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