blob: ab08e1832228a74869bc6e7aeb517b0e29e8b044 [file] [log] [blame]
/* Fallback functions when the main IOMMU code is not compiled in. This
code is roughly equivalent to i386. */
#include <linux/mm.h>
#include <linux/init.h>
#include <linux/pci.h>
#include <linux/string.h>
#include <linux/dma-mapping.h>
#include <linux/scatterlist.h>
#include <asm/gart.h>
#include <asm/processor.h>
#include <asm/dma.h>
static int
check_addr(char *name, struct device *hwdev, dma_addr_t bus, size_t size)
if (hwdev && bus + size > *hwdev->dma_mask) {
if (*hwdev->dma_mask >= DMA_32BIT_MASK)
"nommu_%s: overflow %Lx+%zu of device mask %Lx\n",
name, (long long)bus, size,
(long long)*hwdev->dma_mask);
return 0;
return 1;
static dma_addr_t
nommu_map_single(struct device *hwdev, void *ptr, size_t size,
int direction)
dma_addr_t bus = virt_to_bus(ptr);
if (!check_addr("map_single", hwdev, bus, size))
return bad_dma_address;
return bus;
static void nommu_unmap_single(struct device *dev, dma_addr_t addr,size_t size,
int direction)
/* 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.
static int nommu_map_sg(struct device *hwdev, struct scatterlist *sg,
int nents, int direction)
struct scatterlist *s;
int i;
for_each_sg(sg, s, nents, i) {
s->dma_address = virt_to_bus(sg_virt(s));
if (!check_addr("map_sg", hwdev, s->dma_address, s->length))
return 0;
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.
static void nommu_unmap_sg(struct device *dev, struct scatterlist *sg,
int nents, int dir)
const struct dma_mapping_ops nommu_dma_ops = {
.map_single = nommu_map_single,
.unmap_single = nommu_unmap_single,
.map_sg = nommu_map_sg,
.unmap_sg = nommu_unmap_sg,
.is_phys = 1,
void __init no_iommu_init(void)
if (dma_ops)
force_iommu = 0; /* no HW IOMMU */
dma_ops = &nommu_dma_ops;