Currently only the (more difficult) first generation E/T series is
supported. Here the TCAM is only 4-way associative, and to know where
the hardware will search for a FDB entry, we need to perform the same
hash algorithm in order to install the entry in the correct bin.

On P/Q/R/S, the TCAM should be fully associative. However the SPI
command interface is different, and because I don't have access to a
new-generation device at the moment, support for it is TODO.

Signed-off-by: Vladimir Oltean <olte...@gmail.com>
---
 drivers/net/dsa/sja1105/sja1105_main.c | 193 +++++++++++++++++++++++++
 1 file changed, 193 insertions(+)

diff --git a/drivers/net/dsa/sja1105/sja1105_main.c 
b/drivers/net/dsa/sja1105/sja1105_main.c
index 78bdb577c16b..afcca9926497 100644
--- a/drivers/net/dsa/sja1105/sja1105_main.c
+++ b/drivers/net/dsa/sja1105/sja1105_main.c
@@ -190,6 +190,9 @@ static int sja1105_init_static_fdb(struct sja1105_private 
*priv)
 
        table = &priv->static_config.tables[BLK_IDX_L2_LOOKUP];
 
+       /* We only populate the FDB table through dynamic
+        * L2 Address Lookup entries
+        */
        if (table->entry_count) {
                kfree(table->entries);
                table->entry_count = 0;
@@ -703,6 +706,190 @@ static void sja1105_adjust_link(struct dsa_switch *ds, 
int port,
                sja1105_adjust_port_config(priv, port, phydev->speed, true);
 }
 
+#define fdb(bin, index) \
+       ((bin) * SJA1105ET_FDB_BIN_SIZE + (index))
+#define is_bin_index_valid(i) \
+       ((i) >= 0 && (i) < SJA1105ET_FDB_BIN_SIZE)
+
+static int
+sja1105_is_fdb_entry_in_bin(struct sja1105_private *priv, int bin,
+                           const u8 *addr, u16 vid,
+                           struct sja1105_l2_lookup_entry *fdb_match,
+                           int *last_unused)
+{
+       int index_in_bin;
+
+       for (index_in_bin = 0; index_in_bin < SJA1105ET_FDB_BIN_SIZE;
+            index_in_bin++) {
+               struct sja1105_l2_lookup_entry l2_lookup = { 0 };
+
+               /* Skip unused entries, optionally marking them
+                * into the return value
+                */
+               if (sja1105_dynamic_config_read(priv, BLK_IDX_L2_LOOKUP,
+                                               fdb(bin, index_in_bin),
+                                               &l2_lookup)) {
+                       if (last_unused)
+                               *last_unused = index_in_bin;
+                       continue;
+               }
+
+               if (l2_lookup.macaddr == ether_addr_to_u64(addr) &&
+                   l2_lookup.vlanid == vid) {
+                       if (fdb_match)
+                               *fdb_match = l2_lookup;
+                       return index_in_bin;
+               }
+       }
+       /* Return an invalid entry index if not found */
+       return SJA1105ET_FDB_BIN_SIZE;
+}
+
+static int sja1105_fdb_add(struct dsa_switch *ds, int port,
+                          const unsigned char *addr, u16 vid)
+{
+       struct sja1105_l2_lookup_entry l2_lookup = { 0 };
+       struct sja1105_private *priv = ds->priv;
+       struct device *dev = ds->dev;
+       int bin, index_in_bin;
+       int last_unused;
+
+       bin = sja1105_fdb_hash(priv, addr, vid);
+
+       index_in_bin = sja1105_is_fdb_entry_in_bin(priv, bin, addr, vid,
+                                                  &l2_lookup, &last_unused);
+       if (is_bin_index_valid(index_in_bin)) {
+               /* We have an FDB entry. Is our port in the destination
+                * mask? If yes, we need to do nothing. If not, we need
+                * to rewrite the entry by adding this port to it.
+                */
+               if (l2_lookup.destports & BIT(port))
+                       return 0;
+               l2_lookup.destports |= BIT(port);
+       } else {
+               /* We don't have an FDB entry. We construct a new one and
+                * try to find a place for it within the FDB table.
+                */
+               l2_lookup.macaddr = ether_addr_to_u64(addr);
+               l2_lookup.destports = BIT(port);
+               l2_lookup.vlanid = vid;
+
+               if (is_bin_index_valid(last_unused)) {
+                       index_in_bin = last_unused;
+               } else {
+                       /* Bin is full, need to evict somebody.
+                        * Choose victim at random. If you get these messages
+                        * often, you may need to consider changing the
+                        * distribution function:
+                        * static_config[BLK_IDX_L2_LOOKUP_PARAMS].entries->poly
+                        */
+                       get_random_bytes(&index_in_bin, sizeof(u8));
+                       index_in_bin %= SJA1105ET_FDB_BIN_SIZE;
+                       dev_warn(dev, "Warning, FDB bin %d full while adding 
entry for %pM. Evicting entry %u.\n",
+                                bin, addr, index_in_bin);
+                       /* Evict entry */
+                       sja1105_dynamic_config_write(priv, BLK_IDX_L2_LOOKUP,
+                                                    fdb(bin, index_in_bin),
+                                                    NULL, false);
+               }
+       }
+       l2_lookup.index = fdb(bin, index_in_bin);
+
+       return sja1105_dynamic_config_write(priv, BLK_IDX_L2_LOOKUP,
+                               l2_lookup.index, &l2_lookup, true);
+}
+
+static int sja1105_fdb_del(struct dsa_switch *ds, int port,
+                          const unsigned char *addr, u16 vid)
+{
+       struct sja1105_l2_lookup_entry l2_lookup = { 0 };
+       struct sja1105_private *priv = ds->priv;
+       u8 bin, index_in_bin;
+       bool keep;
+
+       bin = sja1105_fdb_hash(priv, addr, vid);
+
+       index_in_bin = sja1105_is_fdb_entry_in_bin(priv, bin, addr, vid,
+                                                  &l2_lookup, NULL);
+       if (!is_bin_index_valid(index_in_bin))
+               return 0;
+
+       /* We have an FDB entry. Is our port in the destination mask? If yes,
+        * we need to remove it. If the resulting port mask becomes empty, we
+        * need to completely evict the FDB entry.
+        * Otherwise we just write it back.
+        */
+       if (l2_lookup.destports & BIT(port))
+               l2_lookup.destports &= ~BIT(port);
+       if (l2_lookup.destports)
+               keep = true;
+       else
+               keep = false;
+
+       return sja1105_dynamic_config_write(priv, BLK_IDX_L2_LOOKUP,
+                                           fdb(bin, index_in_bin),
+                                           &l2_lookup, keep);
+}
+
+static int sja1105_fdb_dump(struct dsa_switch *ds, int port,
+                           dsa_fdb_dump_cb_t *cb, void *data)
+{
+       struct sja1105_private *priv = ds->priv;
+       struct device *dev = ds->dev;
+       int i;
+
+       for (i = 0; i < MAX_L2_LOOKUP_COUNT; i++) {
+               struct sja1105_l2_lookup_entry l2_lookup;
+               u8 macaddr[ETH_ALEN];
+               int rc;
+
+               memset(&l2_lookup, 0, sizeof(l2_lookup));
+               rc = sja1105_dynamic_config_read(priv, BLK_IDX_L2_LOOKUP,
+                                                i, &l2_lookup);
+               /* No fdb entry at i, not an issue */
+               if (rc == -EINVAL)
+                       continue;
+               if (rc) {
+                       dev_err(dev, "Failed to dump FDB: %d\n", rc);
+                       return rc;
+               }
+
+               /* FDB dump callback is per port. This means we have to
+                * disregard a valid entry if it's not for this port, even if
+                * only to revisit it later. This is inefficient because the
+                * 1024-sized FDB table needs to be traversed 4 times through
+                * SPI during a 'bridge fdb show' command.
+                */
+               if (!(l2_lookup.destports & BIT(port)))
+                       continue;
+               u64_to_ether_addr(l2_lookup.macaddr, macaddr);
+               cb(macaddr, l2_lookup.vlanid, false, data);
+       }
+       return 0;
+}
+
+#undef fdb
+#undef is_bin_index_valid
+
+/* This callback needs to be present */
+static int sja1105_mdb_prepare(struct dsa_switch *ds, int port,
+                              const struct switchdev_obj_port_mdb *mdb)
+{
+       return 0;
+}
+
+static void sja1105_mdb_add(struct dsa_switch *ds, int port,
+                           const struct switchdev_obj_port_mdb *mdb)
+{
+       sja1105_fdb_add(ds, port, mdb->addr, mdb->vid);
+}
+
+static int sja1105_mdb_del(struct dsa_switch *ds, int port,
+                          const struct switchdev_obj_port_mdb *mdb)
+{
+       return sja1105_fdb_del(ds, port, mdb->addr, mdb->vid);
+}
+
 static int sja1105_bridge_member(struct dsa_switch *ds, int port,
                                 struct net_device *br, bool member)
 {
@@ -796,8 +983,14 @@ static const struct dsa_switch_ops sja1105_switch_ops = {
        .get_tag_protocol       = sja1105_get_tag_protocol,
        .setup                  = sja1105_setup,
        .adjust_link            = sja1105_adjust_link,
+       .port_fdb_dump          = sja1105_fdb_dump,
+       .port_fdb_add           = sja1105_fdb_add,
+       .port_fdb_del           = sja1105_fdb_del,
        .port_bridge_join       = sja1105_bridge_join,
        .port_bridge_leave      = sja1105_bridge_leave,
+       .port_mdb_prepare       = sja1105_mdb_prepare,
+       .port_mdb_add           = sja1105_mdb_add,
+       .port_mdb_del           = sja1105_mdb_del,
 };
 
 static int sja1105_probe(struct spi_device *spi)
-- 
2.17.1

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