staging: comedi: me4000: tidy up the chanlist checking

The ai_check_chanlist() function validates that the cmd->chanlist is compatible
with the hardware. This is step 5 of the (*do_cmdtest).

For aesthetics, rename this function so it has namespace associated with the
driver and tidy up the code.

To minimize the noise, change the dev_err() to dev_dbg().
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/me4000.c

@@ -598,67 +598,35 @@ static int me4000_ai_cancel(struct comedi_device *dev,
 	return 0;
 }
 
-static int ai_check_chanlist(struct comedi_device *dev,
-			     struct comedi_subdevice *s, struct comedi_cmd *cmd)
+static int me4000_ai_check_chanlist(struct comedi_device *dev,
+				    struct comedi_subdevice *s,
+				    struct comedi_cmd *cmd)
 {
-	const struct me4000_board *thisboard = comedi_board(dev);
-	int aref;
+	const struct me4000_board *board = comedi_board(dev);
+	unsigned int max_diff_chan = board->ai_diff_nchan;
+	unsigned int aref0 = CR_AREF(cmd->chanlist[0]);
 	int i;
 
-	/* Check whether a channel list is available */
-	if (!cmd->chanlist_len) {
-		dev_err(dev->class_dev, "No channel list available\n");
-		return -EINVAL;
-	}
-
-	/* Check the channel list size */
-	if (cmd->chanlist_len > ME4000_AI_CHANNEL_LIST_COUNT) {
-		dev_err(dev->class_dev, "Channel list is to large\n");
-		return -EINVAL;
-	}
-
-	/* Check the pointer */
-	if (!cmd->chanlist) {
-		dev_err(dev->class_dev, "NULL pointer to channel list\n");
-		return -EFAULT;
-	}
-
-	/* Check whether aref is equal for all entries */
-	aref = CR_AREF(cmd->chanlist[0]);
 	for (i = 0; i < cmd->chanlist_len; i++) {
-		if (CR_AREF(cmd->chanlist[i]) != aref) {
-			dev_err(dev->class_dev,
+		unsigned int chan = CR_CHAN(cmd->chanlist[i]);
+		unsigned int range = CR_RANGE(cmd->chanlist[i]);
+		unsigned int aref = CR_AREF(cmd->chanlist[i]);
+
+		if (aref != aref0) {
+			dev_dbg(dev->class_dev,
 				"Mode is not equal for all entries\n");
 			return -EINVAL;
 		}
-	}
 
-	/* Check whether channels are available for this ending */
-	if (aref == SDF_DIFF) {
-		for (i = 0; i < cmd->chanlist_len; i++) {
-			if (CR_CHAN(cmd->chanlist[i]) >=
-			    thisboard->ai_diff_nchan) {
-				dev_err(dev->class_dev,
+		if (aref == SDF_DIFF) {
+			if (chan >= max_diff_chan) {
+				dev_dbg(dev->class_dev,
 					"Channel number to high\n");
 				return -EINVAL;
 			}
-		}
-	} else {
-		for (i = 0; i < cmd->chanlist_len; i++) {
-			if (CR_CHAN(cmd->chanlist[i]) >= thisboard->ai_nchan) {
-				dev_err(dev->class_dev,
-					"Channel number to high\n");
-				return -EINVAL;
-			}
-		}
-	}
 
-	/* Check if bipolar is set for all entries when in differential mode */
-	if (aref == SDF_DIFF) {
-		for (i = 0; i < cmd->chanlist_len; i++) {
-			if (CR_RANGE(cmd->chanlist[i]) != 1 &&
-			    CR_RANGE(cmd->chanlist[i]) != 2) {
-				dev_err(dev->class_dev,
+			if (!comedi_range_is_bipolar(s, range)) {
+				dev_dbg(dev->class_dev,
 				       "Bipolar is not selected in differential mode\n");
 				return -EINVAL;
 			}
@@ -1091,10 +1059,11 @@ static int me4000_ai_do_cmd_test(struct comedi_device *dev,
 	if (err)
 		return 4;
 
-	/*
-	 * Stage 5. Check the channel list.
-	 */
-	if (ai_check_chanlist(dev, s, cmd))
+	/* Step 5: check channel list if it exists */
+	if (cmd->chanlist && cmd->chanlist_len > 0)
+		err |= me4000_ai_check_chanlist(dev, s, cmd);
+
+	if (err)
 		return 5;
 
 	return 0;