net: dsa: vsc73xx: add port_stp_state_set function

This isn't a fully functional implementation of 802.1D, but
port_stp_state_set is required for a future tag8021q operations.

This implementation handles properly all states, but vsc73xx doesn't
forward STP packets.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: Pawel Dembicki <paweldembicki@gmail.com>
Link: https://patch.msgid.link/20240713211620.1125910-2-paweldembicki@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/dsa/vitesse-vsc73xx-core.c

@@ -164,6 +164,10 @@
 #define VSC73XX_AGENCTRL	0xf0
 #define VSC73XX_CAPRST		0xff
 
+#define VSC73XX_SRCMASKS_CPU_COPY		BIT(27)
+#define VSC73XX_SRCMASKS_MIRROR			BIT(26)
+#define VSC73XX_SRCMASKS_PORTS_MASK		GENMASK(7, 0)
+
 #define VSC73XX_MACACCESS_CPU_COPY		BIT(14)
 #define VSC73XX_MACACCESS_FWD_KILL		BIT(13)
 #define VSC73XX_MACACCESS_IGNORE_VLAN		BIT(12)
@@ -623,9 +627,6 @@ static int vsc73xx_setup(struct dsa_switch *ds)
 	vsc73xx_write(vsc, VSC73XX_BLOCK_SYSTEM, 0, VSC73XX_GMIIDELAY,
 		      VSC73XX_GMIIDELAY_GMII0_GTXDELAY_2_0_NS |
 		      VSC73XX_GMIIDELAY_GMII0_RXDELAY_2_0_NS);
-	/* Enable reception of frames on all ports */
-	vsc73xx_write(vsc, VSC73XX_BLOCK_ANALYZER, 0, VSC73XX_RECVMASK,
-		      0x5f);
 	/* IP multicast flood mask (table 144) */
 	vsc73xx_write(vsc, VSC73XX_BLOCK_ANALYZER, 0, VSC73XX_IFLODMSK,
 		      0xff);
@@ -788,10 +789,6 @@ static void vsc73xx_mac_link_down(struct phylink_config *config,
 	/* Allow backward dropping of frames from this port */
 	vsc73xx_update_bits(vsc, VSC73XX_BLOCK_ARBITER, 0,
 			    VSC73XX_SBACKWDROP, BIT(port), BIT(port));
-
-	/* Receive mask (disable forwarding) */
-	vsc73xx_update_bits(vsc, VSC73XX_BLOCK_ANALYZER, 0,
-			    VSC73XX_RECVMASK, BIT(port), 0);
 }
 
 static void vsc73xx_mac_link_up(struct phylink_config *config,
@@ -844,10 +841,6 @@ static void vsc73xx_mac_link_up(struct phylink_config *config,
 	vsc73xx_update_bits(vsc, VSC73XX_BLOCK_ARBITER, 0,
 			    VSC73XX_ARBDISC, BIT(port), 0);
 
-	/* Enable port (forwarding) in the receive mask */
-	vsc73xx_update_bits(vsc, VSC73XX_BLOCK_ANALYZER, 0,
-			    VSC73XX_RECVMASK, BIT(port), BIT(port));
-
 	/* Disallow backward dropping of frames from this port */
 	vsc73xx_update_bits(vsc, VSC73XX_BLOCK_ARBITER, 0,
 			    VSC73XX_SBACKWDROP, BIT(port), 0);
@@ -1039,6 +1032,86 @@ static void vsc73xx_phylink_get_caps(struct dsa_switch *dsa, int port,
 	config->mac_capabilities = MAC_SYM_PAUSE | MAC_10 | MAC_100 | MAC_1000;
 }
 
+static void vsc73xx_refresh_fwd_map(struct dsa_switch *ds, int port, u8 state)
+{
+	struct dsa_port *other_dp, *dp = dsa_to_port(ds, port);
+	struct vsc73xx *vsc = ds->priv;
+	u16 mask;
+
+	if (state != BR_STATE_FORWARDING) {
+		/* Ports that aren't in the forwarding state must not
+		 * forward packets anywhere.
+		 */
+		vsc73xx_update_bits(vsc, VSC73XX_BLOCK_ANALYZER, 0,
+				    VSC73XX_SRCMASKS + port,
+				    VSC73XX_SRCMASKS_PORTS_MASK, 0);
+
+		dsa_switch_for_each_available_port(other_dp, ds) {
+			if (other_dp == dp)
+				continue;
+			vsc73xx_update_bits(vsc, VSC73XX_BLOCK_ANALYZER, 0,
+					    VSC73XX_SRCMASKS + other_dp->index,
+					    BIT(port), 0);
+		}
+
+		return;
+	}
+
+	/* Forwarding ports must forward to the CPU and to other ports
+	 * in the same bridge
+	 */
+	vsc73xx_update_bits(vsc, VSC73XX_BLOCK_ANALYZER, 0,
+			    VSC73XX_SRCMASKS + CPU_PORT, BIT(port), BIT(port));
+
+	mask = BIT(CPU_PORT);
+
+	dsa_switch_for_each_user_port(other_dp, ds) {
+		int other_port = other_dp->index;
+
+		if (port == other_port || !dsa_port_bridge_same(dp, other_dp) ||
+		    other_dp->stp_state != BR_STATE_FORWARDING)
+			continue;
+
+		mask |= BIT(other_port);
+
+		vsc73xx_update_bits(vsc, VSC73XX_BLOCK_ANALYZER, 0,
+				    VSC73XX_SRCMASKS + other_port,
+				    BIT(port), BIT(port));
+	}
+
+	vsc73xx_update_bits(vsc, VSC73XX_BLOCK_ANALYZER, 0,
+			    VSC73XX_SRCMASKS + port,
+			    VSC73XX_SRCMASKS_PORTS_MASK, mask);
+}
+
+/* FIXME: STP frames aren't forwarded at this moment. BPDU frames are
+ * forwarded only from and to PI/SI interface. For more info see chapter
+ * 2.7.1 (CPU Forwarding) in datasheet.
+ * This function is required for tag_8021q operations.
+ */
+static void vsc73xx_port_stp_state_set(struct dsa_switch *ds, int port,
+				       u8 state)
+{
+	struct vsc73xx *vsc = ds->priv;
+	u32 val;
+
+	val = (state == BR_STATE_BLOCKING || state == BR_STATE_DISABLED) ?
+	      0 : BIT(port);
+	vsc73xx_update_bits(vsc, VSC73XX_BLOCK_ANALYZER, 0,
+			    VSC73XX_RECVMASK, BIT(port), val);
+
+	val = (state == BR_STATE_LEARNING || state == BR_STATE_FORWARDING) ?
+	      BIT(port) : 0;
+	vsc73xx_update_bits(vsc, VSC73XX_BLOCK_ANALYZER, 0,
+			    VSC73XX_LEARNMASK, BIT(port), val);
+
+	/* CPU Port should always forward packets when user ports are forwarding
+	 * so let's configure it from other ports only.
+	 */
+	if (port != CPU_PORT)
+		vsc73xx_refresh_fwd_map(ds, port, state);
+}
+
 static const struct phylink_mac_ops vsc73xx_phylink_mac_ops = {
 	.mac_config = vsc73xx_mac_config,
 	.mac_link_down = vsc73xx_mac_link_down,
@@ -1057,6 +1130,7 @@ static const struct dsa_switch_ops vsc73xx_ds_ops = {
 	.port_disable = vsc73xx_port_disable,
 	.port_change_mtu = vsc73xx_change_mtu,
 	.port_max_mtu = vsc73xx_get_max_mtu,
+	.port_stp_state_set = vsc73xx_port_stp_state_set,
 	.phylink_get_caps = vsc73xx_phylink_get_caps,
 };