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