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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: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
David Brownell 2008-10-15 22:03:14 -07:00 committed by Linus Torvalds
parent 2f8d11971b
commit 0f6d504e73
3 changed files with 28 additions and 2 deletions
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5
Documentation/gpio.txt
View File

@ -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

18
drivers/gpio/gpiolib.c
View File

@ -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.

7
include/asm-generic/gpio.h
View File

@ -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