Associating devices with multiple parents

[Mitch Bradley]

Here is the situation:  We (OLPC) have an audio codec that is strongly
associated with an audio controller, but it also has some registers that
you get at with I2C.

In some sense, the codec has two parents, the audio controller
(connected via I2S) and the I2C controller.

Is there an established Linux convention for expressing that dual-parent
relationship for I2C?  The phandle schemes for cross-tree gpio, clk, and
interrupt relationships obviously bear some resemblance to the problem,
but I haven't seen anything for I2C.

(We actually have two devices with the same problem - the other is an
LCD panel controller than wants to be a child of the display device, but
also has some I2C registers accessed by an IC2 controller that's not
part of the display controller.)