staging: comedi: cb_pcidas: use subdevice readback for 'caldac_value'

Use the comedi_subdevice 'readback' member and the core provided (*insn_read)
to handle the readback of the write-only caldac subdevice. Remove the then
unused 'caldac_value' member from the private data.

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/cb_pcidas.c b/drivers/staging/comedi/drivers/cb_pcidas.c
index d33b37c83ee83b46ec6f182ec05f5af0a5725911..f92ad26d38ff119e8a1b3b4ff1fc4ab124791102 100644 (file)
--- a/drivers/staging/comedi/drivers/cb_pcidas.c
+++ b/drivers/staging/comedi/drivers/cb_pcidas.c
@@ -356,7 +356,6 @@ struct cb_pcidas_private {
        /* divisors of master clock for analog output pacing */
        unsigned int ao_divisor1;
        unsigned int ao_divisor2;
-       unsigned int caldac_value[NUM_CHANNELS_8800];
        unsigned int trimpot_value[NUM_CHANNELS_8402];
        unsigned int dac08_value;
        unsigned int calibration_source;
@@ -615,32 +614,20 @@ static int cb_pcidas_caldac_insn_write(struct comedi_device *dev,
                                       struct comedi_insn *insn,
                                       unsigned int *data)
 {
-       struct cb_pcidas_private *devpriv = dev->private;
        unsigned int chan = CR_CHAN(insn->chanspec);
 
        if (insn->n) {
                unsigned int val = data[insn->n - 1];
 
-               if (devpriv->caldac_value[chan] != val) {
+               if (s->readback[chan] != val) {
                        caldac_8800_write(dev, chan, val);
-                       devpriv->caldac_value[chan] = val;
+                       s->readback[chan] = val;
                }
        }
 
        return insn->n;
 }
 
-static int caldac_read_insn(struct comedi_device *dev,
-                           struct comedi_subdevice *s,
-                           struct comedi_insn *insn, unsigned int *data)
-{
-       struct cb_pcidas_private *devpriv = dev->private;
-
-       data[0] = devpriv->caldac_value[CR_CHAN(insn->chanspec)];
-
-       return 1;
-}
-
 /* 1602/16 pregain offset */
 static void dac08_write(struct comedi_device *dev, unsigned int value)
 {
@@ -1514,11 +1501,15 @@ static int cb_pcidas_auto_attach(struct comedi_device *dev,
        s->subdev_flags = SDF_READABLE | SDF_WRITABLE | SDF_INTERNAL;
        s->n_chan = NUM_CHANNELS_8800;
        s->maxdata = 0xff;
-       s->insn_read = caldac_read_insn;
        s->insn_write = cb_pcidas_caldac_insn_write;
+
+       ret = comedi_alloc_subdev_readback(s);
+       if (ret)
+               return ret;
+
        for (i = 0; i < s->n_chan; i++) {
                caldac_8800_write(dev, i, s->maxdata / 2);
-               devpriv->caldac_value[i] = s->maxdata / 2;
+               s->readback[i] = s->maxdata / 2;
        }
 
        /*  trim potentiometer */