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 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);
 91
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Linux/lib/iommu-helper.c
