staging: comedi: core: introduce comedi_chan_range_is_{bi,uni}polar()

Introduce two helper functions to check if a subdevice range_table_list
for a given channel/range is bipolar or unipolar.
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/comedidev.h

@@ -307,6 +307,20 @@ static inline bool comedi_range_is_unipolar(struct comedi_subdevice *s,
 	return s->range_table->range[range].min >= 0;
 }
 
+static inline bool comedi_chan_range_is_bipolar(struct comedi_subdevice *s,
+						unsigned int chan,
+						unsigned int range)
+{
+	return s->range_table_list[chan]->range[range].min < 0;
+}
+
+static inline bool comedi_chan_range_is_unipolar(struct comedi_subdevice *s,
+						 unsigned int chan,
+						 unsigned int range)
+{
+	return s->range_table_list[chan]->range[range].min >= 0;
+}
+
 /* munge between offset binary and two's complement values */
 static inline unsigned int comedi_offset_munge(struct comedi_subdevice *s,
 					       unsigned int val)