staging: comedi: adv_pci1710: refactor ai range programming

The gain codes used to program the analog output range are currently
stored in const char arrays. The values look a bit "magic" and it's
not clear how they associate with the comedi_lrange without looking
through user manuals.

Refactor the ai range programming to clarify the driver and remove
the magic numbers. Also, refine the bits in the range register that
set the differential and unipolar modes.
Signed-off-by: NH Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: NIan Abbott <abbotti@mev.co.uk>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/adv_pci1710.c

@@ -41,6 +41,9 @@
 #define PCI171X_AD_DATA_REG	0x00	/* R:   A/D data */
 #define PCI171X_SOFTTRG_REG	0x00	/* W:   soft trigger for A/D */
 #define PCI171X_RANGE_REG	0x02	/* W:   A/D gain/range register */
+#define PCI171X_RANGE_DIFF	BIT(5)
+#define PCI171X_RANGE_UNI	BIT(4)
+#define PCI171X_RANGE_GAIN(x)	(((x) & 0x7) << 0)
 #define PCI171X_MUX_REG		0x04	/* W:   A/D multiplexor control */
 #define PCI171X_STATUS_REG	0x06	/* R:   status register */
 #define PCI171X_STATUS_IRQ	BIT(11)	/* 1=IRQ occurred */
@@ -63,56 +66,47 @@
 #define PCI171X_DO_REG		0x10	/* W:   digital outputs */
 #define PCI171X_TIMER_BASE	0x18	/* R/W: 8254 timer */
 
-static const struct comedi_lrange range_pci1710_3 = {
+static const struct comedi_lrange pci1710_ai_range = {
 	9, {
-		BIP_RANGE(5),
-		BIP_RANGE(2.5),
-		BIP_RANGE(1.25),
-		BIP_RANGE(0.625),
-		BIP_RANGE(10),
-		UNI_RANGE(10),
-		UNI_RANGE(5),
-		UNI_RANGE(2.5),
-		UNI_RANGE(1.25)
+		BIP_RANGE(5),		/* gain 1   (0x00) */
+		BIP_RANGE(2.5),		/* gain 2   (0x01) */
+		BIP_RANGE(1.25),	/* gain 4   (0x02) */
+		BIP_RANGE(0.625),	/* gain 8   (0x03) */
+		BIP_RANGE(10),		/* gain 0.5 (0x04) */
+		UNI_RANGE(10),		/* gain 1   (0x00 | UNI) */
+		UNI_RANGE(5),		/* gain 2   (0x01 | UNI) */
+		UNI_RANGE(2.5),		/* gain 4   (0x02 | UNI) */
+		UNI_RANGE(1.25)		/* gain 8   (0x03 | UNI) */
 	}
 };
 
-static const char range_codes_pci1710_3[] = { 0x00, 0x01, 0x02, 0x03, 0x04,
-					      0x10, 0x11, 0x12, 0x13 };
-
-static const struct comedi_lrange range_pci1710hg = {
+static const struct comedi_lrange pci1710hg_ai_range = {
 	12, {
-		BIP_RANGE(5),
-		BIP_RANGE(0.5),
-		BIP_RANGE(0.05),
-		BIP_RANGE(0.005),
-		BIP_RANGE(10),
-		BIP_RANGE(1),
-		BIP_RANGE(0.1),
-		BIP_RANGE(0.01),
-		UNI_RANGE(10),
-		UNI_RANGE(1),
-		UNI_RANGE(0.1),
-		UNI_RANGE(0.01)
+		BIP_RANGE(5),		/* gain 1    (0x00) */
+		BIP_RANGE(0.5),		/* gain 10   (0x01) */
+		BIP_RANGE(0.05),	/* gain 100  (0x02) */
+		BIP_RANGE(0.005),	/* gain 1000 (0x03) */
+		BIP_RANGE(10),		/* gain 0.5  (0x04) */
+		BIP_RANGE(1),		/* gain 5    (0x05) */
+		BIP_RANGE(0.1),		/* gain 50   (0x06) */
+		BIP_RANGE(0.01),	/* gain 500  (0x07) */
+		UNI_RANGE(10),		/* gain 1    (0x00 | UNI) */
+		UNI_RANGE(1),		/* gain 10   (0x01 | UNI) */
+		UNI_RANGE(0.1),		/* gain 100  (0x02 | UNI) */
+		UNI_RANGE(0.01)		/* gain 1000 (0x03 | UNI) */
 	}
 };
 
-static const char range_codes_pci1710hg[] = { 0x00, 0x01, 0x02, 0x03, 0x04,
-					      0x05, 0x06, 0x07, 0x10, 0x11,
-					      0x12, 0x13 };
-
-static const struct comedi_lrange range_pci17x1 = {
+static const struct comedi_lrange pci1711_ai_range = {
 	5, {
-		BIP_RANGE(10),
-		BIP_RANGE(5),
-		BIP_RANGE(2.5),
-		BIP_RANGE(1.25),
-		BIP_RANGE(0.625)
+		BIP_RANGE(10),		/* gain 1  (0x00) */
+		BIP_RANGE(5),		/* gain 2  (0x01) */
+		BIP_RANGE(2.5),		/* gain 4  (0x02) */
+		BIP_RANGE(1.25),	/* gain 8  (0x03) */
+		BIP_RANGE(0.625)	/* gain 16 (0x04) */
 	}
 };
 
-static const char range_codes_pci17x1[] = { 0x00, 0x01, 0x02, 0x03, 0x04 };
-
 static const struct comedi_lrange pci171x_ao_range = {
 	2, {
 		UNI_RANGE(5),
@@ -132,7 +126,6 @@ struct boardtype {
 	const char *name;	/*  board name */
 	int n_aichan;		/*  num of A/D chans */
 	const struct comedi_lrange *rangelist_ai;	/*  rangelist for A/D */
-	const char *rangecode_ai;	/*  range codes for programming */
 	unsigned int is_pci1713:1;
 	unsigned int has_large_fifo:1;	/* 4K or 1K FIFO */
 	unsigned int has_diff_ai:1;
@@ -144,8 +137,7 @@ static const struct boardtype boardtypes[] = {
 	[BOARD_PCI1710] = {
 		.name		= "pci1710",
 		.n_aichan	= 16,
-		.rangelist_ai	= &range_pci1710_3,
-		.rangecode_ai	= range_codes_pci1710_3,
+		.rangelist_ai	= &pci1710_ai_range,
 		.has_large_fifo	= 1,
 		.has_diff_ai	= 1,
 		.has_ao		= 1,
@@ -154,8 +146,7 @@ static const struct boardtype boardtypes[] = {
 	[BOARD_PCI1710HG] = {
 		.name		= "pci1710hg",
 		.n_aichan	= 16,
-		.rangelist_ai	= &range_pci1710hg,
-		.rangecode_ai	= range_codes_pci1710hg,
+		.rangelist_ai	= &pci1710hg_ai_range,
 		.has_large_fifo	= 1,
 		.has_diff_ai	= 1,
 		.has_ao		= 1,
@@ -164,16 +155,14 @@ static const struct boardtype boardtypes[] = {
 	[BOARD_PCI1711] = {
 		.name		= "pci1711",
 		.n_aichan	= 16,
-		.rangelist_ai	= &range_pci17x1,
-		.rangecode_ai	= range_codes_pci17x1,
+		.rangelist_ai	= &pci1711_ai_range,
 		.has_ao		= 1,
 		.has_di_do	= 1,
 	},
 	[BOARD_PCI1713] = {
 		.name		= "pci1713",
 		.n_aichan	= 32,
-		.rangelist_ai	= &range_pci1710_3,
-		.rangecode_ai	= range_codes_pci1710_3,
+		.rangelist_ai	= &pci1710_ai_range,
 		.is_pci1713	= 1,
 		.has_large_fifo	= 1,
 		.has_diff_ai	= 1,
@@ -181,8 +170,7 @@ static const struct boardtype boardtypes[] = {
 	[BOARD_PCI1731] = {
 		.name		= "pci1731",
 		.n_aichan	= 16,
-		.rangelist_ai	= &range_pci17x1,
-		.rangecode_ai	= range_codes_pci17x1,
+		.rangelist_ai	= &pci1711_ai_range,
 		.has_di_do	= 1,
 	},
 };
@@ -196,6 +184,7 @@ struct pci1710_private {
 	unsigned int act_chanlist[32];	/*  list of scanned channel */
 	unsigned char saved_seglen;	/* len of the non-repeating chanlist */
 	unsigned char da_ranges;	/*  copy of D/A outpit range register */
+	unsigned char unipolar_gain;	/* adjust for unipolar gain codes */
 };
 
 static int pci171x_ai_check_chanlist(struct comedi_device *dev,
@@ -270,7 +259,6 @@ static void pci171x_ai_setup_chanlist(struct comedi_device *dev,
 				      unsigned int n_chan,
 				      unsigned int seglen)
 {
-	const struct boardtype *board = dev->board_ptr;
 	struct pci1710_private *devpriv = dev->private;
 	unsigned int first_chan = CR_CHAN(chanlist[0]);
 	unsigned int last_chan = CR_CHAN(chanlist[seglen - 1]);
@@ -280,11 +268,15 @@ static void pci171x_ai_setup_chanlist(struct comedi_device *dev,
 		unsigned int chan = CR_CHAN(chanlist[i]);
 		unsigned int range = CR_RANGE(chanlist[i]);
 		unsigned int aref = CR_AREF(chanlist[i]);
-		unsigned int rangeval;
+		unsigned int rangeval = 0;
 
-		rangeval = board->rangecode_ai[range];
 		if (aref == AREF_DIFF)
-			rangeval |= 0x0020;
+			rangeval |= PCI171X_RANGE_DIFF;
+		if (comedi_range_is_unipolar(s, range)) {
+			rangeval |= PCI171X_RANGE_UNI;
+			range -= devpriv->unipolar_gain;
+		}
+		rangeval |= PCI171X_RANGE_GAIN(range);
 
 		/* select channel and set range */
 		outw(chan | (chan << 8), dev->iobase + PCI171X_MUX_REG);
@@ -758,6 +750,7 @@ static int pci1710_auto_attach(struct comedi_device *dev,
 	struct pci1710_private *devpriv;
 	struct comedi_subdevice *s;
 	int ret, subdev, n_subdevices;
+	int i;
 
 	if (context < ARRAY_SIZE(boardtypes))
 		board = &boardtypes[context];
@@ -823,6 +816,15 @@ static int pci1710_auto_attach(struct comedi_device *dev,
 			s->do_cmd	= pci171x_ai_cmd;
 			s->cancel	= pci171x_ai_cancel;
 		}
+
+		/* find the value needed to adjust for unipolar gain codes */
+		for (i = 0; i < s->range_table->length; i++) {
+			if (comedi_range_is_unipolar(s, i)) {
+				devpriv->unipolar_gain = i;
+				break;
+			}
+		}
+
 		subdev++;
 	}