net: dsa: rtl8366rb: Support fast aging

This implements fast aging per-port using the special "security"
register, which will flush any learned L2 LUT entries on a port.

The vendor API just enabled setting and clearing this bit, so
we set it to age out any entries on the port and then we clear
it again.
Suggested-by: Vladimir Oltean <olteanv@gmail.com>
Cc: Mauri Sandberg <sandberg@mailfence.com>
Cc: DENG Qingfang <dqfext@gmail.com>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Alvin Šipraga <alsi@bang-olufsen.dk>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/dsa/rtl8366rb.c

@@ -1308,6 +1308,19 @@ rtl8366rb_port_bridge_flags(struct dsa_switch *ds, int port,
 	return 0;
 }
 
+static void
+rtl8366rb_port_fast_age(struct dsa_switch *ds, int port)
+{
+	struct realtek_smi *smi = ds->priv;
+
+	/* This will age out any learned L2 entries */
+	regmap_update_bits(smi->map, RTL8366RB_SECURITY_CTRL,
+			   BIT(port), BIT(port));
+	/* Restore the normal state of things */
+	regmap_update_bits(smi->map, RTL8366RB_SECURITY_CTRL,
+			   BIT(port), 0);
+}
+
 static int rtl8366rb_change_mtu(struct dsa_switch *ds, int port, int new_mtu)
 {
 	struct realtek_smi *smi = ds->priv;
@@ -1720,6 +1733,7 @@ static const struct dsa_switch_ops rtl8366rb_switch_ops = {
 	.port_disable = rtl8366rb_port_disable,
 	.port_pre_bridge_flags = rtl8366rb_port_pre_bridge_flags,
 	.port_bridge_flags = rtl8366rb_port_bridge_flags,
+	.port_fast_age = rtl8366rb_port_fast_age,
 	.port_change_mtu = rtl8366rb_change_mtu,
 	.port_max_mtu = rtl8366rb_max_mtu,
 };