staging: comedi: cb_pcidas64: use subdevice readback for 'caldac_state'

Use the comedi_subdevice 'readback' member and the core provided (*insn_read)
to handle the readback of the write-only calibration subdevice. Remove the
then unused 'caldac_state' 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_pcidas64.c b/drivers/staging/comedi/drivers/cb_pcidas64.c
index 4762e6a..c641778 100644 (file)
--- a/drivers/staging/comedi/drivers/cb_pcidas64.c
+++ b/drivers/staging/comedi/drivers/cb_pcidas64.c
@@ -1107,7 +1107,6 @@ struct pcidas64_private {
        unsigned int ext_trig_falling;
        /*  states of various devices stored to enable read-back */
        unsigned int ad8402_state[2];
-       unsigned int caldac_state[8];
        short ai_cmd_running;
        unsigned int ai_fifo_segment_length;
        struct ext_clock_info ext_clock;
@@ -3550,9 +3549,6 @@ static void caldac_write(struct comedi_device *dev, unsigned int channel,
                         unsigned int value)
 {
        const struct pcidas64_board *thisboard = dev->board_ptr;
-       struct pcidas64_private *devpriv = dev->private;
-
-       devpriv->caldac_state[channel] = value;
 
        switch (thisboard->layout) {
        case LAYOUT_60XX:
@@ -3571,27 +3567,15 @@ static int calib_write_insn(struct comedi_device *dev,
                            struct comedi_subdevice *s,
                            struct comedi_insn *insn, unsigned int *data)
 {
-       struct pcidas64_private *devpriv = dev->private;
        int channel = CR_CHAN(insn->chanspec);
 
        /* return immediately if setting hasn't changed, since
         * programming these things is slow */
-       if (devpriv->caldac_state[channel] == data[0])
+       if (s->readback[channel] == data[0])
                return 1;
 
        caldac_write(dev, channel, data[0]);
-
-       return 1;
-}
-
-static int calib_read_insn(struct comedi_device *dev,
-                          struct comedi_subdevice *s, struct comedi_insn *insn,
-                          unsigned int *data)
-{
-       struct pcidas64_private *devpriv = dev->private;
-       unsigned int channel = CR_CHAN(insn->chanspec);
-
-       data[0] = devpriv->caldac_state[channel];
+       s->readback[channel] = data[0];
 
        return 1;
 }
@@ -3864,10 +3848,16 @@ static int setup_subdevices(struct comedi_device *dev)
                s->maxdata = 0xfff;
        else
                s->maxdata = 0xff;
-       s->insn_read = calib_read_insn;
        s->insn_write = calib_write_insn;
-       for (i = 0; i < s->n_chan; i++)
+
+       ret = comedi_alloc_subdev_readback(s);
+       if (ret)
+               return ret;
+
+       for (i = 0; i < s->n_chan; i++) {
                caldac_write(dev, i, s->maxdata / 2);
+               s->readback[i] = s->maxdata / 2;
+       }
 
        /*  2 channel ad8402 potentiometer */
        s = &dev->subdevices[7];