[PATCH 27/62] staging: comedi: dt2811: use comedi_subdevice 'readback'

[H Hartley Sweeten]

Use the new comedi_subdevice 'readback' member and the core provided
(*insn_read) for the readback of the analog output subdevice channels.

For aesthetics, rename the (*insn_write) function and tidy it up.

Signed-off-by: H Hartley Sweeten <hswee...@visionengravers.com>
Cc: Ian Abbott <abbo...@mev.co.uk>
Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 drivers/staging/comedi/drivers/dt2811.c | 46 ++++++++++++---------------------
 1 file changed, 17 insertions(+), 29 deletions(-)

diff --git a/drivers/staging/comedi/drivers/dt2811.c 
b/drivers/staging/comedi/drivers/dt2811.c
index a2e9caf..fae9149 100644
--- a/drivers/staging/comedi/drivers/dt2811.c
+++ b/drivers/staging/comedi/drivers/dt2811.c
@@ -213,7 +213,6 @@ struct dt2811_private {
                dac_bipolar_5, dac_bipolar_2_5, dac_unipolar_5
        } dac_range[2];
        const struct comedi_lrange *range_type_list[2];
-       unsigned int ao_readback[2];
 };
 
 static const struct comedi_lrange *dac_range_types[] = {
@@ -257,39 +256,24 @@ static int dt2811_ai_insn(struct comedi_device *dev, 
struct comedi_subdevice *s,
        return i;
 }
 
-static int dt2811_ao_insn(struct comedi_device *dev, struct comedi_subdevice 
*s,
-                         struct comedi_insn *insn, unsigned int *data)
+static int dt2811_ao_insn_write(struct comedi_device *dev,
+                               struct comedi_subdevice *s,
+                               struct comedi_insn *insn,
+                               unsigned int *data)
 {
-       struct dt2811_private *devpriv = dev->private;
+       unsigned int chan = CR_CHAN(insn->chanspec);
+       unsigned int val = s->readback[chan];
        int i;
-       int chan;
-
-       chan = CR_CHAN(insn->chanspec);
 
        for (i = 0; i < insn->n; i++) {
-               outb(data[i] & 0xff, dev->iobase + DT2811_DADAT0LO + 2 * chan);
-               outb((data[i] >> 8) & 0xff,
+               val = data[i];
+               outb(val & 0xff, dev->iobase + DT2811_DADAT0LO + 2 * chan);
+               outb((val >> 8) & 0xff,
                     dev->iobase + DT2811_DADAT0HI + 2 * chan);
-               devpriv->ao_readback[chan] = data[i];
        }
+       s->readback[chan] = val;
 
-       return i;
-}
-
-static int dt2811_ao_insn_read(struct comedi_device *dev,
-                              struct comedi_subdevice *s,
-                              struct comedi_insn *insn, unsigned int *data)
-{
-       struct dt2811_private *devpriv = dev->private;
-       int i;
-       int chan;
-
-       chan = CR_CHAN(insn->chanspec);
-
-       for (i = 0; i < insn->n; i++)
-               data[i] = devpriv->ao_readback[chan];
-
-       return i;
+       return insn->n;
 }
 
 static int dt2811_di_insn_bits(struct comedi_device *dev,
@@ -429,12 +413,16 @@ static int dt2811_attach(struct comedi_device *dev, 
struct comedi_devconfig *it)
        s->type = COMEDI_SUBD_AO;
        s->subdev_flags = SDF_WRITABLE;
        s->n_chan = 2;
-       s->insn_write = dt2811_ao_insn;
-       s->insn_read = dt2811_ao_insn_read;
        s->maxdata = 0xfff;
        s->range_table_list = devpriv->range_type_list;
        devpriv->range_type_list[0] = dac_range_types[devpriv->dac_range[0]];
        devpriv->range_type_list[1] = dac_range_types[devpriv->dac_range[1]];
+       s->insn_write = dt2811_ao_insn_write;
+       s->insn_read = comedi_readback_insn_read;
+
+       ret = comedi_alloc_subdev_readback(s);
+       if (ret)
+               return ret;
 
        s = &dev->subdevices[2];
        /* di subdevice */
-- 
2.0.3

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