kernel/dma-coherent.c

   1 /*
   2  * Coherent per-device memory handling.
   3  * Borrowed from i386
   4  */
   5 #include <linux/kernel.h>
   6 #include <linux/dma-mapping.h>
   7
   8 struct dma_coherent_mem {
   9         void            *virt_base;
  10         u32             device_base;
  11         int             size;
  12         int             flags;
  13         unsigned long   *bitmap;
  14 };
  15
  16 int dma_declare_coherent_memory(struct device *dev, dma_addr_t bus_addr,
  17                                 dma_addr_t device_addr, size_t size, int flags)
  18 {
  19         void __iomem *mem_base = NULL;
  20         int pages = size >> PAGE_SHIFT;
  21         int bitmap_size = BITS_TO_LONGS(pages) * sizeof(long);
  22
  23         if ((flags & (DMA_MEMORY_MAP | DMA_MEMORY_IO)) == 0)
  24                 goto out;
  25         if (!size)
  26                 goto out;
  27         if (dev->dma_mem)
  28                 goto out;
  29
  30         /* FIXME: this routine just ignores DMA_MEMORY_INCLUDES_CHILDREN */
  31
  32         mem_base = ioremap(bus_addr, size);
  33         if (!mem_base)
  34                 goto out;
  35
  36         dev->dma_mem = kzalloc(sizeof(struct dma_coherent_mem), GFP_KERNEL);
  37         if (!dev->dma_mem)
  38                 goto out;
  39         dev->dma_mem->bitmap = kzalloc(bitmap_size, GFP_KERNEL);
  40         if (!dev->dma_mem->bitmap)
  41                 goto free1_out;
  42
  43         dev->dma_mem->virt_base = mem_base;
  44         dev->dma_mem->device_base = device_addr;
  45         dev->dma_mem->size = pages;
  46         dev->dma_mem->flags = flags;
  47
  48         if (flags & DMA_MEMORY_MAP)
  49                 return DMA_MEMORY_MAP;
  50
  51         return DMA_MEMORY_IO;
  52
  53  free1_out:
  54         kfree(dev->dma_mem);
  55  out:
  56         if (mem_base)
  57                 iounmap(mem_base);
  58         return 0;
  59 }
  60 EXPORT_SYMBOL(dma_declare_coherent_memory);
  61
  62 void dma_release_declared_memory(struct device *dev)
  63 {
  64         struct dma_coherent_mem *mem = dev->dma_mem;
  65
  66         if (!mem)
  67                 return;
  68         dev->dma_mem = NULL;
  69         iounmap(mem->virt_base);
  70         kfree(mem->bitmap);
  71         kfree(mem);
  72 }
  73 EXPORT_SYMBOL(dma_release_declared_memory);
  74
  75 void *dma_mark_declared_memory_occupied(struct device *dev,
  76                                         dma_addr_t device_addr, size_t size)
  77 {
  78         struct dma_coherent_mem *mem = dev->dma_mem;
  79         int pos, err;
  80
  81         size += device_addr & ~PAGE_MASK;
  82
  83         if (!mem)
  84                 return ERR_PTR(-EINVAL);
  85
  86         pos = (device_addr - mem->device_base) >> PAGE_SHIFT;
  87         err = bitmap_allocate_region(mem->bitmap, pos, get_order(size));
  88         if (err != 0)
  89                 return ERR_PTR(err);
  90         return mem->virt_base + (pos << PAGE_SHIFT);
  91 }
  92 EXPORT_SYMBOL(dma_mark_declared_memory_occupied);
  93
  94 /**
  95  * dma_alloc_from_coherent() - try to allocate memory from the per-device coherent area
  96  *
  97  * @dev:        device from which we allocate memory
  98  * @size:       size of requested memory area
  99  * @dma_handle: This will be filled with the correct dma handle
 100  * @ret:        This pointer will be filled with the virtual address
 101  *              to allocated area.
 102  *
 103  * This function should be only called from per-arch dma_alloc_coherent()
 104  * to support allocation from per-device coherent memory pools.
 105  *
 106  * Returns 0 if dma_alloc_coherent should continue with allocating from
 107  * generic memory areas, or !0 if dma_alloc_coherent should return @ret.
 108  */
 109 int dma_alloc_from_coherent(struct device *dev, ssize_t size,
 110                                        dma_addr_t *dma_handle, void **ret)
 111 {
 112         struct dma_coherent_mem *mem;
 113         int order = get_order(size);
 114         int pageno;
 115
 116         if (!dev)
 117                 return 0;
 118         mem = dev->dma_mem;
 119         if (!mem)
 120                 return 0;
 121
 122         pageno = bitmap_find_free_region(mem->bitmap, mem->size, order);
 123         if (pageno >= 0) {
 124                 /*
 125                  * Memory was found in the per-device arena.
 126                  */
 127                 *dma_handle = mem->device_base + (pageno << PAGE_SHIFT);
 128                 *ret = mem->virt_base + (pageno << PAGE_SHIFT);
 129                 memset(*ret, 0, size);
 130         } else if (mem->flags & DMA_MEMORY_EXCLUSIVE) {
 131                 /*
 132                  * The per-device arena is exhausted and we are not
 133                  * permitted to fall back to generic memory.
 134                  */
 135                 *ret = NULL;
 136         } else {
 137                 /*
 138                  * The per-device arena is exhausted and we are
 139                  * permitted to fall back to generic memory.
 140                  */
 141                  return 0;
 142         }
 143         return 1;
 144 }
 145 EXPORT_SYMBOL(dma_alloc_from_coherent);
 146
 147 /**
 148  * dma_release_from_coherent() - try to free the memory allocated from per-device coherent memory pool
 149  * @dev:        device from which the memory was allocated
 150  * @order:      the order of pages allocated
 151  * @vaddr:      virtual address of allocated pages
 152  *
 153  * This checks whether the memory was allocated from the per-device
 154  * coherent memory pool and if so, releases that memory.
 155  *
 156  * Returns 1 if we correctly released the memory, or 0 if
 157  * dma_release_coherent() should proceed with releasing memory from
 158  * generic pools.
 159  */
 160 int dma_release_from_coherent(struct device *dev, int order, void *vaddr)
 161 {
 162         struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;
 163
 164         if (mem && vaddr >= mem->virt_base && vaddr <
 165                    (mem->virt_base + (mem->size << PAGE_SHIFT))) {
 166                 int page = (vaddr - mem->virt_base) >> PAGE_SHIFT;
 167
 168                 bitmap_release_region(mem->bitmap, page, order);
 169                 return 1;
 170         }
 171         return 0;
 172 }
 173 EXPORT_SYMBOL(dma_release_from_coherent);