ramips: enable SFP port for Ubiquiti ER-X-SFP

SFP cage of this device is connected via a AT8031 phy to port 5 of the switch.
This phy act as a RGMII-to-SerDes converter.

Also a I2C clock gate needs to be enabled in order to access the SFP module via I2C bus.
SFP cage also has module detect pin which is connected to I2C gpio expander.

With this patch the kernel/PHYLINK now can detect, readout and use the SFP module/port.

NOTE: SFP cage / AT8033 PHY only support 1000base-X encoding!
This means that some SGMII modules can work and only at forced 1GBit/full-duplex!

Signed-off-by: René van Dorst <opensource@vdorst.com>

target/linux/ramips/dts/mt7621_ubnt_edgerouter-x-sfp.dts

@@ -5,13 +5,71 @@
 / {
 	model = "Ubiquiti EdgeRouter X SFP";
 	compatible = "ubnt,edgerouter-x-sfp", "mediatek,mt7621-soc";
+
+	sfp_eth5: sfp_eth5 {
+		compatible = "sff,sfp";
+		i2c-bus = <&i2c>;
+		mod-def0-gpio = <&expander0 5 GPIO_ACTIVE_LOW>;
+		maximum-power-milliwatt = <1000>;
+	};
 };
 
 &i2c {
 	status = "okay";
 
-	pca9555@25 {
+	/*
+	 * PCA9655 GPIO expander
+	 *  0-POE power port eth0
+	 *  1-POE power port eth1
+	 *  2-POE power port eth2
+	 *  3-POE power port eth3
+	 *  4-POE power port eth4
+	 *  5-SFP_MOD_DEF0#
+	 *  6-
+	 *  7-
+	 *  8-Pull up to VCC
+	 *  9-Pull down to GND
+	 * 10-Pull down to GND
+	 * 11-Pull down to GND
+	 * 12-Pull down to GND
+	 * 13-Pull down to GND
+	 * 14-Pull down to GND
+	 * 15-Pull down to GND
+	 */
+	expander0: pca9555@25 {
 		compatible = "nxp,pca9555";
+		interrupt-parent = <&gpio>;
+		interrupts = <8 IRQ_TYPE_EDGE_FALLING>;
+		gpio-controller;
+		#gpio-cells = <2>;
 		reg = <0x25>;
 	};
 };
+
+&gpio {
+	sfp_i2c_clk_gate {
+		gpio-hog;
+		gpios = <7 GPIO_ACTIVE_LOW>;
+		output-high;
+	};
+};
+
+&mdio {
+	ephy7: ethernet-phy@7 {
+		reg = <7>;
+		sfp = <&sfp_eth5>;
+	};
+};
+
+&switch0 {
+	ports {
+		port@5 {
+			reg = <5>;
+			label = "eth5";
+			phy-handle = <&ephy7>;
+			phy-mode = "rgmii-rxid";
+			mtd-mac-address = <&factory 0x22>;
+			mtd-mac-address-increment = <5>;
+		};
+	};
+};

target/linux/ramips/mt7621/base-files/etc/board.d/02_network

@@ -42,10 +42,12 @@ ramips_setup_interfaces()
 	mikrotik,routerboard-750gr3)
 		ucidef_set_interfaces_lan_wan "lan2 lan3 lan4 lan5" "wan"
 		;;
-	ubnt,edgerouter-x|\
-	ubnt,edgerouter-x-sfp)
+	ubnt,edgerouter-x)
 		ucidef_set_interface_lan "eth0 eth1 eth2 eth3 eth4"
 		;;
+	ubnt,edgerouter-x-sfp)
+		ucidef_set_interface_lan "eth0 eth1 eth2 eth3 eth4 eth5"
+		;;
 	*)
 		ucidef_set_interfaces_lan_wan "lan1 lan2 lan3 lan4" "wan"
 		;;

target/linux/ramips/mt7621/config-5.4

@@ -19,6 +19,7 @@ CONFIG_ARCH_USE_QUEUED_RWLOCKS=y
 CONFIG_ARCH_USE_QUEUED_SPINLOCKS=y
 CONFIG_ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT=y
 CONFIG_ARCH_WANT_IPC_PARSE_VERSION=y
+CONFIG_AT803X_PHY=y
 CONFIG_BLK_MQ_PCI=y
 CONFIG_BOARD_SCACHE=y
 CONFIG_BOUNCE=y