net: ftgmac100: add handling of mdio/phy nodes for ast2400/2500

phy-handle can't be handled well for ast2400/2500 which has an embedded
MDIO controller. Add ftgmac100_mdio_setup for ast2400/2500 and initialize
PHYs from mdio child node with of_mdiobus_register.
Signed-off-by: Ivan Mikhaylov <i.mikhaylov@yadro.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/faraday/ftgmac100.c

@@ -1631,6 +1631,7 @@ static int ftgmac100_setup_mdio(struct net_device *netdev)
 	struct ftgmac100 *priv = netdev_priv(netdev);
 	struct platform_device *pdev = to_platform_device(priv->dev);
 	struct device_node *np = pdev->dev.of_node;
+	struct device_node *mdio_np;
 	int i, err = 0;
 	u32 reg;
 
@@ -1662,12 +1663,16 @@ static int ftgmac100_setup_mdio(struct net_device *netdev)
 	for (i = 0; i < PHY_MAX_ADDR; i++)
 		priv->mii_bus->irq[i] = PHY_POLL;
 
-	err = mdiobus_register(priv->mii_bus);
+	mdio_np = of_get_child_by_name(np, "mdio");
+
+	err = of_mdiobus_register(priv->mii_bus, mdio_np);
 	if (err) {
 		dev_err(priv->dev, "Cannot register MDIO bus!\n");
 		goto err_register_mdiobus;
 	}
 
+	of_node_put(mdio_np);
+
 	return 0;
 
 err_register_mdiobus:
@@ -1835,11 +1840,22 @@ static int ftgmac100_probe(struct platform_device *pdev)
 	} else if (np && of_get_property(np, "phy-handle", NULL)) {
 		struct phy_device *phy;
 
+		/* Support "mdio"/"phy" child nodes for ast2400/2500 with
+		 * an embedded MDIO controller. Automatically scan the DTS for
+		 * available PHYs and register them.
+		 */
+		if (of_device_is_compatible(np, "aspeed,ast2400-mac") ||
+		    of_device_is_compatible(np, "aspeed,ast2500-mac")) {
+			err = ftgmac100_setup_mdio(netdev);
+			if (err)
+				goto err_setup_mdio;
+		}
+
 		phy = of_phy_get_and_connect(priv->netdev, np,
 					     &ftgmac100_adjust_link);
 		if (!phy) {
 			dev_err(&pdev->dev, "Failed to connect to phy\n");
-			goto err_setup_mdio;
+			goto err_phy_connect;
 		}
 
 		/* Indicate that we support PAUSE frames (see comment in