staging: comedi: dt2811: simplify analog output range options

The D/A ranges are not programmable. Currently this driver uses some
configuration options to select the comedi_lrange for each channel.
This is a bit messy and it requires the user to make sure the correct
option value is used.

The range information isn't used by the driver. The user space library
uses it to convert between raw data values and physical units. If the
user passed an incorrect option when attaching the driver the conversion
will be incorrect.

Simplify the analog output ranges by providing a range_table that
contains all the possible output ranges. The user can then select the
correct range when converting values.
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/dt2811.c

@@ -37,8 +37,14 @@
  *	   0 = [-5, 5]
  *	   1 = [-2.5, 2.5]
  *	   2 = [0, 5]
- *   [4] - D/A 0 range (same as A/D range)
- *   [5] - D/A 1 range (same as A/D range)
+ *   [4] - D/A 0 range (deprecated, see below)
+ *   [5] - D/A 1 range (deprecated, see below)
+ *
+ * Notes:
+ *   - D/A ranges are not programmable. The AO subdevice has a range_table
+ *     containing all the possible analog output ranges. Use the range
+ *     that matches your board configuration to convert between data
+ *     values and physical units.
  */
 
 #include <linux/module.h>
@@ -147,6 +153,23 @@ static const struct comedi_lrange range_dt2811_pgl_ai_5_bipolar = {
 	}
 };
 
+/*
+ * The Analog Output range is set per-channel using jumpers on the board.
+ *
+ *			DAC0 Jumpers		DAC1 Jumpers
+ * Output Range		W5  W6  W7  W8		W1  W2  W3  W4
+ * -5V to +5V		In  Out In  Out		In  Out In  Out
+ * -2.5V to +2.5V	In  Out Out In		In  Out Out In
+ * 0 to +5V		Out In  Out In		Out In  Out In
+ */
+static const struct comedi_lrange dt2811_ao_ranges = {
+	3, {
+		BIP_RANGE(5),	/* default setting from factory */
+		BIP_RANGE(2.5),
+		UNI_RANGE(5)
+	}
+};
+
 #define TIMEOUT 10000
 
 struct dt2811_board {
@@ -164,16 +187,6 @@ struct dt2811_private {
 	enum {
 		adc_singleended, adc_diff, adc_pseudo_diff
 	} adc_mux;
-	enum {
-		dac_bipolar_5, dac_bipolar_2_5, dac_unipolar_5
-	} dac_range[2];
-	const struct comedi_lrange *range_type_list[2];
-};
-
-static const struct comedi_lrange *dac_range_types[] = {
-	&range_bipolar5,
-	&range_bipolar2_5,
-	&range_unipolar5
 };
 
 static int dt2811_ai_eoc(struct comedi_device *dev,
@@ -294,34 +307,6 @@ static int dt2811_attach(struct comedi_device *dev, struct comedi_devconfig *it)
 		devpriv->adc_mux = adc_singleended;
 		break;
 	}
-	switch (it->options[4]) {
-	case 0:
-		devpriv->dac_range[0] = dac_bipolar_5;
-		break;
-	case 1:
-		devpriv->dac_range[0] = dac_bipolar_2_5;
-		break;
-	case 2:
-		devpriv->dac_range[0] = dac_unipolar_5;
-		break;
-	default:
-		devpriv->dac_range[0] = dac_bipolar_5;
-		break;
-	}
-	switch (it->options[5]) {
-	case 0:
-		devpriv->dac_range[1] = dac_bipolar_5;
-		break;
-	case 1:
-		devpriv->dac_range[1] = dac_bipolar_2_5;
-		break;
-	case 2:
-		devpriv->dac_range[1] = dac_unipolar_5;
-		break;
-	default:
-		devpriv->dac_range[1] = dac_bipolar_5;
-		break;
-	}
 
 	s = &dev->subdevices[0];
 	/* initialize the ADC subdevice */
@@ -349,9 +334,7 @@ static int dt2811_attach(struct comedi_device *dev, struct comedi_devconfig *it)
 	s->subdev_flags = SDF_WRITABLE;
 	s->n_chan = 2;
 	s->maxdata = 0xfff;
-	s->range_table_list = devpriv->range_type_list;
-	devpriv->range_type_list[0] = dac_range_types[devpriv->dac_range[0]];
-	devpriv->range_type_list[1] = dac_range_types[devpriv->dac_range[1]];
+	s->range_table = &dt2811_ao_ranges;
 	s->insn_write = dt2811_ao_insn_write;
 
 	ret = comedi_alloc_subdev_readback(s);