release/src-rt-6.x.4708/linux/linux-2.6.36/lib/iommu-helper.c

   1 /*
   2  * IOMMU helper functions for the free area management
   3  */
   4
   5 #include <linux/module.h>
   6 #include <linux/bitmap.h>
   7
   8 int iommu_is_span_boundary(unsigned int index, unsigned int nr,
   9                            unsigned long shift,
  10                            unsigned long boundary_size)
  11 {
  12         BUG_ON(!is_power_of_2(boundary_size));
  13
  14         shift = (shift + index) & (boundary_size - 1);
  15         return shift + nr > boundary_size;
  16 }
  17
  18 unsigned long iommu_area_alloc(unsigned long *map, unsigned long size,
  19                                unsigned long start, unsigned int nr,
  20                                unsigned long shift, unsigned long boundary_size,
  21                                unsigned long align_mask)
  22 {
  23         unsigned long index;
  24
  25         /* We don't want the last of the limit */
  26         size -= 1;
  27 again:
  28         index = bitmap_find_next_zero_area(map, size, start, nr, align_mask);
  29         if (index < size) {
  30                 if (iommu_is_span_boundary(index, nr, shift, boundary_size)) {
  31                         /* we could do more effectively */
  32                         start = index + 1;
  33                         goto again;
  34                 }
  35                 bitmap_set(map, index, nr);
  36                 return index;
  37         }
  38         return -1;
  39 }
  40 EXPORT_SYMBOL(iommu_area_alloc);