dt-bindings: watchdog: aspeed,ast2400-wdt: Convert to DT schema

Squash warnings such as:

```
arch/arm/boot/dts/aspeed/aspeed-bmc-facebook-galaxy100.dtb: /ahb/apb@1e600000/watchdog@1e785000: failed to match any schema with compatible: ['aspeed,ast2400-wdt']
```

The schema binding additionally defines the clocks property over the
prose binding to align with use of the node in the DTS files.

Signed-off-by: Andrew Jeffery <[email protected]>
Reviewed-by: Rob Herring <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Rob Herring (Arm) <[email protected]>

Author: amboar

Documentation/devicetree/bindings/watchdog/aspeed,ast2400-wdt.yaml

@@ -0,0 +1,142 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/watchdog/aspeed,ast2400-wdt.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Aspeed watchdog timer controllers
+
+maintainers:
+  - Andrew Jeffery <[email protected]>
+
+properties:
+  compatible:
+    enum:
+      - aspeed,ast2400-wdt
+      - aspeed,ast2500-wdt
+      - aspeed,ast2600-wdt
+
+  reg:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+    description: >
+      The clock used to drive the watchdog counter. From the AST2500 no source
+      other than the 1MHz clock can be selected, so the clocks property is
+      optional.
+
+  aspeed,reset-type:
+    $ref: /schemas/types.yaml#/definitions/string
+    enum:
+      - cpu
+      - soc
+      - system
+      - none
+    default: system
+    description: >
+      The watchdog can be programmed to generate one of three different types of
+      reset when a timeout occcurs.
+
+      Specifying 'cpu' will only reset the processor on a timeout event.
+
+      Specifying 'soc' will reset a configurable subset of the SoC's controllers
+      on a timeout event. Controllers critical to the SoC's operation may remain
+      untouched. The set of SoC controllers to reset may be specified via the
+      aspeed,reset-mask property if the node has the aspeed,ast2500-wdt or
+      aspeed,ast2600-wdt compatible.
+
+      Specifying 'system' will reset all controllers on a timeout event, as if
+      EXTRST had been asserted.
+
+      Specifying 'none' will cause the timeout event to have no reset effect.
+      Another watchdog engine on the chip must be used for chip reset operations.
+
+  aspeed,alt-boot:
+    $ref: /schemas/types.yaml#/definitions/flag
+    description: >
+      Direct the watchdog to configure the SoC to boot from the alternative boot
+      region if a timeout occurs.
+
+  aspeed,external-signal:
+    $ref: /schemas/types.yaml#/definitions/flag
+    description: >
+      Assert the timeout event on an external signal pin associated with the
+      watchdog controller instance. The pin must be muxed appropriately.
+
+  aspeed,ext-pulse-duration:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description: >
+      The duration, in microseconds, of the pulse emitted on the external signal
+      pin.
+
+  aspeed,ext-push-pull:
+    $ref: /schemas/types.yaml#/definitions/flag
+    description: >
+      If aspeed,external-signal is specified in the node, set the external
+      signal pin's drive type to push-pull. If aspeed,ext-push-pull is not
+      specified then the pin is configured as open-drain.
+
+  aspeed,ext-active-high:
+    $ref: /schemas/types.yaml#/definitions/flag
+    description: >
+      If both aspeed,external-signal and aspeed,ext-push-pull are specified in
+      the node, set the pulse polarity to active-high. If aspeed,ext-active-high
+      is not specified then the pin is configured as active-low.
+
+  aspeed,reset-mask:
+    $ref: /schemas/types.yaml#/definitions/uint32-array
+    minItems: 1
+    maxItems: 2
+    description: >
+      A bitmask indicating which peripherals will be reset if the watchdog
+      timer expires. On AST2500 SoCs this should be a single word defined using
+      the AST2500_WDT_RESET_* macros; on AST2600 SoCs this should be a two-word
+      array with the first word defined using the AST2600_WDT_RESET1_* macros,
+      and the second word defined using the AST2600_WDT_RESET2_* macros.
+
+required:
+  - compatible
+  - reg
+
+allOf:
+  - if:
+      anyOf:
+        - required:
+            - aspeed,ext-push-pull
+        - required:
+            - aspeed,ext-active-high
+        - required:
+            - aspeed,reset-mask
+    then:
+      properties:
+        compatible:
+          enum:
+            - aspeed,ast2500-wdt
+            - aspeed,ast2600-wdt
+  - if:
+      required:
+        - aspeed,ext-active-high
+    then:
+      required:
+        - aspeed,ext-push-pull
+
+additionalProperties: false
+
+examples:
+  - |
+    watchdog@1e785000 {
+        compatible = "aspeed,ast2400-wdt";
+        reg = <0x1e785000 0x1c>;
+        aspeed,reset-type = "system";
+        aspeed,external-signal;
+    };
+  - |
+    #include <dt-bindings/watchdog/aspeed-wdt.h>
+    watchdog@1e785040 {
+        compatible = "aspeed,ast2600-wdt";
+        reg = <0x1e785040 0x40>;
+        aspeed,reset-type = "soc";
+        aspeed,reset-mask = <AST2600_WDT_RESET1_DEFAULT
+                            (AST2600_WDT_RESET2_DEFAULT & ~AST2600_WDT_RESET2_LPC)>;
+    };