iort_pmsi_get_msi_info
ret = iort_pmsi_get_msi_info(dev, &dev_id, NULL);
ret = iort_pmsi_get_msi_info(dev, &dev_id, &pa);
int iort_pmsi_get_msi_info(struct device *dev, u32 *dev_id, phys_addr_t *pa);