From c4b5be98fe78508e7199d6919eb712feba9a4f01 Mon Sep 17 00:00:00 2001 From: Felipe Balbi Date: Wed, 26 May 2010 14:42:23 -0700 Subject: gpiolib: introduce set_debounce method A few architectures, like OMAP, allow you to set a debouncing time for the gpio before generating the IRQ. Teach gpiolib about that. Mark said: : This would be generally useful for embedded systems, especially where : the interrupt concerned is a wake source. It allows drivers to avoid : spurious interrupts from noisy sources so if the hardware supports it : the driver can avoid having to explicitly wait for the signal to become : stable and software has to cope with fewer events. We've lived without : it for quite some time, though. David said: : I looked at adding debounce support to the generic GPIO calls (and thus : gpiolib) some time back, but decided against it. I forget why at this : time (check list archives) but it wasn't because of lack of utility in : certain contexts. : : One thing to watch out for is just how variable the hardware capabilities : are. Atmel GPIOs have something like a fixed number of 32K clock cycles : for debounce, twl4030 had something odd, OMAPs were more like the Atmel : chips but with a different clock. In some cases debouncing had to be : ganged, not per-GPIO. And so forth. Signed-off-by: Felipe Balbi Cc: Tony Lindgren Cc: David Brownell Reviewed-by: Mark Brown Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/gpio.h | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'include/linux/gpio.h') diff --git a/include/linux/gpio.h b/include/linux/gpio.h index 4e949a5b5b8..03f616b78cf 100644 --- a/include/linux/gpio.h +++ b/include/linux/gpio.h @@ -51,6 +51,11 @@ static inline int gpio_direction_output(unsigned gpio, int value) return -ENOSYS; } +static inline int gpio_set_debounce(unsigned gpio, unsigned debounce) +{ + return -ENOSYS; +} + static inline int gpio_get_value(unsigned gpio) { /* GPIO can never have been requested or set as {in,out}put */ -- cgit v1.2.3