diff --git a/sys/dev/gpio/gpiobus.c b/sys/dev/gpio/gpiobus.c
--- a/sys/dev/gpio/gpiobus.c
+++ b/sys/dev/gpio/gpiobus.c
@@ -752,7 +752,7 @@
 	}
 }
 
-static int
+int
 gpiobus_read_ivar(device_t dev, device_t child, int which, uintptr_t *result)
 {
 	struct gpiobus_ivar *devi;
diff --git a/sys/dev/gpio/gpiobusvar.h b/sys/dev/gpio/gpiobusvar.h
--- a/sys/dev/gpio/gpiobusvar.h
+++ b/sys/dev/gpio/gpiobusvar.h
@@ -179,6 +179,7 @@
 int gpiobus_init_softc(device_t);
 int gpiobus_alloc_ivars(struct gpiobus_ivar *);
 void gpiobus_free_ivars(struct gpiobus_ivar *);
+int gpiobus_read_ivar(device_t, device_t, int, uintptr_t *);
 int gpiobus_acquire_pin(device_t, uint32_t);
 int gpiobus_release_pin(device_t, uint32_t);