5.5.2. How does it all fit together?

Simplified example:

1. bus driver is loaded (Platform, USB, PCI...)
   • knows how to match devices and drivers
   • usually knows how to detect a device on the bus
   • maybe generates hotplug events for userspace
2. bus driver detects devices:
   • statically by platform code
   • during bus driver initalization
   • when a device is hotplugged
3. somewhere during startup some drivers get loaded
   • bus driver tries to match when new drivers or devices appear
4. matching:
   • driver usually exports table of handled devices
   • matching is bus dependant, can not be implemented generically
   • no match && hotplugging enabled:
     • old: setup environment and call hotplug function (/proc/sys/kernel/hotplug)
     • today: udev/udevd handles this
     • try to autoload / modprobe correct module
     • if success retry matching
5. if match:
   • call driver probe() function:
     • if < 0: failure
     • if >= 0: ok, driver is bound to device