path: root/Documentation/gpio.txt
diff options
authorDavid Brownell <dbrownell@users.sourceforge.net>2008-10-16 05:03:14 (GMT)
committerLinus Torvalds <torvalds@linux-foundation.org>2008-10-16 18:21:40 (GMT)
commit0f6d504e73b49374c6093efe6aa60ab55058248a (patch)
tree414c9e591ba23b2126bc9cad4e0efb1b60693b2d /Documentation/gpio.txt
parent2f8d11971b9f54362437ce70f4d1911f0996d542 (diff)
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>
Diffstat (limited to 'Documentation/gpio.txt')
1 files changed, 3 insertions, 2 deletions
diff --git a/Documentation/gpio.txt b/Documentation/gpio.txt
index 18022e2..8a7c459 100644
--- a/Documentation/gpio.txt
+++ b/Documentation/gpio.txt
@@ -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

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