blob: ed47fb81e6049672d593f8adf504cd57190f7ff0 [file] [log] [blame]
/*
* Dynamic DMA mapping support. Common code
*/
#include <linux/types.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/pci.h>
#include <asm/io.h>
dma_addr_t bad_dma_address = -1UL;
/* Map a set of buffers described by scatterlist in streaming
* mode for DMA. This is the scather-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 pci_map_sg(struct pci_dev *hwdev, struct scatterlist *sg,
int nents, int direction)
{
int i;
BUG_ON(direction == PCI_DMA_NONE);
/*
* temporary 2.4 hack
*/
for (i = 0; i < nents; i++ ) {
struct scatterlist *s = &sg[i];
void *addr = s->address;
if (addr)
BUG_ON(s->page || s->offset);
else if (s->page)
addr = page_address(s->page) + s->offset;
else
BUG();
s->dma_address = pci_map_single(hwdev, addr, s->length, direction);
if (unlikely(s->dma_address == bad_dma_address))
goto error;
}
return nents;
error:
pci_unmap_sg(hwdev, sg, i, direction);
return 0;
}
/* 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 pci_unmap_sg(struct pci_dev *dev, struct scatterlist *sg,
int nents, int dir)
{
int i;
for (i = 0; i < nents; i++) {
struct scatterlist *s = &sg[i];
BUG_ON(s->address == NULL && s->page == NULL);
BUG_ON(s->dma_address == 0);
pci_unmap_single(dev, s->dma_address, s->length, dir);
}
}