net: dsa: make LAG IDs one-based

The DSA LAG API will be changed to become more similar with the bridge
data structures, where struct dsa_bridge holds an unsigned int num,
which is generated by DSA and is one-based. We have a similar thing
going with the DSA LAG, except that isn't stored anywhere, it is
calculated dynamically by dsa_lag_id() by iterating through dst->lags.

The idea of encoding an invalid (or not requested) LAG ID as zero for
the purpose of simplifying checks in drivers means that the LAG IDs
passed by DSA to drivers need to be one-based too. So back-and-forth
conversion is needed when indexing the dst->lags array, as well as in
drivers which assume a zero-based index.
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/dsa/mv88e6xxx/chip.c

@@ -1630,10 +1630,11 @@ static int mv88e6xxx_pvt_map(struct mv88e6xxx_chip *chip, int dev, int port)
 			 * FORWARD frames, which use the LAG ID as the
 			 * source port, we must translate dev/port to
 			 * the special "LAG device" in the PVT, using
-			 * the LAG ID as the port number.
+			 * the LAG ID (one-based) as the port number
+			 * (zero-based).
 			 */
 			dev = MV88E6XXX_G2_PVT_ADDR_DEV_TRUNK;
-			port = dsa_lag_id(dst, dp->lag_dev);
+			port = dsa_lag_id(dst, dp->lag_dev) - 1;
 		}
 	}
 
@@ -6186,7 +6187,7 @@ static bool mv88e6xxx_lag_can_offload(struct dsa_switch *ds,
 		return false;
 
 	id = dsa_lag_id(ds->dst, lag_dev);
-	if (id < 0 || id >= ds->num_lag_ids)
+	if (id <= 0 || id > ds->num_lag_ids)
 		return false;
 
 	dsa_lag_foreach_port(dp, ds->dst, lag_dev)
@@ -6217,7 +6218,8 @@ static int mv88e6xxx_lag_sync_map(struct dsa_switch *ds,
 	u16 map = 0;
 	int id;
 
-	id = dsa_lag_id(ds->dst, lag_dev);
+	/* DSA LAG IDs are one-based, hardware is zero-based */
+	id = dsa_lag_id(ds->dst, lag_dev) - 1;
 
 	/* Build the map of all ports to distribute flows destined for
 	 * this LAG. This can be either a local user port, or a DSA
@@ -6361,7 +6363,8 @@ static int mv88e6xxx_port_lag_join(struct dsa_switch *ds, int port,
 	if (!mv88e6xxx_lag_can_offload(ds, lag_dev, info))
 		return -EOPNOTSUPP;
 
-	id = dsa_lag_id(ds->dst, lag_dev);
+	/* DSA LAG IDs are one-based */
+	id = dsa_lag_id(ds->dst, lag_dev) - 1;
 
 	mv88e6xxx_reg_lock(chip);
 

drivers/net/dsa/qca8k.c

@@ -2654,7 +2654,7 @@ qca8k_lag_can_offload(struct dsa_switch *ds,
 	int id, members = 0;
 
 	id = dsa_lag_id(ds->dst, lag_dev);
-	if (id < 0 || id >= ds->num_lag_ids)
+	if (id <= 0 || id > ds->num_lag_ids)
 		return false;
 
 	dsa_lag_foreach_port(dp, ds->dst, lag_dev)
@@ -2732,7 +2732,8 @@ qca8k_lag_refresh_portmap(struct dsa_switch *ds, int port,
 	int ret, id, i;
 	u32 val;
 
-	id = dsa_lag_id(ds->dst, lag_dev);
+	/* DSA LAG IDs are one-based, hardware is zero-based */
+	id = dsa_lag_id(ds->dst, lag_dev) - 1;
 
 	/* Read current port member */
 	ret = regmap_read(priv->regmap, QCA8K_REG_GOL_TRUNK_CTRL0, &val);

include/net/dsa.h

@@ -163,9 +163,10 @@ struct dsa_switch_tree {
 	unsigned int last_switch;
 };
 
+/* LAG IDs are one-based, the dst->lags array is zero-based */
 #define dsa_lags_foreach_id(_id, _dst)				\
-	for ((_id) = 0; (_id) < (_dst)->lags_len; (_id)++)	\
-		if ((_dst)->lags[(_id)])
+	for ((_id) = 1; (_id) <= (_dst)->lags_len; (_id)++)	\
+		if ((_dst)->lags[(_id) - 1])
 
 #define dsa_lag_foreach_port(_dp, _dst, _lag)			\
 	list_for_each_entry((_dp), &(_dst)->ports, list)	\
@@ -178,7 +179,8 @@ struct dsa_switch_tree {
 static inline struct net_device *dsa_lag_dev(struct dsa_switch_tree *dst,
 					     unsigned int id)
 {
-	return dst->lags[id];
+	/* DSA LAG IDs are one-based, dst->lags is zero-based */
+	return dst->lags[id - 1];
 }
 
 static inline int dsa_lag_id(struct dsa_switch_tree *dst,

net/dsa/dsa2.c

@@ -86,13 +86,13 @@ void dsa_lag_map(struct dsa_switch_tree *dst, struct net_device *lag_dev)
 {
 	unsigned int id;
 
-	if (dsa_lag_id(dst, lag_dev) >= 0)
+	if (dsa_lag_id(dst, lag_dev) > 0)
 		/* Already mapped */
 		return;
 
-	for (id = 0; id < dst->lags_len; id++) {
+	for (id = 1; id <= dst->lags_len; id++) {
 		if (!dsa_lag_dev(dst, id)) {
-			dst->lags[id] = lag_dev;
+			dst->lags[id - 1] = lag_dev;
 			return;
 		}
 	}
@@ -124,7 +124,7 @@ void dsa_lag_unmap(struct dsa_switch_tree *dst, struct net_device *lag_dev)
 
 	dsa_lags_foreach_id(id, dst) {
 		if (dsa_lag_dev(dst, id) == lag_dev) {
-			dst->lags[id] = NULL;
+			dst->lags[id - 1] = NULL;
 			break;
 		}
 	}

net/dsa/tag_dsa.c

@@ -251,7 +251,7 @@ static struct sk_buff *dsa_rcv_ll(struct sk_buff *skb, struct net_device *dev,
 		 * so we inject the frame directly on the upper
 		 * team/bond.
 		 */
-		skb->dev = dsa_lag_dev(cpu_dp->dst, source_port);
+		skb->dev = dsa_lag_dev(cpu_dp->dst, source_port + 1);
 	} else {
 		skb->dev = dsa_master_find_slave(dev, source_device,
 						 source_port);