nfp: reintroduce ndo_get_port_parent_id for representor ports

NFP does not register devlink ports for representors (without
the "devlink: expose PF and VF representors as ports" series
there are no port flavours to expose them as).

Commit c25f08ac ("nfp: remove ndo_get_port_parent_id implementation")
went to far in removing ndo_get_port_parent_id for representors.
This causes redirection offloads to fail, and switch_id attribute
missing.

Reintroduce the ndo_get_port_parent_id callback for representor ports.

Fixes: c25f08ac ("nfp: remove ndo_get_port_parent_id implementation")
Signed-off-by: NPieter Jansen van Vuuren <pieter.jansenvanvuuren@netronome.com>
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/netronome/nfp/nfp_net_repr.c

@@ -273,6 +273,7 @@ const struct net_device_ops nfp_repr_netdev_ops = {
 	.ndo_fix_features	= nfp_repr_fix_features,
 	.ndo_set_features	= nfp_port_set_features,
 	.ndo_set_mac_address    = eth_mac_addr,
+	.ndo_get_port_parent_id	= nfp_port_get_port_parent_id,
 	.ndo_get_devlink_port	= nfp_devlink_get_devlink_port,
 };
 

drivers/net/ethernet/netronome/nfp/nfp_port.c

@@ -30,6 +30,22 @@ struct nfp_port *nfp_port_from_netdev(struct net_device *netdev)
 	return NULL;
 }
 
+int nfp_port_get_port_parent_id(struct net_device *netdev,
+				struct netdev_phys_item_id *ppid)
+{
+	struct nfp_port *port;
+	const u8 *serial;
+
+	port = nfp_port_from_netdev(netdev);
+	if (!port)
+		return -EOPNOTSUPP;
+
+	ppid->id_len = nfp_cpp_serial(port->app->cpp, &serial);
+	memcpy(&ppid->id, serial, ppid->id_len);
+
+	return 0;
+}
+
 int nfp_port_setup_tc(struct net_device *netdev, enum tc_setup_type type,
 		      void *type_data)
 {