net/mlx5: Driver events notifier API

Use atomic notifier chain to fire events to mlx5 core driver
consumers (mlx5e/mlx5_ib) and provide mlx5 register/unregister notifier
API.

This API will replace the current mlx5_interface->event callback and all
the logic around it, especially the delayed events logic introduced by
commit 97834eba ("net/mlx5: Delay events till ib registration ends")

Which is not needed anymore with this new API where the mlx5 interface
can dynamically register/unregister its notifier.
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>

drivers/net/ethernet/mellanox/mlx5/core/events.c

@@ -35,7 +35,8 @@ static struct mlx5_nb events_nbs_ref[] = {
 struct mlx5_events {
 	struct mlx5_core_dev *dev;
 	struct mlx5_event_nb  notifiers[ARRAY_SIZE(events_nbs_ref)];
-
+	/* driver notifier chain */
+	struct atomic_notifier_head nh;
 	/* port module events stats */
 	struct mlx5_pme_stats pme_stats;
 };
@@ -300,6 +301,7 @@ int mlx5_events_init(struct mlx5_core_dev *dev)
 	if (!events)
 		return -ENOMEM;
 
+	ATOMIC_INIT_NOTIFIER_HEAD(&events->nh);
 	events->dev = dev;
 	dev->priv.events = events;
 	return 0;
@@ -330,3 +332,24 @@ void mlx5_events_stop(struct mlx5_core_dev *dev)
 	for (i = ARRAY_SIZE(events_nbs_ref) - 1; i >= 0 ; i--)
 		mlx5_eq_notifier_unregister(dev, &events->notifiers[i].nb);
 }
+
+int mlx5_notifier_register(struct mlx5_core_dev *dev, struct notifier_block *nb)
+{
+	struct mlx5_events *events = dev->priv.events;
+
+	return atomic_notifier_chain_register(&events->nh, nb);
+}
+EXPORT_SYMBOL(mlx5_notifier_register);
+
+int mlx5_notifier_unregister(struct mlx5_core_dev *dev, struct notifier_block *nb)
+{
+	struct mlx5_events *events = dev->priv.events;
+
+	return atomic_notifier_chain_unregister(&events->nh, nb);
+}
+EXPORT_SYMBOL(mlx5_notifier_unregister);
+
+int mlx5_notifier_call_chain(struct mlx5_events *events, unsigned int event, void *data)
+{
+	return atomic_notifier_call_chain(&events->nh, event, data);
+}

drivers/net/ethernet/mellanox/mlx5/core/lib/mlx5.h

@@ -73,5 +73,6 @@ struct mlx5_pme_stats {
 };
 
 void mlx5_get_pme_stats(struct mlx5_core_dev *dev, struct mlx5_pme_stats *stats);
+int mlx5_notifier_call_chain(struct mlx5_events *events, unsigned int event, void *data);
 
 #endif

include/linux/mlx5/driver.h

@@ -46,6 +46,7 @@
 #include <linux/mempool.h>
 #include <linux/interrupt.h>
 #include <linux/idr.h>
+#include <linux/notifier.h>
 
 #include <linux/mlx5/device.h>
 #include <linux/mlx5/doorbell.h>
@@ -1062,6 +1063,9 @@ struct mlx5_interface {
 void *mlx5_get_protocol_dev(struct mlx5_core_dev *mdev, int protocol);
 int mlx5_register_interface(struct mlx5_interface *intf);
 void mlx5_unregister_interface(struct mlx5_interface *intf);
+int mlx5_notifier_register(struct mlx5_core_dev *dev, struct notifier_block *nb);
+int mlx5_notifier_unregister(struct mlx5_core_dev *dev, struct notifier_block *nb);
+
 int mlx5_core_query_vendor_id(struct mlx5_core_dev *mdev, u32 *vendor_id);
 
 int mlx5_cmd_create_vport_lag(struct mlx5_core_dev *dev);