iommu-helper.c

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

#include <linux/export.h>
#include <linux/bitmap.h>
#include <linux/bug.h>

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;

    /* We don't want the last of the limit */
    size -= 1;
again:
    index = bitmap_find_next_zero_area(map, size, start, nr, align_mask);
    if (index < size) {
        if (iommu_is_span_boundary(index, nr, shift, boundary_size)) {
            /* we could do more effectively */
            start = index + 1;
            goto again;
        }
        bitmap_set(map, index, nr);
        return index;
    }
    return -1;
}
EXPORT_SYMBOL(iommu_area_alloc);