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| author | Felipe Balbi <felipe.balbi@nokia.com> | 2010-05-26 23:42:23 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-05-27 18:12:42 +0200 |
| commit | c4b5be98fe78508e7199d6919eb712feba9a4f01 (patch) | |
| tree | 9e688dd076cea9213f8bcbda3627aa7941a01879 /include | |
| parent | gpiolib: make gpiochip_add() show a better error message (diff) | |
| download | linux-c4b5be98fe78508e7199d6919eb712feba9a4f01.tar.xz linux-c4b5be98fe78508e7199d6919eb712feba9a4f01.zip | |
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')
| -rw-r--r-- | include/asm-generic/gpio.h | 5 | ||||
| -rw-r--r-- | include/linux/gpio.h | 5 |
2 files changed, 10 insertions, 0 deletions
diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h index fb1ecf8baa90..4f3d75e1ad39 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); 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 */ |