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authorFelipe Balbi <felipe.balbi@nokia.com>2010-05-26 14:42:23 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2010-05-27 09:12:42 -0700
commitc4b5be98fe78508e7199d6919eb712feba9a4f01 (patch)
tree9e688dd076cea9213f8bcbda3627aa7941a01879 /include/asm-generic/gpio.h
parent796a8e423ac8afe9e98ad96e668f50142bdd7825 (diff)
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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/asm-generic/gpio.h')
-rw-r--r--include/asm-generic/gpio.h5
1 files changed, 5 insertions, 0 deletions
diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h
index fb1ecf8baa9..4f3d75e1ad3 100644
--- a/include/asm-generic/gpio.h
+++ b/include/asm-generic/gpio.h
@@ -90,6 +90,9 @@ struct gpio_chip {
unsigned offset);
int (*direction_output)(struct gpio_chip *chip,
unsigned offset, int value);
+ int (*set_debounce)(struct gpio_chip *chip,
+ unsigned offset, unsigned debounce);
+
void (*set)(struct gpio_chip *chip,
unsigned offset, int value);
@@ -123,6 +126,8 @@ extern void gpio_free(unsigned gpio);
extern int gpio_direction_input(unsigned gpio);
extern int gpio_direction_output(unsigned gpio, int value);
+extern int gpio_set_debounce(unsigned gpio, unsigned debounce);
+
extern int gpio_get_value_cansleep(unsigned gpio);
extern void gpio_set_value_cansleep(unsigned gpio, int value);