net: mvmdio: check the MII_ADDR_C45 bit is not set for smi operations

Add a check for the read and write smi operations, to ensure the
MII_ADDR_C45 bit isn't set. This will be needed as soon as the xSMI
support is added to the mvmdio driver.

Signed-off-by: Antoine Tenart <antoine.tenart@free-electrons.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/marvell/mvmdio.c

@@ -126,6 +126,9 @@ static int orion_mdio_read(struct mii_bus *bus, int mii_id,
 	u32 val;
 	int ret;
 
+	if (regnum & MII_ADDR_C45)
+		return -EOPNOTSUPP;
+
 	ret = orion_mdio_wait_ready(&orion_mdio_smi_ops, bus);
 	if (ret < 0)
 		goto out;
@@ -157,6 +160,9 @@ static int orion_mdio_write(struct mii_bus *bus, int mii_id,
 	struct orion_mdio_dev *dev = bus->priv;
 	int ret;
 
+	if (regnum & MII_ADDR_C45)
+		return -EOPNOTSUPP;
+
 	ret = orion_mdio_wait_ready(&orion_mdio_smi_ops, bus);
 	if (ret < 0)
 		goto out;