lan78xx: Read MAC address from DT if present

There is a standard mechanism for locating and using a MAC address from
the Device Tree. Use this facility in the lan78xx driver to support
applications without programmed EEPROM or OTP. At the same time,
regularise the handling of the different address sources.

Signed-off-by: Phil Elwell <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/usb/lan78xx.c

···
 #include <linux/irqchip/chained_irq.h>
 #include <linux/microchipphy.h>
 #include <linux/phy.h>
+#include <linux/of_net.h>
 #include "lan78xx.h"
 
 #define DRIVER_AUTHOR	"WOOJUNG HUH <[e-mail]>"
···
 	addr[5] = (addr_hi >> 8) & 0xFF;
 
 	if (!is_valid_ether_addr(addr)) {
-		/* reading mac address from EEPROM or OTP */
-		if ((lan78xx_read_eeprom(dev, EEPROM_MAC_OFFSET, ETH_ALEN,
-					 addr) == 0) ||
-		    (lan78xx_read_otp(dev, EEPROM_MAC_OFFSET, ETH_ALEN,
-				      addr) == 0)) {
-			if (is_valid_ether_addr(addr)) {
-				/* eeprom values are valid so use them */
-				netif_dbg(dev, ifup, dev->net,
-					  "MAC address read from EEPROM");
-			} else {
-				/* generate random MAC */
-				random_ether_addr(addr);
-				netif_dbg(dev, ifup, dev->net,
-					  "MAC address set to random addr");
-			}
-
-			addr_lo = addr[0] | (addr[1] << 8) |
-				  (addr[2] << 16) | (addr[3] << 24);
-			addr_hi = addr[4] | (addr[5] << 8);
-
-			ret = lan78xx_write_reg(dev, RX_ADDRL, addr_lo);
-			ret = lan78xx_write_reg(dev, RX_ADDRH, addr_hi);
+		if (!eth_platform_get_mac_address(&dev->udev->dev, addr)) {
+			/* valid address present in Device Tree */
+			netif_dbg(dev, ifup, dev->net,
+				  "MAC address read from Device Tree");
+		} else if (((lan78xx_read_eeprom(dev, EEPROM_MAC_OFFSET,
+						 ETH_ALEN, addr) == 0) ||
+			    (lan78xx_read_otp(dev, EEPROM_MAC_OFFSET,
+					      ETH_ALEN, addr) == 0)) &&
+			   is_valid_ether_addr(addr)) {
+			/* eeprom values are valid so use them */
+			netif_dbg(dev, ifup, dev->net,
+				  "MAC address read from EEPROM");
 		} else {
 			/* generate random MAC */
 			random_ether_addr(addr);
 			netif_dbg(dev, ifup, dev->net,
 				  "MAC address set to random addr");
 		}
+
+		addr_lo = addr[0] | (addr[1] << 8) |
+			  (addr[2] << 16) | (addr[3] << 24);
+		addr_hi = addr[4] | (addr[5] << 8);
+
+		ret = lan78xx_write_reg(dev, RX_ADDRL, addr_lo);
+		ret = lan78xx_write_reg(dev, RX_ADDRH, addr_hi);
 	}
 
 	ret = lan78xx_write_reg(dev, MAF_LO(0), addr_lo);