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 <linux/dma-mapping.h>
   8
   9 #include <asm/proto.h>
  10 #include <asm/processor.h>
  11 #include <asm/dma.h>
  12
  13 static int
  14 check_addr(char *name, struct device *hwdev, dma_addr_t bus, size_t size)
  15 {
  16         if (hwdev && bus + size > *hwdev->dma_mask) {
  17                 if (*hwdev->dma_mask >= DMA_32BIT_MASK)
  18                         printk(KERN_ERR
  19                             "nommu_%s: overflow %Lx+%zu of device mask %Lx\n",
  20                                 name, (long long)bus, size,
  21                                 (long long)*hwdev->dma_mask);
  22                 return 0;
  23         }
  24         return 1;
  25 }
  26
  27 static dma_addr_t
  28 nommu_map_single(struct device *hwdev, void *ptr, size_t size,
  29                int direction)
  30 {
  31         dma_addr_t bus = virt_to_bus(ptr);
  32         if (!check_addr("map_single", hwdev, bus, size))
  33                                 return bad_dma_address;
  34         return bus;
  35 }
  36
  37 void nommu_unmap_single(struct device *dev, dma_addr_t addr,size_t size,
  38                         int direction)
  39 {
  40 }
  41
  42 /* Map a set of buffers described by scatterlist in streaming
  43  * mode for DMA.  This is the scatter-gather version of the
  44  * above pci_map_single interface.  Here the scatter gather list
  45  * elements are each tagged with the appropriate dma address
  46  * and length.  They are obtained via sg_dma_{address,length}(SG).
  47  *
  48  * NOTE: An implementation may be able to use a smaller number of
  49  *       DMA address/length pairs than there are SG table elements.
  50  *       (for example via virtual mapping capabilities)
  51  *       The routine returns the number of addr/length pairs actually
  52  *       used, at most nents.
  53  *
  54  * Device ownership issues as mentioned above for pci_map_single are
  55  * the same here.
  56  */
  57 int nommu_map_sg(struct device *hwdev, struct scatterlist *sg,
  58                int nents, int direction)
  59 {
  60         int i;
  61
  62         BUG_ON(direction == DMA_NONE);
  63         for (i = 0; i < nents; i++ ) {
  64                 struct scatterlist *s = &sg[i];
  65                 BUG_ON(!s->page);
  66                 s->dma_address = virt_to_bus(page_address(s->page) +s->offset);
  67                 if (!check_addr("map_sg", hwdev, s->dma_address, s->length))
  68                         return 0;
  69                 s->dma_length = s->length;
  70         }
  71         return nents;
  72 }
  73
  74 /* Unmap a set of streaming mode DMA translations.
  75  * Again, cpu read rules concerning calls here are the same as for
  76  * pci_unmap_single() above.
  77  */
  78 void nommu_unmap_sg(struct device *dev, struct scatterlist *sg,
  79                   int nents, int dir)
  80 {
  81 }
  82
  83 struct dma_mapping_ops nommu_dma_ops = {
  84         .map_single = nommu_map_single,
  85         .unmap_single = nommu_unmap_single,
  86         .map_sg = nommu_map_sg,
  87         .unmap_sg = nommu_unmap_sg,
  88         .is_phys = 1,
  89 };
  90
  91 void __init no_iommu_init(void)
  92 {
  93         if (dma_ops)
  94                 return;
  95         dma_ops = &nommu_dma_ops;
  96 }