This patch adds a new field to the network device structure to reference
a time stamping device on the MII bus.  By decoupling the time stamping
function from the PHY device, we pave the way to allowing a non-PHY
device to take this role.

Signed-off-by: Richard Cochran <richardcoch...@gmail.com>
---
 drivers/net/phy/mdio_bus.c | 51 +++++++++++++++++++++++++++++++++++++++++++++-
 include/linux/netdevice.h  |  1 +
 2 files changed, 51 insertions(+), 1 deletion(-)

diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
index 24b5511222c8..fdac8c8ac272 100644
--- a/drivers/net/phy/mdio_bus.c
+++ b/drivers/net/phy/mdio_bus.c
@@ -717,6 +717,47 @@ static int mdio_uevent(struct device *dev, struct 
kobj_uevent_env *env)
        return 0;
 }
 
+static bool mdiodev_supports_timestamping(struct mdio_device *mdiodev)
+{
+       if (mdiodev->ts_info  && mdiodev->hwtstamp &&
+           mdiodev->rxtstamp && mdiodev->txtstamp)
+               return true;
+       else
+               return false;
+}
+
+static int mdiobus_netdev_notification(struct notifier_block *nb,
+                                      unsigned long msg, void *ptr)
+{
+       struct net_device *netdev = netdev_notifier_info_to_dev(ptr);
+       struct phy_device *phydev = netdev->phydev;
+       struct mdio_device *mdev;
+       struct mii_bus *bus;
+       int i;
+
+       if (netdev->mdiots || msg != NETDEV_UP || !phydev)
+               return NOTIFY_DONE;
+
+       /*
+        * Examine the MII bus associated with the PHY that is
+        * attached to the MAC.  If there is a time stamping device
+        * on the bus, then connect it to the network device.
+        */
+       bus = phydev->mdio.bus;
+
+       for (i = 0; i < PHY_MAX_ADDR; i++) {
+               mdev = bus->mdio_map[i];
+               if (!mdev)
+                       continue;
+               if (mdiodev_supports_timestamping(mdev)) {
+                       netdev->mdiots = mdev;
+                       return NOTIFY_OK;
+               }
+       }
+
+       return NOTIFY_DONE;
+}
+
 #ifdef CONFIG_PM
 static int mdio_bus_suspend(struct device *dev)
 {
@@ -772,6 +813,10 @@ struct bus_type mdio_bus_type = {
 };
 EXPORT_SYMBOL(mdio_bus_type);
 
+static struct notifier_block mdiobus_netdev_notifier __read_mostly = {
+       .notifier_call = mdiobus_netdev_notification,
+};
+
 int __init mdio_bus_init(void)
 {
        int ret;
@@ -782,14 +827,18 @@ int __init mdio_bus_init(void)
                if (ret)
                        class_unregister(&mdio_bus_class);
        }
+       if (ret)
+               return ret;
+
+       return register_netdevice_notifier(&mdiobus_netdev_notifier);
 
-       return ret;
 }
 EXPORT_SYMBOL_GPL(mdio_bus_init);
 
 #if IS_ENABLED(CONFIG_PHYLIB)
 void mdio_bus_exit(void)
 {
+       unregister_netdevice_notifier(&mdiobus_netdev_notifier);
        class_unregister(&mdio_bus_class);
        bus_unregister(&mdio_bus_type);
 }
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 5fbb9f1da7fd..223d691aa0b0 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1943,6 +1943,7 @@ struct net_device {
        struct netprio_map __rcu *priomap;
 #endif
        struct phy_device       *phydev;
+       struct mdio_device      *mdiots;
        struct lock_class_key   *qdisc_tx_busylock;
        struct lock_class_key   *qdisc_running_key;
        bool                    proto_down;
-- 
2.11.0

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