diff --git a/include/asm-generic/memory_model.h b/include/asm-generic/memory_model.h
index 4b4b056a6eb0..5148150cc80b 100644
--- a/include/asm-generic/memory_model.h
+++ b/include/asm-generic/memory_model.h
@@ -1,6 +1,8 @@
 #ifndef __ASM_MEMORY_MODEL_H
 #define __ASM_MEMORY_MODEL_H
 
+#include <linux/pfn.h>
+
 #ifndef __ASSEMBLY__
 
 #if defined(CONFIG_FLATMEM)
@@ -72,7 +74,7 @@
 /*
  * Convert a physical address to a Page Frame Number and back
  */
-#define	__phys_to_pfn(paddr)	((unsigned long)((paddr) >> PAGE_SHIFT))
+#define	__phys_to_pfn(paddr)	PHYS_PFN(paddr)
 #define	__pfn_to_phys(pfn)	PFN_PHYS(pfn)
 
 #define page_to_pfn __page_to_pfn
diff --git a/include/linux/pfn.h b/include/linux/pfn.h
index 7646637221f3..97f3e88aead4 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