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

Holger Brunck
2021-12-07T19:08:02Z

The mv88e6352, mv88e6240 and mv88e6176 have a serdes interface. This patch
allows to configure the output swing to a desired value in the
devicetree node of the port. As the chips only supports eight dedicated
values we return EINVAL if the value in the DTS does not match.

CC: Andrew Lunn <andrew@lunn.ch>
CC: Jakub Kicinski <kuba@kernel.org>
CC: Marek Behún <kabel@kernel.org>
Signed-off-by: Holger Brunck <holger.brunck@hitachienergy.com>
---
drivers/net/dsa/mv88e6xxx/chip.c | 18 ++++++++++++++
drivers/net/dsa/mv88e6xxx/chip.h | 4 ++++
drivers/net/dsa/mv88e6xxx/serdes.c | 48 ++++++++++++++++++++++++++++++++++++++
drivers/net/dsa/mv88e6xxx/serdes.h | 5 ++++
4 files changed, 75 insertions(+)

diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c
index f00cbf5..1d337dd8 100644
--- a/drivers/net/dsa/mv88e6xxx/chip.c
+++ b/drivers/net/dsa/mv88e6xxx/chip.c
@@ -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,
};

diff --git a/drivers/net/dsa/mv88e6xxx/chip.h b/drivers/net/dsa/mv88e6xxx/chip.h
index 8271b8a..ef5fc26 100644
--- a/drivers/net/dsa/mv88e6xxx/chip.h
+++ b/drivers/net/dsa/mv88e6xxx/chip.h
@@ -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);
diff --git a/drivers/net/dsa/mv88e6xxx/serdes.c b/drivers/net/dsa/mv88e6xxx/serdes.c
index 5527301..448535c 100644
--- a/drivers/net/dsa/mv88e6xxx/serdes.c
+++ b/drivers/net/dsa/mv88e6xxx/serdes.c
@@ -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)
{
diff --git a/drivers/net/dsa/mv88e6xxx/serdes.h b/drivers/net/dsa/mv88e6xxx/serdes.h
index 8dd8ed2..526139c 100644
--- a/drivers/net/dsa/mv88e6xxx/serdes.h
+++ b/drivers/net/dsa/mv88e6xxx/serdes.h
@@ -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)
--
1.8.3.1