mv88e6xxx: Add SERDES Support for mv88e6321

Add serdes and pcs_ops functions for mv88e6321. In mv88e6321
2 ports support serdes functionality; port 0 and port 1. These ports are
serdes-only ports.

Changes:

1. Add a function support to return the lane address for the port based on
cmode.
2. Reuse mv88e6352's serdes_get_regs* and pcs_init functions for mv88e6321.

Tested on mv88e6321 switch port 0.

Co-developed-by: Thomas Eckerman <thomas.eckerman.ext@ericsson.com>
Signed-off-by: Thomas Eckerman <thomas.eckerman.ext@ericsson.com>
Signed-off-by: Fidan Aliyeva <fidan.aliyeva.ext@ericsson.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/20260528210310.1365858-4-fidan.aliyeva.ext@ericsson.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: fidanali16

drivers/net/dsa/mv88e6xxx/chip.c

@@ -5272,10 +5272,14 @@ static const struct mv88e6xxx_ops mv88e6321_ops = {
 	.vtu_loadpurge = mv88e6352_g1_vtu_loadpurge,
 	.stu_getnext = mv88e6352_g1_stu_getnext,
 	.stu_loadpurge = mv88e6352_g1_stu_loadpurge,
+	.serdes_get_lane = mv88e6321_serdes_get_lane,
+	.serdes_get_regs_len = mv88e6352_serdes_get_regs_len,
+	.serdes_get_regs = mv88e6352_serdes_get_regs,
 	.gpio_ops = &mv88e6352_gpio_ops,
 	.avb_ops = &mv88e6352_avb_ops,
 	.ptp_ops = &mv88e6352_ptp_ops,
 	.phylink_get_caps = mv88e632x_phylink_get_caps,
+	.pcs_ops = &mv88e6352_pcs_ops,
 };
 
 static const struct mv88e6xxx_ops mv88e6341_ops = {

drivers/net/dsa/mv88e6xxx/serdes.c

@@ -241,6 +241,24 @@ void mv88e6352_serdes_get_regs(struct mv88e6xxx_chip *chip, int port, void *_p)
 	}
 }
 
+int mv88e6321_serdes_get_lane(struct mv88e6xxx_chip *chip, int port)
+{
+	int lane = -ENODEV;
+	u8 cmode;
+
+	if (port != 0 && port != 1)
+		return lane;
+
+	cmode = chip->ports[port].cmode;
+
+	if (cmode == MV88E6XXX_PORT_STS_CMODE_100BASEX ||
+	    cmode == MV88E6XXX_PORT_STS_CMODE_1000BASEX ||
+	    cmode == MV88E6XXX_PORT_STS_CMODE_SGMII)
+		lane = port + MV88E6321_PORT0_LANE;
+
+	return lane;
+}
+
 int mv88e6341_serdes_get_lane(struct mv88e6xxx_chip *chip, int port)
 {
 	u8 cmode = chip->ports[port].cmode;

drivers/net/dsa/mv88e6xxx/serdes.h

@@ -14,6 +14,8 @@
 
 struct phylink_link_state;
 
+#define MV88E6321_PORT0_LANE		0x0c
+
 #define MV88E6352_ADDR_SERDES		0x0f
 #define MV88E6352_SERDES_PAGE_FIBER	0x01
 #define MV88E6352_SERDES_IRQ		0x0b
@@ -114,6 +116,7 @@ struct phylink_link_state;
 int mv88e6xxx_pcs_decode_state(struct device *dev, u16 bmsr, u16 lpa,
 			       u16 status, struct phylink_link_state *state);
 
+int mv88e6321_serdes_get_lane(struct mv88e6xxx_chip *chip, int port);
 int mv88e6341_serdes_get_lane(struct mv88e6xxx_chip *chip, int port);
 int mv88e6352_serdes_get_lane(struct mv88e6xxx_chip *chip, int port);
 int mv88e6390_serdes_get_lane(struct mv88e6xxx_chip *chip, int port);