Commit 976e893b authored by H Hartley Sweeten's avatar H Hartley Sweeten Committed by Greg Kroah-Hartman
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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: default avatarH Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: default avatarIan Abbott <abbotti@mev.co.uk>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent baacf6ca

drivers/staging/comedi/drivers/adv_pci1710.c

+8 −5
Original line number Diff line number Diff line
@@ -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++) {