Re: [PATCH v3 2/2] dt-bindings: serial: Document WK2xxx SPI UART bindings

[Conor Dooley <conor@kernel.org>]

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On Fri, Sep 04, 2026 at 06:52:43PM +0800, zjzhao wrote:
> Add a DT binding for the WK2xxx SPI to UART bridge ICs (WK2124, WK2132,
> WK2168, WK2202 and WK2204) from WKmic (Chengdu Weikai Microelectronics).
> Each UART channel is described by a serial@N child node that carries its
> own serial and RS-485 properties. Also register the wkmic vendor prefix.
> 
> Signed-off-by: zjzhao <zjzhao@edatec.cn>
> ---
>  .../bindings/serial/wkmic,wk2xxx.yaml         | 115 ++++++++++++++++++
>  .../devicetree/bindings/vendor-prefixes.yaml  |   2 +
>  2 files changed, 117 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/serial/wkmic,wk2xxx.yaml
> 
> diff --git a/Documentation/devicetree/bindings/serial/wkmic,wk2xxx.yaml b/Documentation/devicetree/bindings/serial/wkmic,wk2xxx.yaml
> new file mode 100644
> index 000000000000..c781482c0f2d
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/serial/wkmic,wk2xxx.yaml

Filename patching a compatible please.

> @@ -0,0 +1,115 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/serial/wkmic,wk2xxx.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: WKmic WK2xxx SPI to UART bridge
> +
> +maintainers:
> +  - EDATEC Technology Co., Ltd. <zjzhao@edatec.cn>

This should be your name. We want people here.

> +
> +description:
> +  The WK2xxx family (WK2124, WK2132, WK2168, WK2202 and WK2204) are SPI to
> +  UART bridge ICs from WKmic (Chengdu Weikai Microelectronics). Each IC
> +  exposes two or four full-duplex UART channels with 256-byte RX/TX FIFOs
> +  through a single SPI slave interface and one interrupt line. Each channel
> +  is described by a "serial@N" child node that carries its own serial and
> +  RS-485 properties.
> +
> +properties:
> +  compatible:
> +    enum:
> +      - wkmic,wk2124
> +      - wkmic,wk2132
> +      - wkmic,wk2168
> +      - wkmic,wk2202
> +      - wkmic,wk2204

Why are these devices not compatible with one another?
If they aren't, state why in your commit message.
pw-bot: changes-requested

> +
> +  reg:
> +    maxItems: 1
> +
> +  interrupts:
> +    description:
> +      When missing, the device driver uses polling instead.
> +    maxItems: 1
> +
> +  clock-frequency:
> +    description:
> +      Crystal or external clock frequency for the IC in Hz. The WK2xxx has
> +      no internal clock, so this must match the connected crystal.
> +    default: 11059200

I think I would drop this default and make the property required.

> +    minimum: 1
> +    maximum: 30000000

I find the 1 Hz minimum hard to believe!

> +
> +  "#address-cells":
> +    const: 1
> +
> +  "#size-cells":
> +    const: 0
> +
> +patternProperties:
> +  "^serial@[0-3]$":
> +    type: object
> +    description: A single UART channel of the chip.
> +    allOf:
> +      - $ref: /schemas/serial/serial.yaml#
> +      - $ref: /schemas/serial/rs485.yaml#
> +    properties:
> +      reg:
> +        description: UART channel number on the chip.
> +        maximum: 3
> +    required:
> +      - reg
> +    unevaluatedProperties: false
> +
> +required:
> +  - compatible
> +  - reg
> +  - "#address-cells"
> +  - "#size-cells"
> +
> +allOf:
> +  - $ref: /schemas/spi/spi-peripheral-props.yaml#
> +
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            enum:
> +              - wkmic,wk2132
> +              - wkmic,wk2202
> +    then:
> +      patternProperties:
> +        "^serial@[23]$": false
> +
> +unevaluatedProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/interrupt-controller/irq.h>
> +    spi {
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +
> +        serial@0 {
> +            compatible = "wkmic,wk2132";
> +            reg = <0>;
> +            spi-max-frequency = <10000000>;
> +            clock-frequency = <11059200>;
> +            interrupt-parent = <&gpio>;
> +            interrupts = <24 IRQ_TYPE_LEVEL_LOW>;
> +            #address-cells = <1>;
> +            #size-cells = <0>;
> +
> +            serial@0 {
> +                reg = <0>;
> +            };
> +
> +            serial@1 {
> +                reg = <1>;
> +                rs485-rts-active-low;
> +                linux,rs485-enabled-at-boot-time;
> +            };
> +        };
> +    };
> diff --git a/Documentation/devicetree/bindings/vendor-prefixes.yaml b/Documentation/devicetree/bindings/vendor-prefixes.yaml
> index ba2002969373..654fc8525559 100644
> --- a/Documentation/devicetree/bindings/vendor-prefixes.yaml
> +++ b/Documentation/devicetree/bindings/vendor-prefixes.yaml
> @@ -1907,6 +1907,8 @@ patternProperties:
>      description: Wireless Tag (qiming yunduan)
>    "^wits,.*":
>      description: Shenzhen Merrii Technology Co., Ltd. (WITS)
> +  "^wkmic,.*":
> +    description: Chengdu Weikai Microelectronics Co., Ltd.

"wkmic" doesn't come naturally to me as a non-chinese speaker from
"Chengdu Weikai Microelectronics". Usually we use stock ticker symbols,
or website URLs to form the vendor prefix. I tried lookig for one here
but could not find it. Why not use "weikai," here?

Cheers,
Conor.

>    "^wlf,.*":
>      description: Wolfson Microelectronics
>    "^wm,.*":
> -- 
> 2.43.0
>

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