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>

diff --git a/Documentation/gpio.txt b/Documentation/gpio.txt
index 18022e249c53dc1ad991d74d160551fa32f32070..8a7c45956d2412d69a26f8de991db19ed25a838f 100644 (file)
--- 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

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 317004fd94fbb6908e40e8f0b7482a887845ce13..29a7e6b1be5d8db915909a17164aec251ac91759 100644 (file)
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -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.

diff --cc include/asm-generic/gpio.h
Simple merge