To reduce the potential for bugs, introduce a couple 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 <hswee...@visionengravers.com>
Cc: Ian Abbott <abbo...@mev.co.uk>
Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 drivers/staging/comedi/drivers/pcmuio.c | 49 ++++++++++++++++++++++++---------
 1 file changed, 36 insertions(+), 13 deletions(-)

diff --git a/drivers/staging/comedi/drivers/pcmuio.c 
b/drivers/staging/comedi/drivers/pcmuio.c
index 087911d..9e746a5 100644
--- a/drivers/staging/comedi/drivers/pcmuio.c
+++ b/drivers/staging/comedi/drivers/pcmuio.c
@@ -138,11 +138,35 @@ struct pcmuio_private {
        } asics[PCMUIO_MAX_ASICS];
 };
 
+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;
-       unsigned long iobase = dev->iobase + (asic * PCMUIO_ASIC_IOSIZE);
+       unsigned long iobase = pcmuio_asic_iobase(dev, asic);
        unsigned long flags;
 
        spin_lock_irqsave(&devpriv->asics[asic].pagelock, flags);
@@ -164,7 +188,7 @@ static unsigned int pcmuio_read(struct comedi_device *dev,
                                int asic, int page, int port)
 {
        struct pcmuio_private *devpriv = dev->private;
-       unsigned long iobase = dev->iobase + (asic * PCMUIO_ASIC_IOSIZE);
+       unsigned long iobase = pcmuio_asic_iobase(dev, asic);
        unsigned long flags;
        unsigned int val;
 
@@ -199,10 +223,10 @@ static int pcmuio_dio_insn_bits(struct comedi_device *dev,
                                struct comedi_subdevice *s,
                                struct comedi_insn *insn, unsigned int *data)
 {
+       int asic = pcmuio_subdevice_to_asic(s);
+       int port = pcmuio_subdevice_to_port(s);
        unsigned int mask = data[0] & s->io_bits;       /* outputs only */
        unsigned int bits = data[1];
-       int asic = s->index / 2;
-       int port = (s->index % 2) ? 3 : 0;
        unsigned int val;
 
        /* get inverted state of the channels from the port */
@@ -235,9 +259,9 @@ static int pcmuio_dio_insn_config(struct comedi_device *dev,
                                  struct comedi_subdevice *s,
                                  struct comedi_insn *insn, unsigned int *data)
 {
+       int asic = pcmuio_subdevice_to_asic(s);
+       int port = pcmuio_subdevice_to_port(s);
        unsigned int chan_mask = 1 << CR_CHAN(insn->chanspec);
-       int asic = s->index / 2;
-       int port = (s->index % 2) ? 3 : 0;
 
        switch (data[0]) {
        case INSN_CONFIG_DIO_OUTPUT:
@@ -279,7 +303,7 @@ 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);
 
        devpriv->asics[asic].enabled_mask = 0;
        devpriv->asics[asic].active = 0;
@@ -346,7 +370,7 @@ done:
 
 static int pcmuio_handle_asic_interrupt(struct comedi_device *dev, int asic)
 {
-       unsigned long iobase = dev->iobase + (asic * PCMUIO_ASIC_IOSIZE);
+       unsigned long iobase = pcmuio_asic_iobase(dev, asic);
        unsigned int val;
 
        /* check if there are any interrupts pending */
@@ -381,7 +405,7 @@ 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);
 
        if (!devpriv->asics[asic].continuous &&
            devpriv->asics[asic].stop_count == 0) {
@@ -391,7 +415,6 @@ static int pcmuio_start_intr(struct comedi_device *dev,
                return 1;
        } else {
                unsigned bits = 0, pol_bits = 0, n;
-               int asic = s->index / 2;
                struct comedi_cmd *cmd = &s->async->cmd;
 
                devpriv->asics[asic].enabled_mask = 0;
@@ -418,7 +441,7 @@ 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);
        unsigned long flags;
 
        spin_lock_irqsave(&devpriv->asics[asic].spinlock, flags);
@@ -437,7 +460,7 @@ 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);
        unsigned long flags;
        int event = 0;
 
@@ -464,7 +487,7 @@ 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);
        unsigned long flags;
        int event = 0;
 
-- 
1.8.3.2

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