[net-next 2/2] ravb: Add support for an optional MDIO mode

["Niklas Söderlund" <niklas.soderlund+renesas@ragnatech.se>]

The driver used the OF node of the device itself when registering the
MDIO bus. While this works it creates a problem, it forces any MDIO bus
properties to also be set on the devices OF node. This mixes the
properties of two distinctly different things and is confusing.

This change adds support for an optional mdio node to be defined as a
child to the device OF node. The child node can then be used to describe
MDIO bus properties that the MDIO core can act on when registering the
bus.

If no mdio child node is found the driver fallback to the old behavior
and register the MDIO bus using the device OF node. This change is
backward compatible with old bindings in use.

Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
---
 drivers/net/ethernet/renesas/ravb_main.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
index fa48ff4aba2d..b62f765ce066 100644
--- a/drivers/net/ethernet/renesas/ravb_main.c
+++ b/drivers/net/ethernet/renesas/ravb_main.c
@@ -2564,6 +2564,7 @@ static int ravb_mdio_init(struct ravb_private *priv)
 {
 	struct platform_device *pdev = priv->pdev;
 	struct device *dev = &pdev->dev;
+	struct device_node *mdio_node;
 	struct phy_device *phydev;
 	struct device_node *pn;
 	int error;
@@ -2582,8 +2583,20 @@ static int ravb_mdio_init(struct ravb_private *priv)
 	snprintf(priv->mii_bus->id, MII_BUS_ID_SIZE, "%s-%x",
 		 pdev->name, pdev->id);
 
-	/* Register MDIO bus */
-	error = of_mdiobus_register(priv->mii_bus, dev->of_node);
+	/* Register MDIO bus
+	 *
+	 * Look for a mdio child node, if it exist use it when registering the
+	 * MDIO bus. If no node is found fallback to old behavior and use the
+	 * device OF node. This is used to be able to describe MDIO bus
+	 * properties that are consumed when registering the MDIO bus.
+	 */
+	mdio_node = of_get_child_by_name(dev->of_node, "mdio");
+	if (mdio_node) {
+		error = of_mdiobus_register(priv->mii_bus, mdio_node);
+		of_node_put(mdio_node);
+	} else {
+		error = of_mdiobus_register(priv->mii_bus, dev->of_node);
+	}
 	if (error)
 		goto out_free_bus;
 
-- 
2.44.0