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>

1 files changed, 7 insertions, 0 deletions

diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h
index 2c5744b66dec..04cb1d175df1 100644
--- a/include/asm-generic/gpio.h
+++ b/include/asm-generic/gpio.h
@@ -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