staging: comedi: ni_660x: tidy up Digital I/O subdevice init

Add some whitespace to the Digital I/O subdevice init and add a
comment about the channels. This driver is a bit goofy, only 32 of
the 40 channels can actually be used for Digital I/Os and 32 of
them can be routed to the counters for alternate use.

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/ni_660x.c b/drivers/staging/comedi/drivers/ni_660x.c
index 4f7f5ca..f24009c 100644 (file)
--- a/drivers/staging/comedi/drivers/ni_660x.c
+++ b/drivers/staging/comedi/drivers/ni_660x.c
@@ -964,15 +964,67 @@ static int ni_660x_auto_attach(struct comedi_device *dev,
        /* Old GENERAL-PURPOSE COUNTER/TIME (GPCT) subdevice, no longer used */
        s->type = COMEDI_SUBD_UNUSED;
 
+       /*
+        * Digital I/O subdevice
+        *
+        * There are 40 channels but only the first 32 can be digital I/Os.
+        * The last 8 are dedicated to counters 0 and 1.
+        *
+        * Counter 0-3 signals are from the first TIO chip.
+        * Counter 4-7 signals are from the second TIO chip.
+        *
+        * Comedi       External
+        * PFI Chan     DIO Chan        Counter Signal
+        * -------      --------        --------------
+        *     0            0
+        *     1            1
+        *     2            2
+        *     3            3
+        *     4            4
+        *     5            5
+        *     6            6
+        *     7            7
+        *     8            8           CTR 7 OUT
+        *     9            9           CTR 7 AUX
+        *    10           10           CTR 7 GATE
+        *    11           11           CTR 7 SOURCE
+        *    12           12           CTR 6 OUT
+        *    13           13           CTR 6 AUX
+        *    14           14           CTR 6 GATE
+        *    15           15           CTR 6 SOURCE
+        *    16           16           CTR 5 OUT
+        *    17           17           CTR 5 AUX
+        *    18           18           CTR 5 GATE
+        *    19           19           CTR 5 SOURCE
+        *    20           20           CTR 4 OUT
+        *    21           21           CTR 4 AUX
+        *    22           22           CTR 4 GATE
+        *    23           23           CTR 4 SOURCE
+        *    24           24           CTR 3 OUT
+        *    25           25           CTR 3 AUX
+        *    26           26           CTR 3 GATE
+        *    27           27           CTR 3 SOURCE
+        *    28           28           CTR 2 OUT
+        *    29           29           CTR 2 AUX
+        *    30           30           CTR 2 GATE
+        *    31           31           CTR 2 SOURCE
+        *    32                        CTR 1 OUT
+        *    33                        CTR 1 AUX
+        *    34                        CTR 1 GATE
+        *    35                        CTR 1 SOURCE
+        *    36                        CTR 0 OUT
+        *    37                        CTR 0 AUX
+        *    38                        CTR 0 GATE
+        *    39                        CTR 0 SOURCE
+        */
        s = &dev->subdevices[subdev++];
-       /* DIGITAL I/O SUBDEVICE */
-       s->type = COMEDI_SUBD_DIO;
-       s->subdev_flags = SDF_READABLE | SDF_WRITABLE;
-       s->n_chan = NUM_PFI_CHANNELS;
-       s->maxdata = 1;
-       s->range_table = &range_digital;
-       s->insn_bits = ni_660x_dio_insn_bits;
-       s->insn_config = ni_660x_dio_insn_config;
+       s->type         = COMEDI_SUBD_DIO;
+       s->subdev_flags = SDF_READABLE | SDF_WRITABLE;
+       s->n_chan       = NUM_PFI_CHANNELS;
+       s->maxdata      = 1;
+       s->range_table  = &range_digital;
+       s->insn_bits    = ni_660x_dio_insn_bits;
+       s->insn_config  = ni_660x_dio_insn_config;
 
        /*
         * We use the ioconfig registers to control dio direction, so zero