staging: comedi: export comedi_set_hw_dev()

Chnage the inline `comedi_set_hw_dev()` to an exported function and
change it's return type from `void` to `int` so we can impose some
restrictions (in a later patch) and return an error if necessary.

Only a few comedi drivers call this, although they don't need to if the
hardware device has been attached automatically via
`comedi_auto_config()` and the comedi driver's `auto_attach()` method.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/comedidev.h

@@ -324,14 +324,7 @@ static inline unsigned int bytes_per_sample(const struct comedi_subdevice *subd)
  * known bus type.  Set automatically for auto-configured devices.
  * Automatically set to NULL when detaching hardware device.
  */
-static inline void comedi_set_hw_dev(struct comedi_device *dev,
-				     struct device *hw_dev)
-{
-	struct device *old_hw_dev = dev->hw_dev;
-
-	dev->hw_dev = get_device(hw_dev);
-	put_device(old_hw_dev);
-}
+int comedi_set_hw_dev(struct comedi_device *dev, struct device *hw_dev);
 
 unsigned int comedi_buf_write_alloc(struct comedi_async *, unsigned int);
 unsigned int comedi_buf_write_free(struct comedi_async *, unsigned int);

drivers/staging/comedi/drivers.c

@@ -43,6 +43,16 @@
 
 struct comedi_driver *comedi_drivers;
 
+int comedi_set_hw_dev(struct comedi_device *dev, struct device *hw_dev)
+{
+	struct device *old_hw_dev = dev->hw_dev;
+
+	dev->hw_dev = get_device(hw_dev);
+	put_device(old_hw_dev);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(comedi_set_hw_dev);
+
 int comedi_alloc_subdevices(struct comedi_device *dev, int num_subdevices)
 {
 	struct comedi_subdevice *s;