iommu sg: add IOMMU helper functions for the free area management
[linux-3.10.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 static inline int is_span_boundary(unsigned int index, unsigned int nr,
44                                    unsigned long shift,
45                                    unsigned long boundary_size)
46 {
47         shift = (shift + index) & (boundary_size - 1);
48         return shift + nr > boundary_size;
49 }
50
51 unsigned long iommu_area_alloc(unsigned long *map, unsigned long size,
52                                unsigned long start, unsigned int nr,
53                                unsigned long shift, unsigned long boundary_size,
54                                unsigned long align_mask)
55 {
56         unsigned long index;
57 again:
58         index = find_next_zero_area(map, size, start, nr, align_mask);
59         if (index != -1) {
60                 if (is_span_boundary(index, nr, shift, boundary_size)) {
61                         /* we could do more effectively */
62                         start = index + 1;
63                         goto again;
64                 }
65                 set_bit_area(map, index, nr);
66         }
67         return index;
68 }
69 EXPORT_SYMBOL(iommu_area_alloc);
70
71 void iommu_area_free(unsigned long *map, unsigned long start, unsigned int nr)
72 {
73         unsigned long end = start + nr;
74
75         while (start < end) {
76                 __clear_bit(start, map);
77                 start++;
78         }
79 }
80 EXPORT_SYMBOL(iommu_area_free);