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/* * Dynamic DMA mapping support. */ #include <linux/types.h> #include <linux/mm.h> #include <linux/string.h> #include <linux/pci.h> #include <linux/module.h> #include <asm/io.h> /* Map a set of buffers described by scatterlist in streaming * mode for DMA. This is the scatter-gather version of the * above pci_map_single interface. Here the scatter gather list * elements are each tagged with the appropriate dma address * and length. They are obtained via sg_dma_{address,length}(SG). * * NOTE: An implementation may be able to use a smaller number of * DMA address/length pairs than there are SG table elements. * (for example via virtual mapping capabilities) * The routine returns the number of addr/length pairs actually * used, at most nents. * * Device ownership issues as mentioned above for pci_map_single are * the same here. */ int dma_map_sg(struct device *hwdev, struct scatterlist *sg, int nents, int direction) { int i; BUG_ON(direction == DMA_NONE); for (i = 0; i < nents; i++ ) { struct scatterlist *s = &sg[i]; BUG_ON(!s->page); s->dma_address = virt_to_bus(page_address(s->page) +s->offset); s->dma_length = s->length; } return nents; } EXPORT_SYMBOL(dma_map_sg); /* Unmap a set of streaming mode DMA translations. * Again, cpu read rules concerning calls here are the same as for * pci_unmap_single() above. */ void dma_unmap_sg(struct device *dev, struct scatterlist *sg, int nents, int dir) { int i; for (i = 0; i < nents; i++) { struct scatterlist *s = &sg[i]; BUG_ON(s->page == NULL); BUG_ON(s->dma_address == 0); dma_unmap_single(dev, s->dma_address, s->dma_length, dir); } } EXPORT_SYMBOL(dma_unmap_sg); |