linux/lib/iommu-helper.c
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   1/*
   2 * IOMMU helper functions for the free area management
   3 */
   4
   5#include <linux/module.h>
   6#include <linux/bitmap.h>
   7
   8int iommu_is_span_boundary(unsigned int index, unsigned int nr,
   9                           unsigned long shift,
  10                           unsigned long boundary_size)
  11{
  12        BUG_ON(!is_power_of_2(boundary_size));
  13
  14        shift = (shift + index) & (boundary_size - 1);
  15        return shift + nr > boundary_size;
  16}
  17
  18unsigned long iommu_area_alloc(unsigned long *map, unsigned long size,
  19                               unsigned long start, unsigned int nr,
  20                               unsigned long shift, unsigned long boundary_size,
  21                               unsigned long align_mask)
  22{
  23        unsigned long index;
  24
  25        /* We don't want the last of the limit */
  26        size -= 1;
  27again:
  28        index = bitmap_find_next_zero_area(map, size, start, nr, align_mask);
  29        if (index < size) {
  30                if (iommu_is_span_boundary(index, nr, shift, boundary_size)) {
  31                        /* we could do more effectively */
  32                        start = index + 1;
  33                        goto again;
  34                }
  35                bitmap_set(map, index, nr);
  36                return index;
  37        }
  38        return -1;
  39}
  40EXPORT_SYMBOL(iommu_area_alloc);
  41
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