dt-bindings: serial: Convert NXP lpuart to json-schema

* Freescale low power universal asynchronous receiver/transmitter (lpuart)

Required properties:

- compatible :

  - "fsl,vf610-lpuart" for lpuart compatible with the one integrated

    on Vybrid vf610 SoC with 8-bit register organization

  - "fsl,ls1021a-lpuart" for lpuart compatible with the one integrated

    on LS1021A SoC with 32-bit big-endian register organization

  - "fsl,ls1028a-lpuart" for lpuart compatible with the one integrated

    on LS1028A SoC with 32-bit little-endian register organization

  - "fsl,imx7ulp-lpuart" for lpuart compatible with the one integrated

    on i.MX7ULP SoC with 32-bit little-endian register organization

  - "fsl,imx8qxp-lpuart" for lpuart compatible with the one integrated

    on i.MX8QXP SoC with 32-bit little-endian register organization

  - "fsl,imx8qm-lpuart" for lpuart compatible with the one integrated

    on i.MX8QM SoC with 32-bit little-endian register organization

- reg : Address and length of the register set for the device

- interrupts : Should contain uart interrupt

- clocks : phandle + clock specifier pairs, one for each entry in clock-names

- clock-names : For vf610/ls1021a/ls1028a/imx7ulp, "ipg" clock is for uart

  bus/baud clock. For imx8qxp lpuart, "ipg" clock is bus clock that is used

  to access lpuart controller registers, it also requires "baud" clock for

  module to receive/transmit data.

Optional properties:

- dmas: A list of two dma specifiers, one for each entry in dma-names.

- dma-names: should contain "tx" and "rx".

- rs485-rts-active-low, linux,rs485-enabled-at-boot-time: see rs485.txt

Note: Optional properties for DMA support. Write them both or both not.

Example:

uart0: serial@40027000 {

		compatible = "fsl,vf610-lpuart";

		reg = <0x40027000 0x1000>;

		interrupts = <0 61 0x00>;

		clocks = <&clks VF610_CLK_UART0>;

		clock-names = "ipg";

		dmas = <&edma0 0 2>,

			<&edma0 0 3>;

		dma-names = "rx","tx";

	};

# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)

%YAML 1.2

---

$id: http://devicetree.org/schemas/serial/fsl-lpuart.yaml#

$schema: http://devicetree.org/meta-schemas/core.yaml#

title: Freescale low power universal asynchronous receiver/transmitter (lpuart)

maintainers:

  - Fugang Duan <fugang.duan@nxp.com>

allOf:

  - $ref: "rs485.yaml"

properties:

  compatible:

    enum:

      - fsl,vf610-lpuart

      - fsl,ls1021a-lpuart

      - fsl,ls1028a-lpuart

      - fsl,imx7ulp-lpuart

      - fsl,imx8qxp-lpuart

      - fsl,imx8qm-lpuart

  reg:

    maxItems: 1

  interrupts:

    maxItems: 1

  clocks:

    items:

      - description: ipg clock

      - description: baud clock

    minItems: 1

    maxItems: 2

  clock-names:

    items:

      - const: ipg

      - const: baud

    minItems: 1

    maxItems: 2

  dmas:

    items:

      - description: DMA controller phandle and request line for RX

      - description: DMA controller phandle and request line for TX

  dma-names:

    items:

      - const: rx

      - const: tx

  rs485-rts-active-low: true

  linux,rs485-enabled-at-boot-time: true

required:

  - compatible

  - reg

  - interrupts

  - clocks

  - clock-names

unevaluatedProperties: false

examples:

  - |

    #include <dt-bindings/clock/vf610-clock.h>

    serial@40027000 {

        compatible = "fsl,vf610-lpuart";

        reg = <0x40027000 0x1000>;

        interrupts = <0 61 0x00>;

        clocks = <&clks VF610_CLK_UART0>;

        clock-names = "ipg";

        dmas = <&edma0 0 2>, <&edma0 0 3>;

        dma-names = "rx","tx";

    };