net: add helper eth_hw_addr_crc

Several drivers use the same code as basis for filter hashes. Therefore
let's factor it out to a helper. This way drivers don't have to access
struct netdev_hw_addr internals.
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/etherdevice.h

@@ -20,6 +20,7 @@
 #include <linux/if_ether.h>
 #include <linux/netdevice.h>
 #include <linux/random.h>
+#include <linux/crc32.h>
 #include <asm/unaligned.h>
 #include <asm/bitsperlong.h>
 
@@ -265,6 +266,17 @@ static inline void eth_hw_addr_random(struct net_device *dev)
 	eth_random_addr(dev->dev_addr);
 }
 
+/**
+ * eth_hw_addr_crc - Calculate CRC from netdev_hw_addr
+ * @ha: pointer to hardware address
+ *
+ * Calculate CRC from a hardware address as basis for filter hashes.
+ */
+static inline u32 eth_hw_addr_crc(struct netdev_hw_addr *ha)
+{
+	return ether_crc(ETH_ALEN, ha->addr);
+}
+
 /**
  * ether_addr_copy - Copy an Ethernet address
  * @dst: Pointer to a six-byte array Ethernet address destination