arch/x86_64/kernel/pci-nommu.c

   1 /* Fallback functions when the main IOMMU code is not compiled in. This
   2    code is roughly equivalent to i386. */
   3 #include <linux/mm.h>
   4 #include <linux/init.h>
   5 #include <linux/pci.h>
   6 #include <linux/string.h>
   7 #include <asm/proto.h>
   8 #include <asm/processor.h>
   9 #include <asm/dma.h>
  10
  11 static int
  12 check_addr(char *name, struct device *hwdev, dma_addr_t bus, size_t size)
  13 {
  14         if (hwdev && bus + size > *hwdev->dma_mask) {
  15                 printk(KERN_ERR
  16                     "nommu_%s: overflow %Lx+%lu of device mask %Lx\n",
  17                name, (long long)bus, size, (long long)*hwdev->dma_mask);
  18                 return 0;
  19         }
  20         return 1;
  21 }
  22
  23 static dma_addr_t
  24 nommu_map_single(struct device *hwdev, void *ptr, size_t size,
  25                int direction)
  26 {
  27         dma_addr_t bus = virt_to_bus(ptr);
  28         if (!check_addr("map_single", hwdev, bus, size))
  29                                 return bad_dma_address;
  30         return bus;
  31 }
  32
  33 void nommu_unmap_single(struct device *dev, dma_addr_t addr,size_t size,
  34                         int direction)
  35 {
  36 }
  37
  38 /* Map a set of buffers described by scatterlist in streaming
  39  * mode for DMA.  This is the scatter-gather version of the
  40  * above pci_map_single interface.  Here the scatter gather list
  41  * elements are each tagged with the appropriate dma address
  42  * and length.  They are obtained via sg_dma_{address,length}(SG).
  43  *
  44  * NOTE: An implementation may be able to use a smaller number of
  45  *       DMA address/length pairs than there are SG table elements.
  46  *       (for example via virtual mapping capabilities)
  47  *       The routine returns the number of addr/length pairs actually
  48  *       used, at most nents.
  49  *
  50  * Device ownership issues as mentioned above for pci_map_single are
  51  * the same here.
  52  */
  53 int nommu_map_sg(struct device *hwdev, struct scatterlist *sg,
  54                int nents, int direction)
  55 {
  56         int i;
  57
  58         BUG_ON(direction == DMA_NONE);
  59         for (i = 0; i < nents; i++ ) {
  60                 struct scatterlist *s = &sg[i];
  61                 BUG_ON(!s->page);
  62                 s->dma_address = virt_to_bus(page_address(s->page) +s->offset);
  63                 if (!check_addr("map_sg", hwdev, s->dma_address, s->length))
  64                         return 0;
  65                 s->dma_length = s->length;
  66         }
  67         return nents;
  68 }
  69
  70 /* Unmap a set of streaming mode DMA translations.
  71  * Again, cpu read rules concerning calls here are the same as for
  72  * pci_unmap_single() above.
  73  */
  74 void nommu_unmap_sg(struct device *dev, struct scatterlist *sg,
  75                   int nents, int dir)
  76 {
  77 }
  78
  79 struct dma_mapping_ops nommu_dma_ops = {
  80         .map_single = nommu_map_single,
  81         .unmap_single = nommu_unmap_single,
  82         .map_sg = nommu_map_sg,
  83         .unmap_sg = nommu_unmap_sg,
  84         .is_phys = 1,
  85 };
  86
  87 void __init no_iommu_init(void)
  88 {
  89         if (dma_ops)
  90                 return;
  91         dma_ops = &nommu_dma_ops;
  92 }