Commit 0f6d504e authored by David Brownell's avatar David Brownell Committed by Linus Torvalds
Browse files

gpiolib: gpio_to_irq() hooks 



Add a new gpiolib mechanism: gpio_chip instances can provide mappings
between their (input) GPIOs and any associated IRQs.  This makes it easier
for platforms to support IRQs that are provided by board-specific external
chips instead of as part of their core (such as SOC-integrated GPIOs).

Also update the irq_to_gpio() description, saying to avoid it because it's
not always supported.

Signed-off-by: default avatarDavid Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 2f8d1197

Documentation/gpio.txt

+3 −2
Original line number Diff line number Diff line
@@ -264,7 +264,7 @@ map between them using calls like: 
	/* map GPIO numbers to IRQ numbers */

	int gpio_to_irq(unsigned gpio);



	/* map IRQ numbers to GPIO numbers */

	/* map IRQ numbers to GPIO numbers (avoid using this) */

	int irq_to_gpio(unsigned irq);



Those return either the corresponding number in the other namespace, or
@@ -284,7 +284,8 @@ system wakeup capabilities. 


Non-error values returned from irq_to_gpio() would most commonly be used

with gpio_get_value(), for example to initialize or update driver state

when the IRQ is edge-triggered.

when the IRQ is edge-triggered.  Note that some platforms don't support

this reverse mapping, so you should avoid using it.





Emulating Open Drain Signals

drivers/gpio/gpiolib.c

+18 −0
Original line number Diff line number Diff line
@@ -1010,6 +1010,24 @@ int __gpio_cansleep(unsigned gpio) 
}

EXPORT_SYMBOL_GPL(__gpio_cansleep);



/**

 * __gpio_to_irq() - return the IRQ corresponding to a GPIO

 * @gpio: gpio whose IRQ will be returned (already requested)

 * Context: any

 *

 * This is used directly or indirectly to implement gpio_to_irq().

 * It returns the number of the IRQ signaled by this (input) GPIO,

 * or a negative errno.

 */

int __gpio_to_irq(unsigned gpio)

{

	struct gpio_chip	*chip;



	chip = gpio_to_chip(gpio);

	return chip->to_irq ? chip->to_irq(chip, gpio - chip->base) : -ENXIO;

}

EXPORT_SYMBOL_GPL(__gpio_to_irq);







/* There's no value in making it easy to inline GPIO calls that may sleep.

include/asm-generic/gpio.h

+7 −0
Original line number Diff line number Diff line
@@ -40,6 +40,8 @@ struct module; 
 *	returns either the value actually sensed, or zero

 * @direction_output: configures signal "offset" as output, or returns error

 * @set: assigns output value for signal "offset"

 * @to_irq: optional hook supporting non-static gpio_to_irq() mappings;

 *	implementation may not sleep

 * @dbg_show: optional routine to show contents in debugfs; default code

 *	will be used when this is omitted, but custom code can show extra

 *	state (such as pullup/pulldown configuration).
@@ -73,6 +75,10 @@ struct gpio_chip { 
						unsigned offset, int value);

	void			(*set)(struct gpio_chip *chip,

						unsigned offset, int value);



	int			(*to_irq)(struct gpio_chip *chip,

						unsigned offset);



	void			(*dbg_show)(struct seq_file *s,

						struct gpio_chip *chip);

	int			base;
@@ -112,6 +118,7 @@ extern void __gpio_set_value(unsigned gpio, int value); 


extern int __gpio_cansleep(unsigned gpio);



extern int __gpio_to_irq(unsigned gpio);



#ifdef CONFIG_GPIO_SYSFS

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