tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
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linux
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * IOMMU helper functions for the free area management
4 */
5
6#include <linux/export.h>
7#include <linux/bitmap.h>
8#include <linux/bug.h>
9
10int iommu_is_span_boundary(unsigned int index, unsigned int nr,
11 unsigned long shift,
12 unsigned long boundary_size)
13{
14 BUG_ON(!is_power_of_2(boundary_size));
15
16 shift = (shift + index) & (boundary_size - 1);
17 return shift + nr > boundary_size;
18}
19
20unsigned long iommu_area_alloc(unsigned long *map, unsigned long size,
21 unsigned long start, unsigned int nr,
22 unsigned long shift, unsigned long boundary_size,
23 unsigned long align_mask)
24{
25 unsigned long index;
26
27 /* We don't want the last of the limit */
28 size -= 1;
29again:
30 index = bitmap_find_next_zero_area(map, size, start, nr, align_mask);
31 if (index < size) {
32 if (iommu_is_span_boundary(index, nr, shift, boundary_size)) {
33 start = ALIGN(shift + index, boundary_size) - shift;
34 goto again;
35 }
36 bitmap_set(map, index, nr);
37 return index;
38 }
39 return -1;
40}
41EXPORT_SYMBOL(iommu_area_alloc);