blob: cab471cf3edb33acde2d7516dfb9c326e3aa6b9f [file] [log] [blame]
* 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];
s->dma_address = virt_to_bus(page_address(s->page) +s->offset);
s->dma_length = s->length;
return nents;
/* 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);