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 int iommu_is_span_boundary(unsigned int index, unsigned int nr, 44 unsigned long shift, 45 unsigned long boundary_size) 46 { 47 BUG_ON(!is_power_of_2(boundary_size)); 48 49 shift = (shift + index) & (boundary_size - 1); 50 return shift + nr > boundary_size; 51 } 52 53 unsigned long iommu_area_alloc(unsigned long *map, unsigned long size, 54 unsigned long start, unsigned int nr, 55 unsigned long shift, unsigned long boundary_size, 56 unsigned long align_mask) 57 { 58 unsigned long index; 59 again: 60 index = find_next_zero_area(map, size, start, nr, align_mask); 61 if (index != -1) { 62 if (iommu_is_span_boundary(index, nr, shift, boundary_size)) { 63 /* we could do more effectively */ 64 start = index + 1; 65 goto again; 66 } 67 set_bit_area(map, index, nr); 68 } 69 return index; 70 } 71 EXPORT_SYMBOL(iommu_area_alloc); 72 73 void iommu_area_free(unsigned long *map, unsigned long start, unsigned int nr) 74 { 75 unsigned long end = start + nr; 76 77 while (start < end) { 78 __clear_bit(start, map); 79 start++; 80 } 81 } 82 EXPORT_SYMBOL(iommu_area_free); 83