net: sun8i-emac: Make internal PHY handling more robust

The current implementation of sun8i_get_ephy_nodes() makes quite some
assumptions, in general relying on DT path names is a bad idea.
I think the idea of the code was to determine if we are using the
internal PHY, for which there are simpler and more robust methods:

Rewrite (and rename) the existing function to simply lookup the DT node
that "phy-handle" points to, using the device's DT node.
Then check whether the parent of that PHY node is using an "H3 internal
MDIO" compatible string. If we ever get another internal MDIO bus
implementation, we will probably need code adjustments anyway, so this
is good enough for now.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
[jagan: rebase on master]
Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Acked-by: Maxime Ripard <mripard@kernel.org>
Tested-by: Amit Singh Tomar <amittomer25@gmail.com> # Pine64+
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>

drivers/net/sun8i_emac.c

@@ -810,47 +810,30 @@ static const struct eth_ops sun8i_emac_eth_ops = {
 	.stop                   = sun8i_emac_eth_stop,
 };
 
-static int sun8i_get_ephy_nodes(struct udevice *dev, struct emac_eth_dev *priv)
+static int sun8i_handle_internal_phy(struct udevice *dev, struct emac_eth_dev *priv)
 {
-	int emac_node, ephy_node, ret, ephy_handle;
-
-	emac_node = fdt_path_offset(gd->fdt_blob,
-				    "/soc/ethernet@1c30000");
-	if (emac_node < 0) {
-		debug("failed to get emac node\n");
-		return emac_node;
-	}
-	ephy_handle = fdtdec_lookup_phandle(gd->fdt_blob,
-					    emac_node, "phy-handle");
+	struct ofnode_phandle_args phandle;
+	int ret;
 
-	/* look for mdio-mux node for internal PHY node */
-	ephy_node = fdt_path_offset(gd->fdt_blob,
-				    "/soc/ethernet@1c30000/mdio-mux/mdio@1/ethernet-phy@1");
-	if (ephy_node < 0) {
-		debug("failed to get mdio-mux with internal PHY\n");
-		return ephy_node;
-	}
+	ret = ofnode_parse_phandle_with_args(dev_ofnode(dev), "phy-handle",
+					     NULL, 0, 0, &phandle);
+	if (ret)
+		return ret;
 
-	/* This is not the phy we are looking for */
-	if (ephy_node != ephy_handle)
+	/* If the PHY node is not a child of the internal MDIO bus, we are
+	 * using some external PHY.
+	 */
+	if (!ofnode_device_is_compatible(ofnode_get_parent(phandle.node),
+					 "allwinner,sun8i-h3-mdio-internal"))
 		return 0;
 
-	ret = fdt_node_check_compatible(gd->fdt_blob, ephy_node,
-					"allwinner,sun8i-h3-mdio-internal");
-	if (ret < 0) {
-		debug("failed to find mdio-internal node\n");
-		return ret;
-	}
-
-	ret = clk_get_by_index_nodev(offset_to_ofnode(ephy_node), 0,
-				     &priv->ephy_clk);
+	ret = clk_get_by_index_nodev(phandle.node, 0, &priv->ephy_clk);
 	if (ret) {
 		dev_err(dev, "failed to get EPHY TX clock\n");
 		return ret;
 	}
 
-	ret = reset_get_by_index_nodev(offset_to_ofnode(ephy_node), 0,
-				       &priv->ephy_rst);
+	ret = reset_get_by_index_nodev(phandle.node, 0, &priv->ephy_rst);
 	if (ret) {
 		dev_err(dev, "failed to get EPHY TX reset\n");
 		return ret;
@@ -942,7 +925,7 @@ static int sun8i_emac_eth_ofdata_to_platdata(struct udevice *dev)
 	}
 
 	if (priv->variant == H3_EMAC) {
-		ret = sun8i_get_ephy_nodes(dev, priv);
+		ret = sun8i_handle_internal_phy(dev, priv);
 		if (ret)
 			return ret;
 	}