c4b5be98fe
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>
136 lines
2.6 KiB
C
136 lines
2.6 KiB
C
#ifndef __LINUX_GPIO_H
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#define __LINUX_GPIO_H
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/* see Documentation/gpio.txt */
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#ifdef CONFIG_GENERIC_GPIO
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#include <asm/gpio.h>
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#else
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#include <linux/kernel.h>
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#include <linux/types.h>
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#include <linux/errno.h>
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struct device;
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/*
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* Some platforms don't support the GPIO programming interface.
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*
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* In case some driver uses it anyway (it should normally have
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* depended on GENERIC_GPIO), these routines help the compiler
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* optimize out much GPIO-related code ... or trigger a runtime
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* warning when something is wrongly called.
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*/
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static inline int gpio_is_valid(int number)
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{
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return 0;
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}
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static inline int gpio_request(unsigned gpio, const char *label)
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{
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return -ENOSYS;
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}
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static inline void gpio_free(unsigned gpio)
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{
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might_sleep();
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/* GPIO can never have been requested */
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WARN_ON(1);
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}
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static inline int gpio_direction_input(unsigned gpio)
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{
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return -ENOSYS;
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}
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static inline int gpio_direction_output(unsigned gpio, int value)
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{
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return -ENOSYS;
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}
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static inline int gpio_set_debounce(unsigned gpio, unsigned debounce)
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{
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return -ENOSYS;
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}
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static inline int gpio_get_value(unsigned gpio)
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{
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/* GPIO can never have been requested or set as {in,out}put */
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WARN_ON(1);
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return 0;
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}
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static inline void gpio_set_value(unsigned gpio, int value)
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{
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/* GPIO can never have been requested or set as output */
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WARN_ON(1);
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}
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static inline int gpio_cansleep(unsigned gpio)
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{
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/* GPIO can never have been requested or set as {in,out}put */
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WARN_ON(1);
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return 0;
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}
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static inline int gpio_get_value_cansleep(unsigned gpio)
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{
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/* GPIO can never have been requested or set as {in,out}put */
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WARN_ON(1);
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return 0;
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}
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static inline void gpio_set_value_cansleep(unsigned gpio, int value)
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{
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/* GPIO can never have been requested or set as output */
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WARN_ON(1);
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}
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static inline int gpio_export(unsigned gpio, bool direction_may_change)
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{
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/* GPIO can never have been requested or set as {in,out}put */
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WARN_ON(1);
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return -EINVAL;
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}
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static inline int gpio_export_link(struct device *dev, const char *name,
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unsigned gpio)
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{
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/* GPIO can never have been exported */
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WARN_ON(1);
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return -EINVAL;
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}
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static inline int gpio_sysfs_set_active_low(unsigned gpio, int value)
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{
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/* GPIO can never have been requested */
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WARN_ON(1);
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return -EINVAL;
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}
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static inline void gpio_unexport(unsigned gpio)
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{
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/* GPIO can never have been exported */
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WARN_ON(1);
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}
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static inline int gpio_to_irq(unsigned gpio)
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{
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/* GPIO can never have been requested or set as input */
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WARN_ON(1);
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return -EINVAL;
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}
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static inline int irq_to_gpio(unsigned irq)
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{
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/* irq can never have been returned from gpio_to_irq() */
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WARN_ON(1);
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return -EINVAL;
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}
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#endif
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#endif /* __LINUX_GPIO_H */
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