I am planning to use a triplet of RPi GPIO pins as an additional bit-banged I2C bus on my RPi. This will be run at a lower than typical rate (and level-shifted via a 3.3 to 5.0 V I2C shifter unit) so that it can work over the distance necessary to be the back-bone for a Home Automation control bus that will be populated with the (popular) PCF8574 and 8574A (Philips data-sheet) 8-Bit I/O expanders. These have the nice addition of an Open-drain (FET equivalent to an Open-collector) active-low line that can be connected as a Wired-OR between devices so that the controller (the RPi) gets a low-going interrupt any time any pin on any of the 8574* devices changes to be not the level that it was set to (input pins are to be written to/default to high output level i.e. ~5V).
I am aware of, and plan to use, @joan 's pigpio library with it's support of bit-banged I2C interfaces on arbitrary GPIO pins - and I will be coding in 'C', but can I use this interrupt to replace the (library's) need to constantly poll all the GPIO pins when all that is needed to do is: wait for a change on that interrupt pin?
To a certain extent this is a bit of a place-holder question that I will expand upon as I flesh out this idea in practice!