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                                 unsigned long attrs)
  17{
  18        dma_addr_t addr = page_to_phys(page) + offset;
  19
  20        WARN_ON(size == 0);
  21
  22        if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
  23                dma_cache_sync(dev, page_address(page) + offset, size, dir);
  24
  25        return addr;
  26}
  27
  28static int nommu_map_sg(struct device *dev, struct scatterlist *sg,
  29                        int nents, enum dma_data_direction dir,
  30                        unsigned long attrs)
  31{
  32        struct scatterlist *s;
  33        int i;
  34
  35        WARN_ON(nents == 0 || sg[0].length == 0);
  36
  37        for_each_sg(sg, s, nents, i) {
  38                BUG_ON(!sg_page(s));
  39
  40                if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
  41                        dma_cache_sync(dev, sg_virt(s), s->length, dir);
  42
  43                s->dma_address = sg_phys(s);
  44                s->dma_length = s->length;
  45        }
  46
  47        return nents;
  48}
  49
  50#ifdef CONFIG_DMA_NONCOHERENT
  51static void nommu_sync_single(struct device *dev, dma_addr_t addr,
  52                              size_t size, enum dma_data_direction dir)
  53{
  54        dma_cache_sync(dev, phys_to_virt(addr), size, dir);
  55}
  56
  57static void nommu_sync_sg(struct device *dev, struct scatterlist *sg,
  58                          int nelems, enum dma_data_direction dir)
  59{
  60        struct scatterlist *s;
  61        int i;
  62
  63        for_each_sg(sg, s, nelems, i)
  64                dma_cache_sync(dev, sg_virt(s), s->length, dir);
  65}
  66#endif
  67
  68const struct dma_map_ops nommu_dma_ops = {
  69        .alloc                  = dma_generic_alloc_coherent,
  70        .free                   = dma_generic_free_coherent,
  71        .map_page               = nommu_map_page,
  72        .map_sg                 = nommu_map_sg,
  73#ifdef CONFIG_DMA_NONCOHERENT
  74        .sync_single_for_device = nommu_sync_single,
  75        .sync_sg_for_device     = nommu_sync_sg,
  76#endif
  77        .is_phys                = 1,
  78};
  79
  80void __init no_iommu_init(void)
  81{
  82        if (dma_ops)
  83                return;
  84        dma_ops = &nommu_dma_ops;
  85}
  86