| 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 | } |
| 41 | EXPORT_SYMBOL(iommu_area_alloc); |