gpio: add error return when blocking might occur

External GPIO drivers may not be supported from interrupt context
because they involve blocking bus transactions.  Describe the return
value for this situation, and add the I/O error to operations where it
was missing.

Signed-off-by: Peter Bigot <[email protected]>

Author: pabigot

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)
 {