Merge branch 'core/rcu' into core/rcu-for-linus
[linux-2.6.git] / lib / iommu-helper.c
1 /*
2  * IOMMU helper functions for the free area management
3  */
4
5 #include <linux/module.h>
6 #include <linux/bitops.h>
7
8 static unsigned long find_next_zero_area(unsigned long *map,
9                                          unsigned long size,
10                                          unsigned long start,
11                                          unsigned int nr,
12                                          unsigned long align_mask)
13 {
14         unsigned long index, end, i;
15 again:
16         index = find_next_zero_bit(map, size, start);
17
18         /* Align allocation */
19         index = (index + align_mask) & ~align_mask;
20
21         end = index + nr;
22         if (end >= size)
23                 return -1;
24         for (i = index; i < end; i++) {
25                 if (test_bit(i, map)) {
26                         start = i+1;
27                         goto again;
28                 }
29         }
30         return index;
31 }
32
33 static inline void set_bit_area(unsigned long *map, unsigned long i,
34                                 int len)
35 {
36         unsigned long end = i + len;
37         while (i < end) {
38                 __set_bit(i, map);
39                 i++;
40         }
41 }
42
43 int iommu_is_span_boundary(unsigned int index, unsigned int nr,
44                            unsigned long shift,
45                            unsigned long boundary_size)
46 {
47         BUG_ON(!is_power_of_2(boundary_size));
48
49         shift = (shift + index) & (boundary_size - 1);
50         return shift + nr > boundary_size;
51 }
52
53 unsigned long iommu_area_alloc(unsigned long *map, unsigned long size,
54                                unsigned long start, unsigned int nr,
55                                unsigned long shift, unsigned long boundary_size,
56                                unsigned long align_mask)
57 {
58         unsigned long index;
59 again:
60         index = find_next_zero_area(map, size, start, nr, align_mask);
61         if (index != -1) {
62                 if (iommu_is_span_boundary(index, nr, shift, boundary_size)) {
63                         /* we could do more effectively */
64                         start = index + 1;
65                         goto again;
66                 }
67                 set_bit_area(map, index, nr);
68         }
69         return index;
70 }
71 EXPORT_SYMBOL(iommu_area_alloc);
72
73 void iommu_area_free(unsigned long *map, unsigned long start, unsigned int nr)
74 {
75         unsigned long end = start + nr;
76
77         while (start < end) {
78                 __clear_bit(start, map);
79                 start++;
80         }
81 }
82 EXPORT_SYMBOL(iommu_area_free);