use of a second "reg" entry as deprecated in favor of the
> new phandle-array approach for SoCs that require WDTDCR access.
>
> Signed-off-by: Lad Prabhakar <[email protected]>
> ---
> v1->v2:
> - No change.

Thanks for the update!

> --- a/Documentation/devicetree/bindings/watchdog/renesas,r9a09g057-wdt.yaml
> +++ b/Documentation/devicetree/bindings/watchdog/renesas,r9a09g057-wdt.yaml
> @@ -48,6 +48,17 @@ properties:
>    resets:
>      maxItems: 1
>
> +  renesas,sys:

In Documentation/devicetree/bindings/pci/renesas,r9a08g045-pcie.yaml,
the similar property is called "renesas,sysc".

> +    description:
> +      System controller registers control the start/stop of the WDT, and halt debug.
> +    $ref: /schemas/types.yaml#/definitions/phandle-array
> +    items:
> +      - items:
> +          - description: phandle to system controller
> +          - description: watchdog IP instance index
> +            minimum: 0
> +            maximum: 5
> +
>    timeout-sec: true
>
>  required:
> @@ -73,15 +84,29 @@ allOf:
>            minItems: 2
>          clock-names:
>            minItems: 2
> +        renesas,sys: false
>      else:
>        properties:
>          clocks:
>            maxItems: 1
>          clock-names:
>            maxItems: 1
> -        reg:
> -          minItems: 2
>          resets: false
> +      allOf:
> +        - if:
> +            required:
> +              - renesas,sys
> +          then:
> +            properties:
> +              reg:
> +                maxItems: 1
> +          else:
> +            properties:
> +              reg:
> +                description: Deprecated. Use renesas,sys to pass the offset
> +                             of WDTDCR register instead.

the index of the watchdog IP instance?

> +                minItems: 2
> +                deprecated: true
>
>  additionalProperties: false

Gr{oetje,eeting}s,

                        Geert


--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]

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