xpio_ctrl_discover
xpio_ctrl_discover(gpioadm.gpio_xpio, gpioadm_controller_list_cb,
xpio_ctrl_discover(gpioadm.gpio_xpio, gpioadm_gpio_list_cb, &ggl);
xpio_ctrl_discover(xpio, xpio_ctrl_init_by_name_cb, &init);
extern void xpio_ctrl_discover(xpio_t *, xpio_ctrl_disc_f, void *);