LXR linux/lib/iommu-helper.c

   1/*
   2 * IOMMU helper functions for the free area management
   3 */
   4
   5#include <linux/module.h>
   6#include <linux/bitops.h>
   7
   8static unsigned long find_next_zero_area(unsigned long *map,
   9                                         unsigned long size,
  10                                         unsigned long start,
  11                                         unsigned int nr,
  12                                         unsigned long align_mask)
  13{
  14        unsigned long index, end, i;
  15again:
  16        index = find_next_zero_bit(map, size, start);
  17
  18        /* Align allocation */
  19        index = (index + align_mask) & ~align_mask;
  20
  21        end = index + nr;
  22        if (end >= size)
  23                return -1;
  24        for (i = index; i < end; i++) {
  25                if (test_bit(i, map)) {
  26                        start = i+1;
  27                        goto again;
  28                }
  29        }
  30        return index;
  31}
  32
  33static inline void set_bit_area(unsigned long *map, unsigned long i,
  34                                int len)
  35{
  36        unsigned long end = i + len;
  37        while (i < end) {
  38                __set_bit(i, map);
  39                i++;
  40        }
  41}
  42
  43int iommu_is_span_boundary(unsigned int index, unsigned int nr,
  44                           unsigned long shift,
  45                           unsigned long boundary_size)
  46{
  47        BUG_ON(!is_power_of_2(boundary_size));
  48
  49        shift = (shift + index) & (boundary_size - 1);
  50        return shift + nr > boundary_size;
  51}
  52
  53unsigned long iommu_area_alloc(unsigned long *map, unsigned long size,
  54                               unsigned long start, unsigned int nr,
  55                               unsigned long shift, unsigned long boundary_size,
  56                               unsigned long align_mask)
  57{
  58        unsigned long index;
  59again:
  60        index = find_next_zero_area(map, size, start, nr, align_mask);
  61        if (index != -1) {
  62                if (iommu_is_span_boundary(index, nr, shift, boundary_size)) {
  63                        /* we could do more effectively */
  64                        start = index + 1;
  65                        goto again;
  66                }
  67                set_bit_area(map, index, nr);
  68        }
  69        return index;
  70}
  71EXPORT_SYMBOL(iommu_area_alloc);
  72
  73void iommu_area_free(unsigned long *map, unsigned long start, unsigned int nr)
  74{
  75        unsigned long end = start + nr;
  76
  77        while (start < end) {
  78                __clear_bit(start, map);
  79                start++;
  80        }
  81}
  82EXPORT_SYMBOL(iommu_area_free);
  83