dt-bindings: serial: Convert riscv,sifive-serial to json-schema

Convert the riscv,sifive-serial binding to DT schema using json-schema.
Signed-off-by: Pragnesh Patel <pragnesh.patel@sifive.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/1567592383-8920-1-git-send-email-pragnesh.patel@sifive.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/serial/sifive-serial.txt

-SiFive asynchronous serial interface (UART)
-
-Required properties:
-
-- compatible: should be something similar to
-	      "sifive,<chip>-uart" for the UART as integrated
-	      on a particular chip, and "sifive,uart<version>" for the
-	      general UART IP block programming model.	Supported
-	      compatible strings as of the date of this writing are:
-	      "sifive,fu540-c000-uart" for the SiFive UART v0 as
-	      integrated onto the SiFive FU540 chip, or "sifive,uart0"
-	      for the SiFive UART v0 IP block with no chip integration
-	      tweaks (if any)
-- reg: address and length of the register space
-- interrupts: Should contain the UART interrupt identifier
-- clocks: Should contain a clock identifier for the UART's parent clock
-
-
-UART HDL that corresponds to the IP block version numbers can be found
-here:
-
-https://github.com/sifive/sifive-blocks/tree/master/src/main/scala/devices/uart
-
-
-Example:
-
-uart0: serial@10010000 {
-	compatible = "sifive,fu540-c000-uart", "sifive,uart0";
-	interrupt-parent = <&plic0>;
-	interrupts = <80>;
-	reg = <0x0 0x10010000 0x0 0x1000>;
-	clocks = <&prci PRCI_CLK_TLCLK>;
-};

Documentation/devicetree/bindings/serial/sifive-serial.yaml

+# SPDX-License-Identifier: GPL-2.0
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/serial/sifive-serial.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: SiFive asynchronous serial interface (UART)
+
+maintainers:
+  - Pragnesh Patel <pragnesh.patel@sifive.com>
+  - Paul Walmsley  <paul.walmsley@sifive.com>
+  - Palmer Dabbelt <palmer@sifive.com>
+
+allOf:
+  - $ref: /schemas/serial.yaml#
+
+properties:
+  compatible:
+    items:
+      - const: sifive,fu540-c000-uart
+      - const: sifive,uart0
+
+    description:
+      Should be something similar to "sifive,<chip>-uart"
+      for the UART as integrated on a particular chip,
+      and "sifive,uart<version>" for the general UART IP
+      block programming model.
+
+      UART HDL that corresponds to the IP block version
+      numbers can be found here -
+
+      https://github.com/sifive/sifive-blocks/tree/master/src/main/scala/devices/uart
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - clocks
+
+additionalProperties: false
+
+examples:
+  - |
+      #include <dt-bindings/clock/sifive-fu540-prci.h>
+      serial@10010000 {
+        compatible = "sifive,fu540-c000-uart", "sifive,uart0";
+        interrupt-parent = <&plic0>;
+        interrupts = <80>;
+        reg = <0x0 0x10010000 0x0 0x1000>;
+        clocks = <&prci PRCI_CLK_TLCLK>;
+      };
+
+...