gpio_attach_args
struct gpio_attach_args *gpaa;
gpaa = (struct gpio_attach_args *)ap->a_data;
gpaa = (struct gpio_attach_args *)ap->a_data;
#define GPIOATTACH _IOWR('G', 6, struct gpio_attach_args)
#define GPIODETACH _IOWR('G', 7, struct gpio_attach_args)