diff --git a/include/linux/ioport.h b/include/linux/ioport.h
index 786e7b8..83aa812 100644
--- a/include/linux/ioport.h
+++ b/include/linux/ioport.h
@@ -184,5 +184,9 @@
 extern int iomem_map_sanity_check(resource_size_t addr, unsigned long size);
 extern int iomem_is_exclusive(u64 addr);
 
+extern int
+walk_system_ram_range(unsigned long start_pfn, unsigned long nr_pages,
+		void *arg, int (*func)(unsigned long, unsigned long, void *));
+
 #endif /* __ASSEMBLY__ */
 #endif	/* _LINUX_IOPORT_H */