[PATCH net-next 7/7] net: dsa: motorcomm: Add SerDes PCS
From: David Yang
Date: Wed Sep 09 2026 - 15:10:57 EST
Support in-band negotiation of the SerDes ports.
Signed-off-by: David Yang <mmyangfl@xxxxxxxxx>
---
drivers/net/dsa/motorcomm/Makefile | 1 +
drivers/net/dsa/motorcomm/chip.c | 78 ++++++----
drivers/net/dsa/motorcomm/chip.h | 8 +-
drivers/net/dsa/motorcomm/mdio_bus.c | 28 +++-
drivers/net/dsa/motorcomm/mdio_bus.h | 14 ++
drivers/net/dsa/motorcomm/pcs-921x.c | 209 +++++++++++++++++++++++++++
drivers/net/dsa/motorcomm/pcs.h | 13 ++
7 files changed, 323 insertions(+), 28 deletions(-)
create mode 100644 drivers/net/dsa/motorcomm/pcs-921x.c
create mode 100644 drivers/net/dsa/motorcomm/pcs.h
diff --git a/drivers/net/dsa/motorcomm/Makefile b/drivers/net/dsa/motorcomm/Makefile
index f7cce7eabbb8..1d2c1b3064c4 100644
--- a/drivers/net/dsa/motorcomm/Makefile
+++ b/drivers/net/dsa/motorcomm/Makefile
@@ -3,4 +3,5 @@ obj-$(CONFIG_NET_DSA_YT921X) += yt921x.o
yt921x-objs := chip.o
yt921x-$(CONFIG_NET_DSA_YT921X_LEDS) += leds.o
yt921x-objs += mdio_bus.o
+yt921x-objs += pcs-921x.o
yt921x-objs += smi.o
diff --git a/drivers/net/dsa/motorcomm/chip.c b/drivers/net/dsa/motorcomm/chip.c
index 85a31389050b..4780bb190ede 100644
--- a/drivers/net/dsa/motorcomm/chip.c
+++ b/drivers/net/dsa/motorcomm/chip.c
@@ -28,6 +28,7 @@
#include "chip.h"
#include "leds.h"
#include "mdio_bus.h"
+#include "pcs.h"
#include "smi.h"
struct yt921x_mib_desc {
@@ -3516,6 +3517,10 @@ yt921x_port_up(struct yt921x_priv *priv, int port, unsigned int mode,
if (ps == YT921X_SPEED_NUM)
return -EINVAL;
+ mask = YT921X_PORT_SPEED_M | YT921X_PORT_TX_MAC_EN |
+ YT921X_PORT_RX_MAC_EN | YT921X_PORT_TX_PAUSE |
+ YT921X_PORT_RX_PAUSE | YT921X_PORT_DUPLEX_FULL |
+ YT921X_PORT_CTRL_LINK_AN;
ctrl = YT921X_PORT_SPEED(ps);
if (duplex == DUPLEX_FULL)
ctrl |= YT921X_PORT_DUPLEX_FULL;
@@ -3524,7 +3529,9 @@ yt921x_port_up(struct yt921x_priv *priv, int port, unsigned int mode,
if (rx_pause)
ctrl |= YT921X_PORT_RX_PAUSE;
ctrl |= YT921X_PORT_RX_MAC_EN | YT921X_PORT_TX_MAC_EN;
- res = yt921x_reg_write(priv, YT921X_PORTn_CTRL(port), ctrl);
+ if (pp->serdes && pp->inband)
+ ctrl |= YT921X_PORT_CTRL_LINK_AN;
+ res = yt921x_reg_update_bits(priv, YT921X_PORTn_CTRL(port), mask, ctrl);
if (res)
return res;
@@ -3544,7 +3551,8 @@ yt921x_port_up(struct yt921x_priv *priv, int port, unsigned int mode,
if (rx_pause)
ctrl |= YT921X_SERDES_RX_PAUSE;
mask |= YT921X_SERDES_LINK;
- ctrl |= YT921X_SERDES_LINK;
+ if (!pp->inband)
+ ctrl |= YT921X_SERDES_LINK;
res = yt921x_reg_update_bits(priv, YT921X_SERDESn(port),
mask, ctrl);
if (res)
@@ -3575,7 +3583,6 @@ yt921x_port_config(struct yt921x_priv *priv, int port, unsigned int mode,
struct yt921x_port *pp = &priv->ports[port];
struct device *dev = to_device(priv);
u32 mask;
- u32 ctrl;
int res;
if (BIT(port) & info->internal_mask) {
@@ -3603,28 +3610,6 @@ yt921x_port_config(struct yt921x_priv *priv, int port, unsigned int mode,
if (res)
return res;
- mask = YT921X_SERDES_MODE_M;
- switch (interface) {
- case PHY_INTERFACE_MODE_SGMII:
- ctrl = YT921X_SERDES_MODE_SGMII;
- break;
- case PHY_INTERFACE_MODE_100BASEX:
- ctrl = YT921X_SERDES_MODE_100BASEX;
- break;
- case PHY_INTERFACE_MODE_1000BASEX:
- ctrl = YT921X_SERDES_MODE_1000BASEX;
- break;
- case PHY_INTERFACE_MODE_2500BASEX:
- ctrl = YT921X_SERDES_MODE_2500BASEX;
- break;
- default:
- return -EINVAL;
- }
- res = yt921x_reg_update_bits(priv, YT921X_SERDESn(port),
- mask, ctrl);
- if (res)
- return res;
-
pp->serdes = true;
break;
/* add XMII support here */
@@ -3639,6 +3624,24 @@ yt921x_port_config(struct yt921x_priv *priv, int port, unsigned int mode,
return -EINVAL;
}
+static struct phylink_pcs *
+yt921x_phylink_mac_select_pcs(struct phylink_config *config,
+ phy_interface_t interface)
+{
+ struct dsa_port *dp = dsa_phylink_to_port(config);
+ struct yt921x_priv *priv = to_yt921x_priv(dp->ds);
+
+ switch (interface) {
+ case PHY_INTERFACE_MODE_SGMII:
+ case PHY_INTERFACE_MODE_100BASEX:
+ case PHY_INTERFACE_MODE_1000BASEX:
+ case PHY_INTERFACE_MODE_2500BASEX:
+ return &priv->ports[dp->index].pcs;
+ default:
+ return NULL;
+ }
+}
+
static void
yt921x_phylink_mac_link_down(struct phylink_config *config, unsigned int mode,
phy_interface_t interface)
@@ -4226,6 +4229,11 @@ static int yt921x_chip_setup(struct yt921x_priv *priv)
if (res)
return res;
+ res = yt921x_reg_clear_bits(priv, YT921X_SERDES_CTRL,
+ YT921X_SERDES_CTRL_TEST);
+ if (res)
+ return res;
+
return 0;
}
@@ -4235,6 +4243,8 @@ static int yt921x_dsa_setup(struct dsa_switch *ds)
struct device *dev = to_device(priv);
struct device_node *np = dev->of_node;
struct device_node *child;
+ unsigned long mask;
+ int port;
int res;
mutex_lock(&priv->reg_lock);
@@ -4268,6 +4278,23 @@ static int yt921x_dsa_setup(struct dsa_switch *ds)
return -ENODEV;
}
+ mask = priv->info->serdes_mask;
+ for_each_set_bit(port, &mask, YT921X_PORT_NUM) {
+ struct yt921x_port *pp = &priv->ports[port];
+
+ pp->pcs.ops = &yt921x_phylink_pcs_ops;
+ pp->pcs.poll = true;
+
+ __set_bit(PHY_INTERFACE_MODE_SGMII,
+ pp->pcs.supported_interfaces);
+ __set_bit(PHY_INTERFACE_MODE_100BASEX,
+ pp->pcs.supported_interfaces);
+ __set_bit(PHY_INTERFACE_MODE_1000BASEX,
+ pp->pcs.supported_interfaces);
+ __set_bit(PHY_INTERFACE_MODE_2500BASEX,
+ pp->pcs.supported_interfaces);
+ }
+
mutex_lock(&priv->reg_lock);
res = yt921x_chip_setup(priv);
mutex_unlock(&priv->reg_lock);
@@ -4285,6 +4312,7 @@ static int yt921x_dsa_setup(struct dsa_switch *ds)
}
static const struct phylink_mac_ops yt921x_phylink_mac_ops = {
+ .mac_select_pcs = yt921x_phylink_mac_select_pcs,
.mac_link_down = yt921x_phylink_mac_link_down,
.mac_link_up = yt921x_phylink_mac_link_up,
.mac_config = yt921x_phylink_mac_config,
diff --git a/drivers/net/dsa/motorcomm/chip.h b/drivers/net/dsa/motorcomm/chip.h
index 21132a147d6b..42905e35928b 100644
--- a/drivers/net/dsa/motorcomm/chip.h
+++ b/drivers/net/dsa/motorcomm/chip.h
@@ -42,7 +42,7 @@
#define YT921X_PVID_SEL 0x80014
#define YT921X_PVID_SEL_SVID_PORTn(port) BIT(port)
#define YT921X_SERDES_CTRL 0x80028
-#define YT921X_SERDES_CTRL_PORTn_TEST(port) BIT((port) - 3)
+#define YT921X_SERDES_CTRL_TEST BIT(6)
#define YT921X_SERDES_CTRL_PORTn(port) BIT((port) - 8)
#define YT921X_IO_LEVEL 0x80030
#define YT9215_IO_LEVEL_NORMAL_M GENMASK(5, 4)
@@ -910,6 +910,8 @@ struct yt921x_port {
/* SerDes in use */
bool serdes:1;
+ /* Link from in-band status (PHYLINK_PCS_NEG_INBAND) */
+ bool inband:1;
/* BR_HAIRPIN_MODE */
bool hairpin:1;
/* BR_ISOLATED */
@@ -929,8 +931,12 @@ struct yt921x_port {
struct yt921x_led *leds[YT921X_LED_GROUP_NUM];
#endif
+
+ struct phylink_pcs pcs;
};
+#define pcs_to_yt921x_port(_pcs) container_of((_pcs), struct yt921x_port, pcs)
+
struct yt921x_reg_ops {
int (*read)(void *context, u32 reg, u32 *valp);
int (*write)(void *context, u32 reg, u32 val);
diff --git a/drivers/net/dsa/motorcomm/mdio_bus.c b/drivers/net/dsa/motorcomm/mdio_bus.c
index ba70343f3f33..5a47ed7bff99 100644
--- a/drivers/net/dsa/motorcomm/mdio_bus.c
+++ b/drivers/net/dsa/motorcomm/mdio_bus.c
@@ -19,8 +19,7 @@ static int yt921x_intif_wait(struct yt921x_priv *priv)
&val);
}
-static int
-yt921x_intif_read(struct yt921x_priv *priv, int port, int reg, u16 *valp)
+int yt921x_intif_read(struct yt921x_priv *priv, int port, int reg, u16 *valp)
{
struct device *dev = to_device(priv);
u32 mask;
@@ -86,6 +85,31 @@ yt921x_intif_write(struct yt921x_priv *priv, int port, int reg, u16 val)
return yt921x_intif_wait(priv);
}
+int
+yt921x_intif_modify_changed(struct yt921x_priv *priv, int port, int reg,
+ u16 mask, u16 val)
+{
+ int res;
+ u16 v;
+ u16 u;
+
+ res = yt921x_intif_read(priv, port, reg, &v);
+ if (res)
+ return res;
+
+ u = v;
+ u &= ~mask;
+ u |= val;
+ if (u == v)
+ return 0;
+
+ res = yt921x_intif_write(priv, port, reg, u);
+ if (res)
+ return res;
+
+ return 1;
+}
+
static int yt921x_mbus_int_read(struct mii_bus *mbus, int port, int reg)
{
struct yt921x_priv *priv = mbus->priv;
diff --git a/drivers/net/dsa/motorcomm/mdio_bus.h b/drivers/net/dsa/motorcomm/mdio_bus.h
index 261a71c637f5..d859226fede8 100644
--- a/drivers/net/dsa/motorcomm/mdio_bus.h
+++ b/drivers/net/dsa/motorcomm/mdio_bus.h
@@ -31,6 +31,20 @@
struct yt921x_priv;
+int yt921x_intif_read(struct yt921x_priv *priv, int port, int reg, u16 *valp);
+int yt921x_intif_modify_changed(struct yt921x_priv *priv, int port, int reg,
+ u16 mask, u16 val);
+
+static inline int
+yt921x_intif_modify(struct yt921x_priv *priv, int port, int reg, u16 mask,
+ u16 val)
+{
+ int res;
+
+ res = yt921x_intif_modify_changed(priv, port, reg, mask, val);
+ return res >= 0 ? 0 : res;
+}
+
int yt921x_mbus_int_init(struct yt921x_priv *priv, struct device_node *mnp);
int yt921x_mbus_ext_init(struct yt921x_priv *priv, struct device_node *mnp);
diff --git a/drivers/net/dsa/motorcomm/pcs-921x.c b/drivers/net/dsa/motorcomm/pcs-921x.c
new file mode 100644
index 000000000000..eef6e79c099b
--- /dev/null
+++ b/drivers/net/dsa/motorcomm/pcs-921x.c
@@ -0,0 +1,209 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2026 David Yang
+ */
+
+#include "chip.h"
+#include "mdio_bus.h"
+#include "pcs.h"
+#include "smi.h"
+
+#define to_device(priv) ((priv)->ds.dev)
+
+static int
+yt921x_serdes_config(struct yt921x_priv *priv, int port, unsigned int neg_mode,
+ phy_interface_t interface,
+ const unsigned long *advertising)
+{
+ bool inband = neg_mode & PHYLINK_PCS_NEG_INBAND;
+ struct yt921x_port *pp = &priv->ports[port];
+ bool changed = false;
+ u16 bmcr;
+ u32 mask;
+ u32 ctrl;
+ int adv;
+ int res;
+
+ switch (interface) {
+ case PHY_INTERFACE_MODE_SGMII:
+ ctrl = YT921X_SERDES_MODE_SGMII;
+ break;
+ case PHY_INTERFACE_MODE_100BASEX:
+ ctrl = YT921X_SERDES_MODE_100BASEX;
+ break;
+ case PHY_INTERFACE_MODE_1000BASEX:
+ ctrl = YT921X_SERDES_MODE_1000BASEX;
+ break;
+ case PHY_INTERFACE_MODE_2500BASEX:
+ ctrl = YT921X_SERDES_MODE_2500BASEX;
+ break;
+ default:
+ return -EOPNOTSUPP;
+ }
+
+ res = yt921x_reg_update_bits(priv, YT921X_SERDESn(port),
+ YT921X_SERDES_MODE_M, ctrl);
+ if (res)
+ return res;
+
+ mask = YT921X_PORT_CTRL_LINK_AN | YT921X_PORT_CTRL_PAUSE_AN;
+ ctrl = 0;
+ if (inband)
+ ctrl |= YT921X_PORT_CTRL_LINK_AN;
+ if (neg_mode == PHYLINK_PCS_NEG_INBAND_ENABLED)
+ ctrl |= YT921X_PORT_CTRL_PAUSE_AN;
+ res = yt921x_reg_update_bits(priv, YT921X_PORTn_CTRL(port), mask, ctrl);
+ if (res)
+ return res;
+
+ if (inband) {
+ res = yt921x_reg_clear_bits(priv, YT921X_SERDESn(port),
+ YT921X_SERDES_LINK);
+ if (res)
+ return res;
+ }
+
+ adv = phylink_mii_c22_pcs_encode_advertisement(interface, advertising);
+ if (adv >= 0) {
+ res = yt921x_intif_modify_changed(priv, port, MII_ADVERTISE,
+ U16_MAX, adv);
+ if (res < 0)
+ return res;
+
+ changed = !!res;
+ }
+
+ bmcr = neg_mode == PHYLINK_PCS_NEG_INBAND_ENABLED ? BMCR_ANENABLE : 0;
+ res = yt921x_intif_modify_changed(priv, port, MII_BMCR,
+ BMCR_ANENABLE | BMCR_ISOLATE, bmcr);
+ if (res < 0)
+ return res;
+
+ /* If the ANENABLE bit was changed, the PHY will restart negotiation,
+ * so we don't need to flag a change to trigger its own restart.
+ */
+ if (res)
+ changed = false;
+
+ pp->inband = inband;
+ return changed;
+}
+
+static unsigned int
+yt921x_phylink_pcs_inband_caps(struct phylink_pcs *pcs,
+ phy_interface_t interface)
+{
+ return LINK_INBAND_DISABLE | LINK_INBAND_ENABLE;
+}
+
+static void
+yt921x_phylink_pcs_get_state(struct phylink_pcs *pcs, unsigned int neg_mode,
+ struct phylink_link_state *state)
+{
+ struct yt921x_port *pp = pcs_to_yt921x_port(pcs);
+ struct yt921x_priv *priv = yt921x_port_to_priv(pp);
+ struct device *dev = to_device(priv);
+ int port = pp->index;
+ u16 bmsr;
+ u16 lpa;
+ int res;
+
+ mutex_lock(&priv->reg_lock);
+
+ res = yt921x_intif_read(priv, port, MII_BMSR, &bmsr);
+ if (res)
+ goto out;
+
+ res = yt921x_intif_read(priv, port, MII_LPA, &lpa);
+
+out:
+ mutex_unlock(&priv->reg_lock);
+
+ if (res) {
+ dev_err(dev, "Failed to %s PCS port %d: %i\n", "get state of",
+ port, res);
+ state->link = false;
+ return;
+ }
+
+ phylink_mii_c22_pcs_decode_state(state, neg_mode, bmsr, lpa);
+}
+
+static void yt921x_phylink_pcs_an_restart(struct phylink_pcs *pcs)
+{
+ struct yt921x_port *pp = pcs_to_yt921x_port(pcs);
+ struct yt921x_priv *priv = yt921x_port_to_priv(pp);
+ struct device *dev = to_device(priv);
+ int port = pp->index;
+ int res;
+
+ mutex_lock(&priv->reg_lock);
+ res = yt921x_intif_modify(priv, port, MII_BMCR, BMCR_ANRESTART,
+ BMCR_ANRESTART);
+ mutex_unlock(&priv->reg_lock);
+
+ if (res)
+ dev_err(dev, "Failed to %s PCS port %d: %i\n", "restart",
+ port, res);
+}
+
+static void yt921x_phylink_pcs_disable(struct phylink_pcs *pcs)
+{
+ struct yt921x_port *pp = pcs_to_yt921x_port(pcs);
+ struct yt921x_priv *priv = yt921x_port_to_priv(pp);
+ struct device *dev = to_device(priv);
+ int port = pp->index;
+ int res;
+
+ mutex_lock(&priv->reg_lock);
+ res = yt921x_intif_modify(priv, port, MII_BMCR, BMCR_PDOWN,
+ BMCR_PDOWN);
+ mutex_unlock(&priv->reg_lock);
+
+ if (res)
+ dev_err(dev, "Failed to %s PCS port %d: %i\n", "power down",
+ port, res);
+}
+
+static int yt921x_phylink_pcs_enable(struct phylink_pcs *pcs)
+{
+ struct yt921x_port *pp = pcs_to_yt921x_port(pcs);
+ struct yt921x_priv *priv = yt921x_port_to_priv(pp);
+ int port = pp->index;
+ int res;
+
+ mutex_lock(&priv->reg_lock);
+ res = yt921x_intif_modify(priv, port, MII_BMCR,
+ BMCR_PDOWN | BMCR_ANRESTART, BMCR_ANRESTART);
+ mutex_unlock(&priv->reg_lock);
+
+ return res;
+}
+
+static int
+yt921x_phylink_pcs_config(struct phylink_pcs *pcs, unsigned int neg_mode,
+ phy_interface_t interface,
+ const unsigned long *advertising,
+ bool permit_pause_to_mac)
+{
+ struct yt921x_port *pp = pcs_to_yt921x_port(pcs);
+ struct yt921x_priv *priv = yt921x_port_to_priv(pp);
+ int port = pp->index;
+ int res;
+
+ mutex_lock(&priv->reg_lock);
+ res = yt921x_serdes_config(priv, port, neg_mode, interface,
+ advertising);
+ mutex_unlock(&priv->reg_lock);
+
+ return res;
+}
+
+const struct phylink_pcs_ops yt921x_phylink_pcs_ops = {
+ .pcs_inband_caps = yt921x_phylink_pcs_inband_caps,
+ .pcs_get_state = yt921x_phylink_pcs_get_state,
+ .pcs_an_restart = yt921x_phylink_pcs_an_restart,
+ .pcs_disable = yt921x_phylink_pcs_disable,
+ .pcs_enable = yt921x_phylink_pcs_enable,
+ .pcs_config = yt921x_phylink_pcs_config,
+};
diff --git a/drivers/net/dsa/motorcomm/pcs.h b/drivers/net/dsa/motorcomm/pcs.h
new file mode 100644
index 000000000000..42426558086a
--- /dev/null
+++ b/drivers/net/dsa/motorcomm/pcs.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (c) 2026 David Yang
+ */
+
+#ifndef _YT_PCS_H
+#define _YT_PCS_H
+
+#include <linux/phylink.h>
+
+extern const struct phylink_pcs_ops yt921x_phylink_pcs_ops;
+
+#endif
--
2.53.0