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Subject: Re: [RFC PATCH v2 06/11] dt-bindings: interrupt-controller: Add
 ACLINT MSWI and SSWI bindings
To:     Anup Patel <anup@brainfault.org>, Rob Herring <robh@kernel.org>
Cc:     Anup Patel <anup.patel@wdc.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Palmer Dabbelt <palmerdabbelt@google.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Marc Zyngier <maz@kernel.org>,
        Daniel Lezcano <daniel.lezcano@linaro.org>,
        Atish Patra <atish.patra@wdc.com>,
        Alistair Francis <Alistair.Francis@wdc.com>,
        linux-riscv <linux-riscv@lists.infradead.org>,
        "linux-kernel@vger.kernel.org List" <linux-kernel@vger.kernel.org>,
        DTML <devicetree@vger.kernel.org>, Bin Meng <bmeng.cn@gmail.com>
References: <20210618123851.1344518-1-anup.patel@wdc.com>
 <20210618123851.1344518-7-anup.patel@wdc.com>
 <20210712192207.GA2322460@robh.at.kernel.org>
 <CAAhSdy0=aL+N7fLD4+b0u3j3zj8+xYOFH_WAu3N8wFkJNxFqrg@mail.gmail.com>
From:   Sean Anderson <seanga2@gmail.com>
Message-ID: <5c00f06b-e29e-2c2f-e5e5-dff9d92fa3ff@gmail.com>
Date:   Tue, 27 Jul 2021 02:32:30 -0400
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On 7/13/21 11:27 AM, Anup Patel wrote:
> On Tue, Jul 13, 2021 at 12:52 AM Rob Herring <robh@kernel.org> wrote:
>>
>> On Fri, Jun 18, 2021 at 06:08:46PM +0530, Anup Patel wrote:
>>> We add DT bindings documentation for the ACLINT MSWI and SSWI
>>> devices found on RISC-V SOCs.
>>>
>>> Signed-off-by: Anup Patel <anup.patel@wdc.com>
>>> Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
>>> ---
>>>   .../riscv,aclint-swi.yaml                     | 82 +++++++++++++++++++
>>>   1 file changed, 82 insertions(+)
>>>   create mode 100644 Documentation/devicetree/bindings/interrupt-controller/riscv,aclint-swi.yaml
>>>
>>> diff --git a/Documentation/devicetree/bindings/interrupt-controller/riscv,aclint-swi.yaml b/Documentation/devicetree/bindings/interrupt-controller/riscv,aclint-swi.yaml
>>> new file mode 100644
>>> index 000000000000..b74025542866
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/interrupt-controller/riscv,aclint-swi.yaml
>>> @@ -0,0 +1,82 @@
>>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>>> +%YAML 1.2
>>> +---
>>> +$id: http://devicetree.org/schemas/interrupt-controller/riscv,aclint-swi.yaml#
>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>>> +
>>> +title: RISC-V ACLINT Software Interrupt Devices
>>> +
>>> +maintainers:
>>> +  - Anup Patel <anup.patel@wdc.com>
>>> +
>>> +description:
>>> +  RISC-V SOCs include an implementation of the M-level software interrupt
>>> +  (MSWI) device and the S-level software interrupt (SSWI) device defined
>>> +  in the RISC-V Advanced Core Local Interruptor (ACLINT) specification.
>>> +
>>> +  The ACLINT MSWI and SSWI devices are documented in the RISC-V ACLINT
>>> +  specification located at
>>> +  https://github.com/riscv/riscv-aclint/blob/main/riscv-aclint.adoc.
>>> +
>>> +  The ACLINT MSWI and SSWI devices directly connect to the M-level and
>>> +  S-level software interrupt lines of various HARTs (or CPUs) respectively
>>> +  so the RISC-V per-HART (or per-CPU) local interrupt controller is the
>>> +  parent interrupt controller for the ACLINT MSWI and SSWI devices.
>>> +
>>> +allOf:
>>> +  - $ref: /schemas/interrupt-controller.yaml#
>>> +
>>> +properties:
>>> +  compatible:
>>> +    items:
>>> +      - enum:
>>> +          - riscv,aclint-mswi
>>> +          - riscv,aclint-sswi
>>> +
>>> +    description:
>>> +      Should be "<vendor>,<chip>-aclint-mswi" and "riscv,aclint-mswi" OR
>>> +      "<vendor>,<chip>-aclint-sswi" and "riscv,aclint-sswi".
>>
>> The schema doesn't match the description.
>>
>> There's no actual vendor implementation yet? You could do:
>>
>> items:
>>    - {}
>>    - const: riscv,aclint-mswi
>>
>> But then your example will fail.
> 
> Is it okay to have optional vendor compatible string ?

I think you can express this with something like

properties:
   compatible:
     contains:
       enum:
         - ...

> 
> Vendors can add their specific compatible string if there is some
> special handling required. If there is not special handling required
> then the two compatible strings are enough.
> 
>>
>>> +
>>> +  reg:
>>> +    maxItems: 1
>>> +
>>> +  "#interrupt-cells":
>>> +    const: 0
>>> +
>>> +  interrupts-extended:
>>> +    minItems: 1
>>
>> You need maxItems too. I guess this based on number of cores, so just
>> pick a 'should be enough' value.
> 
> There is a limit on the maximum number of connections between the
> device and HARTs or CPUs so this will be the maxItems over here.
> 
> I will update this in the next patch revision.
> 
>>
>>> +
>>> +  interrupt-controller: true
>>> +
>>> +additionalProperties: false
>>> +
>>> +required:
>>> +  - compatible
>>> +  - reg
>>> +  - interrupts-extended
>>> +  - interrupt-controller
>>> +  - "#interrupt-cells"
>>> +
>>> +examples:
>>> +  - |
>>> +    // Example 1 (RISC-V MSWI device used by Linux RISC-V NoMMU kernel):
>>> +
>>> +    interrupt-controller@2000000 {
>>> +      compatible = "riscv,aclint-mswi";
>>> +      interrupts-extended = <&cpu1intc 3 &cpu2intc 3 &cpu3intc 3 &cpu4intc 3>;
>>
>> interrupts-extended = <&cpu1intc 3>, <&cpu2intc 3>, <&cpu3intc 3>, <&cpu4intc 3>;
> 
> Okay, will update.
> 
>>
>>> +      reg = <0x2000000 0x4000>;
>>> +      interrupt-controller;
>>> +      #interrupt-cells = <0>;
>>> +    };
>>> +
>>> +  - |
>>> +    // Example 2 (RISC-V SSWI device used by Linux RISC-V MMU kernel):
>>> +
>>> +    interrupt-controller@2100000 {
>>> +      compatible = "riscv,aclint-sswi";
>>> +      interrupts-extended = <&cpu1intc 1 &cpu2intc 1 &cpu3intc 1 &cpu4intc 1>;
>>
>> Same here.
> 
> Okay, will update here as well.
> 
>>
>>> +      reg = <0x2100000 0x4000>;
>>> +      interrupt-controller;
>>> +      #interrupt-cells = <0>;
>>> +    };
>>> +...
>>> --
>>> 2.25.1
>>>
>>>
> 
> Regards,
> Anup
> 
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