28735a7253
It's been pointed out that output GPIOs should have an initial value, to avoid signal glitching ... among other things, it can be some time before a driver is ready. This patch corrects that oversight, fixing - documentation - platforms supporting the GPIO interface - users of that call (just one for now, others are pending) There's only one user of this call for now since most platforms are still using non-generic GPIO setup code, which in most cases already couples the initial value with its "set output mode" request. Note that most platforms are clear about the hardware letting the output value be set before the pin direction is changed, but the s3c241x docs are vague on that topic ... so those chips might not avoid the glitches. Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Acked-by: Andrew Victor <andrew@sanpeople.com> Acked-by: Milan Svoboda <msvoboda@ra.rockwell.com> Acked-by: Haavard Skinnemoen <hskinnemoen@atmel.com> Cc: Russell King <rmk@arm.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
28 lines
645 B
C
28 lines
645 B
C
#ifndef __ASM_AVR32_ARCH_GPIO_H
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#define __ASM_AVR32_ARCH_GPIO_H
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#include <linux/compiler.h>
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#include <asm/irq.h>
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/* Arch-neutral GPIO API */
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int __must_check gpio_request(unsigned int gpio, const char *label);
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void gpio_free(unsigned int gpio);
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int gpio_direction_input(unsigned int gpio);
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int gpio_direction_output(unsigned int gpio, int value);
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int gpio_get_value(unsigned int gpio);
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void gpio_set_value(unsigned int gpio, int value);
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static inline int gpio_to_irq(unsigned int gpio)
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{
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return gpio + GPIO_IRQ_BASE;
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}
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static inline int irq_to_gpio(unsigned int irq)
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{
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return irq - GPIO_IRQ_BASE;
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}
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#endif /* __ASM_AVR32_ARCH_GPIO_H */
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