2 files changed, 44 insertions, 2 deletions

diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h
index 6be061d09da9..1beff5166e53 100644
--- a/include/asm-generic/gpio.h
+++ b/include/asm-generic/gpio.h
@@ -32,6 +32,8 @@ struct module;
 /**
  * struct gpio_chip - abstract a GPIO controller
  * @label: for diagnostics
+ * @dev: optional device providing the GPIOs
+ * @owner: helps prevent removal of modules exporting active GPIOs
  * @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
@@ -59,6 +61,7 @@ struct module;
  */
 struct gpio_chip {
         char                    *label;
+        struct device           *dev;
         struct module           *owner;
 
         int                     (*direction_input)(struct gpio_chip *chip,
@@ -74,6 +77,7 @@ struct gpio_chip {
         int                     base;
         u16                     ngpio;
         unsigned                can_sleep:1;
+        unsigned                exported:1;
 };
 
 extern const char *gpiochip_is_requested(struct gpio_chip *chip,
@@ -108,7 +112,18 @@ extern void __gpio_set_value(unsigned gpio, int value);
 extern int __gpio_cansleep(unsigned gpio);
 
 
-#else
+#ifdef CONFIG_GPIO_SYSFS
+
+/*
+ * A sysfs interface can be exported by individual drivers if they want,
+ * but more typically is configured entirely from userspace.
+ */
+extern int gpio_export(unsigned gpio, bool direction_may_change);
+extern void gpio_unexport(unsigned gpio);
+
+#endif  /* CONFIG_GPIO_SYSFS */
+
+#else   /* !CONFIG_HAVE_GPIO_LIB */
 
 static inline int gpio_is_valid(int number)
 {
@@ -137,6 +152,20 @@ static inline void gpio_set_value_cansleep(unsigned gpio, int value)
         gpio_set_value(gpio, value);
 }
 
-#endif
+#endif /* !CONFIG_HAVE_GPIO_LIB */
+
+#ifndef CONFIG_GPIO_SYSFS
+
+/* sysfs support is only available with gpiolib, where it's optional */
+
+static inline int gpio_export(unsigned gpio, bool direction_may_change)
+{
+        return -ENOSYS;
+}
+
+static inline void gpio_unexport(unsigned gpio)
+{
+}
+#endif  /* CONFIG_GPIO_SYSFS */
 
 #endif /* _ASM_GENERIC_GPIO_H */
diff --git a/include/linux/gpio.h b/include/linux/gpio.h
index 98be6c5762b9..730a20b83576 100644
--- a/include/linux/gpio.h
+++ b/include/linux/gpio.h
@@ -79,6 +79,19 @@ static inline void gpio_set_value_cansleep(unsigned gpio, int value)
         WARN_ON(1);
 }
 
+static inline int gpio_export(unsigned gpio, bool direction_may_change)
+{
+        /* GPIO can never have been requested or set as {in,out}put */
+        WARN_ON(1);
+        return -EINVAL;
+}
+
+static inline void gpio_unexport(unsigned gpio)
+{
+        /* GPIO can never have been exported */
+        WARN_ON(1);
+}
+
 static inline int gpio_to_irq(unsigned gpio)
 {
         /* GPIO can never have been requested or set as input */