linux/drivers/base/dma-coherent.c
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   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
   9struct 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
  17int 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}
  61EXPORT_SYMBOL(dma_declare_coherent_memory);
  62
  63void 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}
  74EXPORT_SYMBOL(dma_release_declared_memory);
  75
  76void *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}
  93EXPORT_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 */
 110int 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
 141err:
 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}
 149EXPORT_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 */
 164int 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}
 177EXPORT_SYMBOL(dma_release_from_coherent);
 178