ppbus_read_ivar
error = ppbus_read_ivar(device_parent(dev), PPBUS_IVAR_DMA, &val);
error = ppbus_read_ivar(device_parent(dev), PPBUS_IVAR_IEEE, &val);
error = ppbus_read_ivar(device_parent(dev), PPBUS_IVAR_INTR, &val);
error = ppbus_read_ivar(dev, PPBUS_IVAR_IEEE, &old_ivar);
return (bus->ppbus_read_ivar(device_parent(dev), index, val));
int ppbus_read_ivar(device_t, int, unsigned int *);
ppbus->ppbus_read_ivar = sc_link->parport_read_ivar;
PARPORT_READ_IVAR_T ppbus_read_ivar;
ppbus_read_ivar(bus->sc_dev, PPBUS_IVAR_EPP_PROTO, &epp);