net: emaclite: Support multiple phys connected to one MDIO bus

For system which contains at least two ethernet IP where
one IP manage MDIO bus with several PHYs.

Example dts node:
ethernet_mac0: ethernet@81000000 {
	compatible = "xlnx,xps-ethernetlite-1.00.a";
	device_type = "network";
	interrupt-parent = <&xps_intc_0>;
	interrupts = < 1 0 >;
		local-mac-address = [ 00 0a 35 00 db bb ];
	phy-handle = <&ethernet_mac0_phy0>;
	reg = < 0x81000000 0x10000 >;
	xlnx,duplex = <0x1>;
	xlnx,family = "spartan3e";
	xlnx,include-internal-loopback = <0x0>;
	xlnx,include-mdio = <0x1>;
	xlnx,rx-ping-pong = <0x0>;
	xlnx,tx-ping-pong = <0x0>;
	ethernet_mac0_mdio {
		#address-cells = <1>;
		#size-cells = <0>;
		ethernet_mac0_phy0: phy@1 {
			reg = <0x1>;
		} ;
		ethernet_mac0_phy1: phy@3 {
			reg = <0x3>;
		} ;
	} ;
} ;
ethernet_mac2: ethernet@81040000 {
	compatible = "xlnx,xps-ethernetlite-1.00.a";
	device_type = "network";
	interrupt-parent = <&xps_intc_0>;
	interrupts = < 11 0 >;
		local-mac-address = [ 00 0a 35 00 db bb ];
	phy-handle = <&ethernet_mac0_phy1>;
	reg = < 0x81040000 0x10000 >;
	xlnx,duplex = <0x1>;
	xlnx,family = "spartan3e";
	xlnx,include-internal-loopback = <0x0>;
	xlnx,include-mdio = <0x0>;
	xlnx,rx-ping-pong = <0x0>;
	xlnx,tx-ping-pong = <0x0>;
} ;
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/xilinx/xilinx_emaclite.c

@@ -848,6 +848,7 @@ static int xemaclite_mdio_setup(struct net_local *lp, struct device *dev)
 	int rc;
 	struct resource res;
 	struct device_node *np = of_get_parent(lp->phy_node);
+	struct device_node *npp;
 
 	/* Don't register the MDIO bus if the phy_node or its parent node
 	 * can't be found.
@@ -856,6 +857,17 @@ static int xemaclite_mdio_setup(struct net_local *lp, struct device *dev)
 		dev_err(dev, "Failed to register mdio bus.\n");
 		return -ENODEV;
 	}
+	npp = of_get_parent(np);
+
+	of_address_to_resource(npp, 0, &res);
+	if (lp->ndev->mem_start != res.start) {
+		struct phy_device *phydev;
+		phydev = of_phy_find_device(lp->phy_node);
+		if (!phydev)
+			dev_info(dev,
+				 "MDIO of the phy is not registered yet\n");
+		return 0;
+	}
 
 	/* Enable the MDIO bus by asserting the enable bit in MDIO Control
 	 * register.
@@ -869,7 +881,6 @@ static int xemaclite_mdio_setup(struct net_local *lp, struct device *dev)
 		return -ENOMEM;
 	}
 
-	of_address_to_resource(np, 0, &res);
 	snprintf(bus->id, MII_BUS_ID_SIZE, "%.8llx",
 		 (unsigned long long)res.start);
 	bus->priv = lp;