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                                  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
  28 static 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
  51 static 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
  57 static 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
  68 const 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
  80 void __init no_iommu_init(void)
  81 {
  82         if (dma_ops)
  83                 return;
  84         dma_ops = &nommu_dma_ops;
  85 }