linux-kernel - Re: [PATCH 1/5] irqchip/sifive-plic: Support T-HEAD's C910 PLIC

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Message-ID: <56489d3f1b23a90baf3ef024da09b4c8c02a2204.camel@icenowy.me>
Date:   Mon, 08 May 2023 11:14:32 +0800
From:   Icenowy Zheng <uwu@...nowy.me>
To:     Jisheng Zhang <jszhang@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Marc Zyngier <maz@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Albert Ou <aou@...s.berkeley.edu>
Cc:     linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        linux-riscv@...ts.infradead.org, Guo Ren <guoren@...nel.org>
Subject: Re: [PATCH 1/5] irqchip/sifive-plic: Support T-HEAD's C910 PLIC

在 2023-05-08星期一的 02:23 +0800，Jisheng Zhang写道：
> The T-HEAD's C910 PLIC still needs the delegation bit settingto allow
> access from S-mode, but it doesn't need the edge quirk.

No, the PLIC controller seems to be the same between C906 and C910,
which has level/edge selectable via external signal.

See openc906 and openc910 repositories, especially the documents with
it: 玄铁C9{06,10}集成手册.pdf .

In addition, such problem won't arise when the system uses only level-
triggered interrupts.

> 
> Signed-off-by: Jisheng Zhang <jszhang@...nel.org>
> ---
>  .../bindings/interrupt-controller/sifive,plic-1.0.0.yaml      | 4
> ++++
>  drivers/irqchip/irq-sifive-plic.c                             | 1 +
>  2 files changed, 5 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/interrupt-
> controller/sifive,plic-1.0.0.yaml
> b/Documentation/devicetree/bindings/interrupt-controller/sifive,plic-
> 1.0.0.yaml
> index f75736a061af..64b43a3c3748 100644
> --- a/Documentation/devicetree/bindings/interrupt-
> controller/sifive,plic-1.0.0.yaml
> +++ b/Documentation/devicetree/bindings/interrupt-
> controller/sifive,plic-1.0.0.yaml
> @@ -62,6 +62,10 @@ properties:
>                - starfive,jh7110-plic
>                - canaan,k210-plic
>            - const: sifive,plic-1.0.0
> +      - items:
> +          - enum:
> +              - thead,light-plic
> +          - const: thead,c910-plic
>        - items:
>            - enum:
>                - allwinner,sun20i-d1-plic
> diff --git a/drivers/irqchip/irq-sifive-plic.c b/drivers/irqchip/irq-
> sifive-plic.c
> index e1484905b7bd..71afa2a584d9 100644
> --- a/drivers/irqchip/irq-sifive-plic.c
> +++ b/drivers/irqchip/irq-sifive-plic.c
> @@ -569,6 +569,7 @@ static int __init plic_init(struct device_node
> *node,
>  }
>  
>  IRQCHIP_DECLARE(sifive_plic, "sifive,plic-1.0.0", plic_init);
> +IRQCHIP_DECLARE(thead_c910_plic, "thead,c910-plic", plic_init);
>  IRQCHIP_DECLARE(riscv_plic0, "riscv,plic0", plic_init); /* for
> legacy systems */
>  
>  static int __init plic_edge_init(struct device_node *node,