lib/iommu-helper.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * IOMMU helper functions for the free area management
   4  */
   5
   6 #include <linux/export.h>
   7 #include <linux/bitmap.h>
   8 #include <linux/bug.h>
   9
  10 int iommu_is_span_boundary(unsigned int index, unsigned int nr,
  11                            unsigned long shift,
  12                            unsigned long boundary_size)
  13 {
  14         BUG_ON(!is_power_of_2(boundary_size));
  15
  16         shift = (shift + index) & (boundary_size - 1);
  17         return shift + nr > boundary_size;
  18 }
  19
  20 unsigned long iommu_area_alloc(unsigned long *map, unsigned long size,
  21                                unsigned long start, unsigned int nr,
  22                                unsigned long shift, unsigned long boundary_size,
  23                                unsigned long align_mask)
  24 {
  25         unsigned long index;
  26
  27         /* We don't want the last of the limit */
  28         size -= 1;
  29 again:
  30         index = bitmap_find_next_zero_area(map, size, start, nr, align_mask);
  31         if (index < size) {
  32                 if (iommu_is_span_boundary(index, nr, shift, boundary_size)) {
  33                         start = ALIGN(shift + index, boundary_size) - shift;
  34                         goto again;
  35                 }
  36                 bitmap_set(map, index, nr);
  37                 return index;
  38         }
  39         return -1;
  40 }
  41 EXPORT_SYMBOL(iommu_area_alloc);