Stash the last value written to each AO channel in private data and
support the INSN_READ instruction to read it back. Don't bother setting
the SDF_READABLE subdevice flag though as the hardware isn't really
readable - we're just faking it.
Signed-off-by: Ian Abbott <abbotti@xxxxxxxxx>
---
drivers/staging/comedi/drivers/das08.c | 20 +++++++++++++++++++-
drivers/staging/comedi/drivers/das08.h | 1 +
2 files changed, 20 insertions(+), 1 deletion(-)
diff --git a/drivers/staging/comedi/drivers/das08.c b/drivers/staging/comedi/drivers/das08.c
index b2face0..114f63b 100644
--- a/drivers/staging/comedi/drivers/das08.c
+++ b/drivers/staging/comedi/drivers/das08.c
@@ -373,6 +373,7 @@ static void das08_ao_set_data(struct comedi_device *dev,
unsigned int chan, unsigned int data)
{
const struct das08_board_struct *thisboard = comedi_board(dev);
+ struct das08_private_struct *devpriv = dev->private;
unsigned char lsb;
unsigned char msb;
@@ -389,6 +390,7 @@ static void das08_ao_set_data(struct comedi_device *dev,
/* load DACs */
inb(dev->iobase + DAS08AO_AO_UPDATE);
}
+ devpriv->ao_readback[chan] = data;
}
static void das08_ao_initialize(struct comedi_device *dev,
@@ -417,6 +419,22 @@ static int das08_ao_winsn(struct comedi_device *dev,
return n;
}
+static int das08_ao_rinsn(struct comedi_device *dev,
+ struct comedi_subdevice *s,
+ struct comedi_insn *insn, unsigned int *data)
+{
+ struct das08_private_struct *devpriv = dev->private;
+ unsigned int n;
+ unsigned int chan;
+
+ chan = CR_CHAN(insn->chanspec);
+
+ for (n = 0; n < insn->n; n++)
+ data[n] = devpriv->ao_readback[chan];
+
+ return n;
+}
+
static void i8254_initialize(struct comedi_device *dev)
{
const struct das08_board_struct *thisboard = comedi_board(dev);
@@ -670,12 +688,12 @@ int das08_common_attach(struct comedi_device *dev, unsigned long iobase)
/* ao */
if (thisboard->ao_nbits) {
s->type = COMEDI_SUBD_AO;
-/* XXX lacks read-back insn */
s->subdev_flags = SDF_WRITABLE;
s->n_chan = 2;
s->maxdata = (1 << thisboard->ao_nbits) - 1;
s->range_table = &range_bipolar5;
s->insn_write = das08_ao_winsn;
+ s->insn_read = das08_ao_rinsn;
das08_ao_initialize(dev, s);
} else {
s->type = COMEDI_SUBD_UNUSED;
diff --git a/drivers/staging/comedi/drivers/das08.h b/drivers/staging/comedi/drivers/das08.h
index 5a33993..4231be5 100644
--- a/drivers/staging/comedi/drivers/das08.h
+++ b/drivers/staging/comedi/drivers/das08.h
@@ -52,6 +52,7 @@ struct das08_private_struct {
unsigned int do_bits; /* bits for do register on boards with register dedicated to digital out only */
const unsigned int *pg_gainlist;
struct pci_dev *pdev; /* struct for pci-das08 */
+ unsigned int ao_readback[2]; /* assume 2 AO channels */
};
int das08_common_attach(struct comedi_device *dev, unsigned long iobase);
--
1.7.12
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