diff --git a/include/linux/dma_remapping.h b/include/linux/dma_remapping.h
index 7799a85..136f170 100644
--- a/include/linux/dma_remapping.h
+++ b/include/linux/dma_remapping.h
@@ -17,6 +17,7 @@
 struct root_entry;
 
 extern void free_dmar_iommu(struct intel_iommu *iommu);
+extern int iommu_calculate_agaw(struct intel_iommu *iommu);
 
 extern int dmar_disabled;