VLAN filtering cannot be properly disabled in SJA1105. So in order to
emulate the "no VLAN awareness" behavior (not dropping traffic that is
tagged with a VID that isn't configured on the port), we need to hack
another switch feature: programmable TPID (which is 0x8100 for 802.1Q).
We are reprogramming the TPID to a bogus value (ETH_P_EDSA) which leaves
the switch thinking that all traffic is untagged, and therefore accepts
it.

Under a vlan_filtering bridge, the proper TPID of ETH_P_8021Q is
installed again, and the switch starts identifying 802.1Q-tagged
traffic.

Signed-off-by: Vladimir Oltean <olte...@gmail.com>
---
 drivers/net/dsa/sja1105/sja1105_main.c | 275 ++++++++++++++++++++++++-
 1 file changed, 273 insertions(+), 2 deletions(-)

diff --git a/drivers/net/dsa/sja1105/sja1105_main.c 
b/drivers/net/dsa/sja1105/sja1105_main.c
index afcca9926497..a1d7f3b03099 100644
--- a/drivers/net/dsa/sja1105/sja1105_main.c
+++ b/drivers/net/dsa/sja1105/sja1105_main.c
@@ -263,6 +263,13 @@ static int sja1105_init_static_vlan(struct sja1105_private 
*priv)
        table = &priv->static_config.tables[BLK_IDX_VLAN_LOOKUP];
 
        /* The static VLAN table will only contain the initial pvid of 0.
+        * All other VLANs are to be configured through dynamic entries,
+        * and kept in the static configuration table as backing memory.
+        * The pvid of 0 is sufficient to pass traffic while the ports are
+        * standalone and when vlan_filtering is disabled. When filtering
+        * gets enabled, the switchdev core sets up the VLAN ID 1 and sets
+        * it as the new pvid. Actually 'pvid 1' still comes up in 'bridge
+        * vlan' even when vlan_filtering is off, but it has no effect.
         */
        if (table->entry_count) {
                kfree(table->entries);
@@ -403,8 +410,11 @@ static int sja1105_init_general_params(struct 
sja1105_private *priv)
                .vlmask = 0,
                /* Only update correctionField for 1-step PTP (L2 transport) */
                .ignore2stf = 0,
-               .tpid = ETH_P_8021Q,
-               .tpid2 = ETH_P_8021Q,
+               /* Forcefully disable VLAN filtering by telling
+                * the switch that VLAN has a different EtherType.
+                */
+               .tpid = ETH_P_EDSA,
+               .tpid2 = ETH_P_EDSA,
                /* P/Q/R/S only */
                .queue_ts = 0,
                .egrmirrvid = 0,
@@ -934,12 +944,269 @@ static void sja1105_bridge_leave(struct dsa_switch *ds, 
int port,
        sja1105_bridge_member(ds, port, br, false);
 }
 
+/* For situations where we need to change a setting at runtime that is only
+ * available through the static configuration, resetting the switch in order
+ * to upload the new static config is unavoidable. Back up the settings we
+ * modify at runtime (currently only MAC) and restore them after uploading,
+ * such that this operation is relatively seamless.
+ */
+static int sja1105_static_config_reload(struct sja1105_private *priv)
+{
+       struct sja1105_mac_config_entry *mac;
+       int speed_mbps[SJA1105_NUM_PORTS];
+       int rc, i;
+
+       mac = priv->static_config.tables[BLK_IDX_MAC_CONFIG].entries;
+
+       /* Back up settings changed by sja1105_adjust_port_config and
+        * and restore their defaults.
+        */
+       for (i = 0; i < SJA1105_NUM_PORTS; i++) {
+               speed_mbps[i] = sja1105_speed[mac[i].speed];
+               mac[i].speed = SJA1105_SPEED_AUTO;
+       }
+
+       /* Reset switch and send updated static configuration */
+       rc = sja1105_static_config_upload(priv);
+       if (rc < 0)
+               goto out;
+
+       /* Configure the CGU (PLLs) for MII and RMII PHYs.
+        * For these interfaces there is no dynamic configuration
+        * needed, since PLLs have same settings at all speeds.
+        */
+       rc = sja1105_clocking_setup(priv);
+       if (rc < 0)
+               goto out;
+
+       for (i = 0; i < SJA1105_NUM_PORTS; i++) {
+               bool enabled = (speed_mbps[i] != SJA1105_SPEED_AUTO);
+
+               rc = sja1105_adjust_port_config(priv, i, speed_mbps[i],
+                                               enabled);
+               if (rc < 0)
+                       goto out;
+       }
+out:
+       return rc;
+}
+
+#define sja1105_vlan_filtering_enabled(priv) \
+       (((struct sja1105_general_params_entry *) \
+       ((struct sja1105_private *)priv)->static_config. \
+       tables[BLK_IDX_GENERAL_PARAMS].entries)->tpid == ETH_P_8021Q)
+
+/* The TPID setting belongs to the General Parameters table,
+ * which can only be partially reconfigured at runtime (and not the TPID).
+ * So a switch reset is required.
+ */
+static int sja1105_change_tpid(struct sja1105_private *priv,
+                              u16 tpid, u16 tpid2)
+{
+       struct sja1105_general_params_entry *general_params;
+       struct sja1105_table *table;
+
+       table = &priv->static_config.tables[BLK_IDX_GENERAL_PARAMS];
+       general_params = table->entries;
+       general_params->tpid = tpid;
+       general_params->tpid2 = tpid2;
+       return sja1105_static_config_reload(priv);
+}
+
+static int sja1105_pvid_apply(struct sja1105_private *priv, int port, u16 pvid)
+{
+       struct sja1105_mac_config_entry *mac;
+
+       mac = priv->static_config.tables[BLK_IDX_MAC_CONFIG].entries;
+
+       mac[port].vlanid = pvid;
+
+       return sja1105_dynamic_config_write(priv, BLK_IDX_MAC_CONFIG, port,
+                                          &mac[port], true);
+}
+
+static int sja1105_is_vlan_configured(struct sja1105_private *priv, u16 vid)
+{
+       struct sja1105_vlan_lookup_entry *vlan;
+       int count, i;
+
+       vlan = priv->static_config.tables[BLK_IDX_VLAN_LOOKUP].entries;
+       count = priv->static_config.tables[BLK_IDX_VLAN_LOOKUP].entry_count;
+
+       for (i = 0; i < count; i++)
+               if (vlan[i].vlanid == vid)
+                       return i;
+
+       /* Return an invalid entry index if not found */
+       return -1;
+}
+
+static int sja1105_vlan_apply(struct sja1105_private *priv, int port, u16 vid,
+                             bool enabled, bool untagged)
+{
+       struct sja1105_vlan_lookup_entry *vlan;
+       struct sja1105_table *table;
+       bool keep = true;
+       int match, rc;
+
+       table = &priv->static_config.tables[BLK_IDX_VLAN_LOOKUP];
+
+       match = sja1105_is_vlan_configured(priv, vid);
+       if (match < 0) {
+               /* Can't delete a missing entry. */
+               if (!enabled)
+                       return 0;
+               rc = sja1105_table_resize(table, table->entry_count + 1);
+               if (rc)
+                       return rc;
+               match = table->entry_count - 1;
+       }
+       /* Assign pointer after the resize (it's new memory) */
+       vlan = table->entries;
+       vlan[match].vlanid = vid;
+       if (enabled) {
+               vlan[match].vlan_bc |= BIT(port);
+               vlan[match].vmemb_port |= BIT(port);
+       } else {
+               vlan[match].vlan_bc &= ~BIT(port);
+               vlan[match].vmemb_port &= ~BIT(port);
+       }
+       /* Also unset tag_port if removing this VLAN was requested,
+        * just so we don't have a confusing bitmap (no practical purpose).
+        */
+       if (untagged || !enabled)
+               vlan[match].tag_port &= ~BIT(port);
+       else
+               vlan[match].tag_port |= BIT(port);
+       /* If there's no port left as member of this VLAN,
+        * it's time for it to go.
+        */
+       if (!vlan[match].vmemb_port)
+               keep = false;
+
+       dev_dbg(priv->ds->dev,
+               "%s: port %d, vid %llu, broadcast domain 0x%llx, "
+               "port members 0x%llx, tagged ports 0x%llx, keep %d\n",
+               __func__, port, vlan[match].vlanid, vlan[match].vlan_bc,
+               vlan[match].vmemb_port, vlan[match].tag_port, keep);
+
+       rc = sja1105_dynamic_config_write(priv, BLK_IDX_VLAN_LOOKUP, vid,
+                                         &vlan[match], keep);
+       if (rc < 0)
+               return rc;
+
+       if (!keep)
+               return sja1105_table_delete_entry(table, match);
+
+       return 0;
+}
+
 static enum dsa_tag_protocol
 sja1105_get_tag_protocol(struct dsa_switch *ds, int port)
 {
        return DSA_TAG_PROTO_NONE;
 }
 
+/* This callback needs to be present */
+static int sja1105_vlan_prepare(struct dsa_switch *ds, int port,
+                               const struct switchdev_obj_port_vlan *vlan)
+{
+       return 0;
+}
+
+static int sja1105_vlan_filtering(struct dsa_switch *ds, int port, bool 
enabled)
+{
+       struct sja1105_private *priv = ds->priv;
+       int rc = 0, i;
+
+       /* On SJA1105, VLAN filtering per se is always enabled in hardware.
+        * The only thing we can do to disable it is lie about what the 802.1Q
+        * EtherType is. So it will still try to apply VLAN filtering, but all
+        * ingress traffic (except frames received with EtherType of
+        * ETH_P_EDSA, which are invalid) will be internally tagged with a
+        * distorted VLAN header where the TPID is ETH_P_EDSA, and the VLAN ID
+        * is the port pvid.  So since this operation is global to the switch,
+        * we need to handle the case where multiple bridges span the same
+        * switch device and one of them has a different setting than what is
+        * being requested.
+        */
+       for (i = 0; i < SJA1105_NUM_PORTS; i++) {
+               struct net_device *bridge_dev;
+
+               bridge_dev = dsa_to_port(ds, i)->bridge_dev;
+               if (bridge_dev &&
+                   bridge_dev != dsa_to_port(ds, port)->bridge_dev &&
+                   br_vlan_enabled(bridge_dev) != enabled) {
+                       netdev_err(bridge_dev,
+                                  "VLAN filtering is global to the switch!\n");
+                       return -EINVAL;
+               }
+       }
+
+       if (enabled && !sja1105_vlan_filtering_enabled(priv))
+               /* Enable VLAN filtering.
+                * TODO read these from bridge_dev->protocol.
+                */
+               rc = sja1105_change_tpid(priv, ETH_P_8021Q, ETH_P_8021AD);
+       else if (!enabled && sja1105_vlan_filtering_enabled(priv))
+               /* Disable VLAN filtering. TODO: Install a TPID
+                * that also encodes the switch ID (aka ds->index)
+                * so that stacking switch tags will be supported.
+                */
+               rc = sja1105_change_tpid(priv, ETH_P_EDSA, ETH_P_EDSA);
+       else
+               return 0;
+       if (rc)
+               dev_err(ds->dev, "Failed to change VLAN Ethertype\n");
+
+       return rc;
+}
+
+static void sja1105_vlan_add(struct dsa_switch *ds, int port,
+                            const struct switchdev_obj_port_vlan *vlan)
+{
+       struct sja1105_private *priv = ds->priv;
+       u16 vid;
+       int rc;
+
+       for (vid = vlan->vid_begin; vid <= vlan->vid_end; vid++) {
+               rc = sja1105_vlan_apply(priv, port, vid, true, vlan->flags &
+                                       BRIDGE_VLAN_INFO_UNTAGGED);
+               if (rc < 0) {
+                       dev_err(ds->dev, "Failed to add VLAN %d to port %d: 
%d\n",
+                               vid, port, rc);
+                       return;
+               }
+               if (vlan->flags & BRIDGE_VLAN_INFO_PVID) {
+                       rc = sja1105_pvid_apply(ds->priv, port, vid);
+                       if (rc < 0) {
+                               dev_err(ds->dev, "Failed to set pvid %d on port 
%d: %d\n",
+                                       vid, port, rc);
+                               return;
+                       }
+               }
+       }
+}
+
+static int sja1105_vlan_del(struct dsa_switch *ds, int port,
+                           const struct switchdev_obj_port_vlan *vlan)
+{
+       struct sja1105_private *priv = ds->priv;
+       u16 vid;
+       int rc;
+
+       for (vid = vlan->vid_begin; vid <= vlan->vid_end; vid++) {
+               rc = sja1105_vlan_apply(priv, port, vid, false, vlan->flags &
+                                       BRIDGE_VLAN_INFO_UNTAGGED);
+               if (rc < 0) {
+                       dev_err(ds->dev, "Failed to remove VLAN %d from port 
%d: %d\n",
+                               vid, port, rc);
+                       return rc;
+               }
+       }
+       return 0;
+}
+
 /* The programming model for the SJA1105 switch is "all-at-once" via static
  * configuration tables. Some of these can be dynamically modified at runtime,
  * but not the xMII mode parameters table.
@@ -988,6 +1255,10 @@ static const struct dsa_switch_ops sja1105_switch_ops = {
        .port_fdb_del           = sja1105_fdb_del,
        .port_bridge_join       = sja1105_bridge_join,
        .port_bridge_leave      = sja1105_bridge_leave,
+       .port_vlan_prepare      = sja1105_vlan_prepare,
+       .port_vlan_filtering    = sja1105_vlan_filtering,
+       .port_vlan_add          = sja1105_vlan_add,
+       .port_vlan_del          = sja1105_vlan_del,
        .port_mdb_prepare       = sja1105_mdb_prepare,
        .port_mdb_add           = sja1105_mdb_add,
        .port_mdb_del           = sja1105_mdb_del,
-- 
2.17.1

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