net: dsa: mv88e6xxx: get STU entry on VTU GetNext

Now that the code reads both VTU and STU data on VTU GetNext operation,
fetch the STU entry data of a VTU entry at the same time.

The STU data bits are masked with the VTU data bits and they are now all
read at the same time a VTU GetNext operation is issued.
Signed-off-by: NVivien Didelot <vivien.didelot@savoirfairelinux.com>
Reviewed-by: NAndrew Lunn <andrew@lunn.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/dsa/mv88e6xxx/chip.c

@@ -1292,7 +1292,7 @@ static int _mv88e6xxx_vtu_getnext(struct mv88e6xxx_chip *chip,
 		}
 
 		if (mv88e6xxx_has(chip, MV88E6XXX_FLAG_STU)) {
-			err = mv88e6xxx_g1_vtu_sid_read(chip, &next);
+			err = mv88e6xxx_g1_vtu_stu_get(chip, &next);
 			if (err)
 				return err;
 		}

drivers/net/dsa/mv88e6xxx/global1.h

@@ -72,6 +72,8 @@ int mv88e6xxx_g1_vtu_getnext(struct mv88e6xxx_chip *chip,
 			     struct mv88e6xxx_vtu_entry *entry);
 int mv88e6xxx_g1_vtu_stu_getnext(struct mv88e6xxx_chip *chip,
 				 struct mv88e6xxx_vtu_entry *vtu);
+int mv88e6xxx_g1_vtu_stu_get(struct mv88e6xxx_chip *chip,
+			     struct mv88e6xxx_vtu_entry *vtu);
 int mv88e6xxx_g1_vtu_flush(struct mv88e6xxx_chip *chip);
 
 #endif /* _MV88E6XXX_GLOBAL1_H */

drivers/net/dsa/mv88e6xxx/global1_vtu.c

@@ -194,6 +194,28 @@ int mv88e6xxx_g1_vtu_stu_getnext(struct mv88e6xxx_chip *chip,
 	return mv88e6xxx_g1_vtu_vid_read(chip, entry);
 }
 
+int mv88e6xxx_g1_vtu_stu_get(struct mv88e6xxx_chip *chip,
+			     struct mv88e6xxx_vtu_entry *vtu)
+{
+	struct mv88e6xxx_vtu_entry stu;
+	int err;
+
+	err = mv88e6xxx_g1_vtu_sid_read(chip, vtu);
+	if (err)
+		return err;
+
+	stu.sid = vtu->sid - 1;
+
+	err = mv88e6xxx_g1_vtu_stu_getnext(chip, &stu);
+	if (err)
+		return err;
+
+	if (stu.sid != vtu->sid || !stu.valid)
+		return -EINVAL;
+
+	return 0;
+}
+
 int mv88e6xxx_g1_vtu_getnext(struct mv88e6xxx_chip *chip,
 			     struct mv88e6xxx_vtu_entry *entry)
 {