arch/x86/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/dma-mapping.h>
   4 #include <linux/scatterlist.h>
   5 #include <linux/string.h>
   6 #include <linux/init.h>
   7 #include <linux/gfp.h>
   8 #include <linux/pci.h>
   9 #include <linux/mm.h>
  10
  11 #include <asm/processor.h>
  12 #include <asm/iommu.h>
  13 #include <asm/dma.h>
  14
  15 static int
  16 check_addr(char *name, struct device *hwdev, dma_addr_t bus, size_t size)
  17 {
  18         if (hwdev && !dma_capable(hwdev, bus, size)) {
  19                 if (*hwdev->dma_mask >= DMA_BIT_MASK(32))
  20                         printk(KERN_ERR
  21                             "nommu_%s: overflow %Lx+%zu of device mask %Lx\n",
  22                                 name, (long long)bus, size,
  23                                 (long long)*hwdev->dma_mask);
  24                 return 0;
  25         }
  26         return 1;
  27 }
  28
  29 static dma_addr_t nommu_map_page(struct device *dev, struct page *page,
  30                                  unsigned long offset, size_t size,
  31                                  enum dma_data_direction dir,
  32                                  struct dma_attrs *attrs)
  33 {
  34         dma_addr_t bus = page_to_phys(page) + offset;
  35         WARN_ON(size == 0);
  36         if (!check_addr("map_single", dev, bus, size))
  37                 return DMA_ERROR_CODE;
  38         flush_write_buffers();
  39         return bus;
  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 static int nommu_map_sg(struct device *hwdev, struct scatterlist *sg,
  58                         int nents, enum dma_data_direction dir,
  59                         struct dma_attrs *attrs)
  60 {
  61         struct scatterlist *s;
  62         int i;
  63
  64         WARN_ON(nents == 0 || sg[0].length == 0);
  65
  66         for_each_sg(sg, s, nents, i) {
  67                 BUG_ON(!sg_page(s));
  68                 s->dma_address = sg_phys(s);
  69                 if (!check_addr("map_sg", hwdev, s->dma_address, s->length))
  70                         return 0;
  71                 s->dma_length = s->length;
  72         }
  73         flush_write_buffers();
  74         return nents;
  75 }
  76
  77 static void nommu_sync_single_for_device(struct device *dev,
  78                         dma_addr_t addr, size_t size,
  79                         enum dma_data_direction dir)
  80 {
  81         flush_write_buffers();
  82 }
  83
  84
  85 static void nommu_sync_sg_for_device(struct device *dev,
  86                         struct scatterlist *sg, int nelems,
  87                         enum dma_data_direction dir)
  88 {
  89         flush_write_buffers();
  90 }
  91
  92 struct dma_map_ops nommu_dma_ops = {
  93         .alloc                  = dma_generic_alloc_coherent,
  94         .free                   = dma_generic_free_coherent,
  95         .map_sg                 = nommu_map_sg,
  96         .map_page               = nommu_map_page,
  97         .sync_single_for_device = nommu_sync_single_for_device,
  98         .sync_sg_for_device     = nommu_sync_sg_for_device,
  99         .is_phys                = 1,
 100 };