DT bindings for interrupt outputs that aren't wired up to an interrupt controller

Hi

I'm wondering how to handle the case where the outputs from a device
that generates interrupts are not all wired to an interrupt controller,
and also where different systems wire up different interrupts.

E.g. a datasheet says device generates 3 interrupts A, B and C, but one
system using the device doesn't connect up B and another doesn't connect
up C.

From what I can see, device-tree bindings for a device will tend to list

rigid length and order for the contents of 'interrupt' and 'interrupt-
names' properties, but what happens if one of them isn't wired up in
hardware? Is there such a thing as a null interrupt specifier to put in
the list?

One solution, for devices without bindings yet is to specify interrupts
as optional but require interrupt-names for those that are present so OS
drivers can match the correct interrupt functions to the interrupt
specifiers. E.g for my two example systems

  interrupts = <10>, <11>;
  interrupt-names = "A", "C">;

  interrupts = <10>, <11>;
  interrupt-names = "A", "B";

Is such an approach acceptable?

I've searched quite a bit existing practice in this area but have come
up blank.

Thanks for any help.

-- 
Tixy

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