staging: comedi: rtd520: remove private data 'chan_is_bipolar' member

Currently this driver uses a bitmap in the private data to keep track of
the unipolar/bipolar range for each channel. This is needed to determine
if the data needs to be munged for bipolar samples.

Remove this member from the private data and use the comedi core helper
function comedi_range_is_bipolar() to determine if the data needs to be
munged.
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/rtd520.c

@@ -379,7 +379,6 @@ struct rtd_private {
 	long ai_count;		/* total transfer size (samples) */
 	int xfer_count;		/* # to transfer data. 0->1/2FIFO */
 	int flags;		/* flag event modes */
-	DECLARE_BITMAP(chan_is_bipolar, RTD_MAX_CHANLIST);
 	unsigned fifosz;
 };
 
@@ -438,7 +437,6 @@ static unsigned short rtd_convert_chan_gain(struct comedi_device *dev,
 					    unsigned int chanspec, int index)
 {
 	const struct rtd_boardinfo *board = dev->board_ptr;
-	struct rtd_private *devpriv = dev->private;
 	unsigned int chan = CR_CHAN(chanspec);
 	unsigned int range = CR_RANGE(chanspec);
 	unsigned int aref = CR_AREF(chanspec);
@@ -451,17 +449,14 @@ static unsigned short rtd_convert_chan_gain(struct comedi_device *dev,
 		/* +-5 range */
 		r |= 0x000;
 		r |= (range & 0x7) << 4;
-		__set_bit(index, devpriv->chan_is_bipolar);
 	} else if (range < board->range_uni10) {
 		/* +-10 range */
 		r |= 0x100;
 		r |= ((range - board->range_bip10) & 0x7) << 4;
-		__set_bit(index, devpriv->chan_is_bipolar);
 	} else {
 		/* +10 range */
 		r |= 0x200;
 		r |= ((range - board->range_uni10) & 0x7) << 4;
-		__clear_bit(index, devpriv->chan_is_bipolar);
 	}
 
 	switch (aref) {
@@ -561,6 +556,7 @@ static int rtd_ai_rinsn(struct comedi_device *dev,
 			unsigned int *data)
 {
 	struct rtd_private *devpriv = dev->private;
+	unsigned int range = CR_RANGE(insn->chanspec);
 	int ret;
 	int n;
 
@@ -586,9 +582,11 @@ static int rtd_ai_rinsn(struct comedi_device *dev,
 		/* read data */
 		d = readw(devpriv->las1 + LAS1_ADC_FIFO);
 		d = d >> 3;	/* low 3 bits are marker lines */
-		if (test_bit(0, devpriv->chan_is_bipolar))
-			/* convert to comedi unsigned data */
+
+		/* convert bipolar data to comedi unsigned data */
+		if (comedi_range_is_bipolar(s, range))
 			d = comedi_offset_munge(s, d);
+
 		data[n] = d & s->maxdata;
 	}
 
@@ -611,6 +609,7 @@ static int ai_read_n(struct comedi_device *dev, struct comedi_subdevice *s,
 	int ii;
 
 	for (ii = 0; ii < count; ii++) {
+		unsigned int range = CR_RANGE(cmd->chanlist[async->cur_chan]);
 		unsigned short d;
 
 		if (0 == devpriv->ai_count) {	/* done */
@@ -620,8 +619,9 @@ static int ai_read_n(struct comedi_device *dev, struct comedi_subdevice *s,
 
 		d = readw(devpriv->las1 + LAS1_ADC_FIFO);
 		d = d >> 3;	/* low 3 bits are marker lines */
-		if (test_bit(async->cur_chan, devpriv->chan_is_bipolar))
-			/* convert to comedi unsigned data */
+
+		/* convert bipolar data to comedi unsigned data */
+		if (comedi_range_is_bipolar(s, range))
 			d = comedi_offset_munge(s, d);
 		d &= s->maxdata;