xref: /linux/lib/iommu-helper.c (revision bb9707077b4ee5f77bc9939b057ff8a0d410296f)
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);
42