net: dsa: sja1105: Add support for configuring address ageing time

If STP is active, this setting is applied on bridged ports each time an
Ethernet link is established (topology changes).

Since the setting is global to the switch and a reset is required to
change it, resets are prevented if the new callback does not change the
value that the hardware already is programmed for.
Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/dsa/sja1105/sja1105.h

@@ -12,6 +12,10 @@
 #define SJA1105_NUM_PORTS		5
 #define SJA1105_NUM_TC			8
 #define SJA1105ET_FDB_BIN_SIZE		4
+/* The hardware value is in multiples of 10 ms.
+ * The passed parameter is in multiples of 1 ms.
+ */
+#define SJA1105_AGEING_TIME_MS(ms)	((ms) / 10)
 
 /* Keeps the different addresses between E/T and P/Q/R/S */
 struct sja1105_regs {

drivers/net/dsa/sja1105/sja1105_main.c

@@ -193,8 +193,8 @@ static int sja1105_init_l2_lookup_params(struct sja1105_private *priv)
 {
 	struct sja1105_table *table;
 	struct sja1105_l2_lookup_params_entry default_l2_lookup_params = {
-		/* TODO Learned FDB entries are never forgotten */
-		.maxage = 0,
+		/* Learned FDB entries are forgotten after 300 seconds */
+		.maxage = SJA1105_AGEING_TIME_MS(300000),
 		/* All entries within a FDB bin are available for learning */
 		.dyn_tbsz = SJA1105ET_FDB_BIN_SIZE,
 		/* 2^8 + 2^5 + 2^3 + 2^2 + 2^1 + 1 in Koopman notation */
@@ -1249,10 +1249,35 @@ static int sja1105_setup(struct dsa_switch *ds)
 	return 0;
 }
 
+/* The MAXAGE setting belongs to the L2 Forwarding Parameters table,
+ * which cannot be reconfigured at runtime. So a switch reset is required.
+ */
+static int sja1105_set_ageing_time(struct dsa_switch *ds,
+				   unsigned int ageing_time)
+{
+	struct sja1105_l2_lookup_params_entry *l2_lookup_params;
+	struct sja1105_private *priv = ds->priv;
+	struct sja1105_table *table;
+	unsigned int maxage;
+
+	table = &priv->static_config.tables[BLK_IDX_L2_LOOKUP_PARAMS];
+	l2_lookup_params = table->entries;
+
+	maxage = SJA1105_AGEING_TIME_MS(ageing_time);
+
+	if (l2_lookup_params->maxage == maxage)
+		return 0;
+
+	l2_lookup_params->maxage = maxage;
+
+	return sja1105_static_config_reload(priv);
+}
+
 static const struct dsa_switch_ops sja1105_switch_ops = {
 	.get_tag_protocol	= sja1105_get_tag_protocol,
 	.setup			= sja1105_setup,
 	.adjust_link		= sja1105_adjust_link,
+	.set_ageing_time	= sja1105_set_ageing_time,
 	.get_strings		= sja1105_get_strings,
 	.get_ethtool_stats	= sja1105_get_ethtool_stats,
 	.get_sset_count		= sja1105_get_sset_count,