3 files changed, 112 insertions, 1 deletions

diff --git a/drivers/net/phy/Makefile b/drivers/net/phy/Makefile
index f086a606a87e..33adb3df5f64 100644
--- a/drivers/net/phy/Makefile
+++ b/drivers/net/phy/Makefile
@@ -2,7 +2,7 @@
 # Makefile for Linux PHY drivers
 
 libphy-y			:= phy.o phy-c45.o phy-core.o phy_device.o \
-				   linkmode.o
+				   linkmode.o phy_link_topology.o
 mdio-bus-y			+= mdio_bus.o mdio_device.o
 
 ifdef CONFIG_MDIO_DEVICE
diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 159e71c1c972..d896c799f7c2 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -29,6 +29,7 @@
 #include <linux/phy.h>
 #include <linux/phylib_stubs.h>
 #include <linux/phy_led_triggers.h>
+#include <linux/phy_link_topology.h>
 #include <linux/pse-pd/pse.h>
 #include <linux/property.h>
 #include <linux/rtnetlink.h>
@@ -1526,6 +1527,10 @@ int phy_attach_direct(struct net_device *dev, struct phy_device *phydev,
 
 		if (phydev->sfp_bus_attached)
 			dev->sfp_bus = phydev->sfp_bus;
+
+		err = phy_link_topo_add_phy(dev, phydev, PHY_UPSTREAM_MAC, dev);
+		if (err)
+			goto error;
 	}
 
 	/* Some Ethernet drivers try to connect to a PHY device before
@@ -1953,6 +1958,7 @@ void phy_detach(struct phy_device *phydev)
 	if (dev) {
 		phydev->attached_dev->phydev = NULL;
 		phydev->attached_dev = NULL;
+		phy_link_topo_del_phy(dev, phydev);
 	}
 	phydev->phylink = NULL;
 
diff --git a/drivers/net/phy/phy_link_topology.c b/drivers/net/phy/phy_link_topology.c
new file mode 100644
index 000000000000..4a5d73002a1a
--- /dev/null
+++ b/drivers/net/phy/phy_link_topology.c
@@ -0,0 +1,105 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Infrastructure to handle all PHY devices connected to a given netdev,
+ * either directly or indirectly attached.
+ *
+ * Copyright (c) 2023 Maxime Chevallier<maxime.chevallier@bootlin.com>
+ */
+
+#include <linux/phy_link_topology.h>
+#include <linux/phy.h>
+#include <linux/rtnetlink.h>
+#include <linux/xarray.h>
+
+static int netdev_alloc_phy_link_topology(struct net_device *dev)
+{
+	struct phy_link_topology *topo;
+
+	topo = kzalloc(sizeof(*topo), GFP_KERNEL);
+	if (!topo)
+		return -ENOMEM;
+
+	xa_init_flags(&topo->phys, XA_FLAGS_ALLOC1);
+	topo->next_phy_index = 1;
+
+	dev->link_topo = topo;
+
+	return 0;
+}
+
+int phy_link_topo_add_phy(struct net_device *dev,
+			  struct phy_device *phy,
+			  enum phy_upstream upt, void *upstream)
+{
+	struct phy_link_topology *topo = dev->link_topo;
+	struct phy_device_node *pdn;
+	int ret;
+
+	if (!topo) {
+		ret = netdev_alloc_phy_link_topology(dev);
+		if (ret)
+			return ret;
+
+		topo = dev->link_topo;
+	}
+
+	pdn = kzalloc(sizeof(*pdn), GFP_KERNEL);
+	if (!pdn)
+		return -ENOMEM;
+
+	pdn->phy = phy;
+	switch (upt) {
+	case PHY_UPSTREAM_MAC:
+		pdn->upstream.netdev = (struct net_device *)upstream;
+		if (phy_on_sfp(phy))
+			pdn->parent_sfp_bus = pdn->upstream.netdev->sfp_bus;
+		break;
+	case PHY_UPSTREAM_PHY:
+		pdn->upstream.phydev = (struct phy_device *)upstream;
+		if (phy_on_sfp(phy))
+			pdn->parent_sfp_bus = pdn->upstream.phydev->sfp_bus;
+		break;
+	default:
+		ret = -EINVAL;
+		goto err;
+	}
+	pdn->upstream_type = upt;
+
+	/* Attempt to re-use a previously allocated phy_index */
+	if (phy->phyindex)
+		ret = xa_insert(&topo->phys, phy->phyindex, pdn, GFP_KERNEL);
+	else
+		ret = xa_alloc_cyclic(&topo->phys, &phy->phyindex, pdn,
+				      xa_limit_32b, &topo->next_phy_index,
+				      GFP_KERNEL);
+
+	if (ret)
+		goto err;
+
+	return 0;
+
+err:
+	kfree(pdn);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(phy_link_topo_add_phy);
+
+void phy_link_topo_del_phy(struct net_device *dev,
+			   struct phy_device *phy)
+{
+	struct phy_link_topology *topo = dev->link_topo;
+	struct phy_device_node *pdn;
+
+	if (!topo)
+		return;
+
+	pdn = xa_erase(&topo->phys, phy->phyindex);
+
+	/* We delete the PHY from the topology, however we don't re-set the
+	 * phy->phyindex field. If the PHY isn't gone, we can re-assign it the
+	 * same index next time it's added back to the topology
+	 */
+
+	kfree(pdn);
+}
+EXPORT_SYMBOL_GPL(phy_link_topo_del_phy);