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| author | David Brownell <dbrownell@users.sourceforge.net> | 2008-10-16 07:03:14 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-10-16 20:21:40 +0200 |
| commit | 0f6d504e73b49374c6093efe6aa60ab55058248a (patch) | |
| tree | 414c9e591ba23b2126bc9cad4e0efb1b60693b2d /Documentation/gpio.txt | |
| parent | gpio: i2c expanders use subsys_init (diff) | |
| download | linux-0f6d504e73b49374c6093efe6aa60ab55058248a.tar.xz linux-0f6d504e73b49374c6093efe6aa60ab55058248a.zip | |
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')
| -rw-r--r-- | Documentation/gpio.txt | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/Documentation/gpio.txt b/Documentation/gpio.txt index 18022e249c53..8a7c45956d24 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 |