[PATCH net-next v13 07/18] net: phy: Create a phy_port for PHY-driven SFPs

Maxime Chevallier
2025-09-21T16:06:38Z

Some PHY devices may be used as media-converters to drive SFP ports (for
example, to allow using SFP when the SoC can only output RGMII). This is
already supported to some extend by allowing PHY drivers to registers
themselves as being SFP upstream.

However, the logic to drive the SFP can actually be split to a per-port
control logic, allowing support for multi-port PHYs, or PHYs that can
either drive SFPs or Copper.

To that extent, create a phy_port when registering an SFP bus onto a
PHY. This port is considered a "serdes" port, in that it can feed data
to anther entity on the link. The PHY driver needs to specify the
various PHY_INTERFACE_MODE_XXX that this port supports.

Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Tested-by: Oleksij Rempel <o.rempel@pengutronix.de>
Tested-by: Florian Fainelli <florian.fainelli@broadcom.com>
Tested-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
---
drivers/net/phy/phy_device.c | 24 ++++++++++++++++++++++++
drivers/net/phy/phy_port.c | 15 +++++++++++++++
2 files changed, 39 insertions(+)

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index e8708bc9739c..786e20307943 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -1631,6 +1631,26 @@ static void phy_del_port(struct phy_device *phydev, struct phy_port *port)
phydev->n_ports--;
}

+static int phy_setup_sfp_port(struct phy_device *phydev)
+{
+ struct phy_port *port = phy_port_alloc();
+
+ if (!port)
+ return -ENOMEM;
+
+ port->parent_type = PHY_PORT_PHY;
+ port->phy = phydev;
+
+ /* The PHY is a media converter, the port connected to the SFP cage
+ * is a MII port.
+ */
+ port->is_mii = true;
+
+ phy_add_port(phydev, port);
+
+ return 0;
+}
+
/**
* phy_sfp_probe - probe for a SFP cage attached to this PHY device
* @phydev: Pointer to phy_device
@@ -1652,6 +1672,10 @@ int phy_sfp_probe(struct phy_device *phydev,
ret = sfp_bus_add_upstream(bus, phydev, ops);
sfp_bus_put(bus);
}
+
+ if (phydev->sfp_bus)
+ ret = phy_setup_sfp_port(phydev);
+
return ret;
}
EXPORT_SYMBOL(phy_sfp_probe);
diff --git a/drivers/net/phy/phy_port.c b/drivers/net/phy/phy_port.c
index cf897ed74c4c..6fecaa68350e 100644
--- a/drivers/net/phy/phy_port.c
+++ b/drivers/net/phy/phy_port.c
@@ -113,6 +113,21 @@ void phy_port_update_supported(struct phy_port *port)
phy_caps_medium_get_supported(supported, i, port->lanes);
linkmode_or(port->supported, port->supported, supported);
}
+
+ /* Serdes ports supported through SFP may not have any medium set,
+ * as they will output PHY_INTERFACE_MODE_XXX modes. In that case, derive
+ * the supported list based on these interfaces
+ */
+ if (port->is_mii && linkmode_empty(supported)) {
+ unsigned long interface, link_caps = 0;
+
+ /* Get each interface's caps */
+ for_each_set_bit(interface, port->interfaces,
+ PHY_INTERFACE_MODE_MAX)
+ link_caps |= phy_caps_from_interface(interface);
+
+ phy_caps_linkmodes(link_caps, port->supported);
+ }
}
EXPORT_SYMBOL_GPL(phy_port_update_supported);

--
2.49.0