MOUSEBTN_PIN_LEFT
caps = gpio_pin_caps(sc->sc_gpio, &sc->sc_map, MOUSEBTN_PIN_LEFT);
gpio_pin_ctl(sc->sc_gpio, &sc->sc_map, MOUSEBTN_PIN_LEFT,
left = !gpio_pin_read(sc->sc_gpio, &sc->sc_map, MOUSEBTN_PIN_LEFT);