DMA mapping

In trying to get the USB to compile, I've noticed that the dma_map_single, dma_unmap_single, dma_map_sg, and dma_unmap_sg functions aren't defined in NIOS's (NIOS2, 2.6.9, etc. specifically) dma_mapping.h file. Is there any reason why they're not defined? If not, any suggestions for how to define them? I'm presuming that they just have to be defined to indicate that dma doesn't work. Suggestions?