staging: comedi: ni_at_ao: tidy up atao_ao_winsn()

For aesthetics, rename this function to help with greps.

For channel 0, register group 1 only needs to be selected before
writing the values and restored to group 0 when the writes are
finished. Move the code out of the for () loop.

Use the comedi_ffset_munge() helper to handle the offset binary to
two's complement munging.

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/ni_at_ao.c b/drivers/staging/comedi/drivers/ni_at_ao.c
index 65c4712966a0c35f5de3eb8900a93c30266eea77..7ffa6c039bd6dcb5922544aafd651188bc1767e7 100644 (file)
--- a/drivers/staging/comedi/drivers/ni_at_ao.c
+++ b/drivers/staging/comedi/drivers/ni_at_ao.c
@@ -135,25 +135,32 @@ static void atao_select_reg_group(struct comedi_device *dev, int group)
        outw(devpriv->cfg1, dev->iobase + ATAO_CFG1_REG);
 }
 
-static int atao_ao_winsn(struct comedi_device *dev, struct comedi_subdevice *s,
-                        struct comedi_insn *insn, unsigned int *data)
+static int atao_ao_insn_write(struct comedi_device *dev,
+                             struct comedi_subdevice *s,
+                             struct comedi_insn *insn,
+                             unsigned int *data)
 {
        struct atao_private *devpriv = dev->private;
+       unsigned int chan = CR_CHAN(insn->chanspec);
+       unsigned int val;
        int i;
-       int chan = CR_CHAN(insn->chanspec);
-       short bits;
+
+       if (chan == 0)
+               atao_select_reg_group(dev, 1);
 
        for (i = 0; i < insn->n; i++) {
-               bits = data[i] - 0x800;
-               if (chan == 0)
-                       atao_select_reg_group(dev, 1);
-               outw(bits, dev->iobase + ATAO_AO_REG(chan));
-               if (chan == 0)
-                       atao_select_reg_group(dev, 0);
-               devpriv->ao_readback[chan] = data[i];
+               val = data[i];
+               devpriv->ao_readback[chan] = val;
+
+               /* munge offset binary (unsigned) to two's complement */
+               val = comedi_offset_munge(s, val);
+               outw(val, dev->iobase + ATAO_AO_REG(chan));
        }
 
-       return i;
+       if (chan == 0)
+               atao_select_reg_group(dev, 0);
+
+       return insn->n;
 }
 
 static int atao_ao_rinsn(struct comedi_device *dev, struct comedi_subdevice *s,
@@ -358,7 +365,7 @@ static int atao_attach(struct comedi_device *dev, struct comedi_devconfig *it)
                s->range_table = &range_unipolar10;
        else
                s->range_table = &range_bipolar10;
-       s->insn_write = &atao_ao_winsn;
+       s->insn_write = atao_ao_insn_write;
        s->insn_read = &atao_ao_rinsn;
 
        s = &dev->subdevices[1];