staging: comedi: pcl818: tidy up the analog input (*insn_read)

For aesthetics, move this function out of the async command support
code.

For safety, the INT request (end-of-conversion flag) should be cleared
before doing each conversion and after the final data sample is read.
This driver already clears the flag before starting a conversion but it
does not clear the flag after the final sample.

Refactor the function a bit so that the flag is cleared for a conversion
timeout and after the last sample.

Do a bit of other tidying up during the move.
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/pcl818.c

@@ -443,43 +443,6 @@ static int pcl818_ai_eoc(struct comedi_device *dev,
 	return -EBUSY;
 }
 
-static int pcl818_ai_insn_read(struct comedi_device *dev,
-			       struct comedi_subdevice *s,
-			       struct comedi_insn *insn, unsigned int *data)
-{
-	int ret;
-	int n;
-
-	/* software trigger, DMA and INT off */
-	outb(0, dev->iobase + PCL818_CONTROL);
-
-	/* select channel */
-	outb(muxonechan[CR_CHAN(insn->chanspec)], dev->iobase + PCL818_MUX);
-
-	/* select gain */
-	outb(CR_RANGE(insn->chanspec), dev->iobase + PCL818_RANGE);
-
-	for (n = 0; n < insn->n; n++) {
-
-		/* clear INT (conversion end) flag */
-		outb(0, dev->iobase + PCL818_CLRINT);
-
-		/* start conversion */
-		outb(0, dev->iobase + PCL818_AD_LO);
-
-		ret = comedi_timeout(dev, s, insn, pcl818_ai_eoc, 0);
-		if (ret) {
-			/* clear INT (conversion end) flag */
-			outb(0, dev->iobase + PCL818_CLRINT);
-			return ret;
-		}
-
-		data[n] = pcl818_ai_get_sample(dev, s, NULL);
-	}
-
-	return n;
-}
-
 static bool pcl818_ai_dropout(struct comedi_device *dev,
 			      struct comedi_subdevice *s,
 			      unsigned int chan)
@@ -963,6 +926,42 @@ static int pcl818_ai_cancel(struct comedi_device *dev,
 	return 0;
 }
 
+static int pcl818_ai_insn_read(struct comedi_device *dev,
+			       struct comedi_subdevice *s,
+			       struct comedi_insn *insn,
+			       unsigned int *data)
+{
+	unsigned int chan = CR_CHAN(insn->chanspec);
+	unsigned int range = CR_RANGE(insn->chanspec);
+	int ret = 0;
+	int i;
+
+	/* software trigger, DMA and INT off */
+	outb(0, dev->iobase + PCL818_CONTROL);
+
+	/* select channel */
+	outb(muxonechan[chan], dev->iobase + PCL818_MUX);
+	/* select gain */
+	outb(range, dev->iobase + PCL818_RANGE);
+
+	for (i = 0; i < insn->n; i++) {
+		/* clear INT (conversion end) flag */
+		outb(0, dev->iobase + PCL818_CLRINT);
+		/* start conversion */
+		outb(0, dev->iobase + PCL818_AD_LO);
+
+		ret = comedi_timeout(dev, s, insn, pcl818_ai_eoc, 0);
+		if (ret)
+			break;
+
+		data[i] = pcl818_ai_get_sample(dev, s, NULL);
+	}
+	/* clear INT (conversion end) flag */
+	outb(0, dev->iobase + PCL818_CLRINT);
+
+	return ret ? ret : insn->n;
+}
+
 static int pcl818_ao_insn_write(struct comedi_device *dev,
 				struct comedi_subdevice *s,
 				struct comedi_insn *insn,