net: dsa: Add helper to resolve bridge port from DSA port

In order for a driver to be able to query a bridge for information
about itself, e.g. reading out port flags, it has to use a netdev that
is known to the bridge. In the simple case, that is just the netdev
representing the port, e.g. swp0 or swp1 in this example:

   br0
   / \
swp0 swp1

But in the case of an offloaded lag, this will be the bond or team
interface, e.g. bond0 in this example:

     br0
     /
  bond0
   / \
swp0 swp1

Add a helper that hides some of this complexity from the
drivers. Then, redefine dsa_port_offloads_bridge_port using the helper
to avoid double accounting of the set of possible offloaded uppers.

Signed-off-by: Tobias Waldekranz <tobias@waldekranz.com>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 14 insertions, 0 deletions

diff --git a/include/net/dsa.h b/include/net/dsa.h
index dac303edd33d..57b2c49f72f4 100644
--- a/include/net/dsa.h
+++ b/include/net/dsa.h
@@ -493,6 +493,20 @@ static inline bool dsa_port_is_vlan_filtering(const struct dsa_port *dp)
 		return dp->vlan_filtering;
 }
 
+static inline
+struct net_device *dsa_port_to_bridge_port(const struct dsa_port *dp)
+{
+	if (!dp->bridge_dev)
+		return NULL;
+
+	if (dp->lag_dev)
+		return dp->lag_dev;
+	else if (dp->hsr_dev)
+		return dp->hsr_dev;
+
+	return dp->slave;
+}
+
 typedef int dsa_fdb_dump_cb_t(const unsigned char *addr, u16 vid,
 			      bool is_static, void *data);
 struct dsa_switch_ops {