staging: comedi: pcmuio: add inline helpers to get the 'iobase', 'asic', and 'port'

To reduce the potential for bugs, and better document the code, introduce
some inline helper functions to consolidate the calculations needed to get
the 'iobase' for a given asic and the 'asic' and 'port' associated with a
given subdevice.

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/pcmuio.c

@@ -141,12 +141,36 @@ struct pcmuio_private {
 	unsigned int irq2;
 };
 
+static inline unsigned long pcmuio_asic_iobase(struct comedi_device *dev,
+					       int asic)
+{
+	return dev->iobase + (asic * PCMUIO_ASIC_IOSIZE);
+}
+
+static inline int pcmuio_subdevice_to_asic(struct comedi_subdevice *s)
+{
+	/*
+	 * subdevice 0 and 1 are handled by the first asic
+	 * subdevice 2 and 3 are handled by the second asic
+	 */
+	return s->index / 2;
+}
+
+static inline int pcmuio_subdevice_to_port(struct comedi_subdevice *s)
+{
+	/*
+	 * subdevice 0 and 2 use port registers 0-2
+	 * subdevice 1 and 3 use port registers 3-5
+	 */
+	return (s->index % 2) ? 3 : 0;
+}
+
 static void pcmuio_write(struct comedi_device *dev, unsigned int val,
 			 int asic, int page, int port)
 {
 	struct pcmuio_private *devpriv = dev->private;
 	struct pcmuio_asic *chip = &devpriv->asics[asic];
-	unsigned long iobase = dev->iobase + (asic * PCMUIO_ASIC_IOSIZE);
+	unsigned long iobase = pcmuio_asic_iobase(dev, asic);
 	unsigned long flags;
 
 	spin_lock_irqsave(&chip->pagelock, flags);
@@ -169,7 +193,7 @@ static unsigned int pcmuio_read(struct comedi_device *dev,
 {
 	struct pcmuio_private *devpriv = dev->private;
 	struct pcmuio_asic *chip = &devpriv->asics[asic];
-	unsigned long iobase = dev->iobase + (asic * PCMUIO_ASIC_IOSIZE);
+	unsigned long iobase = pcmuio_asic_iobase(dev, asic);
 	unsigned long flags;
 	unsigned int val;
 
@@ -205,9 +229,9 @@ static int pcmuio_dio_insn_bits(struct comedi_device *dev,
 				struct comedi_insn *insn,
 				unsigned int *data)
 {
+	int asic = pcmuio_subdevice_to_asic(s);
+	int port = pcmuio_subdevice_to_port(s);
 	unsigned int chanmask = (1 << s->n_chan) - 1;
-	int asic = s->index / 2;
-	int port = (s->index % 2) ? 3 : 0;
 	unsigned int mask;
 	unsigned int val;
 
@@ -240,8 +264,8 @@ static int pcmuio_dio_insn_config(struct comedi_device *dev,
 				  struct comedi_insn *insn,
 				  unsigned int *data)
 {
-	int asic = s->index / 2;
-	int port = (s->index % 2) ? 3 : 0;
+	int asic = pcmuio_subdevice_to_asic(s);
+	int port = pcmuio_subdevice_to_port(s);
 	int ret;
 
 	ret = comedi_dio_insn_config(dev, s, insn, data, 0);
@@ -275,7 +299,7 @@ static void pcmuio_stop_intr(struct comedi_device *dev,
 			     struct comedi_subdevice *s)
 {
 	struct pcmuio_private *devpriv = dev->private;
-	int asic = s->index / 2;
+	int asic = pcmuio_subdevice_to_asic(s);
 	struct pcmuio_asic *chip = &devpriv->asics[asic];
 
 	chip->enabled_mask = 0;
@@ -291,7 +315,7 @@ static void pcmuio_handle_intr_subdev(struct comedi_device *dev,
 				      unsigned triggered)
 {
 	struct pcmuio_private *devpriv = dev->private;
-	int asic = s->index / 2;
+	int asic = pcmuio_subdevice_to_asic(s);
 	struct pcmuio_asic *chip = &devpriv->asics[asic];
 	unsigned int len = s->async->cmd.chanlist_len;
 	unsigned oldevents = s->async->events;
@@ -347,7 +371,7 @@ static int pcmuio_handle_asic_interrupt(struct comedi_device *dev, int asic)
 {
 	/* there are could be two asics so we can't use dev->read_subdev */
 	struct comedi_subdevice *s = &dev->subdevices[asic * 2];
-	unsigned long iobase = dev->iobase + (asic * PCMUIO_ASIC_IOSIZE);
+	unsigned long iobase = pcmuio_asic_iobase(dev, asic);
 	unsigned int val;
 
 	/* are there any interrupts pending */
@@ -383,7 +407,7 @@ static int pcmuio_start_intr(struct comedi_device *dev,
 			     struct comedi_subdevice *s)
 {
 	struct pcmuio_private *devpriv = dev->private;
-	int asic = s->index / 2;
+	int asic = pcmuio_subdevice_to_asic(s);
 	struct pcmuio_asic *chip = &devpriv->asics[asic];
 
 	if (!chip->continuous && chip->stop_count == 0) {
@@ -419,7 +443,7 @@ static int pcmuio_start_intr(struct comedi_device *dev,
 static int pcmuio_cancel(struct comedi_device *dev, struct comedi_subdevice *s)
 {
 	struct pcmuio_private *devpriv = dev->private;
-	int asic = s->index / 2;
+	int asic = pcmuio_subdevice_to_asic(s);
 	struct pcmuio_asic *chip = &devpriv->asics[asic];
 	unsigned long flags;
 
@@ -439,7 +463,7 @@ pcmuio_inttrig_start_intr(struct comedi_device *dev, struct comedi_subdevice *s,
 			  unsigned int trignum)
 {
 	struct pcmuio_private *devpriv = dev->private;
-	int asic = s->index / 2;
+	int asic = pcmuio_subdevice_to_asic(s);
 	struct pcmuio_asic *chip = &devpriv->asics[asic];
 	unsigned long flags;
 	int event = 0;
@@ -467,7 +491,7 @@ static int pcmuio_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
 {
 	struct pcmuio_private *devpriv = dev->private;
 	struct comedi_cmd *cmd = &s->async->cmd;
-	int asic = s->index / 2;
+	int asic = pcmuio_subdevice_to_asic(s);
 	struct pcmuio_asic *chip = &devpriv->asics[asic];
 	unsigned long flags;
 	int event = 0;