staging: comedi: icp_multi: remove private data member 'DacCmdStatus'

This private data member isn't really needed. The two functions
that use it, icp_multi_ao_insn_write() and icp_multi_reset(), mask
any previous value before setting the bits. The masking just clears
the variable.

Refactor the code to not use the private data member. This also
removes the need for the private data so remove it's allocation
during the attach.
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/icp_multi.c

@@ -62,6 +62,7 @@
 #define ICP_MULTI_DAC_CSR_BSY	BIT(0)	/* DAC busy */
 #define ICP_MULTI_DAC_CSR_BI	BIT(4)	/* Bipolar output range */
 #define ICP_MULTI_DAC_CSR_RA	BIT(5)	/* Output range 0 = 5V, 1 = 10V */
+#define ICP_MULTI_DAC_CSR_CHAN(x) (((x) & 0x3) << 8)
 #define ICP_MULTI_AO		6	/* R/W: Analogue output data */
 #define ICP_MULTI_DI		8	/* R/W: Digital inputs */
 #define ICP_MULTI_DO		0x0A	/* R/W: Digital outputs */
@@ -93,10 +94,6 @@ static const struct comedi_lrange icp_multi_ranges = {
 
 static const char range_codes_analog[] = { 0x00, 0x20, 0x10, 0x30 };
 
-struct icp_multi_private {
-	unsigned int DacCmdStatus;	/*  DAC Command/Status register */
-};
-
 static int icp_multi_ai_eoc(struct comedi_device *dev,
 			    struct comedi_subdevice *s,
 			    struct comedi_insn *insn,
@@ -168,21 +165,15 @@ static int icp_multi_ao_insn_write(struct comedi_device *dev,
 				   struct comedi_insn *insn,
 				   unsigned int *data)
 {
-	struct icp_multi_private *devpriv = dev->private;
 	unsigned int chan = CR_CHAN(insn->chanspec);
 	unsigned int range = CR_RANGE(insn->chanspec);
+	unsigned int dac_csr;
 	int i;
 
-	/*  Set up range and channel data */
-	/*  Bit 4 = 1 : Bipolar */
-	/*  Bit 5 = 0 : 5V */
-	/*  Bit 5 = 1 : 10V */
-	/*  Bits 8-9 : Channel number */
-	devpriv->DacCmdStatus &= 0xfccf;
-	devpriv->DacCmdStatus |= range_codes_analog[range];
-	devpriv->DacCmdStatus |= (chan << 8);
-
-	writew(devpriv->DacCmdStatus, dev->mmio + ICP_MULTI_DAC_CSR);
+	/* Select channel and range */
+	dac_csr = ICP_MULTI_DAC_CSR_CHAN(chan);
+	dac_csr |= range_codes_analog[range];
+	writew(dac_csr, dev->mmio + ICP_MULTI_DAC_CSR);
 
 	for (i = 0; i < insn->n; i++) {
 		unsigned int val = data[i];
@@ -197,9 +188,8 @@ static int icp_multi_ao_insn_write(struct comedi_device *dev,
 		writew(val, dev->mmio + ICP_MULTI_AO);
 
 		/* Set start conversion bit to write data to channel */
-		devpriv->DacCmdStatus |= ICP_MULTI_DAC_CSR_ST;
-		writew(devpriv->DacCmdStatus, dev->mmio + ICP_MULTI_DAC_CSR);
-		devpriv->DacCmdStatus &= ~ICP_MULTI_DAC_CSR_ST;
+		writew(dac_csr | ICP_MULTI_DAC_CSR_ST,
+		       dev->mmio + ICP_MULTI_DAC_CSR);
 
 		s->readback[chan] = val;
 	}
@@ -247,30 +237,25 @@ static int icp_multi_insn_write_ctr(struct comedi_device *dev,
 
 static int icp_multi_reset(struct comedi_device *dev)
 {
-	struct icp_multi_private *devpriv = dev->private;
-	unsigned int i;
+	int i;
 
 	/* Disable all interrupts and clear any requests */
 	writew(0, dev->mmio + ICP_MULTI_INT_EN);
 	writew(ICP_MULTI_INT_MASK, dev->mmio + ICP_MULTI_INT_STAT);
 
-	/* Set DACs to 0..5V range and 0V output */
+	/* Reset the analog output channels to 0V */
 	for (i = 0; i < 4; i++) {
-		devpriv->DacCmdStatus &= 0xfcce;
+		unsigned int dac_csr = ICP_MULTI_DAC_CSR_CHAN(i);
 
-		/*  Set channel number */
-		devpriv->DacCmdStatus |= (i << 8);
+		/* Select channel and 0..5V range */
+		writew(dac_csr, dev->mmio + ICP_MULTI_DAC_CSR);
 
 		/* Output 0V */
 		writew(0, dev->mmio + ICP_MULTI_AO);
 
-		/*  Set start conversion bit */
-		devpriv->DacCmdStatus |= ICP_MULTI_DAC_CSR_ST;
-
-		/*  Output to command / status register */
-		writew(devpriv->DacCmdStatus, dev->mmio + ICP_MULTI_DAC_CSR);
-
-		/*  Delay to allow DAC time to recover */
+		/* Set start conversion bit to write data to channel */
+		writew(dac_csr | ICP_MULTI_DAC_CSR_ST,
+		       dev->mmio + ICP_MULTI_DAC_CSR);
 		udelay(1);
 	}
 
@@ -284,14 +269,9 @@ static int icp_multi_auto_attach(struct comedi_device *dev,
 				 unsigned long context_unused)
 {
 	struct pci_dev *pcidev = comedi_to_pci_dev(dev);
-	struct icp_multi_private *devpriv;
 	struct comedi_subdevice *s;
 	int ret;
 
-	devpriv = comedi_alloc_devpriv(dev, sizeof(*devpriv));
-	if (!devpriv)
-		return -ENOMEM;
-
 	ret = comedi_pci_enable(dev);
 	if (ret)
 		return ret;