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