diff --git a/include/linux/pfn.h b/include/linux/pfn.h
index 7646637..97f3e88 100644
--- a/include/linux/pfn.h
+++ b/include/linux/pfn.h
@@ -9,5 +9,6 @@
 #define PFN_UP(x)	(((x) + PAGE_SIZE-1) >> PAGE_SHIFT)
 #define PFN_DOWN(x)	((x) >> PAGE_SHIFT)
 #define PFN_PHYS(x)	((phys_addr_t)(x) << PAGE_SHIFT)
+#define PHYS_PFN(x)	((unsigned long)((x) >> PAGE_SHIFT))
 
 #endif