staging: comedi: drivers: refactor comedi_request_region()

Split comedi_request_region() into two helper functions.

__comedi_request_region()
Handles the actual request_region() call.

comedi_request_region()
Calls __comedi_request_region() and then sets dev->iobase if the
request was successful.

This allows drivers to use the __comedi_request_region() helper
to handle the request without setting the dev->iobase.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/comedidev.h

@@ -348,6 +348,8 @@ void comedi_buf_memcpy_from(struct comedi_async *async, unsigned int offset,
 
 int comedi_alloc_subdevices(struct comedi_device *, int);
 
+int __comedi_request_region(struct comedi_device *,
+			    unsigned long start, unsigned long len);
 int comedi_request_region(struct comedi_device *,
 			  unsigned long start, unsigned long len);
 

drivers/staging/comedi/drivers.c

@@ -338,13 +338,13 @@ static void comedi_report_boards(struct comedi_driver *driv)
 }
 
 /**
- * comedi_request_region() - Request an I/O reqion for a legacy driver.
+ * __comedi_request_region() - Request an I/O reqion for a legacy driver.
  * @dev: comedi_device struct
  * @start: base address of the I/O reqion
  * @len: length of the I/O region
  */
-int comedi_request_region(struct comedi_device *dev,
-			  unsigned long start, unsigned long len)
+int __comedi_request_region(struct comedi_device *dev,
+			    unsigned long start, unsigned long len)
 {
 	if (!start) {
 		dev_warn(dev->class_dev,
@@ -358,10 +358,28 @@ int comedi_request_region(struct comedi_device *dev,
 			 dev->board_name, start, len);
 		return -EIO;
 	}
-	dev->iobase = start;
 
 	return 0;
 }
+EXPORT_SYMBOL_GPL(__comedi_request_region);
+
+/**
+ * comedi_request_region() - Request an I/O reqion for a legacy driver.
+ * @dev: comedi_device struct
+ * @start: base address of the I/O reqion
+ * @len: length of the I/O region
+ */
+int comedi_request_region(struct comedi_device *dev,
+			  unsigned long start, unsigned long len)
+{
+	int ret;
+
+	ret = __comedi_request_region(dev, start, len);
+	if (ret == 0)
+		dev->iobase = start;
+
+	return ret;
+}
 EXPORT_SYMBOL_GPL(comedi_request_region);
 
 int comedi_device_attach(struct comedi_device *dev, struct comedi_devconfig *it)