net: dsa: mv88e6xxx: extract device mapping

The Device Mapping register is an indirect table access.

Provide helpers to access this table and explicit the checking of the
new DSA_RTABLE_NONE routing table value.
Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/dsa/mv88e6xxx/chip.c

@@ -216,6 +216,32 @@ static int mv88e6xxx_write(struct mv88e6xxx_chip *chip,
 	return 0;
 }
 
+/* Indirect write to single pointer-data register with an Update bit */
+static int mv88e6xxx_update(struct mv88e6xxx_chip *chip, int addr, int reg,
+			    u16 update)
+{
+	u16 val;
+	int i, err;
+
+	/* Wait until the previous operation is completed */
+	for (i = 0; i < 16; ++i) {
+		err = mv88e6xxx_read(chip, addr, reg, &val);
+		if (err)
+			return err;
+
+		if (!(val & BIT(15)))
+			break;
+	}
+
+	if (i == 16)
+		return -ETIMEDOUT;
+
+	/* Set the Update bit to trigger a write operation */
+	val = BIT(15) | update;
+
+	return mv88e6xxx_write(chip, addr, reg, val);
+}
+
 static int _mv88e6xxx_reg_read(struct mv88e6xxx_chip *chip, int addr, int reg)
 {
 	u16 val;
@@ -3094,9 +3120,39 @@ static int mv88e6xxx_g1_setup(struct mv88e6xxx_chip *chip)
 	return 0;
 }
 
+static int mv88e6xxx_g2_device_mapping_write(struct mv88e6xxx_chip *chip,
+					     int target, int port)
+{
+	u16 val = (target << 8) | (port & 0xf);
+
+	return mv88e6xxx_update(chip, REG_GLOBAL2, GLOBAL2_DEVICE_MAPPING, val);
+}
+
+static int mv88e6xxx_g2_set_device_mapping(struct mv88e6xxx_chip *chip)
+{
+	int target, port;
+	int err;
+
+	/* Initialize the routing port to the 32 possible target devices */
+	for (target = 0; target < 32; ++target) {
+		port = 0xf;
+
+		if (target < DSA_MAX_SWITCHES) {
+			port = chip->ds->rtable[target];
+			if (port == DSA_RTABLE_NONE)
+				port = 0xf;
+		}
+
+		err = mv88e6xxx_g2_device_mapping_write(chip, target, port);
+		if (err)
+			break;
+	}
+
+	return err;
+}
+
 static int mv88e6xxx_g2_setup(struct mv88e6xxx_chip *chip)
 {
-	struct dsa_switch *ds = chip->ds;
 	int err;
 	int i;
 
@@ -3120,20 +3176,9 @@ static int mv88e6xxx_g2_setup(struct mv88e6xxx_chip *chip)
 		return err;
 
 	/* Program the DSA routing table. */
-	for (i = 0; i < 32; i++) {
-		int nexthop = 0x1f;
-
-		if (i != ds->index && i < DSA_MAX_SWITCHES)
-			nexthop = ds->rtable[i] & 0x1f;
-
-		err = _mv88e6xxx_reg_write(
-			chip, REG_GLOBAL2,
-			GLOBAL2_DEVICE_MAPPING,
-			GLOBAL2_DEVICE_MAPPING_UPDATE |
-			(i << GLOBAL2_DEVICE_MAPPING_TARGET_SHIFT) | nexthop);
+	err = mv88e6xxx_g2_set_device_mapping(chip);
 	if (err)
 		return err;
-	}
 
 	/* Clear all trunk masks. */
 	for (i = 0; i < 8; i++) {