iicmux_attach
if ((err = iicmux_attach(dev, busdev, numchannels)) == 0)
int iicmux_attach(device_t dev, device_t busdev, int numbuses);
if ((err = iicmux_attach(dev, device_get_parent(dev), numchan)) == 0)
rv = iicmux_attach(sc->dev, device_get_parent(dev), 8);
error = iicmux_attach(dev, device_get_parent(dev), descr->numchannels);