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staging: comedi: c6xdigio: add readback of last pwm channel values 

Add and (*insn_read) for the PWM subdevice to allow reading back the
last value written to the channels.

There are only 2 PWM channels and they have a maxdata of 500. Pack
the last values in the subdevice 'state' instead of adding a private
data struct to this driver.

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>
hifive-unleashed-5.1
H Hartley Sweeten 2014-03-10 14:07:40 -07:00 committed by Greg Kroah-Hartman
parent a7b31d3996
commit 8d9c93b448
1 changed files with 32 additions and 3 deletions
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35
drivers/staging/comedi/drivers/c6xdigio.c
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@ -162,13 +162,41 @@ static int c6xdigio_pwm_insn_write(struct comedi_device *dev,
unsigned int *data)
{
unsigned int chan = CR_CHAN(insn->chanspec);
unsigned int val = (s->state >> (16 * chan)) & 0xffff;
int i;
for (i = 0; i < insn->n; i++) {
c6xdigio_pwm_write(dev, chan, data[i]);
/* devpriv->ao_readback[chan] = data[i]; */
val = data[i];
c6xdigio_pwm_write(dev, chan, val);
}
return i;
/*
* There are only 2 PWM channels and they have a maxdata of 500.
* Instead of allocating private data to save the values in for
* readback this driver just packs the values for the two channels
* in the s->state.
*/
s->state &= (0xffff << (16 * chan));
s->state |= (val << (16 * chan));
return insn->n;
}
static int c6xdigio_pwm_insn_read(struct comedi_device *dev,
struct comedi_subdevice *s,
struct comedi_insn *insn,
unsigned int *data)
{
unsigned int chan = CR_CHAN(insn->chanspec);
unsigned int val;
int i;
val = (s->state >> (16 * chan)) & 0xffff;
for (i = 0; i < insn->n; i++)
data[i] = val;
return insn->n;
}
static int c6xdigio_encoder_insn_read(struct comedi_device *dev,
@ -243,6 +271,7 @@ static int c6xdigio_attach(struct comedi_device *dev,
s->maxdata = 500;
s->range_table = &range_unknown;
s->insn_write = c6xdigio_pwm_insn_write;
s->insn_read = c6xdigio_pwm_insn_read;
s = &dev->subdevices[1];
/* encoder (counter) subdevice */