Documentation: DT: net: add docs for ralink/mediatek SoC ethernet binding

Add three files. ralink,rt2880-net.txt  descibes the actual frame engine
and the other two describe the switch forntend bindings.
Signed-off-by: John Crispin <blogic@openwrt.org>
Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Michael Lee <igvtee@gmail.com>
Cc: devicetree@vger.kernel.org
Cc: David S. Miller <davem@davemloft.net>
Cc: netdev@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: linux-mediatek@lists.infradead.org
Cc: John Crispin <blogic@openwrt.org>
Cc: Felix Fietkau <nbd@nbd.name>
Cc: Michael Lee <igvtee@gmail.com>
Cc: steven.liu@mediatek.com
Cc: Fred.Chang@mediatek.com
Patchwork: https://patchwork.linux-mips.org/patch/11970/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

Documentation/devicetree/bindings/net/mediatek,mt7620-gsw.txt

+Mediatek Gigabit Switch
+=======================
+
+The mediatek gigabit switch can be found on Mediatek SoCs (mt7620, mt7621).
+
+Required properties:
+- compatible: Should be "mediatek,mt7620-gsw" or "mediatek,mt7621-gsw"
+- reg: Address and length of the register set for the device
+- interrupt-parent: Should be the phandle for the interrupt controller
+  that services interrupts for this device
+- interrupts: Should contain the gigabit switches interrupt
+- resets: Should contain the gigabit switches resets
+- reset-names: Should contain the reset names "gsw"
+
+Example:
+
+gsw@10110000 {
+	compatible = "ralink,mt7620-gsw";
+	reg = <0x10110000 8000>;
+
+	resets = <&rstctrl 23>;
+	reset-names = "gsw";
+
+	interrupt-parent = <&intc>;
+	interrupts = <17>;
+};

Documentation/devicetree/bindings/net/ralink,rt2880-net.txt

+Ralink Frame Engine Ethernet controller
+=======================================
+
+The Ralink frame engine ethernet controller can be found on Ralink and
+Mediatek SoCs (RT288x, RT3x5x, RT366x, RT388x, rt5350, mt7620, mt7621, mt76x8).
+
+Depending on the SoC, there is a number of ports connected to the CPU port
+directly and/or via a (gigabit-)switch.
+
+* Ethernet controller node
+
+Required properties:
+- compatible: Should be one of "ralink,rt2880-eth", "ralink,rt3050-eth",
+  "ralink,rt3050-eth", "ralink,rt3883-eth", "ralink,rt5350-eth",
+  "mediatek,mt7620-eth", "mediatek,mt7621-eth"
+- reg: Address and length of the register set for the device
+- interrupt-parent: Should be the phandle for the interrupt controller
+  that services interrupts for this device
+- interrupts: Should contain the frame engines interrupt
+- resets: Should contain the frame engines resets
+- reset-names: Should contain the reset names "fe". If a switch is present
+  "esw" is also required.
+
+
+* Ethernet port node
+
+Required properties:
+- compatible: Should be "ralink,eth-port"
+- reg: The number of the physical port
+- phy-handle: reference to the node describing the phy
+
+Example:
+
+mdio-bus {
+	...
+	phy0: ethernet-phy@0 {
+		phy-mode = "mii";
+		reg = <0>;
+	};
+};
+
+ethernet@400000 {
+	compatible = "ralink,rt2880-eth";
+	reg = <0x00400000 10000>;
+
+	#address-cells = <1>;
+	#size-cells = <0>;
+
+	resets = <&rstctrl 18>;
+	reset-names = "fe";
+
+	interrupt-parent = <&cpuintc>;
+	interrupts = <5>;
+
+	port@0 {
+		compatible = "ralink,eth-port";
+		reg = <0>;
+		phy-handle = <&phy0>;
+	};
+
+};

Documentation/devicetree/bindings/net/ralink,rt3050-esw.txt

+Ralink Fast Ethernet Embedded Switch
+====================================
+
+The ralink fast ethernet embedded switch can be found on Ralink and Mediatek
+SoCs (RT3x5x, RT5350, MT76x8).
+
+Required properties:
+- compatible: Should be "ralink,rt3050-esw"
+- reg: Address and length of the register set for the device
+- interrupt-parent: Should be the phandle for the interrupt controller
+  that services interrupts for this device
+- interrupts: Should contain the embedded switches interrupt
+- resets: Should contain the embedded switches resets
+- reset-names: Should contain the reset names "esw"
+
+Optional properties:
+- ralink,portmap: can be used to choose if the default switch setup is
+  llllw or wllll
+- ralink,led_polarity: override the active high/low settings of the leds
+
+Example:
+
+esw@10110000 {
+	compatible = "ralink,rt3050-esw";
+	reg = <0x10110000 8000>;
+
+	resets = <&rstctrl 23>;
+	reset-names = "esw";
+
+	interrupt-parent = <&intc>;
+	interrupts = <17>;
+};