diff --git a/include/linux/ioport.h b/include/linux/ioport.h
index 39db059..2cd07cc 100644
--- a/include/linux/ioport.h
+++ b/include/linux/ioport.h
@@ -59,6 +59,7 @@
 #define IORESOURCE_IRQ_HIGHLEVEL	(1<<2)
 #define IORESOURCE_IRQ_LOWLEVEL		(1<<3)
 #define IORESOURCE_IRQ_SHAREABLE	(1<<4)
+#define IORESOURCE_IRQ_OPTIONAL 	(1<<5)
 
 /* PnP DMA specific bits (IORESOURCE_BITS) */
 #define IORESOURCE_DMA_TYPE_MASK	(3<<0)