int sn_pci_dma_supported (struct pci_dev * hwdev, u64 mask);
Return whether the given PCI device DMA address mask can be supported properly. For example, if your device can only drive the low 24-bits during PCI bus mastering, then you would pass 0x00ffffff as the mask to this function. Of course, SN only supports devices that have 32 or more address bits when using the PMU. We could theoretically support <32 bit cards using direct mapping, but we'll worry about that later--on the off chance that someone actually wants to use such a card.