drivers/base/dma-coherent.c

   1 /*
   2  * Coherent per-device memory handling.
   3  * Borrowed from i386
   4  */
   5 #include <linux/slab.h>
   6 #include <linux/kernel.h>
   7 #include <linux/dma-mapping.h>
   8
   9 struct dma_coherent_mem {
  10         void            *virt_base;
  11         dma_addr_t      device_base;
  12         int             size;
  13         int             flags;
  14         unsigned long   *bitmap;
  15 };
  16
  17 int dma_declare_coherent_memory(struct device *dev, dma_addr_t bus_addr,
  18                                 dma_addr_t device_addr, size_t size, int flags)
  19 {
  20         void __iomem *mem_base = NULL;
  21         int pages = size >> PAGE_SHIFT;
  22         int bitmap_size = BITS_TO_LONGS(pages) * sizeof(long);
  23
  24         if ((flags & (DMA_MEMORY_MAP | DMA_MEMORY_IO)) == 0)
  25                 goto out;
  26         if (!size)
  27                 goto out;
  28         if (dev->dma_mem)
  29                 goto out;
  30
  31         /* FIXME: this routine just ignores DMA_MEMORY_INCLUDES_CHILDREN */
  32
  33         mem_base = ioremap(bus_addr, size);
  34         if (!mem_base)
  35                 goto out;
  36
  37         dev->dma_mem = kzalloc(sizeof(struct dma_coherent_mem), GFP_KERNEL);
  38         if (!dev->dma_mem)
  39                 goto out;
  40         dev->dma_mem->bitmap = kzalloc(bitmap_size, GFP_KERNEL);
  41         if (!dev->dma_mem->bitmap)
  42                 goto free1_out;
  43
  44         dev->dma_mem->virt_base = mem_base;
  45         dev->dma_mem->device_base = device_addr;
  46         dev->dma_mem->size = pages;
  47         dev->dma_mem->flags = flags;
  48
  49         if (flags & DMA_MEMORY_MAP)
  50                 return DMA_MEMORY_MAP;
  51
  52         return DMA_MEMORY_IO;
  53
  54  free1_out:
  55         kfree(dev->dma_mem);
  56  out:
  57         if (mem_base)
  58                 iounmap(mem_base);
  59         return 0;
  60 }
  61 EXPORT_SYMBOL(dma_declare_coherent_memory);
  62
  63 void dma_release_declared_memory(struct device *dev)
  64 {
  65         struct dma_coherent_mem *mem = dev->dma_mem;
  66
  67         if (!mem)
  68                 return;
  69         dev->dma_mem = NULL;
  70         iounmap(mem->virt_base);
  71         kfree(mem->bitmap);
  72         kfree(mem);
  73 }
  74 EXPORT_SYMBOL(dma_release_declared_memory);
  75
  76 void *dma_mark_declared_memory_occupied(struct device *dev,
  77                                         dma_addr_t device_addr, size_t size)
  78 {
  79         struct dma_coherent_mem *mem = dev->dma_mem;
  80         int pos, err;
  81
  82         size += device_addr & ~PAGE_MASK;
  83
  84         if (!mem)
  85                 return ERR_PTR(-EINVAL);
  86
  87         pos = (device_addr - mem->device_base) >> PAGE_SHIFT;
  88         err = bitmap_allocate_region(mem->bitmap, pos, get_order(size));
  89         if (err != 0)
  90                 return ERR_PTR(err);
  91         return mem->virt_base + (pos << PAGE_SHIFT);
  92 }
  93 EXPORT_SYMBOL(dma_mark_declared_memory_occupied);
  94
  95 /**
  96  * dma_alloc_from_coherent() - try to allocate memory from the per-device coherent area
  97  *
  98  * @dev:        device from which we allocate memory
  99  * @size:       size of requested memory area
 100  * @dma_handle: This will be filled with the correct dma handle
 101  * @ret:        This pointer will be filled with the virtual address
 102  *              to allocated area.
 103  *
 104  * This function should be only called from per-arch dma_alloc_coherent()
 105  * to support allocation from per-device coherent memory pools.
 106  *
 107  * Returns 0 if dma_alloc_coherent should continue with allocating from
 108  * generic memory areas, or !0 if dma_alloc_coherent should return @ret.
 109  */
 110 int dma_alloc_from_coherent(struct device *dev, ssize_t size,
 111                                        dma_addr_t *dma_handle, void **ret)
 112 {
 113         struct dma_coherent_mem *mem;
 114         int order = get_order(size);
 115         int pageno;
 116
 117         if (!dev)
 118                 return 0;
 119         mem = dev->dma_mem;
 120         if (!mem)
 121                 return 0;
 122
 123         *ret = NULL;
 124
 125         if (unlikely(size > (mem->size << PAGE_SHIFT)))
 126                 goto err;
 127
 128         pageno = bitmap_find_free_region(mem->bitmap, mem->size, order);
 129         if (unlikely(pageno < 0))
 130                 goto err;
 131
 132         /*
 133          * Memory was found in the per-device area.
 134          */
 135         *dma_handle = mem->device_base + (pageno << PAGE_SHIFT);
 136         *ret = mem->virt_base + (pageno << PAGE_SHIFT);
 137         memset(*ret, 0, size);
 138
 139         return 1;
 140
 141 err:
 142         /*
 143          * In the case where the allocation can not be satisfied from the
 144          * per-device area, try to fall back to generic memory if the
 145          * constraints allow it.
 146          */
 147         return mem->flags & DMA_MEMORY_EXCLUSIVE;
 148 }
 149 EXPORT_SYMBOL(dma_alloc_from_coherent);
 150
 151 /**
 152  * dma_release_from_coherent() - try to free the memory allocated from per-device coherent memory pool
 153  * @dev:        device from which the memory was allocated
 154  * @order:      the order of pages allocated
 155  * @vaddr:      virtual address of allocated pages
 156  *
 157  * This checks whether the memory was allocated from the per-device
 158  * coherent memory pool and if so, releases that memory.
 159  *
 160  * Returns 1 if we correctly released the memory, or 0 if
 161  * dma_release_coherent() should proceed with releasing memory from
 162  * generic pools.
 163  */
 164 int dma_release_from_coherent(struct device *dev, int order, void *vaddr)
 165 {
 166         struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;
 167
 168         if (mem && vaddr >= mem->virt_base && vaddr <
 169                    (mem->virt_base + (mem->size << PAGE_SHIFT))) {
 170                 int page = (vaddr - mem->virt_base) >> PAGE_SHIFT;
 171
 172                 bitmap_release_region(mem->bitmap, page, order);
 173                 return 1;
 174         }
 175         return 0;
 176 }
 177 EXPORT_SYMBOL(dma_release_from_coherent);