[PATCH] unify PFN_* macros

Just about every architecture defines some macros to do operations on pfns.
 They're all virtually identical.  This patch consolidates all of them.

One minor glitch is that at least i386 uses them in a very skeletal header
file.  To keep away from #include dependency hell, I stuck the new
definitions in a new, isolated header.

Of all of the implementations, sh64 is the only one that varied by a bit.
It used some masks to ensure that any sign-extension got ripped away before
the arithmetic is done.  This has been posted to that sh64 maintainers and
the development list.

Compiles on x86, x86_64, ia64 and ppc64.

Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 9 insertions, 0 deletions

diff --git a/include/linux/pfn.h b/include/linux/pfn.h
new file mode 100644
index 000000000000..bb01f8b92b56
--- /dev/null
+++ b/include/linux/pfn.h
@@ -0,0 +1,9 @@
+#ifndef _LINUX_PFN_H_
+#define _LINUX_PFN_H_
+
+#define PFN_ALIGN(x)    (((unsigned long)(x) + (PAGE_SIZE - 1)) & PAGE_MASK)
+#define PFN_UP(x)       (((x) + PAGE_SIZE-1) >> PAGE_SHIFT)
+#define PFN_DOWN(x)     ((x) >> PAGE_SHIFT)
+#define PFN_PHYS(x)     ((x) << PAGE_SHIFT)
+
+#endif