net: dsa: mv88e6xxx: extend fid mask

The driver currently manages one FID per port (or bridge group), with a
mask of DSA_MAX_PORTS bits, where 0 means that the FID is in use.

The Marvell 88E6xxx switches support up to 4094 FIDs (from 1 to 0xfff;
FID 0 means that multiple address databases are not being used).

This patch changes the fid_mask for an fid_bitmap of 4096 bits.

>From now on, FIDs 1 to num_ports are reserved for non-bridged ports and
bridge groups (a bridge group gets the FID of its first member). The
remaining bits will be reserved for VLAN entries.
Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/dsa/mv88e6xxx.c

@@ -1091,7 +1091,7 @@ int mv88e6xxx_join_bridge(struct dsa_switch *ds, int port, u32 br_port_mask)
 	ps->bridge_mask[fid] = br_port_mask;
 
 	if (fid != ps->fid[port]) {
-		ps->fid_mask |= 1 << ps->fid[port];
+		clear_bit(ps->fid[port], ps->fid_bitmap);
 		ps->fid[port] = fid;
 		ret = _mv88e6xxx_update_bridge_config(ds, fid);
 	}
@@ -1125,9 +1125,16 @@ int mv88e6xxx_leave_bridge(struct dsa_switch *ds, int port, u32 br_port_mask)
 
 	mutex_lock(&ps->smi_mutex);
 
-	newfid = __ffs(ps->fid_mask);
+	newfid = find_next_zero_bit(ps->fid_bitmap, VLAN_N_VID, 1);
+	if (unlikely(newfid > ps->num_ports)) {
+		netdev_err(ds->ports[port], "all first %d FIDs are used\n",
+			   ps->num_ports);
+		ret = -ENOSPC;
+		goto unlock;
+	}
+
 	ps->fid[port] = newfid;
-	ps->fid_mask &= ~(1 << newfid);
+	set_bit(newfid, ps->fid_bitmap);
 	ps->bridge_mask[fid] &= ~(1 << port);
 	ps->bridge_mask[newfid] = 1 << port;
 
@@ -1135,6 +1142,7 @@ int mv88e6xxx_leave_bridge(struct dsa_switch *ds, int port, u32 br_port_mask)
 	if (!ret)
 		ret = _mv88e6xxx_update_bridge_config(ds, newfid);
 
+unlock:
 	mutex_unlock(&ps->smi_mutex);
 
 	return ret;
@@ -1552,9 +1560,9 @@ static int mv88e6xxx_setup_port(struct dsa_switch *ds, int port)
 	 * ports, and allow each of the 'real' ports to only talk to
 	 * the upstream port.
 	 */
-	fid = __ffs(ps->fid_mask);
+	fid = port + 1;
 	ps->fid[port] = fid;
-	ps->fid_mask &= ~(1 << fid);
+	set_bit(fid, ps->fid_bitmap);
 
 	if (!dsa_is_cpu_port(ds, port))
 		ps->bridge_mask[fid] = 1 << port;
@@ -1853,8 +1861,6 @@ int mv88e6xxx_setup_common(struct dsa_switch *ds)
 
 	ps->id = REG_READ(REG_PORT(0), PORT_SWITCH_ID) & 0xfff0;
 
-	ps->fid_mask = (1 << DSA_MAX_PORTS) - 1;
-
 	INIT_WORK(&ps->bridge_work, mv88e6xxx_bridge_work);
 
 	name = kasprintf(GFP_KERNEL, "dsa%d", ds->index);

drivers/net/dsa/mv88e6xxx.h

@@ -11,6 +11,8 @@
 #ifndef __MV88E6XXX_H
 #define __MV88E6XXX_H
 
+#include <linux/if_vlan.h>
+
 #ifndef UINT64_MAX
 #define UINT64_MAX		(u64)(~((u64)0))
 #endif
@@ -352,9 +354,9 @@ struct mv88e6xxx_priv_state {
 
 	/* hw bridging */
 
-	u32 fid_mask;
-	u8 fid[DSA_MAX_PORTS];
-	u16 bridge_mask[DSA_MAX_PORTS];
+	DECLARE_BITMAP(fid_bitmap, VLAN_N_VID);	/* FIDs 1 to 4095 available */
+	u16 fid[DSA_MAX_PORTS];			/* per (non-bridged) port FID */
+	u16 bridge_mask[DSA_MAX_PORTS];		/* br groups (indexed by FID) */
 
 	unsigned long port_state_update_mask;
 	u8 port_state[DSA_MAX_PORTS];