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
   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 static 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
  43 static inline int is_span_boundary(unsigned int index, unsigned int nr,
  44                                    unsigned long shift,
  45                                    unsigned long boundary_size)
  46 {
  47         shift = (shift + index) & (boundary_size - 1);
  48         return shift + nr > boundary_size;
  49 }
  50
  51 unsigned long iommu_area_alloc(unsigned long *map, unsigned long size,
  52                                unsigned long start, unsigned int nr,
  53                                unsigned long shift, unsigned long boundary_size,
  54                                unsigned long align_mask)
  55 {
  56         unsigned long index;
  57 again:
  58         index = find_next_zero_area(map, size, start, nr, align_mask);
  59         if (index != -1) {
  60                 if (is_span_boundary(index, nr, shift, boundary_size)) {
  61                         /* we could do more effectively */
  62                         start = index + 1;
  63                         goto again;
  64                 }
  65                 set_bit_area(map, index, nr);
  66         }
  67         return index;
  68 }
  69 EXPORT_SYMBOL(iommu_area_alloc);
  70
  71 void iommu_area_free(unsigned long *map, unsigned long start, unsigned int nr)
  72 {
  73         unsigned long end = start + nr;
  74
  75         while (start < end) {
  76                 __clear_bit(start, map);
  77                 start++;
  78         }
  79 }
  80 EXPORT_SYMBOL(iommu_area_free);