net/smscx5xx: use the device tree for mac address

This takes the MAC address for smsc75xx/smsc95xx USB network devices
from a the device tree. This is required to get a usable persistent
address on the popular beagleboard, whose hardware designers
accidentally forgot that an ethernet device really requires an a
MAC address to be functional.

The Raspberry Pi also ships smsc9514 without a serial EEPROM, stores
the MAC address in ROM accessible via VC4 firmware.

The smsc75xx and smsc95xx drivers are just two copies of the
same code, so better fix both.

[lkundrak@v3.sk: updated to use of_get_property() as per suggestion from
Arnd, reworded the message and comments a bit]
Tested-by: Lubomir Rintel <lkundrak@v3.sk>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/usb/smsc75xx.c

@@ -29,6 +29,7 @@
 #include <linux/crc32.h>
 #include <linux/usb/usbnet.h>
 #include <linux/slab.h>
+#include <linux/of_net.h>
 #include "smsc75xx.h"
 
 #define SMSC_CHIPNAME			"smsc75xx"
@@ -761,6 +762,15 @@ static int smsc75xx_ioctl(struct net_device *netdev, struct ifreq *rq, int cmd)
 
 static void smsc75xx_init_mac_address(struct usbnet *dev)
 {
+	const u8 *mac_addr;
+
+	/* maybe the boot loader passed the MAC address in devicetree */
+	mac_addr = of_get_mac_address(dev->udev->dev.of_node);
+	if (mac_addr) {
+		memcpy(dev->net->dev_addr, mac_addr, ETH_ALEN);
+		return;
+	}
+
 	/* try reading mac address from EEPROM */
 	if (smsc75xx_read_eeprom(dev, EEPROM_MAC_OFFSET, ETH_ALEN,
 			dev->net->dev_addr) == 0) {
@@ -772,7 +782,7 @@ static void smsc75xx_init_mac_address(struct usbnet *dev)
 		}
 	}
 
-	/* no eeprom, or eeprom values are invalid. generate random MAC */
+	/* no useful static MAC address found. generate a random one */
 	eth_hw_addr_random(dev->net);
 	netif_dbg(dev, ifup, dev->net, "MAC address set to eth_random_addr\n");
 }

drivers/net/usb/smsc95xx.c

@@ -29,6 +29,7 @@
 #include <linux/crc32.h>
 #include <linux/usb/usbnet.h>
 #include <linux/slab.h>
+#include <linux/of_net.h>
 #include "smsc95xx.h"
 
 #define SMSC_CHIPNAME			"smsc95xx"
@@ -765,6 +766,15 @@ static int smsc95xx_ioctl(struct net_device *netdev, struct ifreq *rq, int cmd)
 
 static void smsc95xx_init_mac_address(struct usbnet *dev)
 {
+	const u8 *mac_addr;
+
+	/* maybe the boot loader passed the MAC address in devicetree */
+	mac_addr = of_get_mac_address(dev->udev->dev.of_node);
+	if (mac_addr) {
+		memcpy(dev->net->dev_addr, mac_addr, ETH_ALEN);
+		return;
+	}
+
 	/* try reading mac address from EEPROM */
 	if (smsc95xx_read_eeprom(dev, EEPROM_MAC_OFFSET, ETH_ALEN,
 			dev->net->dev_addr) == 0) {
@@ -775,7 +785,7 @@ static void smsc95xx_init_mac_address(struct usbnet *dev)
 		}
 	}
 
-	/* no eeprom, or eeprom values are invalid. generate random MAC */
+	/* no useful static MAC address found. generate a random one */
 	eth_hw_addr_random(dev->net);
 	netif_dbg(dev, ifup, dev->net, "MAC address set to eth_random_addr\n");
 }