[PATCH net-next v3 1/2] net: dsa: mt7530: factor out bridge join/leave logic

[Matthias Schiffer]

As preparation for implementing bridge port isolation, move the logic to
add and remove bits in the port matrix into a new helper
mt7530_update_port_member(), which is called from
mt7530_port_bridge_join() and mt7530_port_bridge_leave().

Another part of the preparation is using dsa_port_offloads_bridge_dev()
instead of dsa_port_offloads_bridge() to check for bridge membership, as
we don't have a struct dsa_bridge in mt7530_port_bridge_flags().

The port matrix setting is slightly streamlined, now always first setting
the mt7530_port's pm field and then writing the port matrix from that
field into the hardware register, instead of duplicating the bit
manipulation for both the struct field and the register.

mt7530_port_bridge_join() was previously using |= to update the port
matrix with the port bitmap, which was unnecessary, as pm would only
have the CPU port set before joining a bridge; a simple assignment can
be used for both joining and leaving (and will also work when individual
bits are added/removed in port_bitmap with regard to the previous port
matrix, which is what happens with port isolation).

No functional change intended.

Signed-off-by: Matthias Schiffer <mschiffer at universe-factory.net>
---

v2: no changes
v3: addressed overlooked review comments:
- Ran clang-format on the patch
- Restored code comment
- Extended commit message

Thanks for the clang-format pointer - last time I tried that on kernel
code (years ago), it was rather underwhelming, but it seems it has
improved a lot.

 drivers/net/dsa/mt7530.c | 105 ++++++++++++++++++---------------------
 1 file changed, 48 insertions(+), 57 deletions(-)

diff --git a/drivers/net/dsa/mt7530.c b/drivers/net/dsa/mt7530.c
index 598434d8d6e4..9ce27ce07d77 100644
--- a/drivers/net/dsa/mt7530.c
+++ b/drivers/net/dsa/mt7530.c
@@ -1302,6 +1302,52 @@ mt7530_stp_state_set(struct dsa_switch *ds, int port, u8 state)
 		   FID_PST(FID_BRIDGED, stp_state));
 }
 
+static void mt7530_update_port_member(struct mt7530_priv *priv, int port,
+				      const struct net_device *bridge_dev,
+				      bool join) __must_hold(&priv->reg_mutex)
+{
+	struct dsa_port *dp = dsa_to_port(priv->ds, port), *other_dp;
+	struct mt7530_port *p = &priv->ports[port], *other_p;
+	struct dsa_port *cpu_dp = dp->cpu_dp;
+	u32 port_bitmap = BIT(cpu_dp->index);
+	int other_port;
+
+	dsa_switch_for_each_user_port(other_dp, priv->ds) {
+		other_port = other_dp->index;
+		other_p = &priv->ports[other_port];
+
+		if (dp == other_dp)
+			continue;
+
+		/* Add/remove this port to/from the port matrix of the other
+		 * ports in the same bridge. If the port is disabled, port
+		 * matrix is kept and not being setup until the port becomes
+		 * enabled.
+		 */
+		if (!dsa_port_offloads_bridge_dev(other_dp, bridge_dev))
+			continue;
+
+		if (join) {
+			other_p->pm |= PCR_MATRIX(BIT(port));
+			port_bitmap |= BIT(other_port);
+		} else {
+			other_p->pm &= ~PCR_MATRIX(BIT(port));
+		}
+
+		if (other_p->enable)
+			mt7530_rmw(priv, MT7530_PCR_P(other_port),
+				   PCR_MATRIX_MASK, other_p->pm);
+	}
+
+	/* Add/remove the all other ports to this port matrix. For !join
+	 * (leaving the bridge), only the CPU port will remain in the port matrix
+	 * of this port.
+	 */
+	p->pm = PCR_MATRIX(port_bitmap);
+	if (priv->ports[port].enable)
+		mt7530_rmw(priv, MT7530_PCR_P(port), PCR_MATRIX_MASK, p->pm);
+}
+
 static int
 mt7530_port_pre_bridge_flags(struct dsa_switch *ds, int port,
 			     struct switchdev_brport_flags flags,
@@ -1345,39 +1391,11 @@ mt7530_port_bridge_join(struct dsa_switch *ds, int port,
 			struct dsa_bridge bridge, bool *tx_fwd_offload,
 			struct netlink_ext_ack *extack)
 {
-	struct dsa_port *dp = dsa_to_port(ds, port), *other_dp;
-	struct dsa_port *cpu_dp = dp->cpu_dp;
-	u32 port_bitmap = BIT(cpu_dp->index);
 	struct mt7530_priv *priv = ds->priv;
 
 	mutex_lock(&priv->reg_mutex);
 
-	dsa_switch_for_each_user_port(other_dp, ds) {
-		int other_port = other_dp->index;
-
-		if (dp == other_dp)
-			continue;
-
-		/* Add this port to the port matrix of the other ports in the
-		 * same bridge. If the port is disabled, port matrix is kept
-		 * and not being setup until the port becomes enabled.
-		 */
-		if (!dsa_port_offloads_bridge(other_dp, &bridge))
-			continue;
-
-		if (priv->ports[other_port].enable)
-			mt7530_set(priv, MT7530_PCR_P(other_port),
-				   PCR_MATRIX(BIT(port)));
-		priv->ports[other_port].pm |= PCR_MATRIX(BIT(port));
-
-		port_bitmap |= BIT(other_port);
-	}
-
-	/* Add the all other ports to this port matrix. */
-	if (priv->ports[port].enable)
-		mt7530_rmw(priv, MT7530_PCR_P(port),
-			   PCR_MATRIX_MASK, PCR_MATRIX(port_bitmap));
-	priv->ports[port].pm |= PCR_MATRIX(port_bitmap);
+	mt7530_update_port_member(priv, port, bridge.dev, true);
 
 	/* Set to fallback mode for independent VLAN learning */
 	mt7530_rmw(priv, MT7530_PCR_P(port), PCR_PORT_VLAN_MASK,
@@ -1478,38 +1496,11 @@ static void
 mt7530_port_bridge_leave(struct dsa_switch *ds, int port,
 			 struct dsa_bridge bridge)
 {
-	struct dsa_port *dp = dsa_to_port(ds, port), *other_dp;
-	struct dsa_port *cpu_dp = dp->cpu_dp;
 	struct mt7530_priv *priv = ds->priv;
 
 	mutex_lock(&priv->reg_mutex);
 
-	dsa_switch_for_each_user_port(other_dp, ds) {
-		int other_port = other_dp->index;
-
-		if (dp == other_dp)
-			continue;
-
-		/* Remove this port from the port matrix of the other ports
-		 * in the same bridge. If the port is disabled, port matrix
-		 * is kept and not being setup until the port becomes enabled.
-		 */
-		if (!dsa_port_offloads_bridge(other_dp, &bridge))
-			continue;
-
-		if (priv->ports[other_port].enable)
-			mt7530_clear(priv, MT7530_PCR_P(other_port),
-				     PCR_MATRIX(BIT(port)));
-		priv->ports[other_port].pm &= ~PCR_MATRIX(BIT(port));
-	}
-
-	/* Set the cpu port to be the only one in the port matrix of
-	 * this port.
-	 */
-	if (priv->ports[port].enable)
-		mt7530_rmw(priv, MT7530_PCR_P(port), PCR_MATRIX_MASK,
-			   PCR_MATRIX(BIT(cpu_dp->index)));
-	priv->ports[port].pm = PCR_MATRIX(BIT(cpu_dp->index));
+	mt7530_update_port_member(priv, port, bridge.dev, false);
 
 	/* When a port is removed from the bridge, the port would be set up
 	 * back to the default as is at initial boot which is a VLAN-unaware
-- 
2.45.2