From e6de1808f8ebfeb7e49f3c5a30cb8f2032beb287 Mon Sep 17 00:00:00 2001 From: Guennadi Liakhovetski Date: Mon, 28 Apr 2008 02:14:46 -0700 Subject: gpio: define gpio_is_valid() Introduce a gpio_is_valid() predicate; use it in gpiolib. Signed-off-by: Guennadi Liakhovetski [ use inline function; follow the gpio_* naming convention; work without gpiolib; all programming interfaces need docs ] Signed-off-by: David Brownell Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/gpio.txt | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'Documentation/gpio.txt') diff --git a/Documentation/gpio.txt b/Documentation/gpio.txt index 54630095aa3..c35ca9e40d4 100644 --- a/Documentation/gpio.txt +++ b/Documentation/gpio.txt @@ -107,6 +107,16 @@ type of GPIO controller, and on one particular board 80-95 with an FPGA. The numbers need not be contiguous; either of those platforms could also use numbers 2000-2063 to identify GPIOs in a bank of I2C GPIO expanders. +If you want to initialize a structure with an invalid GPIO number, use +some negative number (perhaps "-EINVAL"); that will never be valid. To +test if a number could reference a GPIO, you may use this predicate: + + int gpio_is_valid(int number); + +A number that's not valid will be rejected by calls which may request +or free GPIOs (see below). Other numbers may also be rejected; for +example, a number might be valid but unused on a given board. + Whether a platform supports multiple GPIO controllers is currently a platform-specific implementation issue. -- cgit v1.2.3