staging: comedi: daqboard2000: redo DAC status macros and fix busy

Rename the macros defining values for the DAC status register to avoid
CamelCase, and to make it clear which register they are associated with.
Refactor the macros defining the regular DAC channel "busy" bits into a
single macro that takes the DAC channel number as a parameter.

Add a macro to define the offset of the read-only DAC status register.
It is the same offset as the DAC control register, which is write-only.

The code in `daqboard2000_ao_eoc()` that checks the status for
completion of the DAC conversion looks wrong.  The register has a "busy"
bit for each channel, but the existing code only works for channels 0
and 1.  The driver only supports two DAC channels at the moment, so the
bug is currently harmless, but fix it so we can support four DAC
channels on some board models.
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/daqboard2000.c

@@ -162,7 +162,8 @@ static const struct comedi_lrange range_daqboard2000_ai = {
 #define DB2K_REG_ACQ_RESULTS_SHADOW		0x14		/* u16 */
 #define DB2K_REG_ACQ_ADC_RESULT			0x18		/* u16 */
 #define DB2K_REG_DAC_SCAN_COUNTER		0x1c		/* u16 */
-#define DB2K_REG_DAC_CONTROL			0x20		/* u16 */
+#define DB2K_REG_DAC_CONTROL			0x20		/* u16 (w) */
+#define DB2K_REG_DAC_STATUS			0x20		/* u16 (r) */
 #define DB2K_REG_DAC_FIFO			0x24		/* s16 */
 #define DB2K_REG_DAC_PACER_CLOCK_DIV		0x2a		/* u16 */
 #define DB2K_REG_REF_DACS			0x2c		/* u16 */
@@ -215,14 +216,11 @@ static const struct comedi_lrange range_daqboard2000_ai = {
 #define DB2K_ACQ_STATUS_DAC_PACER_OVERRUN		0x0200
 
 /* DAC status */
-#define DAQBOARD2000_DacFull                     0x0001
-#define DAQBOARD2000_RefBusy                     0x0002
-#define DAQBOARD2000_TrgBusy                     0x0004
-#define DAQBOARD2000_CalBusy                     0x0008
-#define DAQBOARD2000_Dac0Busy                    0x0010
-#define DAQBOARD2000_Dac1Busy                    0x0020
-#define DAQBOARD2000_Dac2Busy                    0x0040
-#define DAQBOARD2000_Dac3Busy                    0x0080
+#define DB2K_DAC_STATUS_DAC_FULL			0x0001
+#define DB2K_DAC_STATUS_REF_BUSY			0x0002
+#define DB2K_DAC_STATUS_TRIG_BUSY			0x0004
+#define DB2K_DAC_STATUS_CAL_BUSY			0x0008
+#define DB2K_DAC_STATUS_DAC_BUSY(x)			(0x0010 << (x))
 
 /* DAC control */
 #define DB2K_DAC_CONTROL_ENABLE_BIT			0x0001
@@ -400,8 +398,8 @@ static int daqboard2000_ao_eoc(struct comedi_device *dev,
 	unsigned int chan = CR_CHAN(insn->chanspec);
 	unsigned int status;
 
-	status = readw(dev->mmio + DB2K_REG_DAC_CONTROL);
-	if ((status & ((chan + 1) * 0x0010)) == 0)
+	status = readw(dev->mmio + DB2K_REG_DAC_STATUS);
+	if ((status & DB2K_DAC_STATUS_DAC_BUSY(chan)) == 0)
 		return 0;
 	return -EBUSY;
 }
@@ -574,8 +572,8 @@ static void daqboard2000_activateReferenceDacs(struct comedi_device *dev)
 	writew(0x80 | DAQBOARD2000_PosRefDacSelect,
 	       dev->mmio + DB2K_REG_REF_DACS);
 	for (timeout = 0; timeout < 20; timeout++) {
-		val = readw(dev->mmio + DB2K_REG_DAC_CONTROL);
-		if ((val & DAQBOARD2000_RefBusy) == 0)
+		val = readw(dev->mmio + DB2K_REG_DAC_STATUS);
+		if ((val & DB2K_DAC_STATUS_REF_BUSY) == 0)
 			break;
 		udelay(2);
 	}
@@ -584,8 +582,8 @@ static void daqboard2000_activateReferenceDacs(struct comedi_device *dev)
 	writew(0x80 | DAQBOARD2000_NegRefDacSelect,
 	       dev->mmio + DB2K_REG_REF_DACS);
 	for (timeout = 0; timeout < 20; timeout++) {
-		val = readw(dev->mmio + DB2K_REG_DAC_CONTROL);
-		if ((val & DAQBOARD2000_RefBusy) == 0)
+		val = readw(dev->mmio + DB2K_REG_DAC_STATUS);
+		if ((val & DB2K_DAC_STATUS_REF_BUSY) == 0)
 			break;
 		udelay(2);
 	}