7560fa60fc
Add a <linux/gpio.h> defining fail/warn stubs for GPIO calls on platforms that don't support the GPIO programming interface. That includes the arch-specific implementation glue otherwise. This facilitates a new model for GPIO usage: drivers that can use GPIOs if they're available, but don't require them. One example of such a driver is NAND driver for various FreeScale chips. On platforms update with GPIO support, they can be used instead of a worst-case delay to verify that the BUSY signal is off. (Also includes a couple minor unrelated doc updates.) Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
95 lines
1.8 KiB
C
95 lines
1.8 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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/*
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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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/* 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_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_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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