iommu-helper: use bitmap library
[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/bitmap.h>
7
8 int 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
18 unsigned 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;
27 again:
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 }
40 EXPORT_SYMBOL(iommu_area_alloc);
41
42 unsigned long iommu_num_pages(unsigned long addr, unsigned long len,
43                               unsigned long io_page_size)
44 {
45         unsigned long size = (addr & (io_page_size - 1)) + len;
46
47         return DIV_ROUND_UP(size, io_page_size);
48 }
49 EXPORT_SYMBOL(iommu_num_pages);