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                 if (*hwdev->dma_mask >= 0xffffffffULL)
  16                         printk(KERN_ERR
  17                             "nommu_%s: overflow %Lx+%lu of device mask %Lx\n",
  18                                 name, (long long)bus, size, (long long)*hwdev->dma_mask);
  19                 return 0;
  20         }
  21         return 1;
  22 }
  23
  24 static dma_addr_t
  25 nommu_map_single(struct device *hwdev, void *ptr, size_t size,
  26                int direction)
  27 {
  28         dma_addr_t bus = virt_to_bus(ptr);
  29         if (!check_addr("map_single", hwdev, bus, size))
  30                                 return bad_dma_address;
  31         return bus;
  32 }
  33
  34 void nommu_unmap_single(struct device *dev, dma_addr_t addr,size_t size,
  35                         int direction)
  36 {
  37 }
  38
  39 /* Map a set of buffers described by scatterlist in streaming
  40  * mode for DMA.  This is the scatter-gather version of the
  41  * above pci_map_single interface.  Here the scatter gather list
  42  * elements are each tagged with the appropriate dma address
  43  * and length.  They are obtained via sg_dma_{address,length}(SG).
  44  *
  45  * NOTE: An implementation may be able to use a smaller number of
  46  *       DMA address/length pairs than there are SG table elements.
  47  *       (for example via virtual mapping capabilities)
  48  *       The routine returns the number of addr/length pairs actually
  49  *       used, at most nents.
  50  *
  51  * Device ownership issues as mentioned above for pci_map_single are
  52  * the same here.
  53  */
  54 int nommu_map_sg(struct device *hwdev, struct scatterlist *sg,
  55                int nents, int direction)
  56 {
  57         int i;
  58
  59         BUG_ON(direction == DMA_NONE);
  60         for (i = 0; i < nents; i++ ) {
  61                 struct scatterlist *s = &sg[i];
  62                 BUG_ON(!s->page);
  63                 s->dma_address = virt_to_bus(page_address(s->page) +s->offset);
  64                 if (!check_addr("map_sg", hwdev, s->dma_address, s->length))
  65                         return 0;
  66                 s->dma_length = s->length;
  67         }
  68         return nents;
  69 }
  70
  71 /* Unmap a set of streaming mode DMA translations.
  72  * Again, cpu read rules concerning calls here are the same as for
  73  * pci_unmap_single() above.
  74  */
  75 void nommu_unmap_sg(struct device *dev, struct scatterlist *sg,
  76                   int nents, int dir)
  77 {
  78 }
  79
  80 struct dma_mapping_ops nommu_dma_ops = {
  81         .map_single = nommu_map_single,
  82         .unmap_single = nommu_unmap_single,
  83         .map_sg = nommu_map_sg,
  84         .unmap_sg = nommu_unmap_sg,
  85         .is_phys = 1,
  86 };
  87
  88 void __init no_iommu_init(void)
  89 {
  90         if (dma_ops)
  91                 return;
  92         dma_ops = &nommu_dma_ops;
  93 }