gpiolib: request/free hooks

Add a new internal mechanism to gpiolib to support low power
operations by letting gpio_chip instances see when their GPIOs
are in use.  When no GPIOs are active, chips may be able to
enter lower powered runtime states by disabling clocks and/or
power domains.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: "Magnus Damm" <magnus.damm@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 9 insertions, 0 deletions

diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h
index 04cb1d175df..81797ec9ab2 100644
--- a/include/asm-generic/gpio.h
+++ b/include/asm-generic/gpio.h
@@ -35,6 +35,10 @@ struct module;
  * @label: for diagnostics
  * @dev: optional device providing the GPIOs
  * @owner: helps prevent removal of modules exporting active GPIOs
+ * @request: optional hook for chip-specific activation, such as
+ *      enabling module power and clock; may sleep
+ * @free: optional hook for chip-specific deactivation, such as
+ *      disabling module power and clock; may sleep
  * @direction_input: configures signal "offset" as input, or returns error
  * @get: returns value for signal "offset"; for output signals this
  *      returns either the value actually sensed, or zero
@@ -67,6 +71,11 @@ struct gpio_chip {
         struct device           *dev;
         struct module           *owner;
 
+        int                     (*request)(struct gpio_chip *chip,
+                                                unsigned offset);
+        void                    (*free)(struct gpio_chip *chip,
+                                                unsigned offset);
+
         int                     (*direction_input)(struct gpio_chip *chip,
                                                 unsigned offset);
         int                     (*get)(struct gpio_chip *chip,