dma_map_page
dma_map_page((_hwdev) == NULL ? NULL : &(_hwdev)->dev, _page,\
pg_dma[i] = dma_map_page(hw_to_dev(hw), vm_page, 0, PAGE_SIZE, DMA_BIDIRECTIONAL);
return dma_map_page(dev->dma_device, page, offset, size, direction);