Documentation/gpio.txt mentions GENERIC_GPIO

Documentation/gpio.txt should mention the Kconfig GENERIC_GPIO flag, for
platforms to declare when relevant.  This should help minimize goofs like
omitting it, or not depending on it when needed.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Documentation/gpio.txt

@@ -66,7 +66,9 @@ registers; another might implement it by delegating through abstractions
 used for several very different kinds of GPIO controller.
 
 That said, if the convention is supported on their platform, drivers should
-use it when possible:
+use it when possible.  Platforms should declare GENERIC_GPIO support in
+Kconfig (boolean true), which multi-platform drivers can depend on when
+using the include file:
 
 	#include <asm/gpio.h>