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staging: comedi: mf6x4: A/D converter uses 2's complement coding

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According to the user's manual, the A/D converter uses 2's complement
coding. Use the comedi_offset_munge() helper to convert the data to
the offset binary format used by comedi.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
 drivers/staging/comedi/drivers/mf6x4.c | 5 ++---
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
H Hartley Sweeten 2015-10-06 11:11:11 -07:00 committed by Greg Kroah-Hartman
parent c9ab30239a
commit 5970633419
1 changed files with 5 additions and 4 deletions
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9
drivers/staging/comedi/drivers/mf6x4.c
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@ -38,7 +38,7 @@
#define MF6X4_GPIOC_DACEN BIT(26)
/* BAR1 registers */
#define MF6X4_ADDATA_R 0x00
#define MF6X4_ADDATA_REG 0x00
#define MF6X4_ADCTRL_REG 0x00
#define MF6X4_ADCTRL_CHAN(x) BIT(chan)
#define MF6X4_DIN_R 0x10
@ -134,9 +134,9 @@ static int mf6x4_ai_insn_read(struct comedi_device *dev,
unsigned int *data)
{
unsigned int chan = CR_CHAN(insn->chanspec);
unsigned int d;
int ret;
int i;
int d;
/* Set the ADC channel number in the scan list */
iowrite16(MF6X4_ADCTRL_CHAN(chan), dev->mmio + MF6X4_ADCTRL_REG);
@ -150,9 +150,10 @@ static int mf6x4_ai_insn_read(struct comedi_device *dev,
return ret;
/* Read the actual value */
d = ioread16(dev->mmio + MF6X4_ADDATA_R);
d = ioread16(dev->mmio + MF6X4_ADDATA_REG);
d &= s->maxdata;
data[i] = d;
/* munge the 2's complement data to offset binary */
data[i] = comedi_offset_munge(s, d);
}
iowrite16(0x0, dev->mmio + MF6X4_ADCTRL_REG);