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authorFelipe Balbi <felipe.balbi@nokia.com>2010-05-27 01:42:23 +0400
committerLinus Torvalds <torvalds@linux-foundation.org>2010-05-27 20:12:42 +0400
commitc4b5be98fe78508e7199d6919eb712feba9a4f01 (patch)
tree9e688dd076cea9213f8bcbda3627aa7941a01879 /include/linux/gpio.h
parent796a8e423ac8afe9e98ad96e668f50142bdd7825 (diff)
downloadlinux-c4b5be98fe78508e7199d6919eb712feba9a4f01.tar.xz
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 <felipe.balbi@nokia.com> Cc: Tony Lindgren <tony@atomide.com> Cc: David Brownell <david-b@pacbell.net> Reviewed-by: Mark Brown <broonie@opensource.wolfsonmicro.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/gpio.h')
-rw-r--r--include/linux/gpio.h5
1 files changed, 5 insertions, 0 deletions
diff --git a/include/linux/gpio.h b/include/linux/gpio.h
index 4e949a5b5b85..03f616b78cfa 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 */