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 a bit.
Add a comment about the 'readback' member.
Signed-off-by: H Hartley Sweeten <hsweeten@xxxxxxxxxxxxxxxxxxx>
Cc: Ian Abbott <abbotti@xxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/staging/comedi/drivers/skel.c | 66 +++++++++++++++++++----------------
1 file changed, 35 insertions(+), 31 deletions(-)
diff --git a/drivers/staging/comedi/drivers/skel.c b/drivers/staging/comedi/drivers/skel.c
index a118678..342f74e 100644
--- a/drivers/staging/comedi/drivers/skel.c
+++ b/drivers/staging/comedi/drivers/skel.c
@@ -114,11 +114,7 @@ static const struct skel_board skel_boards[] = {
feel free to suggest moving the variable to the struct comedi_device struct.
*/
struct skel_private {
-
int data;
-
- /* Used for AO readback */
- unsigned int ao_readback[2];
};
/* This function doesn't require a particular form, this is just
@@ -305,38 +301,29 @@ static int skel_ai_cmdtest(struct comedi_device *dev,
return 0;
}
-static int skel_ao_winsn(struct comedi_device *dev, struct comedi_subdevice *s,
- struct comedi_insn *insn, unsigned int *data)
+static int skel_ao_insn_write(struct comedi_device *dev,
+ struct comedi_subdevice *s,
+ struct comedi_insn *insn,
+ unsigned int *data)
{
- struct skel_private *devpriv = dev->private;
+ unsigned int chan = CR_CHAN(insn->chanspec);
+ unsigned int val = s->readback[chan];
int i;
- int chan = CR_CHAN(insn->chanspec);
- /* Writing a list of values to an AO channel is probably not
- * very useful, but that's how the interface is defined. */
+ /*
+ * Writing a list of values to an AO channel is probably not
+ * very useful, but that's how the interface is defined.
+ */
for (i = 0; i < insn->n; i++) {
+ val = data[i];
+
/* a typical programming sequence */
- /* outw(data[i],dev->iobase + SKEL_DA0 + chan); */
- devpriv->ao_readback[chan] = data[i];
+ /* outw(data[i], dev->iobase + SKEL_DA0 + chan); */
}
+ /* save the last value for readback */
+ s->readback[chan] = val;
- /* return the number of samples read/written */
- return i;
-}
-
-/* AO subdevices should have a read insn as well as a write insn.
- * Usually this means copying a value stored in devpriv. */
-static int skel_ao_rinsn(struct comedi_device *dev, struct comedi_subdevice *s,
- struct comedi_insn *insn, unsigned int *data)
-{
- struct skel_private *devpriv = dev->private;
- int i;
- int chan = CR_CHAN(insn->chanspec);
-
- for (i = 0; i < insn->n; i++)
- data[i] = devpriv->ao_readback[chan];
-
- return i;
+ return insn->n;
}
/*
@@ -446,8 +433,25 @@ static int skel_common_attach(struct comedi_device *dev)
s->n_chan = 1;
s->maxdata = 0xffff;
s->range_table = &range_bipolar5;
- s->insn_write = skel_ao_winsn;
- s->insn_read = skel_ao_rinsn;
+ s->insn_write = skel_ao_insn_write;
+ /*
+ * AO subdevices should have a (*insn_read) as well. Usually the
+ * hardware is not readable so the channel values need to be stored
+ * somewhere for readback. The comedi_subdevice has a 'readback'
+ * member to handle this.
+ *
+ * The comedi_readback_insn_read() function provides the (*insn_read)
+ * to return the 'readback' values.
+ *
+ * The comedi_alloc_subdev_readback() function will allocate memory
+ * for s->n_chan 'readback' values. The core will kfree the memory
+ * when the driver is detached.
+ */
+ s->insn_read = comedi_readback_insn_read;
+
+ ret = comedi_alloc_subdev_readback(s);
+ if (ret)
+ return ret;
s = &dev->subdevices[2];
/* digital i/o subdevice */
--
2.0.3
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