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staging: comedi: me4000: introduce me4000_ai_get_sample() 

The hardware returns two's complement values for the analog input
samples. These need to be converted to the unsigned binary format
that the comedi core expects. Introduce a helper function to handle
this.

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 2015-08-05 10:45:19 -07:00 committed by Greg Kroah-Hartman
parent 36d59d70ba
commit 7022781c46
1 changed files with 13 additions and 10 deletions
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23
drivers/staging/comedi/drivers/me4000.c
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@ -445,6 +445,16 @@ static void me4000_reset(struct comedi_device *dev)
outl(0x1, dev->iobase + ME4000_DIO_CTRL_REG);
}
static unsigned int me4000_ai_get_sample(struct comedi_device *dev,
struct comedi_subdevice *s)
{
unsigned int val;
/* read two's complement value and munge to offset binary */
val = inl(dev->iobase + ME4000_AI_DATA_REG);
return comedi_offset_munge(s, val);
}
static int me4000_ai_eoc(struct comedi_device *dev,
struct comedi_subdevice *s,
struct comedi_insn *insn,
@ -515,8 +525,7 @@ static int me4000_ai_insn_read(struct comedi_device *dev,
if (ret)
break;
/* read two's complement value and munge to offset binary */
val = inl(dev->iobase + ME4000_AI_DATA_REG);
val = me4000_ai_get_sample(dev, s);
data[i] = comedi_offset_munge(s, val);
}
@ -953,10 +962,7 @@ static irqreturn_t me4000_ai_isr(int irq, void *dev_id)
}
for (i = 0; i < c; i++) {
/* Read value from data fifo */
lval = inl(dev->iobase + ME4000_AI_DATA_REG) & 0xFFFF;
lval ^= 0x8000;
lval = me4000_ai_get_sample(dev, s);
if (!comedi_buf_write_samples(s, &lval, 1))
break;
}
@ -976,10 +982,7 @@ static irqreturn_t me4000_ai_isr(int irq, void *dev_id)
/* Poll data until fifo empty */
while (inl(dev->iobase + ME4000_AI_STATUS_REG) &
ME4000_AI_STATUS_EF_DATA) {
/* Read value from data fifo */
lval = inl(dev->iobase + ME4000_AI_DATA_REG) & 0xFFFF;
lval ^= 0x8000;
lval = me4000_ai_get_sample(dev, s);
if (!comedi_buf_write_samples(s, &lval, 1))
break;
}