staging: comedi: pcl711: add differential input support for 8112 boards

The ACL-8112 boards can do differential analog inputs. Add support for
this mode.

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>

diff --git a/drivers/staging/comedi/drivers/pcl711.c b/drivers/staging/comedi/drivers/pcl711.c
index 8aa3d92..1386d8f 100644 (file)
--- a/drivers/staging/comedi/drivers/pcl711.c
+++ b/drivers/staging/comedi/drivers/pcl711.c
@@ -82,6 +82,7 @@ supported.
 #define PCL711_MUX_CHAN(x)     (((x) & 0xf) << 0)
 #define PCL711_MUX_CS0         (1 << 4)
 #define PCL711_MUX_CS1         (1 << 5)
+#define PCL711_MUX_DIFF                (PCL711_MUX_CS0 | PCL711_MUX_CS1)
 #define PCL711_MODE            0x0b
 #define PCL711_SOFTTRIG                0x0c
 #define PCL711_DO_LO           0x0d
@@ -229,16 +230,22 @@ static void pcl711_set_changain(struct comedi_device *dev,
        const struct pcl711_board *board = comedi_board(dev);
        unsigned int chan = CR_CHAN(chanspec);
        unsigned int range = CR_RANGE(chanspec);
+       unsigned int aref = CR_AREF(chanspec);
        unsigned int mux = 0;
 
        outb(range, dev->iobase + PCL711_GAIN);
 
        if (board->is_8112) {
                /* Select the correct MPC508A chip */
-               if (chan < 8)
-                       mux |= PCL711_MUX_CS0;
-               else
-                       mux |= PCL711_MUX_CS1;
+               if (aref == AREF_DIFF) {
+                       chan &= 0x7;
+                       mux |= PCL711_MUX_DIFF;
+               } else {
+                       if (chan < 8)
+                               mux |= PCL711_MUX_CS0;
+                       else
+                               mux |= PCL711_MUX_CS1;
+               }
        }
        outb(mux | PCL711_MUX_CHAN(chan), dev->iobase + PCL711_MUX_REG);
 }
@@ -515,6 +522,8 @@ static int pcl711_attach(struct comedi_device *dev, struct comedi_devconfig *it)
        s = &dev->subdevices[0];
        s->type         = COMEDI_SUBD_AI;
        s->subdev_flags = SDF_READABLE | SDF_GROUND;
+       if (board->is_8112)
+               s->subdev_flags |= SDF_DIFF;
        s->n_chan       = board->n_aichan;
        s->maxdata      = 0xfff;
        s->range_table  = board->ai_range_type;