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

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Message-ID: <20230822104854.1fa5f1aa@donnerap.manchester.arm.com>
Date:   Tue, 22 Aug 2023 10:48:54 +0100
From:   Andre Przywara <andre.przywara@....com>
To:     Aleksandr Shubin <privatesub2@...il.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

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.

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>;
> +    };
> +
> +...