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   1 /*
   2  * IOMMU helper functions for the free area management
   3  */
   4
   5 #include <linux/module.h>
   6 #include <linux/bitops.h>
   7
   8 static 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;
  15 again:
  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
  33 void iommu_area_reserve(unsigned long *map, unsigned long i, int len)
  34 {
  35         unsigned long end = i + len;
  36         while (i < end) {
  37                 __set_bit(i, map);
  38                 i++;
  39         }
  40 }
  41
  42 int iommu_is_span_boundary(unsigned int index, unsigned int nr,
  43                            unsigned long shift,
  44                            unsigned long boundary_size)
  45 {
  46         BUG_ON(!is_power_of_2(boundary_size));
  47
  48         shift = (shift + index) & (boundary_size - 1);
  49         return shift + nr > boundary_size;
  50 }
  51
  52 unsigned long iommu_area_alloc(unsigned long *map, unsigned long size,
  53                                unsigned long start, unsigned int nr,
  54                                unsigned long shift, unsigned long boundary_size,
  55                                unsigned long align_mask)
  56 {
  57         unsigned long index;
  58 again:
  59         index = find_next_zero_area(map, size, start, nr, align_mask);
  60         if (index != -1) {
  61                 if (iommu_is_span_boundary(index, nr, shift, boundary_size)) {
  62                         /* we could do more effectively */
  63                         start = index + 1;
  64                         goto again;
  65                 }
  66                 iommu_area_reserve(map, index, nr);
  67         }
  68         return index;
  69 }
  70 EXPORT_SYMBOL(iommu_area_alloc);
  71
  72 void iommu_area_free(unsigned long *map, unsigned long start, unsigned int nr)
  73 {
  74         unsigned long end = start + nr;
  75
  76         while (start < end) {
  77                 __clear_bit(start, map);
  78                 start++;
  79         }
  80 }
  81 EXPORT_SYMBOL(iommu_area_free);
  82
  83 unsigned long iommu_num_pages(unsigned long addr, unsigned long len,
  84                               unsigned long io_page_size)
  85 {
  86         unsigned long size = (addr & (io_page_size - 1)) + len;
  87
  88         return DIV_ROUND_UP(size, io_page_size);
  89 }
  90 EXPORT_SYMBOL(iommu_num_pages);