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/gfp.h>
   7 #include <linux/pci.h>
   8 #include <linux/mm.h>
   9
  10 #include <asm/processor.h>
  11 #include <asm/iommu.h>
  12 #include <asm/dma.h>
  13
  14 #define NOMMU_MAPPING_ERROR             0
  15
  16 static int
  17 check_addr(char *name, struct device *hwdev, dma_addr_t bus, size_t size)
  18 {
  19         if (hwdev && !dma_capable(hwdev, bus, size)) {
  20                 if (*hwdev->dma_mask >= DMA_BIT_MASK(32))
  21                         printk(KERN_ERR
  22                             "nommu_%s: overflow %Lx+%zu of device mask %Lx\n",
  23                                 name, (long long)bus, size,
  24                                 (long long)*hwdev->dma_mask);
  25                 return 0;
  26         }
  27         return 1;
  28 }
  29
  30 static dma_addr_t nommu_map_page(struct device *dev, struct page *page,
  31                                  unsigned long offset, size_t size,
  32                                  enum dma_data_direction dir,
  33                                  unsigned long attrs)
  34 {
  35         dma_addr_t bus = page_to_phys(page) + offset;
  36         WARN_ON(size == 0);
  37         if (!check_addr("map_single", dev, bus, size))
  38                 return NOMMU_MAPPING_ERROR;
  39         flush_write_buffers();
  40         return bus;
  41 }
  42
  43 /* Map a set of buffers described by scatterlist in streaming
  44  * mode for DMA.  This is the scatter-gather version of the
  45  * above pci_map_single interface.  Here the scatter gather list
  46  * elements are each tagged with the appropriate dma address
  47  * and length.  They are obtained via sg_dma_{address,length}(SG).
  48  *
  49  * NOTE: An implementation may be able to use a smaller number of
  50  *       DMA address/length pairs than there are SG table elements.
  51  *       (for example via virtual mapping capabilities)
  52  *       The routine returns the number of addr/length pairs actually
  53  *       used, at most nents.
  54  *
  55  * Device ownership issues as mentioned above for pci_map_single are
  56  * the same here.
  57  */
  58 static int nommu_map_sg(struct device *hwdev, struct scatterlist *sg,
  59                         int nents, enum dma_data_direction dir,
  60                         unsigned long attrs)
  61 {
  62         struct scatterlist *s;
  63         int i;
  64
  65         WARN_ON(nents == 0 || sg[0].length == 0);
  66
  67         for_each_sg(sg, s, nents, i) {
  68                 BUG_ON(!sg_page(s));
  69                 s->dma_address = sg_phys(s);
  70                 if (!check_addr("map_sg", hwdev, s->dma_address, s->length))
  71                         return 0;
  72                 s->dma_length = s->length;
  73         }
  74         flush_write_buffers();
  75         return nents;
  76 }
  77
  78 static void nommu_sync_single_for_device(struct device *dev,
  79                         dma_addr_t addr, size_t size,
  80                         enum dma_data_direction dir)
  81 {
  82         flush_write_buffers();
  83 }
  84
  85
  86 static void nommu_sync_sg_for_device(struct device *dev,
  87                         struct scatterlist *sg, int nelems,
  88                         enum dma_data_direction dir)
  89 {
  90         flush_write_buffers();
  91 }
  92
  93 static int nommu_mapping_error(struct device *dev, dma_addr_t dma_addr)
  94 {
  95         return dma_addr == NOMMU_MAPPING_ERROR;
  96 }
  97
  98 const struct dma_map_ops nommu_dma_ops = {
  99         .alloc                  = dma_generic_alloc_coherent,
 100         .free                   = dma_generic_free_coherent,
 101         .map_sg                 = nommu_map_sg,
 102         .map_page               = nommu_map_page,
 103         .sync_single_for_device = nommu_sync_single_for_device,
 104         .sync_sg_for_device     = nommu_sync_sg_for_device,
 105         .is_phys                = 1,
 106         .mapping_error          = nommu_mapping_error,
 107         .dma_supported          = x86_dma_supported,
 108 };