// SPDX-License-Identifier: GPL-2.0
  /*
   * IOMMU helper functions for the free area management
   */
  
  #include <linux/export.h>
  #include <linux/bitmap.h>
  #include <linux/bug.h>
  
  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;
  
  	/* We don't want the last of the limit */
  	size -= 1;
  again:
  	index = bitmap_find_next_zero_area(map, size, start, nr, align_mask);
  	if (index < size) {
  		if (iommu_is_span_boundary(index, nr, shift, boundary_size)) {
  			start = ALIGN(shift + index, boundary_size) - shift;
  			goto again;
  		}
  		bitmap_set(map, index, nr);
  		return index;
  	}
  	return -1;
  }
  EXPORT_SYMBOL(iommu_area_alloc);