/*
   * IOMMU helper functions for the free area management
   */
  
  #include <linux/module.h>
  #include <linux/bitops.h>
  
  static unsigned long find_next_zero_area(unsigned long *map,
  					 unsigned long size,
  					 unsigned long start,
  					 unsigned int nr,
  					 unsigned long align_mask)
  {
  	unsigned long index, end, i;
  again:
  	index = find_next_zero_bit(map, size, start);
  
  	/* Align allocation */
  	index = (index + align_mask) & ~align_mask;
  
  	end = index + nr;
  	if (end >= size)
  		return -1;
  	for (i = index; i < end; i++) {
  		if (test_bit(i, map)) {
  			start = i+1;
  			goto again;
  		}
  	}
  	return index;
  }
  
  static inline void set_bit_area(unsigned long *map, unsigned long i,
  				int len)
  {
  	unsigned long end = i + len;
  	while (i < end) {
  		__set_bit(i, map);
  		i++;
  	}
  }

  int iommu_is_span_boundary(unsigned int index, unsigned int nr,
  			   unsigned long shift,
  			   unsigned long boundary_size)

  {

  	BUG_ON(!is_power_of_2(boundary_size));

  	shift = (shift + index) & (boundary_size - 1);
  	return shift + nr > boundary_size;
  }
  
  unsigned long iommu_area_alloc(unsigned long *map, unsigned long size,
  			       unsigned long start, unsigned int nr,
  			       unsigned long shift, unsigned long boundary_size,
  			       unsigned long align_mask)
  {
  	unsigned long index;
  again:
  	index = find_next_zero_area(map, size, start, nr, align_mask);
  	if (index != -1) {

  		if (iommu_is_span_boundary(index, nr, shift, boundary_size)) {

  			/* we could do more effectively */
  			start = index + 1;
  			goto again;
  		}
  		set_bit_area(map, index, nr);
  	}
  	return index;
  }
  EXPORT_SYMBOL(iommu_area_alloc);
  
  void iommu_area_free(unsigned long *map, unsigned long start, unsigned int nr)
  {
  	unsigned long end = start + nr;
  
  	while (start < end) {
  		__clear_bit(start, map);
  		start++;
  	}
  }
  EXPORT_SYMBOL(iommu_area_free);