staging: comedi: das800: tidy up das800_ai_insn_read()

Introduce a couple helper functions to read the 16-bit analog input
sample and to wait for the analog conversion to complete.

Tidy up the das800_ai_insn_read() function by using the new helpers.
Also, remove the need for 'thisboard' in the function by checking the
subdevice 'maxdata' variable to determine the analog input resolution.

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>

1 files changed, 35 insertions, 28 deletions

diff --git a/drivers/staging/comedi/drivers/das800.c b/drivers/staging/comedi/drivers/das800.c
index cc4202eb3958..c30309cbc855 100644
--- a/drivers/staging/comedi/drivers/das800.c
+++ b/drivers/staging/comedi/drivers/das800.c
@@ -473,6 +473,14 @@ static int das800_ai_do_cmd(struct comedi_device *dev,
         return 0;
 }
 
+static unsigned int das800_ai_get_sample(struct comedi_device *dev)
+{
+        unsigned int lsb = inb(dev->iobase + DAS800_LSB);
+        unsigned int msb = inb(dev->iobase + DAS800_MSB);
+
+        return (msb << 8) | lsb;
+}
+
 static irqreturn_t das800_interrupt(int irq, void *d)
 {
         short i;                /* loop index */
@@ -570,61 +578,60 @@ static irqreturn_t das800_interrupt(int irq, void *d)
         return IRQ_HANDLED;
 }
 
+static int das800_wait_for_conv(struct comedi_device *dev, int timeout)
+{
+        int i;
+
+        for (i = 0; i < timeout; i++) {
+                if (!(inb(dev->iobase + DAS800_STATUS) & BUSY))
+                        return 0;
+        }
+        return -ETIME;
+}
+
 static int das800_ai_insn_read(struct comedi_device *dev,
                                struct comedi_subdevice *s,
                                struct comedi_insn *insn,
                                unsigned int *data)
 {
-        const struct das800_board *thisboard = comedi_board(dev);
         struct das800_private *devpriv = dev->private;
-        int i, n;
-        int chan;
-        int range;
-        int lsb, msb;
-        int timeout = 1000;
+        unsigned int chan = CR_CHAN(insn->chanspec);
+        unsigned int range = CR_RANGE(insn->chanspec);
         unsigned long irq_flags;
+        unsigned int val;
+        int ret;
+        int i;
 
         das800_disable(dev);
 
         /* set multiplexer */
-        chan = CR_CHAN(insn->chanspec);
-
         spin_lock_irqsave(&dev->spinlock, irq_flags);
         das800_ind_write(dev, chan | devpriv->do_bits, CONTROL1);
         spin_unlock_irqrestore(&dev->spinlock, irq_flags);
 
         /* set gain / range */
-        range = CR_RANGE(insn->chanspec);
-        if (thisboard->resolution == 12 && range)
+        if (s->maxdata == 0x0fff && range)
                 range += 0x7;
         range &= 0xf;
         outb(range, dev->iobase + DAS800_GAIN);
 
         udelay(5);
 
-        for (n = 0; n < insn->n; n++) {
+        for (i = 0; i < insn->n; i++) {
                 /* trigger conversion */
                 outb_p(0, dev->iobase + DAS800_MSB);
 
-                for (i = 0; i < timeout; i++) {
-                        if (!(inb(dev->iobase + DAS800_STATUS) & BUSY))
-                                break;
-                }
-                if (i == timeout) {
-                        comedi_error(dev, "timeout");
-                        return -ETIME;
-                }
-                lsb = inb(dev->iobase + DAS800_LSB);
-                msb = inb(dev->iobase + DAS800_MSB);
-                if (thisboard->resolution == 12) {
-                        data[n] = (lsb >> 4) & 0xff;
-                        data[n] |= (msb << 4);
-                } else {
-                        data[n] = (msb << 8) | lsb;
-                }
+                ret = das800_wait_for_conv(dev, 1000);
+                if (ret)
+                        return ret;
+
+                val = das800_ai_get_sample(dev);
+                if (s->maxdata == 0x0fff)
+                        val >>= 4;      /* 12-bit sample */
+                data[i] = val & s->maxdata;
         }
 
-        return n;
+        return insn->n;
 }
 
 static int das800_di_insn_bits(struct comedi_device *dev,