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

Convert the NXP lpuart binding to DT schema format using json-schema.
Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Link: https://lore.kernel.org/r/1597721685-9280-5-git-send-email-Anson.Huang@nxp.comSigned-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/serial/fsl-lpuart.txt

-* 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";
-	};

Documentation/devicetree/bindings/serial/fsl-lpuart.yaml

+# 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";
+    };