root/lib/iommu-helper.c

DEFINITIONS

1. find_next_zero_area
2. iommu_area_reserve
3. iommu_is_span_boundary
4. iommu_area_alloc
5. iommu_area_free

/*
 * IOMMU helper functions for the free area management
 */

#include <linux/module.h>
#include <linux/bitops.h>

static unsigned long find_next_zero_area(unsigned long *map,
                                         unsigned long size,
                                         unsigned long start,
                                         unsigned int nr,
                                         unsigned long align_mask)
{
        unsigned long index, end, i;
again:
        index = find_next_zero_bit(map, size, start);

        /* Align allocation */
        index = (index + align_mask) & ~align_mask;

        end = index + nr;
        if (end >= size)
                return -1;
        for (i = index; i < end; i++) {
                if (test_bit(i, map)) {
                        start = i+1;
                        goto again;
                }
        }
        return index;
}

void iommu_area_reserve(unsigned long *map, unsigned long i, int len)
{
        unsigned long end = i + len;
        while (i < end) {
                __set_bit(i, map);
                i++;
        }
}

int iommu_is_span_boundary(unsigned int index, unsigned int nr,
                           unsigned long shift,
                           unsigned long boundary_size)
{
        BUG_ON(!is_power_of_2(boundary_size));

        shift = (shift + index) & (boundary_size - 1);
        return shift + nr > boundary_size;
}

unsigned long iommu_area_alloc(unsigned long *map, unsigned long size,
                               unsigned long start, unsigned int nr,
                               unsigned long shift, unsigned long boundary_size,
                               unsigned long align_mask)
{
        unsigned long index;
again:
        index = find_next_zero_area(map, size, start, nr, align_mask);
        if (index != -1) {
                if (iommu_is_span_boundary(index, nr, shift, boundary_size)) {
                        /* we could do more effectively */
                        start = index + 1;
                        goto again;
                }
                iommu_area_reserve(map, index, nr);
        }
        return index;
}
EXPORT_SYMBOL(iommu_area_alloc);

void iommu_area_free(unsigned long *map, unsigned long start, unsigned int nr)
{
        unsigned long end = start + nr;

        while (start < end) {
                __clear_bit(start, map);
                start++;
        }
}
EXPORT_SYMBOL(iommu_area_free);