dt-bindings: serial: Convert rs485 bindings to json-schema

* RS485 serial communications

The RTS signal is capable of automatically controlling line direction for

the built-in half-duplex mode.

The properties described hereafter shall be given to a half-duplex capable

UART node.

Optional properties:

- rs485-rts-delay: prop-encoded-array <a b> where:

  * a is the delay between rts signal and beginning of data sent in milliseconds.

      it corresponds to the delay before sending data.

  * b is the delay between end of data sent and rts signal in milliseconds

      it corresponds to the delay after sending data and actual release of the line.

  If this property is not specified, <0 0> is assumed.

- rs485-rts-active-low: drive RTS low when sending (default is high).

- linux,rs485-enabled-at-boot-time: empty property telling to enable the rs485

  feature at boot time. It can be disabled later with proper ioctl.

- rs485-rx-during-tx: empty property that enables the receiving of data even

  while sending data.

RS485 example for Atmel USART:

	usart0: serial@fff8c000 {

		compatible = "atmel,at91sam9260-usart";

		reg = <0xfff8c000 0x4000>;

		interrupts = <7>;

		atmel,use-dma-rx;

		atmel,use-dma-tx;

		linux,rs485-enabled-at-boot-time;

		rs485-rts-delay = <0 200>;		// in milliseconds

	};

See rs485.yaml

# SPDX-License-Identifier: GPL-2.0

%YAML 1.2

---

$id: http://devicetree.org/schemas/serial/rs485.yaml#

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

title: RS485 serial communications Bindings

description: The RTS signal is capable of automatically controlling

             line direction for the built-in half-duplex mode.

             The properties described hereafter shall be given to a

             half-duplex capable UART node.

maintainers:

  -  Rob Herring <robh@kernel.org>

properties:

  rs485-rts-delay:

    description: prop-encoded-array <a b>

    allOf:

      - $ref: /schemas/types.yaml#/definitions/uint32-array

      - items:

          items:

            - description:

                Delay between rts signal and beginning of data sent in milliseconds.

                It corresponds to the delay before sending data.

              default: 0

              maximum: 1000

            - description:

                Delay between end of data sent and rts signal in milliseconds.

                It corresponds to the delay after sending data and actual release of the line.

              default: 0

              maximum: 1000

  rs485-rts-active-low:

    description: drive RTS low when sending (default is high).

    $ref: /schemas/types.yaml#/definitions/flag

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

    description: enables the rs485 feature at boot time. It can be disabled later with proper ioctl.

    $ref: /schemas/types.yaml#/definitions/flag

  rs485-rx-during-tx:

   description: enables the receiving of data even while sending data.

   $ref: /schemas/types.yaml#/definitions/flag