staging: comedi: cb_pcidas64: use subdevice readback for 'ad8402_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 'ad8402_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 17c98a59b44f4c0e763b2ae07edb648e3c7082ee..d80f34d35ee3cf571600e3a517f4eaa2b31a6adb 100644 (file)
--- a/drivers/staging/comedi/drivers/cb_pcidas64.c
+++ b/drivers/staging/comedi/drivers/cb_pcidas64.c
@@ -1105,8 +1105,6 @@ struct pcidas64_private {
        uint8_t i2c_cal_range_bits;
        /*  configure digital triggers to trigger on falling edge */
        unsigned int ext_trig_falling;
-       /*  states of various devices stored to enable read-back */
-       unsigned int ad8402_state[2];
        short ai_cmd_running;
        unsigned int ai_fifo_segment_length;
        struct ext_clock_info ext_clock;
@@ -3595,8 +3593,6 @@ static void ad8402_write(struct comedi_device *dev, unsigned int channel,
        unsigned int bitstream = ((channel & 0x3) << 8) | (value & 0xff);
        static const int ad8402_udelay = 1;
 
-       devpriv->ad8402_state[channel] = value;
-
        register_bits = SELECT_8402_64XX_BIT;
        udelay(ad8402_udelay);
        writew(register_bits, devpriv->main_iobase + CALIBRATION_REG);
@@ -3622,33 +3618,20 @@ static int ad8402_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->ad8402_state[channel] == data[0])
+       if (s->readback[channel] == data[0])
                return 1;
 
-       devpriv->ad8402_state[channel] = data[0];
+       s->readback[channel] = data[0];
 
        ad8402_write(dev, channel, data[0]);
 
        return 1;
 }
 
-static int ad8402_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->ad8402_state[channel];
-
-       return 1;
-}
-
 static uint16_t read_eeprom(struct comedi_device *dev, uint8_t address)
 {
        struct pcidas64_private *devpriv = dev->private;
@@ -3871,11 +3854,17 @@ static int setup_subdevices(struct comedi_device *dev)
                s->type = COMEDI_SUBD_CALIB;
                s->subdev_flags = SDF_READABLE | SDF_WRITABLE | SDF_INTERNAL;
                s->n_chan = 2;
-               s->insn_read = ad8402_read_insn;
-               s->insn_write = ad8402_write_insn;
                s->maxdata = 0xff;
-               for (i = 0; i < s->n_chan; i++)
+               s->insn_write = ad8402_write_insn;
+
+               ret = comedi_alloc_subdev_readback(s);
+               if (ret)
+                       return ret;
+
+               for (i = 0; i < s->n_chan; i++) {
                        ad8402_write(dev, i, s->maxdata / 2);
+                       s->readback[i] = s->maxdata / 2;
+               }
        } else
                s->type = COMEDI_SUBD_UNUSED;