dt-bindings: gnss: add u-blox binding

Add binding for u-blox GNSS receivers.

Note that the u-blox product names encodes form factor (e.g. "neo"),
chipset (e.g. "8") and variant (e.g. "q"), but that only formfactor and
chipset is used for the compatible strings (for now).
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/gnss/u-blox.txt

+u-blox GNSS Receiver DT binding
+
+The u-blox GNSS receivers can use UART, DDC (I2C), SPI and USB interfaces.
+
+Please see Documentation/devicetree/bindings/gnss/gnss.txt for generic
+properties.
+
+Required properties:
+
+- compatible	: Must be one of
+
+			"u-blox,neo-8"
+			"u-blox,neo-m8"
+
+- vcc-supply	: Main voltage regulator
+
+Required properties (DDC):
+- reg		: DDC (I2C) slave address
+
+Required properties (SPI):
+- reg		: SPI chip select address
+
+Required properties (USB):
+- reg		: Number of the USB hub port or the USB host-controller port
+                  to which this device is attached
+
+Optional properties:
+
+- timepulse-gpios	: Time pulse GPIO
+- u-blox,extint-gpios	: GPIO connected to the "external interrupt" input pin
+- v-bckp-supply	: Backup voltage regulator
+
+Example:
+
+serial@1234 {
+	compatible = "ns16550a";
+
+	gnss {
+		compatible = "u-blox,neo-8";
+
+		v-bckp-supply = <&gnss_v_bckp_reg>;
+		vcc-supply = <&gnss_vcc_reg>;
+	};
+};

Documentation/devicetree/bindings/vendor-prefixes.txt

@@ -384,6 +384,7 @@ tronsmart	Tronsmart
 truly	Truly Semiconductors Limited
 tsd	Theobroma Systems Design und Consulting GmbH
 tyan	Tyan Computer Corporation
+u-blox	u-blox
 ucrobotics	uCRobotics
 ubnt	Ubiquiti Networks
 udoo	Udoo