staging: comedi: pcl818: introduce pcl818_ai_clear_eoc()

Introduce a helper function to clear the end-of-conversion flag.

This flag is set when an analog input conversion is finished and the
hardware generates an interrupt request. Writing any value to the
register resets the flag and re-enables the interrupt.

Remove the clearing of the flag in pcl818_handle_eoc(). The interrupt
function will handle clearing the flag.
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/pcl818.c

@@ -400,6 +400,13 @@ static void pcl818_ai_setup_next_dma(struct comedi_device *dev,
 	devpriv->dma_runs_to_end--;
 }
 
+static void pcl818_ai_clear_eoc(struct comedi_device *dev)
+{
+	/* writing any value clears the interrupt request */
+	outb(0, dev->iobase + PCL818_CLRINT);
+}
+
+
 static unsigned int pcl818_ai_get_fifo_sample(struct comedi_device *dev,
 					      struct comedi_subdevice *s,
 					      unsigned int *chan)
@@ -500,7 +507,6 @@ static void pcl818_handle_eoc(struct comedi_device *dev,
 	unsigned int val;
 
 	if (pcl818_ai_eoc(dev, s, NULL, 0)) {
-		outb(0, dev->iobase + PCL818_STATUS);	/* clear INT request */
 		comedi_error(dev, "A/D mode1/3 IRQ without DRDY!");
 		s->cancel(dev, s);
 		s->async->events |= COMEDI_CB_EOA | COMEDI_CB_ERROR;
@@ -508,7 +514,6 @@ static void pcl818_handle_eoc(struct comedi_device *dev,
 	}
 
 	val = pcl818_ai_get_sample(dev, s, &chan);
-	outb(0, dev->iobase + PCL818_CLRINT);	/* clear INT request */
 
 	if (pcl818_ai_dropout(dev, s, chan))
 		return;
@@ -598,7 +603,7 @@ static irqreturn_t pcl818_interrupt(int irq, void *d)
 	struct comedi_subdevice *s = dev->read_subdev;
 
 	if (!dev->attached || !devpriv->ai_cmd_running) {
-		outb(0, dev->iobase + PCL818_CLRINT);
+		pcl818_ai_clear_eoc(dev);
 		return IRQ_HANDLED;
 	}
 
@@ -611,7 +616,6 @@ static irqreturn_t pcl818_interrupt(int irq, void *d)
 		 */
 		devpriv->ai_act_scan = 0;
 		s->cancel(dev, s);
-		outb(0, dev->iobase + PCL818_CLRINT);
 		return IRQ_HANDLED;
 	}
 
@@ -622,7 +626,7 @@ static irqreturn_t pcl818_interrupt(int irq, void *d)
 	else
 		pcl818_handle_eoc(dev, s);
 
-	outb(0, dev->iobase + PCL818_CLRINT);
+	pcl818_ai_clear_eoc(dev);
 
 	comedi_event(dev, s);
 	return IRQ_HANDLED;
@@ -913,8 +917,9 @@ static int pcl818_ai_cancel(struct comedi_device *dev,
 	pcl818_start_pacer(dev, false);
 	outb(0, dev->iobase + PCL818_AD_LO);
 	pcl818_ai_get_sample(dev, s, NULL);
-	outb(0, dev->iobase + PCL818_CLRINT);	/* clear INT request */
 	outb(0, dev->iobase + PCL818_CONTROL);	/* Stop A/D */
+	pcl818_ai_clear_eoc(dev);
+
 	if (devpriv->usefifo) {	/*  FIFO shutdown */
 		outb(0, dev->iobase + PCL818_FI_INTCLR);
 		outb(0, dev->iobase + PCL818_FI_FLUSH);
@@ -945,8 +950,7 @@ static int pcl818_ai_insn_read(struct comedi_device *dev,
 	outb(range, dev->iobase + PCL818_RANGE);
 
 	for (i = 0; i < insn->n; i++) {
-		/* clear INT (conversion end) flag */
-		outb(0, dev->iobase + PCL818_CLRINT);
+		pcl818_ai_clear_eoc(dev);
 		/* start conversion */
 		outb(0, dev->iobase + PCL818_AD_LO);
 
@@ -956,8 +960,7 @@ static int pcl818_ai_insn_read(struct comedi_device *dev,
 
 		data[i] = pcl818_ai_get_sample(dev, s, NULL);
 	}
-	/* clear INT (conversion end) flag */
-	outb(0, dev->iobase + PCL818_CLRINT);
+	pcl818_ai_clear_eoc(dev);
 
 	return ret ? ret : insn->n;
 }
@@ -1044,7 +1047,7 @@ static void pcl818_reset(struct comedi_device *dev)
 	outb(0, dev->iobase + PCL818_CONTROL);
 	outb(0, dev->iobase + PCL818_CNTENABLE);
 	outb(0, dev->iobase + PCL818_MUX);
-	outb(0, dev->iobase + PCL818_CLRINT);
+	pcl818_ai_clear_eoc(dev);
 
 	/* Stop pacer */
 	i8254_set_mode(timer_base, 0, 2, I8254_MODE0 | I8254_BINARY);