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>

diff --git a/drivers/staging/comedi/drivers/das800.c b/drivers/staging/comedi/drivers/das800.c
index cc4202e..c30309c 100644 (file)
--- 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,