staging: comedi: aio_aio12_8: fix ai (*insn_read)

According to the user manual, analog input bipolar data is 2's
complement and unipolar is straight binry. Use the core helpers
to munge the data appropriately.

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/aio_aio12_8.c b/drivers/staging/comedi/drivers/aio_aio12_8.c
index 2262da0..e76a130 100644 (file)
--- a/drivers/staging/comedi/drivers/aio_aio12_8.c
+++ b/drivers/staging/comedi/drivers/aio_aio12_8.c
@@ -120,13 +120,15 @@ static int aio_aio12_8_ai_eoc(struct comedi_device *dev,
 
 static int aio_aio12_8_ai_read(struct comedi_device *dev,
                               struct comedi_subdevice *s,
-                              struct comedi_insn *insn, unsigned int *data)
+                              struct comedi_insn *insn,
+                              unsigned int *data)
 {
        unsigned int chan = CR_CHAN(insn->chanspec);
        unsigned int range = CR_RANGE(insn->chanspec);
+       unsigned int val;
        unsigned char control;
        int ret;
-       int n;
+       int i;
 
        /*
         * Setup the control byte for internal 2MHz clock, 3uS conversion,
@@ -138,7 +140,7 @@ static int aio_aio12_8_ai_read(struct comedi_device *dev,
        /* Read status to clear EOC latch */
        inb(dev->iobase + AIO12_8_STATUS_REG);
 
-       for (n = 0; n < insn->n; n++) {
+       for (i = 0; i < insn->n; i++) {
                /*  Setup and start conversion */
                outb(control, dev->iobase + AIO12_8_ADC_REG);
 
@@ -147,7 +149,13 @@ static int aio_aio12_8_ai_read(struct comedi_device *dev,
                if (ret)
                        return ret;
 
-               data[n] = inw(dev->iobase + AIO12_8_ADC_REG) & s->maxdata;
+               val = inw(dev->iobase + AIO12_8_ADC_REG) & s->maxdata;
+
+               /* munge bipolar 2's complement data to offset binary */
+               if (comedi_range_is_bipolar(s, range))
+                       val = comedi_offset_munge(s, val);
+
+               data[i] = val;
        }
 
        return insn->n;