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
  13 static 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
  26 static 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
  48 static 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
  54 static 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
  65 struct dma_map_ops nommu_dma_ops = {
  66         .alloc_coherent         = dma_generic_alloc_coherent,
  67         .free_coherent          = 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
  77 void __init no_iommu_init(void)
  78 {
  79         if (dma_ops)
  80                 return;
  81         dma_ops = &nommu_dma_ops;
  82 }