diff --git a/arch/s390/include/asm/io.h b/arch/s390/include/asm/io.h
index cd6b9ee..ba516f8 100644
--- a/arch/s390/include/asm/io.h
+++ b/arch/s390/include/asm/io.h
@@ -38,6 +38,15 @@
 {
 }
 
+static inline void __iomem *ioport_map(unsigned long port, unsigned int nr)
+{
+	return NULL;
+}
+
+static inline void ioport_unmap(void __iomem *p)
+{
+}
+
 /*
  * s390 needs a private implementation of pci_iomap since ioremap with its
  * offset parameter isn't sufficient. That's because BAR spaces are not