net: axienet: fix MDIO bus naming

The MDIO bus for this driver was being named using the result of
of_address_to_resource on a node which may not have any resource on it,
but the return value of that call was not checked so it was using some
random value in the bus name. Change to name the MDIO bus based on the
resource start of the actual Ethernet register block.
Signed-off-by: Robert Hancock <hancock@sedsystems.ca>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/xilinx/xilinx_axienet.h

@@ -380,6 +380,7 @@ struct axidma_bd {
  * @dev:	Pointer to device structure
  * @phy_node:	Pointer to device node structure
  * @mii_bus:	Pointer to MII bus structure
+ * @regs_start: Resource start for axienet device addresses
  * @regs:	Base address for the axienet_local device address space
  * @dma_regs:	Base address for the axidma device address space
  * @dma_err_tasklet: Tasklet structure to process Axi DMA errors
@@ -421,6 +422,7 @@ struct axienet_local {
 	struct mii_bus *mii_bus;	/* MII bus reference */
 
 	/* IO registers, dma functions and IRQs */
+	resource_size_t regs_start;
 	void __iomem *regs;
 	void __iomem *dma_regs;
 

drivers/net/ethernet/xilinx/xilinx_axienet_main.c

@@ -1480,6 +1480,7 @@ static int axienet_probe(struct platform_device *pdev)
 	lp->options = XAE_OPTION_DEFAULTS;
 	/* Map device registers */
 	ethres = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	lp->regs_start = ethres->start;
 	lp->regs = devm_ioremap_resource(&pdev->dev, ethres);
 	if (IS_ERR(lp->regs)) {
 		dev_err(&pdev->dev, "could not map Axi Ethernet regs.\n");

drivers/net/ethernet/xilinx/xilinx_axienet_mdio.c

@@ -127,7 +127,7 @@ int axienet_mdio_setup(struct axienet_local *lp, struct device_node *np)
 	int ret;
 	u32 clk_div, host_clock;
 	struct mii_bus *bus;
-	struct resource res;
+	struct device_node *mdio_node;
 	struct device_node *np1;
 
 	/* clk_div can be calculated by deriving it from the equation:
@@ -199,10 +199,9 @@ int axienet_mdio_setup(struct axienet_local *lp, struct device_node *np)
 	if (!bus)
 		return -ENOMEM;
 
-	np1 = of_get_parent(lp->phy_node);
-	of_address_to_resource(np1, 0, &res);
-	snprintf(bus->id, MII_BUS_ID_SIZE, "%.8llx",
-		 (unsigned long long) res.start);
+	mdio_node = of_get_parent(lp->phy_node);
+	snprintf(bus->id, MII_BUS_ID_SIZE, "axienet-%.8llx",
+		 (unsigned long long)lp->regs_start);
 
 	bus->priv = lp;
 	bus->name = "Xilinx Axi Ethernet MDIO";
@@ -211,7 +210,7 @@ int axienet_mdio_setup(struct axienet_local *lp, struct device_node *np)
 	bus->parent = lp->dev;
 	lp->mii_bus = bus;
 
-	ret = of_mdiobus_register(bus, np1);
+	ret = of_mdiobus_register(bus, mdio_node);
 	if (ret) {
 		mdiobus_free(bus);
 		lp->mii_bus = NULL;