net: phy: Introduce PHY ports representation

Ethernet provides a wide variety of layer 1 protocols and standards for
data transmission. The front-facing ports of an interface have their own
complexity and configurability.

Introduce a representation of these front-facing ports. The current code
is minimalistic and only support ports controlled by PHY devices, but
the plan is to extend that to SFP as well as raw Ethernet MACs that
don't use PHY devices.

This minimal port representation allows describing the media and number
of pairs of a BaseT port. From that information, we can derive the
linkmodes usable on the port, which can be used to limit the
capabilities of an interface.

For now, the port pairs and medium is derived from devicetree, defined
by the PHY driver, or populated with default values (as we assume that
all PHYs expose at least one port).

The typical example is 100M ethernet. 100BaseTX works using only 2
pairs on a Cat 5 cables. However, in the situation where a 10/100/1000
capable PHY is wired to its RJ45 port through 2 pairs only, we have no
way of detecting that. The "max-speed" DT property can be used, but a
more accurate representation can be used :

mdi {
	connector-0 {
		media = "BaseT";
		pairs = <2>;
	};
};

From that information, we can derive the max speed reachable on the
port.

Another benefit of having that is to avoid vendor-specific DT properties
(micrel,fiber-mode or ti,fiber-mode).

This basic representation is meant to be expanded, by the introduction
of port ops, userspace listing of ports, and support for multi-port
devices.

Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/20260108080041.553250-4-maxime.chevallier@bootlin.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 192 insertions, 0 deletions

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 81984d4ebb7c..f9cacdfb516e 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -30,6 +30,7 @@
 #include <linux/phylib_stubs.h>
 #include <linux/phy_led_triggers.h>
 #include <linux/phy_link_topology.h>
+#include <linux/phy_port.h>
 #include <linux/pse-pd/pse.h>
 #include <linux/property.h>
 #include <linux/ptp_clock_kernel.h>
@@ -845,6 +846,13 @@ struct phy_device *phy_device_create(struct mii_bus *bus, int addr, u32 phy_id,
 
 	dev->state = PHY_DOWN;
 	INIT_LIST_HEAD(&dev->leds);
+	INIT_LIST_HEAD(&dev->ports);
+
+	/* The driver's probe function must change that to the real number
+	 * of ports possible on the PHY. We assume by default we are dealing
+	 * with a single-port PHY
+	 */
+	dev->max_n_ports = 1;
 
 	mutex_init(&dev->lock);
 	INIT_DELAYED_WORK(&dev->state_queue, phy_state_machine);
@@ -1590,6 +1598,51 @@ void phy_sfp_detach(void *upstream, struct sfp_bus *bus)
 }
 EXPORT_SYMBOL(phy_sfp_detach);
 
+static int phy_add_port(struct phy_device *phydev, struct phy_port *port)
+{
+	int ret = 0;
+
+	if (phydev->n_ports == phydev->max_n_ports)
+		return -EBUSY;
+
+	/* We set all ports as active by default, PHY drivers may deactivate
+	 * them (when unused)
+	 */
+	port->active = true;
+
+	if (port->is_mii) {
+		if (phydev->drv && phydev->drv->attach_mii_port)
+			ret = phydev->drv->attach_mii_port(phydev, port);
+	} else {
+		if (phydev->drv && phydev->drv->attach_mdi_port)
+			ret = phydev->drv->attach_mdi_port(phydev, port);
+	}
+
+	if (ret)
+		return ret;
+
+	/* The PHY driver might have added, removed or set medium/pairs info,
+	 * so update the port supported accordingly.
+	 */
+	phy_port_update_supported(port);
+
+	list_add(&port->head, &phydev->ports);
+
+	phydev->n_ports++;
+
+	return 0;
+}
+
+static void phy_del_port(struct phy_device *phydev, struct phy_port *port)
+{
+	if (!phydev->n_ports)
+		return;
+
+	list_del(&port->head);
+
+	phydev->n_ports--;
+}
+
 /**
  * phy_sfp_probe - probe for a SFP cage attached to this PHY device
  * @phydev: Pointer to phy_device
@@ -3325,6 +3378,138 @@ exit:
 	return 0;
 }
 
+static void phy_cleanup_ports(struct phy_device *phydev)
+{
+	struct phy_port *tmp, *port;
+
+	list_for_each_entry_safe(port, tmp, &phydev->ports, head) {
+		phy_del_port(phydev, port);
+		phy_port_destroy(port);
+	}
+}
+
+static int phy_default_setup_single_port(struct phy_device *phydev)
+{
+	struct phy_port *port = phy_port_alloc();
+	unsigned long mode;
+
+	if (!port)
+		return -ENOMEM;
+
+	port->parent_type = PHY_PORT_PHY;
+	port->phy = phydev;
+
+	/* Let the PHY driver know that this port was never described anywhere.
+	 * This is the usual case, where we assume single-port PHY devices with
+	 * no SFP. In that case, the port supports exactly the same thing as
+	 * the PHY itself.
+	 *
+	 * However, this can also be because we have a combo-port PHY, with
+	 * only one port described in DT, through SFP for example.
+	 *
+	 * In that case, the PHY driver will be in charge of saying what we can
+	 * do on that non-represented port.
+	 */
+	port->not_described = true;
+	linkmode_copy(port->supported, phydev->supported);
+	port->mediums = phy_caps_mediums_from_linkmodes(port->supported);
+
+	for_each_set_bit(mode, port->supported, __ETHTOOL_LINK_MODE_MASK_NBITS)
+		port->pairs = max_t(int, port->pairs,
+				    ethtool_linkmode_n_pairs(mode));
+
+	phy_add_port(phydev, port);
+
+	return 0;
+}
+
+static int of_phy_ports(struct phy_device *phydev)
+{
+	struct device_node *node = phydev->mdio.dev.of_node;
+	struct device_node *mdi;
+	struct phy_port *port;
+	int err;
+
+	if (!IS_ENABLED(CONFIG_OF_MDIO))
+		return 0;
+
+	if (!node)
+		return 0;
+
+	mdi = of_get_child_by_name(node, "mdi");
+	if (!mdi)
+		return 0;
+
+	for_each_available_child_of_node_scoped(mdi, port_node) {
+		port = phy_of_parse_port(port_node);
+		if (IS_ERR(port)) {
+			err = PTR_ERR(port);
+			goto out_err;
+		}
+
+		port->parent_type = PHY_PORT_PHY;
+		port->phy = phydev;
+		err = phy_add_port(phydev, port);
+		if (err) {
+			phy_port_destroy(port);
+			goto out_err;
+		}
+	}
+	of_node_put(mdi);
+
+	return 0;
+
+out_err:
+	phy_cleanup_ports(phydev);
+	of_node_put(mdi);
+	return err;
+}
+
+static int phy_setup_ports(struct phy_device *phydev)
+{
+	__ETHTOOL_DECLARE_LINK_MODE_MASK(ports_supported);
+	struct phy_port *port;
+	int ret;
+
+	ret = of_phy_ports(phydev);
+	if (ret)
+		return ret;
+
+	if (phydev->n_ports < phydev->max_n_ports) {
+		ret = phy_default_setup_single_port(phydev);
+		if (ret)
+			goto out;
+	}
+
+	linkmode_zero(ports_supported);
+
+	/* Aggregate the supported modes, which are made-up of :
+	 *  - What the PHY itself supports
+	 *  - What the sum of all ports support
+	 */
+	list_for_each_entry(port, &phydev->ports, head)
+		if (port->active)
+			linkmode_or(ports_supported, ports_supported,
+				    port->supported);
+
+	if (!linkmode_empty(ports_supported))
+		linkmode_and(phydev->supported, phydev->supported,
+			     ports_supported);
+
+	/* For now, the phy->port field is set as the first active port's type */
+	list_for_each_entry(port, &phydev->ports, head)
+		if (port->active) {
+			phydev->port = phy_port_get_type(port);
+			break;
+		}
+
+	return 0;
+
+out:
+	phy_cleanup_ports(phydev);
+	return ret;
+}
+
 /**
  * fwnode_mdio_find_device - Given a fwnode, find the mdio_device
  * @fwnode: pointer to the mdio_device's fwnode
@@ -3462,6 +3647,11 @@ static int phy_probe(struct device *dev)
 		phydev->is_gigabit_capable = 1;
 
 	of_set_phy_supported(phydev);
+
+	err = phy_setup_ports(phydev);
+	if (err)
+		goto out;
+
 	phy_advertise_supported(phydev);
 
 	/* Get PHY default EEE advertising modes and handle them as potentially
@@ -3537,6 +3727,8 @@ static int phy_remove(struct device *dev)
 
 	phydev->state = PHY_DOWN;
 
+	phy_cleanup_ports(phydev);
+
 	sfp_bus_del_upstream(phydev->sfp_bus);
 	phydev->sfp_bus = NULL;