[v3 2/2] dsa: mv88e6xxx: make serdes SGMII/Fiber output amplitude configurable

@@ -2861,6 +2861,8 @@ static int mv88e6xxx_setup_upstream_port(struct mv88e6xxx_chip *chip, int port)
 static int mv88e6xxx_setup_port(struct mv88e6xxx_chip *chip, int port)
 {
 	struct dsa_switch *ds = chip->ds;
+	struct dsa_port *dp;
+	int tx_amp;
 	int err;
 	u16 reg;
 

@@ -3014,6 +3016,19 @@ static int mv88e6xxx_setup_port(struct mv88e6xxx_chip *chip, int port)
 			return err;
 	}
 
+	if (chip->info->ops->serdes_set_tx_amplitude) {
+		dp = dsa_to_port(ds, port);
+		if (dp &&
+		    !of_property_read_u32(dp->dn,
+					  "serdes-tx-amplitude-millivolt",
+					  &tx_amp)) {
+			err = mv88e6352_serdes_set_tx_amplitude(chip, port,
+								tx_amp);
+			if (err)
+				return err;
+		}
+	}
+
 	/* Port based VLAN map: give each port the same default address
 	 * database, and allow bidirectional communication between the
 	 * CPU and DSA port(s), and the other ports.

@@ -4076,6 +4091,7 @@ static int mv88e6xxx_set_eeprom(struct dsa_switch *ds,
 	.serdes_irq_status = mv88e6352_serdes_irq_status,
 	.serdes_get_regs_len = mv88e6352_serdes_get_regs_len,
 	.serdes_get_regs = mv88e6352_serdes_get_regs,
+	.serdes_set_tx_amplitude = mv88e6352_serdes_set_tx_amplitude,
 	.gpio_ops = &mv88e6352_gpio_ops,
 	.phylink_validate = mv88e6352_phylink_validate,
 };

@@ -4356,6 +4372,7 @@ static int mv88e6xxx_set_eeprom(struct dsa_switch *ds,
 	.serdes_irq_status = mv88e6352_serdes_irq_status,
 	.serdes_get_regs_len = mv88e6352_serdes_get_regs_len,
 	.serdes_get_regs = mv88e6352_serdes_get_regs,
+	.serdes_set_tx_amplitude = mv88e6352_serdes_set_tx_amplitude,
 	.gpio_ops = &mv88e6352_gpio_ops,
 	.avb_ops = &mv88e6352_avb_ops,
 	.ptp_ops = &mv88e6352_ptp_ops,

@@ -4762,6 +4779,7 @@ static int mv88e6xxx_set_eeprom(struct dsa_switch *ds,
 	.serdes_get_stats = mv88e6352_serdes_get_stats,
 	.serdes_get_regs_len = mv88e6352_serdes_get_regs_len,
 	.serdes_get_regs = mv88e6352_serdes_get_regs,
+	.serdes_set_tx_amplitude = mv88e6352_serdes_set_tx_amplitude,
 	.phylink_validate = mv88e6352_phylink_validate,
 };
 

@@ -586,6 +586,10 @@ struct mv88e6xxx_ops {
 	void (*serdes_get_regs)(struct mv88e6xxx_chip *chip, int port,
 				void *_p);
 
+	/* SERDES SGMII/Fiber Output Amplitude */
+	int (*serdes_set_tx_amplitude)(struct mv88e6xxx_chip *chip, int port,
+				       int val);
+
 	/* Address Translation Unit operations */
 	int (*atu_get_hash)(struct mv88e6xxx_chip *chip, u8 *hash);
 	int (*atu_set_hash)(struct mv88e6xxx_chip *chip, u8 hash);

@@ -1307,6 +1307,54 @@ void mv88e6390_serdes_get_regs(struct mv88e6xxx_chip *chip, int port, void *_p)
 	}
 }
 
+struct mv88e6352_serdes_amp_to_val {
+	int mv;
+	u16 regval;
+};
+
+static struct mv88e6352_serdes_amp_to_val mv88e6352_serdes_amp_to_val[] = {
+	/* Mapping of configurable millivolt values to the register value */
+	{ 14, 0},
+	{ 112, 1},
+	{ 210, 2},
+	{ 308, 3},
+	{ 406, 4},
+	{ 504, 5},
+	{ 602, 6},
+	{ 700, 7},
+};
+
+int mv88e6352_serdes_set_tx_amplitude(struct mv88e6xxx_chip *chip, int port,
+				      int val)
+{
+	bool found = false;
+	u16 reg;
+	int err;
+	int i;
+
+	if (!mv88e6352_port_has_serdes(chip, port))
+		return -EOPNOTSUPP;
+
+	for (i = 0; i < ARRAY_SIZE(mv88e6352_serdes_amp_to_val); ++i) {
+		if (mv88e6352_serdes_amp_to_val[i].mv == val) {
+			reg = mv88e6352_serdes_amp_to_val[i].regval;
+			found = true;
+			break;
+		}
+	}
+
+	if (!found)
+		return -EINVAL;
+
+	err = mv88e6352_serdes_read(chip, MV88E6352_SERDES_SPEC_CTRL2, &reg);
+	if (err)
+		return err;
+
+	reg = (reg & MV88E6352_SERDES_OUT_AMP_MASK) | val;
+
+	return mv88e6352_serdes_write(chip, MV88E6352_SERDES_SPEC_CTRL2, reg);
+}
+
 static int mv88e6393x_serdes_power_lane(struct mv88e6xxx_chip *chip, int lane,
 					bool on)
 {

@@ -27,6 +27,8 @@
 #define MV88E6352_SERDES_INT_FIBRE_ENERGY	BIT(4)
 #define MV88E6352_SERDES_INT_STATUS	0x13
 
+#define MV88E6352_SERDES_SPEC_CTRL2	0x1a
+#define MV88E6352_SERDES_OUT_AMP_MASK		0xfffc
 
 #define MV88E6341_PORT5_LANE		0x15
 

@@ -176,6 +178,9 @@ int mv88e6390_serdes_get_stats(struct mv88e6xxx_chip *chip, int port,
 int mv88e6390_serdes_get_regs_len(struct mv88e6xxx_chip *chip, int port);
 void mv88e6390_serdes_get_regs(struct mv88e6xxx_chip *chip, int port, void *_p);
 
+int mv88e6352_serdes_set_tx_amplitude(struct mv88e6xxx_chip *chip, int port,
+				      int val);
+
 /* Return the (first) SERDES lane address a port is using, -errno otherwise. */
 static inline int mv88e6xxx_serdes_get_lane(struct mv88e6xxx_chip *chip,
 					    int port)