staging: dpaa2-switch: properly setup switching domains

staging: dpaa2-switch: properly setup switching domains

Until now, the DPAA2 switch was not capable to properly setup its
switching domains depending on the existence, or lack thereof, of a
upper bridge device. This meant that all switch ports of a DPSW object
were switching by default even though they were not under the same
bridge device.

Another issue was the inability to actually add the CPU in the flooding
domains (broadcast, unknown unicast etc) of a particular switch port.
This meant that a simple ping on a switch interface was not possible
since no broadcast ARP frame would actually reach the CPU queues.

This patch tries to fix exactly these problems by:

* Creating and managing a FDB table for each flooding domain. This means
  that when a switch interface is not bridged it will use its own FDB
  table. While in bridged mode all DPAA2 switch interfaces under the
  same upper will use the same FDB table, thus leverage the same FDB
  entries.

* Adding a new MC firmware command - dpsw_set_egress_flood() - through
  which the driver can setup the flooding domains as needed. For
  example, when the switch interface is standalone, thus not in a
  bridge with any other DPAA2 switch port, it will setup its broadcast
  and unknown unicast flooding domains to only include the control
  interface (the queues that reach the CPU and the driver can dequeue
  from). This flooding domain changes when the interface joins a bridge
  and is configured to include, beside the control interface, all other
  DPAA2 switch interfaces.

We impose a minimum limit of FDB tables available equal to the number of
switch interfaces so that we guarantee that, in the maximal
configuration - all interfaces are standalone, each switch port will
have a private FDB table. At the same time, we only probe DPSW objects
that have the flooding and broadcast replicators configured to be per
FDB (DPSW_*_PER_FDB). Without this, the dpaa2-switch driver would not
be able to configure multiple switching domains.

At probe time, a FDB table will be allocated for each port. At a bridge
join event, the switch port will either continue to use the current FDB
table (if it's the first dpaa2-switch port to join that bridge) or will
switch to use the FDB table associated with the port that it's already
under the bridge. If a FDB switch is necessary, the private FDB table
which was previously used will be returned to the pool of unused FDBs.

Upon a bridge leave, the switch port needs a private FDB table thus it
will search and get the first unused FDB table. This way, all the other
ports remaining under the bridge will continue to use the same FDB
table.

Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>