dt-bindings: auxdisplay: img-ascii-lcd: Convert to json-schema

Convert the Device Tree binding documentation for ASCII LCD displays on
Imagination Technologies boards to json-schema.

Drop bogus regmap property.
Add example.
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Link: https://lore.kernel.org/r/6e74aa466d39ddc9abe502e054d04e8cc7b76b40.1627402094.git.geert@linux-m68k.org
[robh: add type to 'offset']
Signed-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/auxdisplay/img,ascii-lcd.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/auxdisplay/img,ascii-lcd.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: ASCII LCD displays on Imagination Technologies boards
+
+maintainers:
+  - Paul Burton <paulburton@kernel.org>
+
+properties:
+  compatible:
+    enum:
+      - img,boston-lcd
+      - mti,malta-lcd
+      - mti,sead3-lcd
+
+  reg:
+    maxItems: 1
+
+  offset:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description:
+      Offset in bytes to the LCD registers within the system controller
+
+required:
+  - compatible
+
+oneOf:
+  - required:
+      - reg
+  - required:
+      - offset
+
+if:
+  properties:
+    compatible:
+      contains:
+        const: img,boston-lcd
+then:
+  required:
+    - reg
+else:
+  required:
+    - offset
+
+additionalProperties: false
+
+examples:
+  - |
+    lcd: lcd@17fff000 {
+            compatible = "img,boston-lcd";
+            reg = <0x17fff000 0x8>;
+    };

Documentation/devicetree/bindings/auxdisplay/img-ascii-lcd.txt

-Binding for ASCII LCD displays on Imagination Technologies boards
-
-Required properties:
-- compatible : should be one of:
-    "img,boston-lcd"
-    "mti,malta-lcd"
-    "mti,sead3-lcd"
-
-Required properties for "img,boston-lcd":
-- reg : memory region locating the device registers
-
-Required properties for "mti,malta-lcd" or "mti,sead3-lcd":
-- regmap: phandle of the system controller containing the LCD registers
-- offset: offset in bytes to the LCD registers within the system controller
-
-The layout of the registers & properties of the display are determined
-from the compatible string, making this binding somewhat trivial.

MAINTAINERS

@@ -9040,7 +9040,7 @@ F:	drivers/usb/atm/ueagle-atm.c
 IMGTEC ASCII LCD DRIVER
 M:	Paul Burton <paulburton@kernel.org>
 S:	Maintained
-F:	Documentation/devicetree/bindings/auxdisplay/img-ascii-lcd.txt
+F:	Documentation/devicetree/bindings/auxdisplay/img,ascii-lcd.yaml
 F:	drivers/auxdisplay/img-ascii-lcd.c
 
 IMGTEC IR DECODER DRIVER