net-sysfs: expose physical switch id for particular device

Signed-off-by: Jiri Pirko <jiri@resnulli.us>
Reviewed-by: Thomas Graf <tgraf@suug.ch>
Acked-by: John Fastabend <john.r.fastabend@intel.com>
Acked-by: Andy Gospodarek <gospo@cumulusnetworks.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/Documentation/ABI/testing/sysfs-class-net b/Documentation/ABI/testing/sysfs-class-net
index e1b2e78..beb8ec4 100644
--- a/Documentation/ABI/testing/sysfs-class-net
+++ b/Documentation/ABI/testing/sysfs-class-net
@@ -216,3 +216,11 @@
 Description:
 		Indicates the interface protocol type as a decimal value. See
 		include/uapi/linux/if_arp.h for all possible values.
+
+What:		/sys/class/net/<iface>/phys_switch_id
+Date:		November 2014
+KernelVersion:	3.19
+Contact:	netdev@vger.kernel.org
+Description:
+		Indicates the unique physical switch identifier of a switch this
+		port belongs to, as a string.