net: dsa: ocelot: use simple HSR offload helpers

Accelerate TX packet duplication with HSR rings.

This is only possible with the NPI-based "ocelot" tagging protocol, not
with "ocelot-8021q", because the latter does not use dsa_xmit_port_mask().

This has 2 implications:
- Depending on tagging protocol, we should set (or not set) the offload
feature flags. Switching tagging protocols is done with ports down, by
design. Additional calls to dsa_port_simple_hsr_join() can be put in
the ds->ops->change_tag_protocol() path, as I had originally tried,
but this would not work: dsa_user_setup_tagger() would later clear
the feature flag that we just set. So the additional call to
dsa_port_simple_hsr_join() should sit in the ds->ops->port_enable()
call.

- When joining a HSR ring and we are currently using "ocelot-8021q",
there are cases when we should return -EOPNOTSUPP (pessimistic) and
cases when we shouldn't (optimistic). In the pessimistic case, it is a
configuration that the port won't support even with the right tagging
protocol. Distinguishing between these 2 cases matters because if we
just return -EOPNOTSUPP regardless, we lose the dp->hsr_dev pointer
and can no longer replay the offload later for the optimistic case,
from felix_port_enable().

Signed-off-by: Vladimir Oltean <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

drivers/net/dsa/ocelot/felix.c

···
 {
 	struct dsa_port *dp = dsa_to_port(ds, port);
 	struct ocelot *ocelot = ds->priv;
+	struct felix *felix = ocelot_to_felix(ocelot);
 
 	if (!dsa_port_is_user(dp))
 		return 0;
···
 		}
 	}
 
-	return 0;
+	if (!dp->hsr_dev || felix->tag_proto == DSA_TAG_PROTO_OCELOT_8021Q)
+		return 0;
+
+	return dsa_port_simple_hsr_join(ds, port, dp->hsr_dev, NULL);
+}
+
+static void felix_port_disable(struct dsa_switch *ds, int port)
+{
+	struct dsa_port *dp = dsa_to_port(ds, port);
+	struct ocelot *ocelot = ds->priv;
+	struct felix *felix = ocelot_to_felix(ocelot);
+
+	if (!dsa_port_is_user(dp))
+		return;
+
+	if (!dp->hsr_dev || felix->tag_proto == DSA_TAG_PROTO_OCELOT_8021Q)
+		return;
+
+	dsa_port_simple_hsr_leave(ds, port, dp->hsr_dev);
 }
 
 static void felix_port_qos_map_init(struct ocelot *ocelot, int port)
···
 	ocelot_port_get_mm_stats(ocelot, port, stats);
 }
 
+/* Depending on port type, we may be able to support the offload later (with
+ * the "ocelot"/"seville" tagging protocols), or never.
+ * If we return 0, the dp->hsr_dev reference is kept for later; if we return
+ * -EOPNOTSUPP, it is cleared (which helps to not bother
+ * dsa_port_simple_hsr_leave() with an offload that didn't pass validation).
+ */
+static int felix_port_hsr_join(struct dsa_switch *ds, int port,
+			       struct net_device *hsr,
+			       struct netlink_ext_ack *extack)
+{
+	struct ocelot *ocelot = ds->priv;
+	struct felix *felix = ocelot_to_felix(ocelot);
+
+	if (felix->tag_proto == DSA_TAG_PROTO_OCELOT_8021Q) {
+		int err;
+
+		err = dsa_port_simple_hsr_validate(ds, port, hsr, extack);
+		if (err)
+			return err;
+
+		NL_SET_ERR_MSG_MOD(extack,
+				   "Offloading not supported with \"ocelot-8021q\"");
+		return 0;
+	}
+
+	if (!(dsa_to_port(ds, port)->user->flags & IFF_UP))
+		return 0;
+
+	return dsa_port_simple_hsr_join(ds, port, hsr, extack);
+}
+
+static int felix_port_hsr_leave(struct dsa_switch *ds, int port,
+				struct net_device *hsr)
+{
+	struct ocelot *ocelot = ds->priv;
+	struct felix *felix = ocelot_to_felix(ocelot);
+
+	if (felix->tag_proto == DSA_TAG_PROTO_OCELOT_8021Q)
+		return 0;
+
+	if (!(dsa_to_port(ds, port)->user->flags & IFF_UP))
+		return 0;
+
+	return dsa_port_simple_hsr_leave(ds, port, hsr);
+}
+
 static const struct phylink_mac_ops felix_phylink_mac_ops = {
 	.mac_select_pcs		= felix_phylink_mac_select_pcs,
 	.mac_config		= felix_phylink_mac_config,
···
 	.get_ts_info			= felix_get_ts_info,
 	.phylink_get_caps		= felix_phylink_get_caps,
 	.port_enable			= felix_port_enable,
+	.port_disable			= felix_port_disable,
 	.port_fast_age			= felix_port_fast_age,
 	.port_fdb_dump			= felix_fdb_dump,
 	.port_fdb_add			= felix_fdb_add,
···
 	.port_del_dscp_prio		= felix_port_del_dscp_prio,
 	.port_set_host_flood		= felix_port_set_host_flood,
 	.port_change_conduit		= felix_port_change_conduit,
+	.port_hsr_join			= felix_port_hsr_join,
+	.port_hsr_leave			= felix_port_hsr_leave,
 };
 
 int felix_register_switch(struct device *dev, resource_size_t switch_base,