LXR linux/arch/sh/kernel/dma-nommu.c

   1/*
   2 * DMA mapping support for platforms lacking IOMMUs.
   3 *
   4 * Copyright (C) 2009  Paul Mundt
   5 *
   6 * This file is subject to the terms and conditions of the GNU General Public
   7 * License.  See the file "COPYING" in the main directory of this archive
   8 * for more details.
   9 */
  10#include <linux/dma-mapping.h>
  11#include <linux/io.h>
  12
  13static dma_addr_t nommu_map_page(struct device *dev, struct page *page,
  14                                 unsigned long offset, size_t size,
  15                                 enum dma_data_direction dir,
  16                                 struct dma_attrs *attrs)
  17{
  18        dma_addr_t addr = page_to_phys(page) + offset;
  19
  20        WARN_ON(size == 0);
  21        dma_cache_sync(dev, page_address(page) + offset, size, dir);
  22
  23        return addr;
  24}
  25
  26static int nommu_map_sg(struct device *dev, struct scatterlist *sg,
  27                        int nents, enum dma_data_direction dir,
  28                        struct dma_attrs *attrs)
  29{
  30        struct scatterlist *s;
  31        int i;
  32
  33        WARN_ON(nents == 0 || sg[0].length == 0);
  34
  35        for_each_sg(sg, s, nents, i) {
  36                BUG_ON(!sg_page(s));
  37
  38                dma_cache_sync(dev, sg_virt(s), s->length, dir);
  39
  40                s->dma_address = sg_phys(s);
  41                s->dma_length = s->length;
  42        }
  43
  44        return nents;
  45}
  46
  47#ifdef CONFIG_DMA_NONCOHERENT
  48static void nommu_sync_single(struct device *dev, dma_addr_t addr,
  49                              size_t size, enum dma_data_direction dir)
  50{
  51        dma_cache_sync(dev, phys_to_virt(addr), size, dir);
  52}
  53
  54static void nommu_sync_sg(struct device *dev, struct scatterlist *sg,
  55                          int nelems, enum dma_data_direction dir)
  56{
  57        struct scatterlist *s;
  58        int i;
  59
  60        for_each_sg(sg, s, nelems, i)
  61                dma_cache_sync(dev, sg_virt(s), s->length, dir);
  62}
  63#endif
  64
  65struct dma_map_ops nommu_dma_ops = {
  66        .alloc                  = dma_generic_alloc_coherent,
  67        .free                   = dma_generic_free_coherent,
  68        .map_page               = nommu_map_page,
  69        .map_sg                 = nommu_map_sg,
  70#ifdef CONFIG_DMA_NONCOHERENT
  71        .sync_single_for_device = nommu_sync_single,
  72        .sync_sg_for_device     = nommu_sync_sg,
  73#endif
  74        .is_phys                = 1,
  75};
  76
  77void __init no_iommu_init(void)
  78{
  79        if (dma_ops)
  80                return;
  81        dma_ops = &nommu_dma_ops;
  82}
  83