net: phy: Introduce ethernet link topology representation
authorMaxime Chevallier <maxime.chevallier@bootlin.com>
Thu, 4 Apr 2024 09:29:51 +0000 (11:29 +0200)
committerDavid S. Miller <davem@davemloft.net>
Sat, 6 Apr 2024 17:25:14 +0000 (18:25 +0100)
Link topologies containing multiple network PHYs attached to the same
net_device can be found when using a PHY as a media converter for use
with an SFP connector, on which an SFP transceiver containing a PHY can
be used.

With the current model, the transceiver's PHY can't be used for
operations such as cable testing, timestamping, macsec offload, etc.

The reason being that most of the logic for these configuration, coming
from either ethtool netlink or ioctls tend to use netdev->phydev, which
in multi-phy systems will reference the PHY closest to the MAC.

Introduce a numbering scheme allowing to enumerate PHY devices that
belong to any netdev, which can in turn allow userspace to take more
precise decisions with regard to each PHY's configuration.

The numbering is maintained per-netdev, in a phy_device_list.
The numbering works similarly to a netdevice's ifindex, with
identifiers that are only recycled once INT_MAX has been reached.

This prevents races that could occur between PHY listing and SFP
transceiver removal/insertion.

The identifiers are assigned at phy_attach time, as the numbering
depends on the netdevice the phy is attached to. The PHY index can be
re-used for PHYs that are persistent.

Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
MAINTAINERS
drivers/net/phy/Makefile
drivers/net/phy/phy_device.c
drivers/net/phy/phy_link_topology.c [new file with mode: 0644]
include/linux/netdevice.h
include/linux/phy.h
include/linux/phy_link_topology.h [new file with mode: 0644]
include/linux/phy_link_topology_core.h [new file with mode: 0644]
include/uapi/linux/ethtool.h
net/core/dev.c

index 046598b471b78fab902f1e3d084beded07b21e21..4745ea94d46364e13e32d74b0c01816bd7dab545 100644 (file)
@@ -8015,6 +8015,8 @@ F:        include/linux/mii.h
 F:     include/linux/of_net.h
 F:     include/linux/phy.h
 F:     include/linux/phy_fixed.h
+F:     include/linux/phy_link_topology.h
+F:     include/linux/phy_link_topology_core.h
 F:     include/linux/phylib_stubs.h
 F:     include/linux/platform_data/mdio-bcm-unimac.h
 F:     include/linux/platform_data/mdio-gpio.h
index 202ed7f450da6f9c9286b1b00e5c27cc8dc596a9..1d8be374915f302c79b7c4af7a9d633961c73cb0 100644 (file)
@@ -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
index 6c6ec947570929536fe321c4063eefd32afb6649..452fc8b3406deb5020e809347abac68711bdc06e 100644 (file)
@@ -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>
@@ -1511,6 +1512,11 @@ 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->link_topo, phydev,
+                                           PHY_UPSTREAM_MAC, dev);
+               if (err)
+                       goto error;
        }
 
        /* Some Ethernet drivers try to connect to a PHY device before
@@ -1938,6 +1944,7 @@ void phy_detach(struct phy_device *phydev)
        if (dev) {
                phydev->attached_dev->phydev = NULL;
                phydev->attached_dev = NULL;
+               phy_link_topo_del_phy(dev->link_topo, 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 (file)
index 0000000..985941c
--- /dev/null
@@ -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/netdevice.h>
+#include <linux/phy.h>
+#include <linux/rtnetlink.h>
+#include <linux/xarray.h>
+
+struct phy_link_topology *phy_link_topo_create(struct net_device *dev)
+{
+       struct phy_link_topology *topo;
+
+       topo = kzalloc(sizeof(*topo), GFP_KERNEL);
+       if (!topo)
+               return ERR_PTR(-ENOMEM);
+
+       xa_init_flags(&topo->phys, XA_FLAGS_ALLOC1);
+       topo->next_phy_index = 1;
+
+       return topo;
+}
+
+void phy_link_topo_destroy(struct phy_link_topology *topo)
+{
+       if (!topo)
+               return;
+
+       xa_destroy(&topo->phys);
+       kfree(topo);
+}
+
+int phy_link_topo_add_phy(struct phy_link_topology *topo,
+                         struct phy_device *phy,
+                         enum phy_upstream upt, void *upstream)
+{
+       struct phy_device_node *pdn;
+       int ret;
+
+       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);
+
+               /* Errors could be either -ENOMEM or -EBUSY. If the phy has an
+                * index, and there's another entry at the same index, this is
+                * unexpected and we still error-out
+                */
+               if (ret)
+                       goto err;
+               return 0;
+       }
+
+       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 phy_link_topology *topo,
+                          struct phy_device *phy)
+{
+       struct phy_device_node *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);
index 0c198620ac93e03d811e4f734c779c8bce6e8203..d45f330d083df11eeb0fbe49b9be22a1bb23182d 100644 (file)
@@ -40,7 +40,6 @@
 #include <net/dcbnl.h>
 #endif
 #include <net/netprio_cgroup.h>
-
 #include <linux/netdev_features.h>
 #include <linux/neighbour.h>
 #include <uapi/linux/netdevice.h>
@@ -52,6 +51,7 @@
 #include <net/net_trackers.h>
 #include <net/net_debug.h>
 #include <net/dropreason-core.h>
+#include <linux/phy_link_topology_core.h>
 
 struct netpoll_info;
 struct device;
@@ -1974,6 +1974,7 @@ enum netdev_reg_state {
  *     @fcoe_ddp_xid:  Max exchange id for FCoE LRO by ddp
  *
  *     @priomap:       XXX: need comments on this one
+ *     @link_topo:     Physical link topology tracking attached PHYs
  *     @phydev:        Physical device may attach itself
  *                     for hardware timestamping
  *     @sfp_bus:       attached &struct sfp_bus structure.
@@ -2364,6 +2365,7 @@ struct net_device {
 #if IS_ENABLED(CONFIG_CGROUP_NET_PRIO)
        struct netprio_map __rcu *priomap;
 #endif
+       struct phy_link_topology        *link_topo;
        struct phy_device       *phydev;
        struct sfp_bus          *sfp_bus;
        struct lock_class_key   *qdisc_tx_busylock;
index e6e83304558e07b1133b42302261639068e192b3..8c848c79b1fda6ebd46ff17c511c72e3af000836 100644 (file)
@@ -550,6 +550,9 @@ struct macsec_ops;
  * @drv: Pointer to the driver for this PHY instance
  * @devlink: Create a link between phy dev and mac dev, if the external phy
  *           used by current mac interface is managed by another mac interface.
+ * @phyindex: Unique id across the phy's parent tree of phys to address the PHY
+ *           from userspace, similar to ifindex. A zero index means the PHY
+ *           wasn't assigned an id yet.
  * @phy_id: UID for this device found during discovery
  * @c45_ids: 802.3-c45 Device Identifiers if is_c45.
  * @is_c45:  Set to true if this PHY uses clause 45 addressing.
@@ -650,6 +653,7 @@ struct phy_device {
 
        struct device_link *devlink;
 
+       u32 phyindex;
        u32 phy_id;
 
        struct phy_c45_device_ids c45_ids;
diff --git a/include/linux/phy_link_topology.h b/include/linux/phy_link_topology.h
new file mode 100644 (file)
index 0000000..6b79feb
--- /dev/null
@@ -0,0 +1,72 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * PHY device list allow maintaining a list of PHY devices that are
+ * part of a netdevice's link topology. PHYs can for example be chained,
+ * as is the case when using a PHY that exposes an SFP module, on which an
+ * SFP transceiver that embeds a PHY is connected.
+ *
+ * This list can then be used by userspace to leverage individual PHY
+ * capabilities.
+ */
+#ifndef __PHY_LINK_TOPOLOGY_H
+#define __PHY_LINK_TOPOLOGY_H
+
+#include <linux/ethtool.h>
+#include <linux/phy_link_topology_core.h>
+
+struct xarray;
+struct phy_device;
+struct net_device;
+struct sfp_bus;
+
+struct phy_device_node {
+       enum phy_upstream upstream_type;
+
+       union {
+               struct net_device       *netdev;
+               struct phy_device       *phydev;
+       } upstream;
+
+       struct sfp_bus *parent_sfp_bus;
+
+       struct phy_device *phy;
+};
+
+struct phy_link_topology {
+       struct xarray phys;
+       u32 next_phy_index;
+};
+
+static inline struct phy_device *
+phy_link_topo_get_phy(struct phy_link_topology *topo, u32 phyindex)
+{
+       struct phy_device_node *pdn = xa_load(&topo->phys, phyindex);
+
+       if (pdn)
+               return pdn->phy;
+
+       return NULL;
+}
+
+#if IS_REACHABLE(CONFIG_PHYLIB)
+int phy_link_topo_add_phy(struct phy_link_topology *topo,
+                         struct phy_device *phy,
+                         enum phy_upstream upt, void *upstream);
+
+void phy_link_topo_del_phy(struct phy_link_topology *lt, struct phy_device *phy);
+
+#else
+static inline int phy_link_topo_add_phy(struct phy_link_topology *topo,
+                                       struct phy_device *phy,
+                                       enum phy_upstream upt, void *upstream)
+{
+       return 0;
+}
+
+static inline void phy_link_topo_del_phy(struct phy_link_topology *topo,
+                                        struct phy_device *phy)
+{
+}
+#endif
+
+#endif /* __PHY_LINK_TOPOLOGY_H */
diff --git a/include/linux/phy_link_topology_core.h b/include/linux/phy_link_topology_core.h
new file mode 100644 (file)
index 0000000..0a64790
--- /dev/null
@@ -0,0 +1,25 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __PHY_LINK_TOPOLOGY_CORE_H
+#define __PHY_LINK_TOPOLOGY_CORE_H
+
+struct phy_link_topology;
+
+#if IS_REACHABLE(CONFIG_PHYLIB)
+
+struct phy_link_topology *phy_link_topo_create(struct net_device *dev);
+void phy_link_topo_destroy(struct phy_link_topology *topo);
+
+#else
+
+static inline struct phy_link_topology *phy_link_topo_create(struct net_device *dev)
+{
+       return NULL;
+}
+
+static inline void phy_link_topo_destroy(struct phy_link_topology *topo)
+{
+}
+
+#endif
+
+#endif /* __PHY_LINK_TOPOLOGY_CORE_H */
index 11fc18988bc247be09d3f14ac1fe4b9f6e17941b..95c2f09f0d0a11c2fac9206cab0ebe102b3a2280 100644 (file)
@@ -2268,4 +2268,20 @@ struct ethtool_link_settings {
         * __u32 map_lp_advertising[link_mode_masks_nwords];
         */
 };
+
+/**
+ * enum phy_upstream - Represents the upstream component a given PHY device
+ * is connected to, as in what is on the other end of the MII bus. Most PHYs
+ * will be attached to an Ethernet MAC controller, but in some cases, there's
+ * an intermediate PHY used as a media-converter, which will driver another
+ * MII interface as its output.
+ * @PHY_UPSTREAM_MAC: Upstream component is a MAC (a switch port,
+ *                   or ethernet controller)
+ * @PHY_UPSTREAM_PHY: Upstream component is a PHY (likely a media converter)
+ */
+enum phy_upstream {
+       PHY_UPSTREAM_MAC,
+       PHY_UPSTREAM_PHY,
+};
+
 #endif /* _UAPI_LINUX_ETHTOOL_H */
index 92f5bddbc2de47b8e6a1054a4871d126b172ed27..854a3a28a8d85b335a9158378ae0cca6dfbf8b36 100644 (file)
 #include <net/page_pool/types.h>
 #include <net/page_pool/helpers.h>
 #include <net/rps.h>
+#include <linux/phy_link_topology_core.h>
 
 #include "dev.h"
 #include "net-sysfs.h"
@@ -10962,6 +10963,12 @@ struct net_device *alloc_netdev_mqs(int sizeof_priv, const char *name,
 #ifdef CONFIG_NET_SCHED
        hash_init(dev->qdisc_hash);
 #endif
+       dev->link_topo = phy_link_topo_create(dev);
+       if (IS_ERR(dev->link_topo)) {
+               dev->link_topo = NULL;
+               goto free_all;
+       }
+
        dev->priv_flags = IFF_XMIT_DST_RELEASE | IFF_XMIT_DST_RELEASE_PERM;
        setup(dev);
 
@@ -11050,6 +11057,8 @@ void free_netdev(struct net_device *dev)
        free_percpu(dev->xdp_bulkq);
        dev->xdp_bulkq = NULL;
 
+       phy_link_topo_destroy(dev->link_topo);
+
        /*  Compatibility with error handling in drivers */
        if (dev->reg_state == NETREG_UNINITIALIZED) {
                netdev_freemem(dev);