dt-bindings: gnss: Convert UBlox Neo-6M binding to a schema

The UBlox Neo 6M is supported by Linux thanks to its device tree
binding.

Now that we have the DT validation in place, let's convert the device
tree bindings for that driver over to a YAML schema.

Cc: Johan Hovold <johan@kernel.org>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://lore.kernel.org/r/20210901091852.479202-22-maxime@cerno.tech
Signed-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/gnss/u-blox,neo-6m.yaml

@@ -0,0 +1,62 @@
+# SPDX-License-Identifier: GPL-2.0
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/gnss/u-blox,neo-6m.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: U-blox GNSS Receiver Device Tree Bindings
+
+maintainers:
+  - Johan Hovold <johan@kernel.org>
+
+description: >
+  The U-blox GNSS receivers can use UART, DDC (I2C), SPI and USB interfaces.
+
+properties:
+  compatible:
+    enum:
+      - u-blox,neo-6m
+      - u-blox,neo-8
+      - u-blox,neo-m8
+
+  reg:
+    description: >
+      The DDC Slave Address, SPI chip select address, the number of the USB hub
+      port or the USB host-controller port to which this device is attached,
+      depending on the bus used. Required for the DDC, SPI or USB busses.
+
+  vcc-supply:
+    description: >
+      Main voltage regulator
+
+  timepulse-gpios:
+    maxItems: 1
+    description: >
+      Time pulse GPIO
+
+  u-blox,extint-gpios:
+    maxItems: 1
+    description: >
+      GPIO connected to the "external interrupt" input pin
+  
+  v-bckp-supply:
+    description: >
+      Backup voltage regulator
+
+  current-speed: true
+
+required:
+  - compatible
+  - vcc-supply
+
+additionalProperties: false
+
+examples:
+  - |
+    serial {
+        gnss {
+            compatible = "u-blox,neo-8";
+            v-bckp-supply = <&gnss_v_bckp_reg>;
+            vcc-supply = <&gnss_vcc_reg>;
+        };
+    };