qeth: bridgeport support - address notifications

Introduce functions to enable and disable bridgeport address
notification feature, sysfs attributes for access to these
functions from userspace, and udev events emitted when a host
joins or exits a bridgeport-enabled HiperSocket channel.

Signed-off-by: Eugene Crosser <eugene.crosser@ru.ibm.com>
Signed-off-by: Frank Blaschka <frank.blaschka@de.ibm.com>
Reviewed-by: Ursula Braun <ursula.braun@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/s390/qeth.txt

@@ -19,3 +19,32 @@ BRIDGEPORT=statechange -  indicates that the Bridge Port device changed
 ROLE={primary|secondary|none} - the role assigned to the port.
 
 STATE={active|standby|inactive} - the newly assumed state of the port.
+
+When run on HiperSockets Bridge Capable Port hardware with host address
+notifications enabled, a udev event with ACTION=CHANGE is emitted.
+It is emitted on behalf of the corresponding ccwgroup device when a host
+or a VLAN is registered or unregistered on the network served by the device.
+The event has the following attributes:
+
+BRIDGEDHOST={reset|register|deregister|abort} - host address
+  notifications are started afresh, a new host or VLAN is registered or
+  deregistered on the Bridge Port HiperSockets channel, or address
+  notifications are aborted.
+
+VLAN=numeric-vlan-id - VLAN ID on which the event occurred. Not included
+  if no VLAN is involved in the event.
+
+MAC=xx:xx:xx:xx:xx:xx - MAC address of the host that is being registered
+  or deregistered from the HiperSockets channel. Not reported if the
+  event reports the creation or destruction of a VLAN.
+
+NTOK_BUSID=x.y.zzzz - device bus ID (CSSID, SSID and device number).
+
+NTOK_IID=xx - device IID.
+
+NTOK_CHPID=xx - device CHPID.
+
+NTOK_CHID=xxxx - device channel ID.
+
+Note that the NTOK_* attributes refer to devices other than  the one
+connected to the system on which the OS is running.