[PATCH] Make asm-generic/ioctl.h more generic using conditionals.

["Robert P. J. Day" <rpjday@mindspring.com>]

Allow individual architectures to override a small set of macros
before including asm-generic/ioctl.h, in order to greatly simplify a
number of existing ioctl.h files.

The overrideable macros would be:

	_IOC_SIZEBITS
	_IOC_DIRBITS
	_IOC_NONE
	_IOC_WRITE
	_IOC_READ

---

  i've submitted this once before, and it didn't seem to garner a lot
of attention one way or the other.  this patch can be applied
standalone and shouldn't affect anything, but it would subsequently
allow at least a few ioctl.h files to be shortened considerably.

diff --git a/include/asm-generic/ioctl.h b/include/asm-generic/ioctl.h
index cd02729..4fb087a 100644
--- a/include/asm-generic/ioctl.h
+++ b/include/asm-generic/ioctl.h
@@ -21,8 +21,19 @@
  */
 #define _IOC_NRBITS	8
 #define _IOC_TYPEBITS	8
-#define _IOC_SIZEBITS	14
-#define _IOC_DIRBITS	2
+
+/*
+ * Let any architecture override either of the following before
+ * including this file.
+ */
+
+#ifndef _IOC_SIZEBITS
+# define _IOC_SIZEBITS	14
+#endif
+
+#ifndef _IOC_DIRBITS
+# define _IOC_DIRBITS	2
+#endif

 #define _IOC_NRMASK	((1 << _IOC_NRBITS)-1)
 #define _IOC_TYPEMASK	((1 << _IOC_TYPEBITS)-1)
@@ -35,11 +46,21 @@
 #define _IOC_DIRSHIFT	(_IOC_SIZESHIFT+_IOC_SIZEBITS)

 /*
- * Direction bits.
+ * Direction bits, which any architecture can choose to override
+ * before including this file.
  */
-#define _IOC_NONE	0U
-#define _IOC_WRITE	1U
-#define _IOC_READ	2U
+
+#ifndef _IOC_NONE
+# define _IOC_NONE	0U
+#endif
+
+#ifndef _IOC_WRITE
+# define _IOC_WRITE	1U
+#endif
+
+#ifndef _IOC_READ
+# define _IOC_READ	2U
+#endif

 #define _IOC(dir,type,nr,size) \
 	(((dir)  << _IOC_DIRSHIFT) | \

-- 
========================================================================
Robert P. J. Day
Linux Consulting, Training and Annoying Kernel Pedantry
Waterloo, Ontario, CANADA

http://fsdev.net/wiki/index.php?title=Main_Page
========================================================================