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/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
  15static int
  16check_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
  29static 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 */
  57static 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
  77static void nommu_free_coherent(struct device *dev, size_t size, void *vaddr,
  78                                dma_addr_t dma_addr)
  79{
  80        free_pages((unsigned long)vaddr, get_order(size));
  81}
  82
  83static void nommu_sync_single_for_device(struct device *dev,
  84                        dma_addr_t addr, size_t size,
  85                        enum dma_data_direction dir)
  86{
  87        flush_write_buffers();
  88}
  89
  90
  91static void nommu_sync_sg_for_device(struct device *dev,
  92                        struct scatterlist *sg, int nelems,
  93                        enum dma_data_direction dir)
  94{
  95        flush_write_buffers();
  96}
  97
  98struct dma_map_ops nommu_dma_ops = {
  99        .alloc_coherent         = dma_generic_alloc_coherent,
 100        .free_coherent          = nommu_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};
 107