staging: comedi: quatech_daqp_cs: introduce daqp_ai_get_sample()

Introduce a helper function to get a two's complement sample from
the FIFO and munge it to the offset binary format that comedi uses.

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/quatech_daqp_cs.c b/drivers/staging/comedi/drivers/quatech_daqp_cs.c
index b2effb8..cf144ce 100644 (file)
--- a/drivers/staging/comedi/drivers/quatech_daqp_cs.c
+++ b/drivers/staging/comedi/drivers/quatech_daqp_cs.c
@@ -172,6 +172,20 @@ static int daqp_ai_cancel(struct comedi_device *dev, struct comedi_subdevice *s)
        return 0;
 }
 
+static unsigned int daqp_ai_get_sample(struct comedi_device *dev,
+                                      struct comedi_subdevice *s)
+{
+       unsigned int val;
+
+       /*
+        * Get a two's complement sample from the FIFO and
+        * return the munged offset binary value.
+        */
+       val = inb(dev->iobase + DAQP_FIFO);
+       val |= inb(dev->iobase + DAQP_FIFO) << 8;
+       return comedi_offset_munge(s, val);
+}
+
 /* Interrupt handler
  *
  * Operates in one of two modes.  If devpriv->interrupt_mode is
@@ -209,10 +223,7 @@ static enum irqreturn daqp_interrupt(int irq, void *dev_id)
                                break;
                        }
 
-                       data = inb(dev->iobase + DAQP_FIFO);
-                       data |= inb(dev->iobase + DAQP_FIFO) << 8;
-                       data ^= 0x8000;
-
+                       data = daqp_ai_get_sample(dev, s);
                        comedi_buf_write_samples(s, &data, 1);
 
                        /* If there's a limit, decrement it
@@ -323,9 +334,7 @@ static int daqp_ai_insn_read(struct comedi_device *dev,
                if (wait_for_completion_interruptible(&devpriv->eos))
                        return -EINTR;
 
-               data[i] = inb(dev->iobase + DAQP_FIFO);
-               data[i] |= inb(dev->iobase + DAQP_FIFO) << 8;
-               data[i] ^= 0x8000;
+               data[i] = daqp_ai_get_sample(dev, s);
        }
 
        return insn->n;