Non blocking interrupt

Similar libraries for GPIO support in other languages (Python RPi.GPIO, WiringPi, etc), provide a background thread for interrupt detection, and callback attaching. For example in python:

RPi.GPIO runs a second thread for callback functions. This means that callback functions can be run at the same time as your main program, in immediate response to an edge. For example:

def my_callback(channel):
    print('This is a edge event callback function!')
    print('Edge detected on channel %s'%channel)
    print('This is run in a different thread to your main program')

GPIO.add_event_detect(channel, GPIO.RISING, callback=my_callback)  # add rising edge detection

I know this is difficult to do in Rust with all the safety, ownership and the like, but that will be great to have.

The issue does not name files, tests, or an existing entry point. Start by reviewing the current GPIO API and its Linux sysfs interrupt handling, then clarify the callback, threading, ownership, and safety requirements with maintainers before implementation. Done means an agreed API with documented behavior and coverage for non-blocking interrupt callbacks.