diff --git a/include/drivers/gpio.h b/include/drivers/gpio.h
index dfaa8f9de2216c..8557b384feaf55 100644
--- a/include/drivers/gpio.h
+++ b/include/drivers/gpio.h
@@ -584,6 +584,8 @@ static inline int z_impl_gpio_disable_callback(struct device *port,
  * @retval -EINVAL  Invalid argument.
  * @retval -EBUSY   Interrupt line required to configure pin interrupt is
  *                  already in use.
+ * @retval -EIO I/O error when accessing an external GPIO chip.
+ * @retval -EWOULDBLOCK if operation would block.
  */
 __syscall int gpio_pin_interrupt_configure(struct device *port,
 		unsigned int pin, unsigned int flags);
@@ -629,6 +631,8 @@ static inline int z_impl_gpio_pin_interrupt_configure(struct device *port,
  * @retval 0 If successful.
  * @retval -ENOTSUP if any of the configuration options is not supported.
  * @retval -EINVAL Invalid argument.
+ * @retval -EIO I/O error when accessing an external GPIO chip.
+ * @retval -EWOULDBLOCK if operation would block.
  */
 static inline int gpio_pin_configure(struct device *port, u32_t pin,
 				     unsigned int flags)
@@ -679,6 +683,7 @@ static inline int gpio_pin_configure(struct device *port, u32_t pin,
  *
  * @retval 0 If successful.
  * @retval -EIO I/O error when accessing an external GPIO chip.
+ * @retval -EWOULDBLOCK if operation would block.
  */
 __syscall int gpio_port_get_raw(struct device *port, gpio_port_value_t *value);
 
@@ -707,6 +712,7 @@ static inline int z_impl_gpio_port_get_raw(struct device *port,
  *
  * @retval 0 If successful.
  * @retval -EIO I/O error when accessing an external GPIO chip.
+ * @retval -EWOULDBLOCK if operation would block.
  */
 static inline int gpio_port_get(struct device *port, gpio_port_value_t *value)
 {
@@ -737,6 +743,7 @@ static inline int gpio_port_get(struct device *port, gpio_port_value_t *value)
  *
  * @retval 0 If successful.
  * @retval -EIO I/O error when accessing an external GPIO chip.
+ * @retval -EWOULDBLOCK if operation would block.
  */
 __syscall int gpio_port_set_masked_raw(struct device *port,
 		gpio_port_pins_t mask, gpio_port_value_t value);
@@ -768,6 +775,7 @@ static inline int z_impl_gpio_port_set_masked_raw(struct device *port,
  *
  * @retval 0 If successful.
  * @retval -EIO I/O error when accessing an external GPIO chip.
+ * @retval -EWOULDBLOCK if operation would block.
  */
 static inline int gpio_port_set_masked(struct device *port,
 		gpio_port_pins_t mask, gpio_port_value_t value)
@@ -788,6 +796,7 @@ static inline int gpio_port_set_masked(struct device *port,
  *
  * @retval 0 If successful.
  * @retval -EIO I/O error when accessing an external GPIO chip.
+ * @retval -EWOULDBLOCK if operation would block.
  */
 __syscall int gpio_port_set_bits_raw(struct device *port,
 				     gpio_port_pins_t pins);
@@ -809,6 +818,7 @@ static inline int z_impl_gpio_port_set_bits_raw(struct device *port,
  *
  * @retval 0 If successful.
  * @retval -EIO I/O error when accessing an external GPIO chip.
+ * @retval -EWOULDBLOCK if operation would block.
  */
 static inline int gpio_port_set_bits(struct device *port, gpio_port_pins_t pins)
 {
@@ -823,6 +833,7 @@ static inline int gpio_port_set_bits(struct device *port, gpio_port_pins_t pins)
  *
  * @retval 0 If successful.
  * @retval -EIO I/O error when accessing an external GPIO chip.
+ * @retval -EWOULDBLOCK if operation would block.
  */
 __syscall int gpio_port_clear_bits_raw(struct device *port,
 				       gpio_port_pins_t pins);
@@ -844,6 +855,7 @@ static inline int z_impl_gpio_port_clear_bits_raw(struct device *port,
  *
  * @retval 0 If successful.
  * @retval -EIO I/O error when accessing an external GPIO chip.
+ * @retval -EWOULDBLOCK if operation would block.
  */
 static inline int gpio_port_clear_bits(struct device *port,
 				       gpio_port_pins_t pins)
@@ -859,6 +871,7 @@ static inline int gpio_port_clear_bits(struct device *port,
  *
  * @retval 0 If successful.
  * @retval -EIO I/O error when accessing an external GPIO chip.
+ * @retval -EWOULDBLOCK if operation would block.
  */
 __syscall int gpio_port_toggle_bits(struct device *port, gpio_port_pins_t pins);
 
@@ -880,6 +893,7 @@ static inline int z_impl_gpio_port_toggle_bits(struct device *port,
  *
  * @retval 0 If successful.
  * @retval -EIO I/O error when accessing an external GPIO chip.
+ * @retval -EWOULDBLOCK if operation would block.
  */
 static inline int gpio_port_set_clr_bits_raw(struct device *port,
 		gpio_port_pins_t set_pins, gpio_port_pins_t clear_pins)
@@ -898,6 +912,7 @@ static inline int gpio_port_set_clr_bits_raw(struct device *port,
  *
  * @retval 0 If successful.
  * @retval -EIO I/O error when accessing an external GPIO chip.
+ * @retval -EWOULDBLOCK if operation would block.
  */
 static inline int gpio_port_set_clr_bits(struct device *port,
 		gpio_port_pins_t set_pins, gpio_port_pins_t clear_pins)
@@ -920,6 +935,7 @@ static inline int gpio_port_set_clr_bits(struct device *port,
  * @retval 1 If pin physical level is high.
  * @retval 0 If pin physical level is low.
  * @retval -EIO I/O error when accessing an external GPIO chip.
+ * @retval -EWOULDBLOCK if operation would block.
  */
 static inline int gpio_pin_get_raw(struct device *port, unsigned int pin)
 {
@@ -953,6 +969,7 @@ static inline int gpio_pin_get_raw(struct device *port, unsigned int pin)
  * @retval 1 If pin logical value is 1 / active.
  * @retval 0 If pin logical value is 0 / inactive.
  * @retval -EIO I/O error when accessing an external GPIO chip.
+ * @retval -EWOULDBLOCK if operation would block.
  */
 static inline int gpio_pin_get(struct device *port, unsigned int pin)
 {
@@ -982,6 +999,7 @@ static inline int gpio_pin_get(struct device *port, unsigned int pin)
  *
  * @retval 0 If successful.
  * @retval -EIO I/O error when accessing an external GPIO chip.
+ * @retval -EWOULDBLOCK if operation would block.
  */
 static inline int gpio_pin_set_raw(struct device *port, unsigned int pin,
 				   int value)
@@ -1018,6 +1036,7 @@ static inline int gpio_pin_set_raw(struct device *port, unsigned int pin,
  *
  * @retval 0 If successful.
  * @retval -EIO I/O error when accessing an external GPIO chip.
+ * @retval -EWOULDBLOCK if operation would block.
  */
 static inline int gpio_pin_set(struct device *port, unsigned int pin, int value)
 {
@@ -1041,6 +1060,7 @@ static inline int gpio_pin_set(struct device *port, unsigned int pin, int value)
  *
  * @retval 0 If successful.
  * @retval -EIO I/O error when accessing an external GPIO chip.
+ * @retval -EWOULDBLOCK if operation would block.
  */
 static inline int gpio_pin_toggle(struct device *port, unsigned int pin)
 {