staging: comedi: pcl730: tidy up pcl730_do_insn()

For aesthetic reasons, rename the function.

Use a local variable for the 'reg' offset that is stored in the
comedi_subdevice 'private' pointer to minimize the number of casts.
Also, add local variables for the 'mask' and 'bits'.

The outputs only need to be updated if the 'mask' indicates that the
'bits' are changing. Move the update code into the main 'if (mask)'
block.
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/pcl730.c

@@ -42,19 +42,24 @@ static const struct pcl730_board boardtypes[] = {
 	},
 };
 
-static int pcl730_do_insn(struct comedi_device *dev, struct comedi_subdevice *s,
-			  struct comedi_insn *insn, unsigned int *data)
+static int pcl730_do_insn_bits(struct comedi_device *dev,
+			       struct comedi_subdevice *s,
+			       struct comedi_insn *insn,
+			       unsigned int *data)
 {
-	if (data[0]) {
-		s->state &= ~data[0];
-		s->state |= (data[0] & data[1]);
+	unsigned long reg = (unsigned long)s->private;
+	unsigned int mask = data[0];
+	unsigned int bits = data[1];
+
+	if (mask) {
+		s->state &= ~mask;
+		s->state |= (bits & mask);
+
+		if (mask & 0x00ff)
+			outb(s->state & 0xff, dev->iobase + reg);
+		if (mask & 0xff00)
+			outb((s->state >> 8) & 0xff, dev->iobase + reg + 1);
 	}
-	if (data[0] & 0x00ff)
-		outb(s->state & 0xff,
-		     dev->iobase + ((unsigned long)s->private));
-	if (data[0] & 0xff00)
-		outb((s->state >> 8),
-		     dev->iobase + ((unsigned long)s->private) + 1);
 
 	data[1] = s->state;
 
@@ -90,7 +95,7 @@ static int pcl730_attach(struct comedi_device *dev, struct comedi_devconfig *it)
 	s->subdev_flags = SDF_WRITABLE;
 	s->maxdata = 1;
 	s->n_chan = 16;
-	s->insn_bits = pcl730_do_insn;
+	s->insn_bits = pcl730_do_insn_bits;
 	s->range_table = &range_digital;
 	s->private = (void *)PCL730_IDIO_LO;
 
@@ -110,7 +115,7 @@ static int pcl730_attach(struct comedi_device *dev, struct comedi_devconfig *it)
 	s->subdev_flags = SDF_WRITABLE;
 	s->maxdata = 1;
 	s->n_chan = 16;
-	s->insn_bits = pcl730_do_insn;
+	s->insn_bits = pcl730_do_insn_bits;
 	s->range_table = &range_digital;
 	s->private = (void *)PCL730_DIO_LO;