net: Add sysfs file for port number

Add a sysfs file to enable user space to query the device
port number used by a netdevice instance. This is needed for
devices that have multiple ports on the same PCI function.
Signed-off-by: NAmir Vadai <amirv@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/linux/netdevice.h

@@ -1279,6 +1279,10 @@ struct net_device {
 						 * that share the same link
 						 * layer address
 						 */
+	unsigned short          dev_port;	/* Used to differentiate
+						 * devices that share the same
+						 * function
+						 */
 	spinlock_t		addr_list_lock;
 	struct netdev_hw_addr_list	uc;	/* Unicast mac addresses */
 	struct netdev_hw_addr_list	mc;	/* Multicast mac addresses */

net/core/net-sysfs.c

@@ -104,6 +104,7 @@ static ssize_t netdev_store(struct device *dev, struct device_attribute *attr,
 }
 
 NETDEVICE_SHOW_RO(dev_id, fmt_hex);
+NETDEVICE_SHOW_RO(dev_port, fmt_dec);
 NETDEVICE_SHOW_RO(addr_assign_type, fmt_dec);
 NETDEVICE_SHOW_RO(addr_len, fmt_dec);
 NETDEVICE_SHOW_RO(iflink, fmt_dec);
@@ -373,6 +374,7 @@ static struct attribute *net_class_attrs[] = {
 	&dev_attr_netdev_group.attr,
 	&dev_attr_type.attr,
 	&dev_attr_dev_id.attr,
+	&dev_attr_dev_port.attr,
 	&dev_attr_iflink.attr,
 	&dev_attr_ifindex.attr,
 	&dev_attr_addr_assign_type.attr,