diff --git a/include/linux/iommu-helper.h b/include/linux/iommu-helper.h
index a6d0586e2bf7..3b068e5b5671 100644
--- a/include/linux/iommu-helper.h
+++ b/include/linux/iommu-helper.h
@@ -23,4 +23,7 @@ extern unsigned long iommu_area_alloc(unsigned long *map, unsigned long size,
 extern void iommu_area_free(unsigned long *map, unsigned long start,
 			    unsigned int nr);
 
+extern unsigned long iommu_num_pages(unsigned long addr, unsigned long len,
+				     unsigned long io_page_size);
+
 #endif
diff --git a/lib/iommu-helper.c b/lib/iommu-helper.c
index 5d90074dca75..75dbda03f4fb 100644
--- a/lib/iommu-helper.c
+++ b/lib/iommu-helper.c
@@ -79,3 +79,12 @@ void iommu_area_free(unsigned long *map, unsigned long start, unsigned int nr)
 	}
 }
 EXPORT_SYMBOL(iommu_area_free);
+
+unsigned long iommu_num_pages(unsigned long addr, unsigned long len,
+			      unsigned long io_page_size)
+{
+	unsigned long size = (addr & (io_page_size - 1)) + len;
+
+	return DIV_ROUND_UP(size, io_page_size);
+}
+EXPORT_SYMBOL(iommu_num_pages);