linux-kernel - Re: [PATCH v4 1/2] dt-bindings: timer: thead,c900-aclint-mtimer: separate mtime and mtimecmp regs

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Message-ID: <PN3P287MB03244245A89689589995099FFEBBA@PN3P287MB0324.INDP287.PROD.OUTLOOK.COM>
Date:   Tue, 21 Nov 2023 13:22:24 +0800
From:   Chen Wang <unicorn_wang@...look.com>
To:     Inochi Amaoto <inochiama@...look.com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>
Cc:     Anup Patel <anup@...infault.org>,
        Samuel Holland <samuel.holland@...ive.com>,
        Guo Ren <guoren@...nel.org>,
        Jisheng Zhang <jszhang@...nel.org>,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        linux-riscv@...ts.infradead.org
Subject: Re: [PATCH v4 1/2] dt-bindings: timer: thead,c900-aclint-mtimer:
 separate mtime and mtimecmp regs


On 2023/11/18 15:10, Inochi Amaoto wrote:
> The timer registers of aclint don't follow the clint layout and can
> be mapped on any different offset. As sg2042 uses separated timer
> and mswi for its clint, it should follow the aclint spec and have
> separated registers.
>
> The previous patch introduced a new type of T-HEAD aclint timer which
> has clint timer layout. Although it has the clint timer layout, it
> should follow the aclint spec and uses the separated mtime and mtimecmp
> regs. So a ABI change is needed to make the timer fit the aclint spec.
>
> To make T-HEAD aclint timer more closer to the aclint spec, use
> regs-names to represent the mtimecmp register, which can avoid hack
> for unsupport mtime register of T-HEAD aclint timer.
>
> Signed-off-by: Inochi Amaoto <inochiama@...look.com>
> Fixes: 4734449f7311 ("dt-bindings: timer: Add Sophgo sg2042 CLINT timer")
> Link: https://lists.infradead.org/pipermail/opensbi/2023-October/005693.html
> Link: https://github.com/riscv/riscv-aclint/blob/main/riscv-aclint.adoc
> ---
>   .../timer/thead,c900-aclint-mtimer.yaml       | 42 ++++++++++++++++++-
>   1 file changed, 41 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/devicetree/bindings/timer/thead,c900-aclint-mtimer.yaml b/Documentation/devicetree/bindings/timer/thead,c900-aclint-mtimer.yaml
> index fbd235650e52..053488fb1286 100644
> --- a/Documentation/devicetree/bindings/timer/thead,c900-aclint-mtimer.yaml
> +++ b/Documentation/devicetree/bindings/timer/thead,c900-aclint-mtimer.yaml
> @@ -17,7 +17,20 @@ properties:
>         - const: thead,c900-aclint-mtimer
>
>     reg:
> -    maxItems: 1
> +    oneOf:
> +      - items:
> +          - description: MTIME Registers
> +          - description: MTIMECMP Registers
> +      - items:
> +          - description: MTIMECMP Registers
> +
> +  reg-names:
> +    oneOf:
> +      - items:
> +          - const: mtime
> +          - const: mtimecmp
> +      - items:
> +          - const: mtimecmp
>
>     interrupts-extended:
>       minItems: 1
> @@ -28,8 +41,34 @@ additionalProperties: false
>   required:
>     - compatible
>     - reg
> +  - reg-names
>     - interrupts-extended
>
> +allOf:
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            const: thead,c900-aclint-mtimer
> +    then:
> +      properties:
> +        reg:
> +          items:
> +            - description: MTIMECMP Registers
> +        reg-names:
> +          items:
> +            - const: mtimecmp
> +    else:
> +      properties:
> +        reg:
> +          items:
> +            - description: MTIME Registers
> +            - description: MTIMECMP Registers
> +        reg-names:
> +          items:
> +            - const: mtime
> +            - const: mtimecmp
> +
>   examples:
>     - |
>       timer@...00000 {
> @@ -39,5 +78,6 @@ examples:
>                               <&cpu3intc 7>,
>                               <&cpu4intc 7>;
>         reg = <0xac000000 0x00010000>;
> +      reg-names = "mtimecmp";
>       };
>   ...
Reviewed-by: Chen Wang <unicorn_wang@...look.com>
> --
> 2.42.1
>