dt-bindings: auxdisplay: hd44780: Convert to json-schema

Convert the Hitachi HD44780 Character LCD Controller Device Tree binding
documentation to json-schema.
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/auxdisplay/hit,hd44780.txt

-DT bindings for the Hitachi HD44780 Character LCD Controller
-
-The Hitachi HD44780 Character LCD Controller is commonly used on character LCDs
-that can display one or more lines of text. It exposes an M6800 bus interface,
-which can be used in either 4-bit or 8-bit mode.
-
-Required properties:
-  - compatible: Must contain "hit,hd44780",
-  - data-gpios: Must contain an array of either 4 or 8 GPIO specifiers,
-    referring to the GPIO pins connected to the data signal lines DB0-DB7
-    (8-bit mode) or DB4-DB7 (4-bit mode) of the LCD Controller's bus interface,
-  - enable-gpios: Must contain a GPIO specifier, referring to the GPIO pin
-    connected to the "E" (Enable) signal line of the LCD Controller's bus
-    interface,
-  - rs-gpios: Must contain a GPIO specifier, referring to the GPIO pin
-    connected to the "RS" (Register Select) signal line of the LCD Controller's
-    bus interface,
-  - display-height-chars: Height of the display, in character cells,
-  - display-width-chars: Width of the display, in character cells.
-
-Optional properties:
-  - rw-gpios: Must contain a GPIO specifier, referring to the GPIO pin
-    connected to the "RW" (Read/Write) signal line of the LCD Controller's bus
-    interface,
-  - backlight-gpios: Must contain a GPIO specifier, referring to the GPIO pin
-    used for enabling the LCD's backlight,
-  - internal-buffer-width: Internal buffer width (default is 40 for displays
-    with 1 or 2 lines, and display-width-chars for displays with more than 2
-    lines).
-
-Example:
-
-	auxdisplay {
-		compatible = "hit,hd44780";
-
-		data-gpios = <&hc595 0 GPIO_ACTIVE_HIGH>,
-			     <&hc595 1 GPIO_ACTIVE_HIGH>,
-			     <&hc595 2 GPIO_ACTIVE_HIGH>,
-			     <&hc595 3 GPIO_ACTIVE_HIGH>;
-		enable-gpios = <&hc595 4 GPIO_ACTIVE_HIGH>;
-		rs-gpios = <&hc595 5 GPIO_ACTIVE_HIGH>;
-
-		display-height-chars = <2>;
-		display-width-chars = <16>;
-	};

Documentation/devicetree/bindings/auxdisplay/hit,hd44780.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/auxdisplay/hit,hd44780.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Hitachi HD44780 Character LCD Controller
+
+maintainers:
+  - Geert Uytterhoeven <geert@linux-m68k.org>
+
+description:
+  The Hitachi HD44780 Character LCD Controller is commonly used on character
+  LCDs that can display one or more lines of text. It exposes an M6800 bus
+  interface, which can be used in either 4-bit or 8-bit mode.
+
+properties:
+  compatible:
+    const: hit,hd44780
+
+  data-gpios:
+    description:
+      GPIO pins connected to the data signal lines DB0-DB7 (8-bit mode) or
+      DB4-DB7 (4-bit mode) of the LCD Controller's bus interface.
+    oneOf:
+      - maxItems: 4
+      - maxItems: 8
+
+  enable-gpios:
+    description:
+      GPIO pin connected to the "E" (Enable) signal line of the LCD
+      Controller's bus interface.
+    maxItems: 1
+
+  rs-gpios:
+    description:
+      GPIO pin connected to the "RS" (Register Select) signal line of the LCD
+      Controller's bus interface.
+    maxItems: 1
+
+  rw-gpios:
+    description:
+      GPIO pin connected to the "RW" (Read/Write) signal line of the LCD
+      Controller's bus interface.
+    maxItems: 1
+
+  backlight-gpios:
+    description: GPIO pin used for enabling the LCD's backlight.
+    maxItems: 1
+
+  display-height-chars:
+    description: Height of the display, in character cells,
+    $ref: /schemas/types.yaml#/definitions/uint32
+    minimum: 1
+    maximum: 4
+
+  display-width-chars:
+    description: Width of the display, in character cells.
+    $ref: /schemas/types.yaml#/definitions/uint32
+    minimum: 1
+    maximum: 64
+
+  internal-buffer-width:
+    description:
+      Internal buffer width (default is 40 for displays with 1 or 2 lines, and
+      display-width-chars for displays with more than 2 lines).
+    $ref: /schemas/types.yaml#/definitions/uint32
+    minimum: 1
+    maximum: 64
+
+required:
+  - compatible
+  - data-gpios
+  - enable-gpios
+  - rs-gpios
+  - display-height-chars
+  - display-width-chars
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    auxdisplay {
+            compatible = "hit,hd44780";
+
+            data-gpios = <&hc595 0 GPIO_ACTIVE_HIGH>,
+                         <&hc595 1 GPIO_ACTIVE_HIGH>,
+                         <&hc595 2 GPIO_ACTIVE_HIGH>,
+                         <&hc595 3 GPIO_ACTIVE_HIGH>;
+            enable-gpios = <&hc595 4 GPIO_ACTIVE_HIGH>;
+            rs-gpios = <&hc595 5 GPIO_ACTIVE_HIGH>;
+
+            display-height-chars = <2>;
+            display-width-chars = <16>;
+    };