mlxsw: core: Add registration APIs for system event handler

The purpose of system event handler is to handle system interrupts.
Such interrupts are raised to CPU from system programmable logic
devices, upon specific system wide changes, like line card activation
and deactivation.

The purpose is to create an alternative to trap mechanism, which
delivers these events to driver over PCI bus, but not available for
the driver working over I2C bus.

Mechanism is system dependent and applicable only for the systems
equipped with programmable devices with custom logic.

Add APIs for event handler registration and un-registration and API
which should be invoked from the registered callbacks when system
interrupt is raised to CPU.

Signed-off-by: Vadim Pasternak <vadimp@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: vadimp-nvidia

drivers/net/ethernet/mellanox/mlxsw/core.c

@@ -70,6 +70,8 @@ struct mlxsw_core {
 	struct workqueue_struct *emad_wq;
 	struct list_head rx_listener_list;
 	struct list_head event_listener_list;
+	struct list_head irq_event_handler_list;
+	struct mutex irq_event_handler_lock; /* Locks access to handlers list */
 	struct {
 		atomic64_t tid;
 		struct list_head trans_list;
@@ -2090,6 +2092,18 @@ static void mlxsw_core_health_fini(struct mlxsw_core *mlxsw_core)
 	devlink_health_reporter_destroy(mlxsw_core->health.fw_fatal);
 }
 
+static void mlxsw_core_irq_event_handler_init(struct mlxsw_core *mlxsw_core)
+{
+	INIT_LIST_HEAD(&mlxsw_core->irq_event_handler_list);
+	mutex_init(&mlxsw_core->irq_event_handler_lock);
+}
+
+static void mlxsw_core_irq_event_handler_fini(struct mlxsw_core *mlxsw_core)
+{
+	mutex_destroy(&mlxsw_core->irq_event_handler_lock);
+	WARN_ON(!list_empty(&mlxsw_core->irq_event_handler_list));
+}
+
 static int
 __mlxsw_core_bus_device_register(const struct mlxsw_bus_info *mlxsw_bus_info,
 				 const struct mlxsw_bus *mlxsw_bus,
@@ -2125,6 +2139,7 @@ __mlxsw_core_bus_device_register(const struct mlxsw_bus_info *mlxsw_bus_info,
 	mlxsw_core->bus = mlxsw_bus;
 	mlxsw_core->bus_priv = bus_priv;
 	mlxsw_core->bus_info = mlxsw_bus_info;
+	mlxsw_core_irq_event_handler_init(mlxsw_core);
 
 	err = mlxsw_bus->init(bus_priv, mlxsw_core, mlxsw_driver->profile,
 			      &mlxsw_core->res);
@@ -2233,6 +2248,7 @@ __mlxsw_core_bus_device_register(const struct mlxsw_bus_info *mlxsw_bus_info,
 err_register_resources:
 	mlxsw_bus->fini(bus_priv);
 err_bus_init:
+	mlxsw_core_irq_event_handler_fini(mlxsw_core);
 	if (!reload) {
 		devl_unlock(devlink);
 		devlink_free(devlink);
@@ -2302,6 +2318,7 @@ void mlxsw_core_bus_device_unregister(struct mlxsw_core *mlxsw_core,
 	if (!reload)
 		devl_resources_unregister(devlink);
 	mlxsw_core->bus->fini(mlxsw_core->bus_priv);
+	mlxsw_core_irq_event_handler_fini(mlxsw_core);
 	if (!reload) {
 		devl_unlock(devlink);
 		devlink_free(devlink);
@@ -2772,6 +2789,57 @@ int mlxsw_reg_trans_bulk_wait(struct list_head *bulk_list)
 }
 EXPORT_SYMBOL(mlxsw_reg_trans_bulk_wait);
 
+struct mlxsw_core_irq_event_handler_item {
+	struct list_head list;
+	void (*cb)(struct mlxsw_core *mlxsw_core);
+};
+
+int mlxsw_core_irq_event_handler_register(struct mlxsw_core *mlxsw_core,
+					  mlxsw_irq_event_cb_t cb)
+{
+	struct mlxsw_core_irq_event_handler_item *item;
+
+	item = kzalloc(sizeof(*item), GFP_KERNEL);
+	if (!item)
+		return -ENOMEM;
+	item->cb = cb;
+	mutex_lock(&mlxsw_core->irq_event_handler_lock);
+	list_add_tail(&item->list, &mlxsw_core->irq_event_handler_list);
+	mutex_unlock(&mlxsw_core->irq_event_handler_lock);
+	return 0;
+}
+EXPORT_SYMBOL(mlxsw_core_irq_event_handler_register);
+
+void mlxsw_core_irq_event_handler_unregister(struct mlxsw_core *mlxsw_core,
+					     mlxsw_irq_event_cb_t cb)
+{
+	struct mlxsw_core_irq_event_handler_item *item, *tmp;
+
+	mutex_lock(&mlxsw_core->irq_event_handler_lock);
+	list_for_each_entry_safe(item, tmp,
+				 &mlxsw_core->irq_event_handler_list, list) {
+		if (item->cb == cb) {
+			list_del(&item->list);
+			kfree(item);
+		}
+	}
+	mutex_unlock(&mlxsw_core->irq_event_handler_lock);
+}
+EXPORT_SYMBOL(mlxsw_core_irq_event_handler_unregister);
+
+void mlxsw_core_irq_event_handlers_call(struct mlxsw_core *mlxsw_core)
+{
+	struct mlxsw_core_irq_event_handler_item *item;
+
+	mutex_lock(&mlxsw_core->irq_event_handler_lock);
+	list_for_each_entry(item, &mlxsw_core->irq_event_handler_list, list) {
+		if (item->cb)
+			item->cb(mlxsw_core);
+	}
+	mutex_unlock(&mlxsw_core->irq_event_handler_lock);
+}
+EXPORT_SYMBOL(mlxsw_core_irq_event_handlers_call);
+
 static int mlxsw_core_reg_access_cmd(struct mlxsw_core *mlxsw_core,
 				     const struct mlxsw_reg_info *reg,
 				     char *payload,

drivers/net/ethernet/mellanox/mlxsw/core.h

@@ -215,6 +215,14 @@ int mlxsw_reg_trans_write(struct mlxsw_core *mlxsw_core,
 			  mlxsw_reg_trans_cb_t *cb, unsigned long cb_priv);
 int mlxsw_reg_trans_bulk_wait(struct list_head *bulk_list);
 
+typedef void mlxsw_irq_event_cb_t(struct mlxsw_core *mlxsw_core);
+
+int mlxsw_core_irq_event_handler_register(struct mlxsw_core *mlxsw_core,
+					  mlxsw_irq_event_cb_t cb);
+void mlxsw_core_irq_event_handler_unregister(struct mlxsw_core *mlxsw_core,
+					     mlxsw_irq_event_cb_t cb);
+void mlxsw_core_irq_event_handlers_call(struct mlxsw_core *mlxsw_core);
+
 int mlxsw_reg_query(struct mlxsw_core *mlxsw_core,
 		    const struct mlxsw_reg_info *reg, char *payload);
 int mlxsw_reg_write(struct mlxsw_core *mlxsw_core,