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gpiolib: gpio_to_irq() hooks

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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
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@@ -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