mlxsw: Invoke driver's init/fini methods only if defined

We are going to add a minimal driver on top of the mlxsw core
infrastructure, which will be mainly used for hardware monitoring in
Baseboard management controller (BMC) installations.

Unlike the switch drivers (e.g., spectrum, switchx2), this driver does not
initialize the ASIC and therefore doesn't need to implement the init() and
fini() methods in its 'mlxsw_driver' struct.
Signed-off-by: NVadim Pasternak <vadimp@mellanox.com>
Reviewed-by: NIdo Schimmel <idosch@mellanox.com>
Signed-off-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

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

@@ -1162,9 +1162,11 @@ int mlxsw_core_bus_device_register(const struct mlxsw_bus_info *mlxsw_bus_info,
 	if (err)
 		goto err_hwmon_init;
 
-	err = mlxsw_driver->init(mlxsw_core, mlxsw_bus_info);
-	if (err)
-		goto err_driver_init;
+	if (mlxsw_driver->init) {
+		err = mlxsw_driver->init(mlxsw_core, mlxsw_bus_info);
+		if (err)
+			goto err_driver_init;
+	}
 
 	err = mlxsw_core_debugfs_init(mlxsw_core);
 	if (err)
@@ -1173,7 +1175,8 @@ int mlxsw_core_bus_device_register(const struct mlxsw_bus_info *mlxsw_bus_info,
 	return 0;
 
 err_debugfs_init:
-	mlxsw_core->driver->fini(mlxsw_core);
+	if (mlxsw_core->driver->fini)
+		mlxsw_core->driver->fini(mlxsw_core);
 err_driver_init:
 err_hwmon_init:
 	devlink_unregister(devlink);
@@ -1199,7 +1202,8 @@ void mlxsw_core_bus_device_unregister(struct mlxsw_core *mlxsw_core)
 	struct devlink *devlink = priv_to_devlink(mlxsw_core);
 
 	mlxsw_core_debugfs_fini(mlxsw_core);
-	mlxsw_core->driver->fini(mlxsw_core);
+	if (mlxsw_core->driver->fini)
+		mlxsw_core->driver->fini(mlxsw_core);
 	devlink_unregister(devlink);
 	mlxsw_emad_fini(mlxsw_core);
 	mlxsw_core->bus->fini(mlxsw_core->bus_priv);