[PATCH net-next v15 07/15] net: phy: Introduce generic SFP handling for PHY drivers

Maxime Chevallier
2025-11-06T09:48:24Z

There are currently 4 PHY drivers that can drive downstream SFPs:
marvell.c, marvell10g.c, at803x.c and marvell-88x2222.c. Most of the
logic is boilerplate, either calling into generic phylib helpers (for
SFP PHY attach, bus attach, etc.) or performing the same tasks with a
bit of validation :
- Getting the module's expected interface mode
- Making sure the PHY supports it
- Optionaly perform some configuration to make sure the PHY outputs
the right mode

This can be made more generic by leveraging the phy_port, and its
configure_mii() callback which allows setting a port's interfaces when
the port is a serdes.

Introduce a generic PHY SFP support. If a driver doesn't probe the SFP
bus itself, but an SFP phandle is found in devicetree/firmware, then the
generic PHY SFP support will be used, relying on port ops.

PHY driver need to :
- Register a .attach_port() callback
- When a serdes port is registered to the PHY, drivers must set
port->interfaces to the set of PHY_INTERFACE_MODE the port can output
- If the port has limitations regarding speed, duplex and aneg, the
port can also fine-tune the final linkmodes that can be supported
- The port may register a set of ops, including .configure_mii(), that
will be called at module_insert time to adjust the interface based on
the module detected.

Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
---
drivers/net/phy/phy_device.c | 107 +++++++++++++++++++++++++++++++++++
include/linux/phy.h | 2 +
include/linux/phy_port.h | 2 +
3 files changed, 111 insertions(+)

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 8e51de932e54..9e39424164c3 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -1598,6 +1598,86 @@ void phy_sfp_detach(void *upstream, struct sfp_bus *bus)
}
EXPORT_SYMBOL(phy_sfp_detach);

+static int phy_sfp_module_insert(void *upstream, const struct sfp_eeprom_id *id)
+{
+ __ETHTOOL_DECLARE_LINK_MODE_MASK(sfp_support);
+ struct phy_device *phydev = upstream;
+ const struct sfp_module_caps *caps;
+ struct phy_port *port;
+
+ phy_interface_t iface;
+
+ linkmode_zero(sfp_support);
+
+ port = phy_get_sfp_port(phydev);
+ if (!port)
+ return -EINVAL;
+
+ caps = sfp_get_module_caps(phydev->sfp_bus);
+
+ linkmode_and(sfp_support, port->supported, caps->link_modes);
+ if (linkmode_empty(sfp_support)) {
+ dev_err(&phydev->mdio.dev, "incompatible SFP module inserted, no common linkmode\n");
+ return -EINVAL;
+ }
+
+ iface = sfp_select_interface(phydev->sfp_bus, sfp_support);
+ if (iface == PHY_INTERFACE_MODE_NA) {
+ dev_err(&phydev->mdio.dev, "PHY %s does not support the SFP module's requested MII interfaces\n",
+ phydev_name(phydev));
+ return -EINVAL;
+ }
+
+ if (phydev->n_ports == 1)
+ phydev->port = caps->port;
+
+ if (port->ops && port->ops->configure_mii)
+ return port->ops->configure_mii(port, true, iface);
+
+ return 0;
+}
+
+static void phy_sfp_module_remove(void *upstream)
+{
+ struct phy_device *phydev = upstream;
+ struct phy_port *port = phy_get_sfp_port(phydev);
+
+ if (port && port->ops && port->ops->configure_mii)
+ port->ops->configure_mii(port, false, PHY_INTERFACE_MODE_NA);
+
+ if (phydev->n_ports == 1)
+ phydev->port = PORT_NONE;
+}
+
+static void phy_sfp_link_up(void *upstream)
+{
+ struct phy_device *phydev = upstream;
+ struct phy_port *port = phy_get_sfp_port(phydev);
+
+ if (port && port->ops && port->ops->link_up)
+ port->ops->link_up(port);
+}
+
+static void phy_sfp_link_down(void *upstream)
+{
+ struct phy_device *phydev = upstream;
+ struct phy_port *port = phy_get_sfp_port(phydev);
+
+ if (port && port->ops && port->ops->link_down)
+ port->ops->link_down(port);
+}
+
+static const struct sfp_upstream_ops sfp_phydev_ops = {
+ .attach = phy_sfp_attach,
+ .detach = phy_sfp_detach,
+ .module_insert = phy_sfp_module_insert,
+ .module_remove = phy_sfp_module_remove,
+ .link_up = phy_sfp_link_up,
+ .link_down = phy_sfp_link_down,
+ .connect_phy = phy_sfp_connect_phy,
+ .disconnect_phy = phy_sfp_disconnect_phy,
+};
+
static int phy_add_port(struct phy_device *phydev, struct phy_port *port)
{
int ret = 0;
@@ -1657,6 +1737,7 @@ static int phy_setup_sfp_port(struct phy_device *phydev)
* is a MII port.
*/
port->is_mii = true;
+ port->is_sfp = true;

phy_add_port(phydev, port);

@@ -3497,6 +3578,13 @@ static int phy_setup_ports(struct phy_device *phydev)
if (ret)
return ret;

+ /* Use generic SFP probing only if the driver didn't do so already */
+ if (!phydev->sfp_bus) {
+ ret = phy_sfp_probe(phydev, &sfp_phydev_ops);
+ if (ret)
+ goto out;
+ }
+
if (phydev->n_ports < phydev->max_n_ports) {
ret = phy_default_setup_single_port(phydev);
if (ret)
@@ -3532,6 +3620,25 @@ static int phy_setup_ports(struct phy_device *phydev)
return ret;
}

+/**
+ * phy_get_sfp_port() - Returns the first valid SFP port of a PHY
+ * @phydev: pointer to the PHY device to get the SFP port from
+ *
+ * Returns: The first active SFP (serdes) port of a PHY device, NULL if none
+ * exist.
+ */
+struct phy_port *phy_get_sfp_port(struct phy_device *phydev)
+{
+ struct phy_port *port;
+
+ list_for_each_entry(port, &phydev->ports, head)
+ if (port->active && port->is_sfp)
+ return port;
+
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(phy_get_sfp_port);
+
/**
* fwnode_mdio_find_device - Given a fwnode, find the mdio_device
* @fwnode: pointer to the mdio_device's fwnode
diff --git a/include/linux/phy.h b/include/linux/phy.h
index 0d33669f3471..2a9763e923fd 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -2420,6 +2420,8 @@ int __phy_hwtstamp_set(struct phy_device *phydev,
struct kernel_hwtstamp_config *config,
struct netlink_ext_ack *extack);

+struct phy_port *phy_get_sfp_port(struct phy_device *phydev);
+
extern const struct bus_type mdio_bus_type;
extern const struct class mdio_bus_class;

diff --git a/include/linux/phy_port.h b/include/linux/phy_port.h
index ce0208fbccf7..550c3f4ab19f 100644
--- a/include/linux/phy_port.h
+++ b/include/linux/phy_port.h
@@ -49,6 +49,7 @@ struct phy_port_ops {
* @active: Indicates if the port is currently part of the active link.
* @is_mii: Indicates if this port is MII (Media Independent Interface),
* or MDI (Media Dependent Interface).
+ * @is_sfp: Indicates if this port drives an SFP cage.
*/
struct phy_port {
struct list_head head;
@@ -67,6 +68,7 @@ struct phy_port {
unsigned int not_described:1;
unsigned int active:1;
unsigned int is_mii:1;
+ unsigned int is_sfp:1;
};

struct phy_port *phy_port_alloc(void);
--
2.49.0