if (!drv->probe)
                return -ENODEV;
 
-       down(&dev->visordriver_callback_lock);
+       mutex_lock(&dev->visordriver_callback_lock);
        dev->being_removed = false;
 
        res = drv->probe(dev);
                fix_vbus_dev_info(dev);
        }
 
-       up(&dev->visordriver_callback_lock);
+       mutex_unlock(&dev->visordriver_callback_lock);
        return res;
 }
 
 
        dev = to_visor_device(xdev);
        drv = to_visor_driver(xdev->driver);
-       down(&dev->visordriver_callback_lock);
+       mutex_lock(&dev->visordriver_callback_lock);
        dev->being_removed = true;
        if (drv->remove)
                drv->remove(dev);
-       up(&dev->visordriver_callback_lock);
+       mutex_unlock(&dev->visordriver_callback_lock);
        dev_stop_periodic_work(dev);
 
        put_device(&dev->device);
        POSTCODE_LINUX_4(DEVICE_CREATE_ENTRY_PC, chipset_dev_no, chipset_bus_no,
                         POSTCODE_SEVERITY_INFO);
 
-       sema_init(&dev->visordriver_callback_lock, 1);  /* unlocked */
+       mutex_init(&dev->visordriver_callback_lock);
        dev->device.bus = &visorbus_type;
        dev->device.groups = visorbus_channel_groups;
        device_initialize(&dev->device);