staging: comedi: dt2811: simplify analog input range options

The A/D ranges are not programmable but the gain is. Currently this driver
uses a configuration option to select the comedi_lrange that will be used
for the analog input subdevice. This requires that the user makes sure the
correct option value is used.

The user space library uses the range information to convert between raw
values and physical units. If the user passed an incorrect option when
attaching the driver the conversion will be incorrect.

A previous patch allowed the gain to be set based on the chanspec range.
Prior to that the gain was always set to 1 so any conversion with a gain
that is not 1 would be incorrect anyway.

Simplify the analog input ranges by providing a range_table for the pgh and
pgl boards that contain all the possible range/gain options. The user can
then select the correct range (and gain) when converting values or reading
the analog inputs.
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

@@ -33,14 +33,17 @@
  *	   0 = single-ended (16 channels)
  *	   1 = differential (8 channels)
  *	   2 = pseudo-differential (16 channels)
- *   [3] - A/D range
- *	   0 = [-5, 5]
- *	   1 = [-2.5, 2.5]
- *	   2 = [0, 5]
+ *   [3] - A/D range (deprecated, see below)
  *   [4] - D/A 0 range (deprecated, see below)
  *   [5] - D/A 1 range (deprecated, see below)
  *
  * Notes:
+ *   - A/D ranges are not programmable but the gain is. The AI subdevice has
+ *     a range_table containing all the possible analog input range/gain
+ *     options for the dt2811-pgh or dt2811-pgl. Use the range that matches
+ *     your board configuration and the desired gain to correctly convert
+ *     between data values and physical units and to set the correct output
+ *     gain.
  *   - 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
@@ -99,57 +102,52 @@
 #define DT2811_TMRCTR_MANTISSA(x)	(((x) & 0x7) << 3)
 #define DT2811_TMRCTR_EXPONENT(x)	(((x) & 0x7) << 0)
 
-static const struct comedi_lrange range_dt2811_pgh_ai_5_unipolar = {
-	4, {
-		UNI_RANGE(5),
-		UNI_RANGE(2.5),
-		UNI_RANGE(1.25),
-		UNI_RANGE(0.625)
-	}
-};
-
-static const struct comedi_lrange range_dt2811_pgh_ai_2_5_bipolar = {
-	4, {
-		BIP_RANGE(2.5),
-		BIP_RANGE(1.25),
-		BIP_RANGE(0.625),
-		BIP_RANGE(0.3125)
-	}
-};
-
-static const struct comedi_lrange range_dt2811_pgh_ai_5_bipolar = {
-	4, {
-		BIP_RANGE(5),
-		BIP_RANGE(2.5),
-		BIP_RANGE(1.25),
-		BIP_RANGE(0.625)
-	}
-};
-
-static const struct comedi_lrange range_dt2811_pgl_ai_5_unipolar = {
-	4, {
-		UNI_RANGE(5),
-		UNI_RANGE(0.5),
-		UNI_RANGE(0.05),
-		UNI_RANGE(0.01)
-	}
-};
-
-static const struct comedi_lrange range_dt2811_pgl_ai_2_5_bipolar = {
-	4, {
-		BIP_RANGE(2.5),
-		BIP_RANGE(0.25),
-		BIP_RANGE(0.025),
-		BIP_RANGE(0.005)
+/*
+ * The Analog Input range is set using jumpers on the board.
+ *
+ * Input Range		W9  W10
+ * -5V to +5V		In  Out
+ * -2.5V to +2.5V	In  In
+ * 0V to +5V		Out In
+ *
+ * The gain may be set to 1, 2, 4, or 8 (on the dt2811-pgh) or to
+ * 1, 10, 100, 500 (on the dt2811-pgl).
+ */
+static const struct comedi_lrange dt2811_pgh_ai_ranges = {
+	12, {
+		BIP_RANGE(5),		/* range 0: gain=1 */
+		BIP_RANGE(2.5),		/* range 1: gain=2 */
+		BIP_RANGE(1.25),	/* range 2: gain=4 */
+		BIP_RANGE(0.625),	/* range 3: gain=8 */
+
+		BIP_RANGE(2.5),		/* range 0+4: gain=1 */
+		BIP_RANGE(1.25),	/* range 1+4: gain=2 */
+		BIP_RANGE(0.625),	/* range 2+4: gain=4 */
+		BIP_RANGE(0.3125),	/* range 3+4: gain=8 */
+
+		UNI_RANGE(5),		/* range 0+8: gain=1 */
+		UNI_RANGE(2.5),		/* range 1+8: gain=2 */
+		UNI_RANGE(1.25),	/* range 2+8: gain=4 */
+		UNI_RANGE(0.625)	/* range 3+8: gain=8 */
 	}
 };
 
-static const struct comedi_lrange range_dt2811_pgl_ai_5_bipolar = {
-	4, {
-		BIP_RANGE(5),
-		BIP_RANGE(0.5),
-		BIP_RANGE(0.05),
-		BIP_RANGE(0.01)
+static const struct comedi_lrange dt2811_pgl_ai_ranges = {
+	12, {
+		BIP_RANGE(5),		/* range 0: gain=1 */
+		BIP_RANGE(0.5),		/* range 1: gain=10 */
+		BIP_RANGE(0.05),	/* range 2: gain=100 */
+		BIP_RANGE(0.01),	/* range 3: gain=500 */
+
+		BIP_RANGE(2.5),		/* range 0+4: gain=1 */
+		BIP_RANGE(0.25),	/* range 1+4: gain=10 */
+		BIP_RANGE(0.025),	/* range 2+4: gain=100 */
+		BIP_RANGE(0.005),	/* range 3+4: gain=500 */
+
+		UNI_RANGE(5),		/* range 0+8: gain=1 */
+		UNI_RANGE(0.5),		/* range 1+8: gain=10 */
+		UNI_RANGE(0.05),	/* range 2+8: gain=100 */
+		UNI_RANGE(0.01)		/* range 3+8: gain=500 */
 	}
 };
 
@@ -174,12 +172,17 @@ static const struct comedi_lrange dt2811_ao_ranges = {
 
 struct dt2811_board {
 	const char *name;
-	const struct comedi_lrange *bip_5;
-	const struct comedi_lrange *bip_2_5;
-	const struct comedi_lrange *unip_5;
+	unsigned int is_pgh:1;
 };
 
-enum { card_2811_pgh, card_2811_pgl };
+static const struct dt2811_board boardtypes[] = {
+	{
+		.name		= "dt2811-pgh",
+		.is_pgh		= 1,
+	}, {
+		.name		= "dt2811-pgl",
+	},
+};
 
 static int dt2811_ai_eoc(struct comedi_device *dev,
 			 struct comedi_subdevice *s,
@@ -289,18 +292,8 @@ static int dt2811_attach(struct comedi_device *dev, struct comedi_devconfig *it)
 	s->n_chan = (it->options[2] == 1) ? 8 : 16;
 	s->insn_read = dt2811_ai_insn;
 	s->maxdata = 0xfff;
-	switch (it->options[3]) {
-	case 0:
-	default:
-		s->range_table = board->bip_5;
-		break;
-	case 1:
-		s->range_table = board->bip_2_5;
-		break;
-	case 2:
-		s->range_table = board->unip_5;
-		break;
-	}
+	s->range_table	= board->is_pgh ? &dt2811_pgh_ai_ranges
+					: &dt2811_pgl_ai_ranges;
 
 	/* Analog Output subdevice */
 	s = &dev->subdevices[1];
@@ -336,20 +329,6 @@ static int dt2811_attach(struct comedi_device *dev, struct comedi_devconfig *it)
 	return 0;
 }
 
-static const struct dt2811_board boardtypes[] = {
-	{
-		.name		= "dt2811-pgh",
-		.bip_5		= &range_dt2811_pgh_ai_5_bipolar,
-		.bip_2_5	= &range_dt2811_pgh_ai_2_5_bipolar,
-		.unip_5		= &range_dt2811_pgh_ai_5_unipolar,
-	}, {
-		.name		= "dt2811-pgl",
-		.bip_5		= &range_dt2811_pgl_ai_5_bipolar,
-		.bip_2_5	= &range_dt2811_pgl_ai_2_5_bipolar,
-		.unip_5		= &range_dt2811_pgl_ai_5_unipolar,
-	},
-};
-
 static struct comedi_driver dt2811_driver = {
 	.driver_name	= "dt2811",
 	.module		= THIS_MODULE,