Basic GPIO API just covering GPIO_DIGITAL_OUTPUT.

typedef gpio_pin; /* a configured GPIO pin handle */

/* GPIO configuration of current device - describes how many banks, how many pins
 * in each bank, and capabilities of each pin (analog/discrete i/o & other configuration.)
 */
typedef gpio_conf;

/* retrieve number of gpio banks & pins per bank, possibly more info */
rtems_gpio_get_config(&gpio_conf);

/* fill in gpio_pin struct to use this pin. must be currently unused. */
rtems_gpio_configure_pin(&gpio_pin, bank_number, pin_number, GPIO_DIGITAL_OUTPUT);

/* for a GPIO_DIGITAL_OUTPUT pin, set it to logical high */
rtems_gpio_digital_set(&gpio_pin);

/* for a GPIO_DIGITAL_OUTPUT pin, set it to logical low */
rtems_gpio_digital_clear(&gpio_pin);

/* a currently configured pin is to be released and made unused, allowing repurposing. */
rtems_gpio_release_pin(&gpio_pin);