dt-bindings: watchdog: Convert DW WDT binding to DT schema

Modern device tree bindings are supposed to be created as YAML-files
in accordance with dt-schema. This commit replaces the DW Watchdog
legacy bare text bindings with YAML file. As before the binding states
that the corresponding dts node is supposed to have a registers
range, a watchdog timer references clock source, optional reset line and
pre-timeout interrupt.

Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Cc: Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: linux-mips@vger.kernel.org
Link: https://lore.kernel.org/r/20200530073557.22661-2-Sergey.Semin@baikalelectronics.ru
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

Documentation/devicetree/bindings/watchdog/dw_wdt.txt

@@ -1,24 +0,0 @@
-Synopsys Designware Watchdog Timer
-
-Required Properties:
-
-- compatible	: Should contain "snps,dw-wdt"
-- reg		: Base address and size of the watchdog timer registers.
-- clocks	: phandle + clock-specifier for the clock that drives the
-		watchdog timer.
-
-Optional Properties:
-
-- interrupts	: The interrupt used for the watchdog timeout warning.
-- resets	: phandle pointing to the system reset controller with
-		line index for the watchdog.
-
-Example:
-
-	watchdog0: wd@ffd02000 {
-		compatible = "snps,dw-wdt";
-		reg = <0xffd02000 0x1000>;
-		interrupts = <0 171 4>;
-		clocks = <&per_base_clk>;
-		resets = <&rst WDT0_RESET>;
-	};

Documentation/devicetree/bindings/watchdog/snps,dw-wdt.yaml

@@ -0,0 +1,50 @@
+# SPDX-License-Identifier: GPL-2.0-only
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/watchdog/snps,dw-wdt.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Synopsys Designware Watchdog Timer
+
+allOf:
+  - $ref: "watchdog.yaml#"
+
+maintainers:
+  - Jamie Iles <jamie@jamieiles.com>
+
+properties:
+  compatible:
+    const: snps,dw-wdt
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    description: DW Watchdog pre-timeout interrupt
+    maxItems: 1
+
+  clocks:
+    items:
+      - description: Watchdog timer reference clock
+
+  resets:
+    description: Phandle to the DW Watchdog reset lane
+    maxItems: 1
+
+unevaluatedProperties: false
+
+required:
+  - compatible
+  - reg
+  - clocks
+
+examples:
+  - |
+    watchdog@ffd02000 {
+      compatible = "snps,dw-wdt";
+      reg = <0xffd02000 0x1000>;
+      interrupts = <0 171 4>;
+      clocks = <&per_base_clk>;
+      resets = <&wdt_rst>;
+    };
+...