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

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>

diff --git a/drivers/staging/comedi/drivers/mf6x4.c b/drivers/staging/comedi/drivers/mf6x4.c
index ff4ba15..1e4f080 100644 (file)
--- a/drivers/staging/comedi/drivers/mf6x4.c
+++ b/drivers/staging/comedi/drivers/mf6x4.c
@@ -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);