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staging: comedi: adv_pci1710: support external analog output reference 

The analog outputs can use an external reference to create the D/A output
range. Add an entry to the comedi_lrange table for it and modify the
(*insn_write) to support it.

Note that the D/A output range is 0 to +Vref with a -Vref. The comedi_lrange
does not include the sign of the range. It simmply allows the user to convert
between the 12-bit samples values (0x0000 - 0x0fff) and a physical value (0.0
to 1.0) using the comedilib comedi_to_phys() and comedi_from_phys() functions.
A physical value of 0.0 would actually be 0V with a -Vref and -V with a +Vref
and 1.0 would be +V with a -Vref and 0V with a -Vref. Ths user will need to
work this out but at least they can now use the external reference.

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>
This commit is contained in:
H Hartley Sweeten 2015-11-13 11:11:17 -07:00 committed by Greg Kroah-Hartman
parent baacf6ca54
commit 976e893b61
1 changed files with 8 additions and 5 deletions
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13
drivers/staging/comedi/drivers/adv_pci1710.c
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@ -65,6 +65,8 @@
#define PCI171X_CLRFIFO_REG 0x09 /* W: clear FIFO */
#define PCI171X_DA_REG(x) (0x0a + ((x) * 2)) /* W: D/A register */
#define PCI171X_DAREF_REG 0x0e /* W: D/A reference control */
#define PCI171X_DAREF(c, r) (((r) & 0x3) << ((c) * 2))
#define PCI171X_DAREF_MASK(c) PCI171X_DAREF((c), 0x3)
#define PCI171X_DI_REG 0x10 /* R: digital inputs */
#define PCI171X_DO_REG 0x10 /* W: digital outputs */
#define PCI171X_TIMER_BASE 0x18 /* R/W: 8254 timer */
@ -111,9 +113,10 @@ static const struct comedi_lrange pci1711_ai_range = {
};
static const struct comedi_lrange pci171x_ao_range = {
2, {
UNI_RANGE(5),
UNI_RANGE(10)
3, {
UNI_RANGE(5), /* internal -5V ref */
UNI_RANGE(10), /* internal -10V ref */
RANGE_ext(0, 1) /* external -Vref (+/-10V max) */
}
};
@ -631,8 +634,8 @@ static int pci1710_ao_insn_write(struct comedi_device *dev,
unsigned int val = s->readback[chan];
int i;
devpriv->da_ranges &= ~(1 << (chan << 1));
devpriv->da_ranges |= (range << (chan << 1));
devpriv->da_ranges &= ~PCI171X_DAREF_MASK(chan);
devpriv->da_ranges |= PCI171X_DAREF(chan, range);
outw(devpriv->da_ranges, dev->iobase + PCI171X_DAREF_REG);
for (i = 0; i < insn->n; i++) {