gpio: define gpio_is_valid()

Introduce a gpio_is_valid() predicate; use it in gpiolib.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
    [ use inline function; follow the gpio_* naming convention;
      work without gpiolib; all programming interfaces need docs ]
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>

1 files changed, 12 insertions, 0 deletions

diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h
index 7e77b6ff45bb..464c5b334dc2 100644
--- a/include/asm-generic/gpio.h
+++ b/include/asm-generic/gpio.h
@@ -16,6 +16,12 @@
 #define ARCH_NR_GPIOS           256
 #endif
 
+static inline int gpio_is_valid(int number)
+{
+        /* only some non-negative numbers are valid */
+        return ((unsigned)number) < ARCH_NR_GPIOS;
+}
+
 struct seq_file;
 struct module;
 
@@ -99,6 +105,12 @@ extern int __gpio_cansleep(unsigned gpio);
 
 #else
 
+static inline int gpio_is_valid(int number)
+{
+        /* only non-negative numbers are valid */
+        return number >= 0;
+}
+
 /* platforms that don't directly support access to GPIOs through I2C, SPI,
  * or other blocking infrastructure can use these wrappers.
  */