mirror of https://gitee.com/openkylin/linux.git
61 lines
1.7 KiB
C
61 lines
1.7 KiB
C
/*
|
|
* 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);
|