arch/powerpc/kernel/dma-iommu.c

   1 /*
   2  * Copyright (C) 2006 Benjamin Herrenschmidt, IBM Corporation
   3  *
   4  * Provide default implementations of the DMA mapping callbacks for
   5  * busses using the iommu infrastructure
   6  */
   7
   8 #include <linux/export.h>
   9 #include <asm/iommu.h>
  10
  11 /*
  12  * Generic iommu implementation
  13  */
  14
  15 /* Allocates a contiguous real buffer and creates mappings over it.
  16  * Returns the virtual address of the buffer and sets dma_handle
  17  * to the dma address (mapping) of the first page.
  18  */
  19 static void *dma_iommu_alloc_coherent(struct device *dev, size_t size,
  20                                       dma_addr_t *dma_handle, gfp_t flag,
  21                                       struct dma_attrs *attrs)
  22 {
  23         return iommu_alloc_coherent(dev, get_iommu_table_base(dev), size,
  24                                     dma_handle, dev->coherent_dma_mask, flag,
  25                                     dev_to_node(dev));
  26 }
  27
  28 static void dma_iommu_free_coherent(struct device *dev, size_t size,
  29                                     void *vaddr, dma_addr_t dma_handle,
  30                                     struct dma_attrs *attrs)
  31 {
  32         iommu_free_coherent(get_iommu_table_base(dev), size, vaddr, dma_handle);
  33 }
  34
  35 /* Creates TCEs for a user provided buffer.  The user buffer must be
  36  * contiguous real kernel storage (not vmalloc).  The address passed here
  37  * comprises a page address and offset into that page. The dma_addr_t
  38  * returned will point to the same byte within the page as was passed in.
  39  */
  40 static dma_addr_t dma_iommu_map_page(struct device *dev, struct page *page,
  41                                      unsigned long offset, size_t size,
  42                                      enum dma_data_direction direction,
  43                                      struct dma_attrs *attrs)
  44 {
  45         return iommu_map_page(dev, get_iommu_table_base(dev), page, offset,
  46                               size, device_to_mask(dev), direction, attrs);
  47 }
  48
  49
  50 static void dma_iommu_unmap_page(struct device *dev, dma_addr_t dma_handle,
  51                                  size_t size, enum dma_data_direction direction,
  52                                  struct dma_attrs *attrs)
  53 {
  54         iommu_unmap_page(get_iommu_table_base(dev), dma_handle, size, direction,
  55                          attrs);
  56 }
  57
  58
  59 static int dma_iommu_map_sg(struct device *dev, struct scatterlist *sglist,
  60                             int nelems, enum dma_data_direction direction,
  61                             struct dma_attrs *attrs)
  62 {
  63         return iommu_map_sg(dev, get_iommu_table_base(dev), sglist, nelems,
  64                             device_to_mask(dev), direction, attrs);
  65 }
  66
  67 static void dma_iommu_unmap_sg(struct device *dev, struct scatterlist *sglist,
  68                 int nelems, enum dma_data_direction direction,
  69                 struct dma_attrs *attrs)
  70 {
  71         iommu_unmap_sg(get_iommu_table_base(dev), sglist, nelems, direction,
  72                        attrs);
  73 }
  74
  75 /* We support DMA to/from any memory page via the iommu */
  76 static int dma_iommu_dma_supported(struct device *dev, u64 mask)
  77 {
  78         struct iommu_table *tbl = get_iommu_table_base(dev);
  79
  80         if (!tbl) {
  81                 dev_info(dev, "Warning: IOMMU dma not supported: mask 0x%08llx"
  82                         ", table unavailable\n", mask);
  83                 return 0;
  84         }
  85
  86         if (tbl->it_offset > (mask >> IOMMU_PAGE_SHIFT)) {
  87                 dev_info(dev, "Warning: IOMMU offset too big for device mask\n");
  88                 dev_info(dev, "mask: 0x%08llx, table offset: 0x%08lx\n",
  89                                 mask, tbl->it_offset << IOMMU_PAGE_SHIFT);
  90                 return 0;
  91         } else
  92                 return 1;
  93 }
  94
  95 static u64 dma_iommu_get_required_mask(struct device *dev)
  96 {
  97         struct iommu_table *tbl = get_iommu_table_base(dev);
  98         u64 mask;
  99         if (!tbl)
 100                 return 0;
 101
 102         mask = 1ULL < (fls_long(tbl->it_offset + tbl->it_size) - 1);
 103         mask += mask - 1;
 104
 105         return mask;
 106 }
 107
 108 struct dma_map_ops dma_iommu_ops = {
 109         .alloc                  = dma_iommu_alloc_coherent,
 110         .free                   = dma_iommu_free_coherent,
 111         .mmap                   = dma_direct_mmap_coherent,
 112         .map_sg                 = dma_iommu_map_sg,
 113         .unmap_sg               = dma_iommu_unmap_sg,
 114         .dma_supported          = dma_iommu_dma_supported,
 115         .map_page               = dma_iommu_map_page,
 116         .unmap_page             = dma_iommu_unmap_page,
 117         .get_required_mask      = dma_iommu_get_required_mask,
 118 };
 119 EXPORT_SYMBOL(dma_iommu_ops);