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// SPDX-License-Identifier: GPL-2.0
/* Fallback functions when the main IOMMU code is not compiled in. This
code is roughly equivalent to i386. */
#include <linux/dma-direct.h>
#include <linux/scatterlist.h>
#include <linux/string.h>
#include <linux/gfp.h>
#include <linux/pci.h>
#include <linux/mm.h>
#include <asm/processor.h>
#include <asm/iommu.h>
#include <asm/dma.h>
#define NOMMU_MAPPING_ERROR 0
static int
check_addr(char *name, struct device *hwdev, dma_addr_t bus, size_t size)
{
if (hwdev && !dma_capable(hwdev, bus, size)) {
if (*hwdev->dma_mask >= DMA_BIT_MASK(32))
printk(KERN_ERR
"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_page(struct device *dev, struct page *page,
unsigned long offset, size_t size,
enum dma_data_direction dir,
unsigned long attrs)
{
dma_addr_t bus = phys_to_dma(dev, page_to_phys(page)) + offset;
WARN_ON(size == 0);
if (!check_addr("map_single", dev, bus, size))
return NOMMU_MAPPING_ERROR;
return bus;
}
/* 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, enum dma_data_direction dir,
unsigned long attrs)
{
struct scatterlist *s;
int i;
WARN_ON(nents == 0 || sg[0].length == 0);
for_each_sg(sg, s, nents, i) {
BUG_ON(!sg_page(s));
s->dma_address = sg_phys(s);
if (!check_addr("map_sg", hwdev, s->dma_address, s->length))
return 0;
s->dma_length = s->length;
}
return nents;
}
static int nommu_mapping_error(struct device *dev, dma_addr_t dma_addr)
{
return dma_addr == NOMMU_MAPPING_ERROR;
}
const struct dma_map_ops nommu_dma_ops = {
.alloc = dma_generic_alloc_coherent,
.free = dma_generic_free_coherent,
.map_sg = nommu_map_sg,
.map_page = nommu_map_page,
.is_phys = 1,
.mapping_error = nommu_mapping_error,
.dma_supported = x86_dma_supported,
};
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