diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
index 73b1f1c..59bafa6 100644
--- a/include/linux/swiotlb.h
+++ b/include/linux/swiotlb.h
@@ -88,4 +88,10 @@
 extern int
 swiotlb_dma_supported(struct device *hwdev, u64 mask);
 
+#ifdef CONFIG_SWIOTLB
+extern void __init swiotlb_free(void);
+#else
+static inline void swiotlb_free(void) { }
+#endif
+
 #endif /* __LINUX_SWIOTLB_H */