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 #include <asm/cacheflush.h>
  13
  14 static dma_addr_t nommu_map_page(struct device *dev, struct page *page,
  15                                  unsigned long offset, size_t size,
  16                                  enum dma_data_direction dir,
  17                                  unsigned long attrs)
  18 {
  19         dma_addr_t addr = page_to_phys(page) + offset;
  20
  21         WARN_ON(size == 0);
  22
  23         if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
  24                 sh_sync_dma_for_device(page_address(page) + offset, size, dir);
  25
  26         return addr;
  27 }
  28
  29 static int nommu_map_sg(struct device *dev, struct scatterlist *sg,
  30                         int nents, enum dma_data_direction dir,
  31                         unsigned long attrs)
  32 {
  33         struct scatterlist *s;
  34         int i;
  35
  36         WARN_ON(nents == 0 || sg[0].length == 0);
  37
  38         for_each_sg(sg, s, nents, i) {
  39                 BUG_ON(!sg_page(s));
  40
  41                 if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
  42                         sh_sync_dma_for_device(sg_virt(s), s->length, dir);
  43
  44                 s->dma_address = sg_phys(s);
  45                 s->dma_length = s->length;
  46         }
  47
  48         return nents;
  49 }
  50
  51 #ifdef CONFIG_DMA_NONCOHERENT
  52 static void nommu_sync_single_for_device(struct device *dev, dma_addr_t addr,
  53                               size_t size, enum dma_data_direction dir)
  54 {
  55         sh_sync_dma_for_device(phys_to_virt(addr), size, dir);
  56 }
  57
  58 static void nommu_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
  59                           int nelems, enum dma_data_direction dir)
  60 {
  61         struct scatterlist *s;
  62         int i;
  63
  64         for_each_sg(sg, s, nelems, i)
  65                 sh_sync_dma_for_device(sg_virt(s), s->length, dir);
  66 }
  67 #endif
  68
  69 const struct dma_map_ops nommu_dma_ops = {
  70         .alloc                  = dma_generic_alloc_coherent,
  71         .free                   = dma_generic_free_coherent,
  72         .map_page               = nommu_map_page,
  73         .map_sg                 = nommu_map_sg,
  74 #ifdef CONFIG_DMA_NONCOHERENT
  75         .sync_single_for_device = nommu_sync_single_for_device,
  76         .sync_sg_for_device     = nommu_sync_sg_for_device,
  77 #endif
  78         .is_phys                = 1,
  79 };
  80
  81 void __init no_iommu_init(void)
  82 {
  83         if (dma_ops)
  84                 return;
  85         dma_ops = &nommu_dma_ops;
  86 }