staging: comedi: ni_6527: tidy up ni6527_interrupt()

Rename the CamelCase defines used for the interrupt status register.

The NI6527_STATUS_IRQ bit will be set whenever the device is asserting
an interrupt. Modify the function a bit so this is the only requirement
for the interrupt to be IRQ_HANDLED. Currently an OVERFLOW interrupt is
not handled, though it's unlikely this would occur without an EDGE
interrupt.
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/ni_6527.c

@@ -54,11 +54,10 @@ Updated: Sat, 25 Jan 2003 13:24:40 -0800
 
 #define NI6527_FILT_INTERVAL_REG(x)	(0x08 + (x))
 #define NI6527_FILT_ENA_REG(x)		(0x0c + (x))
-
-#define Change_Status				0x14
-#define MasterInterruptStatus		0x04
-#define Overflow			0x02
-#define EdgeStatus			0x01
+#define NI6527_STATUS_REG		0x14
+#define NI6527_STATUS_IRQ		(1 << 2)
+#define NI6527_STATUS_OVERFLOW		(1 << 1)
+#define NI6527_STATUS_EDGE		(1 << 0)
 
 #define Master_Interrupt_Control		0x15
 #define FallingEdgeIntEnable		0x10
@@ -206,20 +205,22 @@ static irqreturn_t ni6527_interrupt(int irq, void *d)
 	struct comedi_device *dev = d;
 	struct ni6527_private *devpriv = dev->private;
 	struct comedi_subdevice *s = dev->read_subdev;
+	void __iomem *mmio = devpriv->mite->daq_io_addr;
 	unsigned int status;
 
-	status = readb(devpriv->mite->daq_io_addr + Change_Status);
-	if ((status & MasterInterruptStatus) == 0)
-		return IRQ_NONE;
-	if ((status & EdgeStatus) == 0)
+	status = readb(mmio + NI6527_STATUS_REG);
+	if (!(status & NI6527_STATUS_IRQ))
 		return IRQ_NONE;
 
-	writeb(ClrEdge | ClrOverflow,
-	       devpriv->mite->daq_io_addr + Clear_Register);
-
+	if (status & NI6527_STATUS_EDGE) {
 		comedi_buf_put(s->async, 0);
 		s->async->events |= COMEDI_CB_EOS;
 		comedi_event(dev, s);
+	}
+
+	writeb(ClrEdge | ClrOverflow,
+	       mmio + Clear_Register);
+
 	return IRQ_HANDLED;
 }