net: dsa: sja1105: Add support for FDB and MDB management

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 <olteanv@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 43 insertions, 0 deletions

diff --git a/drivers/net/dsa/sja1105/sja1105_dynamic_config.c b/drivers/net/dsa/sja1105/sja1105_dynamic_config.c
index d8f145488063..e73ab28bf632 100644
--- a/drivers/net/dsa/sja1105/sja1105_dynamic_config.c
+++ b/drivers/net/dsa/sja1105/sja1105_dynamic_config.c
@@ -487,3 +487,46 @@ int sja1105_dynamic_config_write(struct sja1105_private *priv,
 
 	return 0;
 }
+
+static u8 sja1105_crc8_add(u8 crc, u8 byte, u8 poly)
+{
+	int i;
+
+	for (i = 0; i < 8; i++) {
+		if ((crc ^ byte) & (1 << 7)) {
+			crc <<= 1;
+			crc ^= poly;
+		} else {
+			crc <<= 1;
+		}
+		byte <<= 1;
+	}
+	return crc;
+}
+
+/* CRC8 algorithm with non-reversed input, non-reversed output,
+ * no input xor and no output xor. Code customized for receiving
+ * the SJA1105 E/T FDB keys (vlanid, macaddr) as input. CRC polynomial
+ * is also received as argument in the Koopman notation that the switch
+ * hardware stores it in.
+ */
+u8 sja1105_fdb_hash(struct sja1105_private *priv, const u8 *addr, u16 vid)
+{
+	struct sja1105_l2_lookup_params_entry *l2_lookup_params =
+		priv->static_config.tables[BLK_IDX_L2_LOOKUP_PARAMS].entries;
+	u64 poly_koopman = l2_lookup_params->poly;
+	/* Convert polynomial from Koopman to 'normal' notation */
+	u8 poly = (u8)(1 + (poly_koopman << 1));
+	u64 vlanid = l2_lookup_params->shared_learn ? 0 : vid;
+	u64 input = (vlanid << 48) | ether_addr_to_u64(addr);
+	u8 crc = 0; /* seed */
+	int i;
+
+	/* Mask the eight bytes starting from MSB one at a time */
+	for (i = 56; i >= 0; i -= 8) {
+		u8 byte = (input & (0xffull << i)) >> i;
+
+		crc = sja1105_crc8_add(crc, byte, poly);
+	}
+	return crc;
+}