Ok, I will improve it.
By the way, if I want to add some functions(maybe workqueue to handle
link status, or debugfs for the driver) in the future. The function is
only one for driver, not each for every pci device, should I turn back to
'module_exit' and 'module_init'?
Maybe workqueue can use 'system_power_efficient_wq' just like libwx
does? 

Generally, you don't have per driver data, only per device data. It
makes the locking simpler, and handling bind/unbind etc.

	Andrew