staging: comedi: pcl816: factor out dma setup to helper functions

To assist in cleaning up the the rest of the driver, factor the initial
dma setup and the next dma buffer setup into helper functions.
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/pcl816.c

@@ -152,6 +152,68 @@ static void pcl816_start_pacer(struct comedi_device *dev, bool load_counters)
 	}
 }
 
+static void pcl816_ai_setup_dma(struct comedi_device *dev,
+				struct comedi_subdevice *s)
+{
+	struct pcl816_private *devpriv = dev->private;
+	struct comedi_cmd *cmd = &s->async->cmd;
+	unsigned int dma_flags;
+	unsigned int bytes;
+
+	bytes = devpriv->hwdmasize;
+	if (cmd->stop_src == TRIG_COUNT) {
+		/*  how many */
+		bytes = s->async->cmd.chanlist_len *
+		s->async->cmd.chanlist_len *
+		sizeof(short);
+
+		/*  how many DMA pages we must fill */
+		devpriv->dma_runs_to_end = bytes / devpriv->hwdmasize;
+
+		/* on last dma transfer must be moved */
+		devpriv->last_dma_run = bytes % devpriv->hwdmasize;
+		devpriv->dma_runs_to_end--;
+		if (devpriv->dma_runs_to_end >= 0)
+			bytes = devpriv->hwdmasize;
+	} else
+		devpriv->dma_runs_to_end = -1;
+
+	devpriv->next_dma_buf = 0;
+	set_dma_mode(devpriv->dma, DMA_MODE_READ);
+	dma_flags = claim_dma_lock();
+	clear_dma_ff(devpriv->dma);
+	set_dma_addr(devpriv->dma, devpriv->hwdmaptr[0]);
+	set_dma_count(devpriv->dma, bytes);
+	release_dma_lock(dma_flags);
+	enable_dma(devpriv->dma);
+}
+
+static void pcl816_ai_setup_next_dma(struct comedi_device *dev,
+				     struct comedi_subdevice *s)
+{
+	struct pcl816_private *devpriv = dev->private;
+	struct comedi_cmd *cmd = &s->async->cmd;
+	unsigned long dma_flags;
+
+	disable_dma(devpriv->dma);
+	if (devpriv->dma_runs_to_end > -1 || cmd->stop_src == TRIG_NONE) {
+		/* switch dma bufs */
+		devpriv->next_dma_buf = 1 - devpriv->next_dma_buf;
+		set_dma_mode(devpriv->dma, DMA_MODE_READ);
+		dma_flags = claim_dma_lock();
+		set_dma_addr(devpriv->dma,
+			     devpriv->hwdmaptr[devpriv->next_dma_buf]);
+		if (devpriv->dma_runs_to_end)
+			set_dma_count(devpriv->dma, devpriv->hwdmasize);
+		else
+			set_dma_count(devpriv->dma, devpriv->last_dma_run);
+		release_dma_lock(dma_flags);
+		enable_dma(devpriv->dma);
+	}
+
+	devpriv->dma_runs_to_end--;
+}
+
 static unsigned int pcl816_ai_get_sample(struct comedi_device *dev,
 					 struct comedi_subdevice *s)
 {
@@ -295,31 +357,13 @@ static irqreturn_t interrupt_pcl816_ai_mode13_dma(int irq, void *d)
 	struct comedi_device *dev = d;
 	struct pcl816_private *devpriv = dev->private;
 	struct comedi_subdevice *s = dev->read_subdev;
-	struct comedi_cmd *cmd = &s->async->cmd;
 	int len, bufptr, this_dma_buf;
-	unsigned long dma_flags;
 	unsigned short *ptr;
 
-	disable_dma(devpriv->dma);
 	this_dma_buf = devpriv->next_dma_buf;
 
-	if (devpriv->dma_runs_to_end > -1 || cmd->stop_src == TRIG_NONE) {
-		/* switch dma bufs */
-		devpriv->next_dma_buf = 1 - devpriv->next_dma_buf;
-		set_dma_mode(devpriv->dma, DMA_MODE_READ);
-		dma_flags = claim_dma_lock();
-/* clear_dma_ff (devpriv->dma); */
-		set_dma_addr(devpriv->dma,
-			     devpriv->hwdmaptr[devpriv->next_dma_buf]);
-		if (devpriv->dma_runs_to_end)
-			set_dma_count(devpriv->dma, devpriv->hwdmasize);
-		else
-			set_dma_count(devpriv->dma, devpriv->last_dma_run);
-		release_dma_lock(dma_flags);
-		enable_dma(devpriv->dma);
-	}
+	pcl816_ai_setup_next_dma(dev, s);
 
-	devpriv->dma_runs_to_end--;
 	outb(0, dev->iobase + PCL816_CLRINT);	/* clear INT request */
 
 	ptr = (unsigned short *)devpriv->dmabuf[this_dma_buf];
@@ -447,7 +491,7 @@ static int pcl816_ai_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
 {
 	struct pcl816_private *devpriv = dev->private;
 	struct comedi_cmd *cmd = &s->async->cmd;
-	unsigned int dma_flags, bytes, dmairq;
+	unsigned int dmairq;
 	unsigned int seglen;
 
 	if (devpriv->ai_cmd_running)
@@ -467,34 +511,8 @@ static int pcl816_ai_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
 	devpriv->ai_poll_ptr = 0;
 	devpriv->irq_was_now_closed = 0;
 
-	if (devpriv->dma) {
-		bytes = devpriv->hwdmasize;
-		if (cmd->stop_src == TRIG_COUNT) {
-			/*  how many */
-			bytes = s->async->cmd.chanlist_len *
-			s->async->cmd.chanlist_len *
-			sizeof(short);
-
-			/*  how many DMA pages we must fill */
-			devpriv->dma_runs_to_end = bytes / devpriv->hwdmasize;
-
-			/* on last dma transfer must be moved */
-			devpriv->last_dma_run = bytes % devpriv->hwdmasize;
-			devpriv->dma_runs_to_end--;
-			if (devpriv->dma_runs_to_end >= 0)
-				bytes = devpriv->hwdmasize;
-		} else
-			devpriv->dma_runs_to_end = -1;
-
-		devpriv->next_dma_buf = 0;
-		set_dma_mode(devpriv->dma, DMA_MODE_READ);
-		dma_flags = claim_dma_lock();
-		clear_dma_ff(devpriv->dma);
-		set_dma_addr(devpriv->dma, devpriv->hwdmaptr[0]);
-		set_dma_count(devpriv->dma, bytes);
-		release_dma_lock(dma_flags);
-		enable_dma(devpriv->dma);
-	}
+	if (devpriv->dma)
+		pcl816_ai_setup_dma(dev, s);
 
 	pcl816_start_pacer(dev, true);
 	dmairq = ((devpriv->dma & 0x3) << 4) | (dev->irq & 0x7);