linux-kernel - Re: [PATCH v5 1/3] dt-bindings: pwm: Add binding for Allwinner D1/T113-S3/R329 PWM controller

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Date:   Wed, 23 Aug 2023 09:57:07 +0300
From:   Александр Шубин 
        <privatesub2@...il.com>
To:     Andre Przywara <andre.przywara@....com>
Cc:     linux-kernel@...r.kernel.org,
        Thierry Reding <thierry.reding@...il.com>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>, Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Chen-Yu Tsai <wens@...e.org>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        Samuel Holland <samuel@...lland.org>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Cristian Ciocaltea <cristian.ciocaltea@...labora.com>,
        linux-pwm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-sunxi@...ts.linux.dev,
        linux-riscv@...ts.infradead.org
Subject: Re: [PATCH v5 1/3] dt-bindings: pwm: Add binding for Allwinner
 D1/T113-S3/R329 PWM controller

Hi Andre,

вт, 22 авг. 2023 г. в 12:49, Andre Przywara <andre.przywara@....com>:
>
> On Mon, 14 Aug 2023 16:32:16 +0300
> Aleksandr Shubin <privatesub2@...il.com> wrote:
>
> Hi Aleksandr,
>
> > Allwinner's D1, T113-S3 and R329 SoCs have a new pwm
> > controller witch is different from the previous pwm-sun4i.
> >
> > The D1 and T113 are identical in terms of peripherals,
> > they differ only in the architecture of the CPU core, and
> > even share the majority of their DT. Because of that,
> > using the same compatible makes sense.
> > The R329 is a different SoC though, and should have
> > a different compatible string added, especially as there
> > is a difference in the number of channels.
> >
> > D1 and T113s SoCs have one PWM controller with 8 channels.
> > R329 SoC has two PWM controllers in both power domains, one of
> > them has 9 channels (CPUX one) and the other has 6 (CPUS one).
> >
> > Add a device tree binding for them.
> >
> > Signed-off-by: Aleksandr Shubin <privatesub2@...il.com>
> > ---
> >  .../bindings/pwm/allwinner,sun20i-pwm.yaml    | 85 +++++++++++++++++++
> >  1 file changed, 85 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/pwm/allwinner,sun20i-pwm.yaml
> >
> > diff --git a/Documentation/devicetree/bindings/pwm/allwinner,sun20i-pwm.yaml b/Documentation/devicetree/bindings/pwm/allwinner,sun20i-pwm.yaml
> > new file mode 100644
> > index 000000000000..9512d4bed322
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/pwm/allwinner,sun20i-pwm.yaml
> > @@ -0,0 +1,85 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/pwm/allwinner,sun20i-pwm.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Allwinner D1, T113-S3 and R329 PWM
> > +
> > +maintainers:
> > +  - Aleksandr Shubin <privatesub2@...il.com>
> > +
> > +properties:
> > +  compatible:
> > +    oneOf:
> > +      - const: allwinner,sun20i-d1-pwm
> > +      - items:
> > +          - const: allwinner,sun20i-r329-pwm
> > +          - const: allwinner,sun20i-d1-pwm
> > +
> > +  reg:
> > +    maxItems: 1
> > +
> > +  "#pwm-cells":
> > +    const: 3
> > +
> > +  clocks:
> > +    items:
> > +      - description: 24 MHz oscillator
> > +      - description: Bus Clock
>
> The manual tells me that the new PWMs can also use APB0 as the
> input clock, which (finally!) allows PWM frequencies above 24 MHz.
> So we should have an explicit reference to that clock - even if the bus
> clock happens to be gated version of APB0.

Should I change it to something like this:
    pwm: pwm@...0c00 {
      compatible = "allwinner,sun20i-d1-pwm";
      reg = <0x02000c00 0x400>;
      clocks = <&ccu CLK_BUS_PWM>, <&dcxo>, <&ccu CLK_APB0>;
      clock-names = "bus", "hosc", "apb0";
      resets = <&ccu RST_BUS_PWM>;
      #pwm-cells = <0x3>;
    };

>
> Cheers,
> Andre
>
> > +
> > +  clock-names:
> > +    items:
> > +      - const: hosc
> > +      - const: bus
> > +
> > +  resets:
> > +    maxItems: 1
> > +
> > +  allwinner,pwm-channels:
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    description: The number of PWM channels configured for this instance
> > +    enum: [6, 9]
> > +
> > +allOf:
> > +  - $ref: pwm.yaml#
> > +
> > +  - if:
> > +      properties:
> > +        compatible:
> > +          contains:
> > +            const: allwinner,sun20i-r329-pwm
> > +
> > +    then:
> > +      required:
> > +        - allwinner,pwm-channels
> > +
> > +    else:
> > +      properties:
> > +        allwinner,pwm-channels: false
> > +
> > +unevaluatedProperties: false
> > +
> > +required:
> > +  - compatible
> > +  - reg
> > +  - "#pwm-cells"
> > +  - clocks
> > +  - clock-names
> > +  - resets
> > +
> > +examples:
> > +  - |
> > +    #include <dt-bindings/clock/sun20i-d1-ccu.h>
> > +    #include <dt-bindings/reset/sun20i-d1-ccu.h>
> > +
> > +    pwm: pwm@...0c00 {
> > +      compatible = "allwinner,sun20i-d1-pwm";
> > +      reg = <0x02000c00 0x400>;
> > +      clocks = <&dcxo>, <&ccu CLK_BUS_PWM>;
> > +      clock-names = "hosc", "bus";
> > +      resets = <&ccu RST_BUS_PWM>;
> > +      #pwm-cells = <0x3>;
> > +    };
> > +
> > +...
>

Cheers,
Aleksandr