Linux Kernel  3.7.1
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iommu-helper.c
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1 /*
2  * IOMMU helper functions for the free area management
3  */
4 
5 #include <linux/export.h>
6 #include <linux/bitmap.h>
7 #include <linux/bug.h>
8 
9 int iommu_is_span_boundary(unsigned int index, unsigned int nr,
10  unsigned long shift,
11  unsigned long boundary_size)
12 {
13  BUG_ON(!is_power_of_2(boundary_size));
14 
15  shift = (shift + index) & (boundary_size - 1);
16  return shift + nr > boundary_size;
17 }
18 
19 unsigned long iommu_area_alloc(unsigned long *map, unsigned long size,
20  unsigned long start, unsigned int nr,
21  unsigned long shift, unsigned long boundary_size,
22  unsigned long align_mask)
23 {
24  unsigned long index;
25 
26  /* We don't want the last of the limit */
27  size -= 1;
28 again:
29  index = bitmap_find_next_zero_area(map, size, start, nr, align_mask);
30  if (index < size) {
31  if (iommu_is_span_boundary(index, nr, shift, boundary_size)) {
32  /* we could do more effectively */
33  start = index + 1;
34  goto again;
35  }
36  bitmap_set(map, index, nr);
37  return index;
38  }
39  return -1;
40 }