method allows bus or device drivers to provide interrupt polarity and trigger
mode to parent busses.
This typically bubbles all the way up to the root bus (e.g. nexus) where the
necessary actions are taken to actually program the hardware.
method takes an interrupt number, it is assumed but not necessarily required
that it is called prior to
argument can be one of:
The interrupt trigger mode is standard for the bus to which the device is
The interrupt is edge triggered.
This means that the interrupt is raised by the rising edge of the signal on
the interrupt line.
The signal typically reverts to the original state so as to cause a spike.
The interrupt is level triggered.
This means that the interrupt is raised when the signal on the interrupt line
transitions and remains unchanged after that until the interrupt has been
serviced, after which the signal transitions back.
argument can be any one of:
The interrupt polarity is standard for the bus to which the device is attached.
The interrupt is activated by a high voltage on the interrupt line.
The interrupt is activated by a low voltage on the interrupt line.