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

Use the comedi_subdevice 'readback' member and the core provided (*insn_read)
to handle the readback of the write-only trimpot calib subdevice. Remove the
then unused 'trimpot_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 d5edb5f..86e3d20 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 trimpot_value[NUM_CHANNELS_8402];
        unsigned int dac08_value;
        unsigned int calibration_source;
 };
@@ -744,33 +743,20 @@ static int cb_pcidas_trimpot_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->trimpot_value[chan] != val) {
+               if (s->readback[chan] != val) {
                        cb_pcidas_trimpot_write(dev, chan, val);
-                       devpriv->trimpot_value[chan] = val;
+                       s->readback[chan] = val;
                }
        }
 
        return insn->n;
 }
 
-static int trimpot_read_insn(struct comedi_device *dev,
-                            struct comedi_subdevice *s,
-                            struct comedi_insn *insn, unsigned int *data)
-{
-       struct cb_pcidas_private *devpriv = dev->private;
-       unsigned int channel = CR_CHAN(insn->chanspec);
-
-       data[0] = devpriv->trimpot_value[channel];
-
-       return 1;
-}
-
 static int cb_pcidas_ai_check_chanlist(struct comedi_device *dev,
                                       struct comedi_subdevice *s,
                                       struct comedi_cmd *cmd)
@@ -1527,11 +1513,15 @@ static int cb_pcidas_auto_attach(struct comedi_device *dev,
                s->n_chan = NUM_CHANNELS_8402;
                s->maxdata = 0xff;
        }
-       s->insn_read = trimpot_read_insn;
        s->insn_write = cb_pcidas_trimpot_insn_write;
+
+       ret = comedi_alloc_subdev_readback(s);
+       if (ret)
+               return ret;
+
        for (i = 0; i < s->n_chan; i++) {
                cb_pcidas_trimpot_write(dev, i, s->maxdata / 2);
-               devpriv->trimpot_value[i] = s->maxdata / 2;
+               s->readback[i] = s->maxdata / 2;
        }
 
        /*  dac08 caldac */