staging: comedi: usbduxsigma: tidy up analog output (*insn_{read, write})

Rename the functions so they have namespace associated with the driver.
Rename the local variable used for the private data pointer.

Return -EBUSY from the (*insn_write) function if an asynchronous command
is running that the write cannot be completed.

Don't save the cached value of the analog output for readback unless
the command to set it is successful.
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/usbduxsigma.c

@@ -853,55 +853,53 @@ static int usbdux_ai_insn_read(struct comedi_device *dev,
 	return i;
 }
 
-/************************************/
-/* analog out */
-
-static int usbdux_ao_insn_read(struct comedi_device *dev,
+static int usbduxsigma_ao_insn_read(struct comedi_device *dev,
 				    struct comedi_subdevice *s,
-			       struct comedi_insn *insn, unsigned int *data)
+				    struct comedi_insn *insn,
+				    unsigned int *data)
 {
-	struct usbduxsigma_private *this_usbduxsub = dev->private;
+	struct usbduxsigma_private *devpriv = dev->private;
+	unsigned int chan = CR_CHAN(insn->chanspec);
 	int i;
-	int chan = CR_CHAN(insn->chanspec);
 
-	down(&this_usbduxsub->sem);
+	down(&devpriv->sem);
 	for (i = 0; i < insn->n; i++)
-		data[i] = this_usbduxsub->outBuffer[chan];
+		data[i] = devpriv->outBuffer[chan];
+	up(&devpriv->sem);
 
-	up(&this_usbduxsub->sem);
-	return i;
+	return insn->n;
 }
 
-static int usbdux_ao_insn_write(struct comedi_device *dev,
+static int usbduxsigma_ao_insn_write(struct comedi_device *dev,
 				     struct comedi_subdevice *s,
-				struct comedi_insn *insn, unsigned int *data)
+				     struct comedi_insn *insn,
+				     unsigned int *data)
 {
-	struct usbduxsigma_private *this_usbduxsub = dev->private;
-	int i, err;
-	int chan = CR_CHAN(insn->chanspec);
+	struct usbduxsigma_private *devpriv = dev->private;
+	unsigned int chan = CR_CHAN(insn->chanspec);
+	int ret;
+	int i;
 
-	down(&this_usbduxsub->sem);
-	if (this_usbduxsub->ao_cmd_running) {
-		up(&this_usbduxsub->sem);
-		return 0;
+	down(&devpriv->sem);
+	if (devpriv->ao_cmd_running) {
+		up(&devpriv->sem);
+		return -EBUSY;
 	}
 
 	for (i = 0; i < insn->n; i++) {
-		/* number of channels: 1 */
-		this_usbduxsub->dux_commands[1] = 1;
-		/* channel number */
-		this_usbduxsub->dux_commands[2] = data[i];
-		this_usbduxsub->outBuffer[chan] = data[i];
-		this_usbduxsub->dux_commands[3] = chan;
-		err = send_dux_commands(dev, SENDDACOMMANDS);
-		if (err < 0) {
-			up(&this_usbduxsub->sem);
-			return err;
+		devpriv->dux_commands[1] = 1;		/* num channels */
+		devpriv->dux_commands[2] = data[i];	/* value */
+		devpriv->dux_commands[3] = chan;	/* channel number */
+		ret = send_dux_commands(dev, SENDDACOMMANDS);
+		if (ret < 0) {
+			up(&devpriv->sem);
+			return ret;
 		}
+		devpriv->outBuffer[chan] = data[i];
 	}
-	up(&this_usbduxsub->sem);
+	up(&devpriv->sem);
 
-	return i;
+	return insn->n;
 }
 
 static int usbduxsigma_ao_inttrig(struct comedi_device *dev,
@@ -1468,8 +1466,8 @@ static int usbduxsigma_attach_common(struct comedi_device *dev)
 	s->len_chanlist	= 4;
 	s->maxdata	= 0x00ff;
 	s->range_table	= &range_unipolar2_5;
-	s->insn_write	= usbdux_ao_insn_write;
-	s->insn_read	= usbdux_ao_insn_read;
+	s->insn_write	= usbduxsigma_ao_insn_write;
+	s->insn_read	= usbduxsigma_ao_insn_read;
 	s->do_cmdtest	= usbduxsigma_ao_cmdtest;
 	s->do_cmd	= usbduxsigma_ao_cmd;
 	s->cancel	= usbdux_ao_cancel;