Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Dynamic DMA mapping support. |
| 3 | */ |
| 4 | |
| 5 | #include <linux/types.h> |
| 6 | #include <linux/mm.h> |
| 7 | #include <linux/string.h> |
| 8 | #include <linux/pci.h> |
| 9 | #include <linux/module.h> |
| 10 | #include <asm/io.h> |
| 11 | |
| 12 | /* Map a set of buffers described by scatterlist in streaming |
| 13 | * mode for DMA. This is the scatter-gather version of the |
| 14 | * above pci_map_single interface. Here the scatter gather list |
| 15 | * elements are each tagged with the appropriate dma address |
| 16 | * and length. They are obtained via sg_dma_{address,length}(SG). |
| 17 | * |
| 18 | * NOTE: An implementation may be able to use a smaller number of |
| 19 | * DMA address/length pairs than there are SG table elements. |
| 20 | * (for example via virtual mapping capabilities) |
| 21 | * The routine returns the number of addr/length pairs actually |
| 22 | * used, at most nents. |
| 23 | * |
| 24 | * Device ownership issues as mentioned above for pci_map_single are |
| 25 | * the same here. |
| 26 | */ |
| 27 | int dma_map_sg(struct device *hwdev, struct scatterlist *sg, |
| 28 | int nents, int direction) |
| 29 | { |
| 30 | int i; |
| 31 | |
| 32 | BUG_ON(direction == DMA_NONE); |
| 33 | for (i = 0; i < nents; i++ ) { |
| 34 | struct scatterlist *s = &sg[i]; |
| 35 | BUG_ON(!s->page); |
| 36 | s->dma_address = virt_to_bus(page_address(s->page) +s->offset); |
| 37 | s->dma_length = s->length; |
| 38 | } |
| 39 | return nents; |
| 40 | } |
| 41 | |
| 42 | EXPORT_SYMBOL(dma_map_sg); |
| 43 | |
| 44 | /* Unmap a set of streaming mode DMA translations. |
| 45 | * Again, cpu read rules concerning calls here are the same as for |
| 46 | * pci_unmap_single() above. |
| 47 | */ |
| 48 | void dma_unmap_sg(struct device *dev, struct scatterlist *sg, |
| 49 | int nents, int dir) |
| 50 | { |
| 51 | int i; |
| 52 | for (i = 0; i < nents; i++) { |
| 53 | struct scatterlist *s = &sg[i]; |
| 54 | BUG_ON(s->page == NULL); |
| 55 | BUG_ON(s->dma_address == 0); |
| 56 | dma_unmap_single(dev, s->dma_address, s->dma_length, dir); |
| 57 | } |
| 58 | } |
| 59 | |
| 60 | EXPORT_SYMBOL(dma_unmap_sg); |