staging: comedi: das1800: introduce das1800_ai_chanspec_bits()

Introduce a helper function for the common code needed to set the
control c register bits for a channel specification.

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/das1800.c b/drivers/staging/comedi/drivers/das1800.c
index 64b5403f9a99168747f2859969c3a7ae5eefd7e1..5694bdb4cfe9264d49d99e62198fbadc06dcfa1c 100644 (file)
--- a/drivers/staging/comedi/drivers/das1800.c
+++ b/drivers/staging/comedi/drivers/das1800.c
@@ -749,25 +749,32 @@ static int control_a_bits(const struct comedi_cmd *cmd)
        return control_a;
 }
 
-/* returns appropriate bits for control register c, depending on command */
-static int control_c_bits(struct comedi_subdevice *s,
-                         const struct comedi_cmd *cmd)
+static unsigned char das1800_ai_chanspec_bits(struct comedi_subdevice *s,
+                                             unsigned int chanspec)
 {
-       unsigned int range = CR_RANGE(cmd->chanlist[0]);
-       unsigned int aref = CR_AREF(cmd->chanlist[0]);
-       int control_c;
+       unsigned int range = CR_RANGE(chanspec);
+       unsigned int aref = CR_AREF(chanspec);
+       unsigned char bits;
 
-       /* set clock source to internal or external, select analog reference,
-        * select unipolar / bipolar
-        */
-       control_c = UQEN;       /* enable upper qram addresses */
+       bits = UQEN;
        if (aref != AREF_DIFF)
-               control_c |= SD;
+               bits |= SD;
        if (aref == AREF_COMMON)
-               control_c |= CMEN;
+               bits |= CMEN;
        if (comedi_range_is_unipolar(s, range))
-               control_c |= UB;
+               bits |= UB;
+
+       return bits;
+}
+
+static int control_c_bits(struct comedi_subdevice *s,
+                         const struct comedi_cmd *cmd)
+{
+       int control_c;
 
+       control_c = das1800_ai_chanspec_bits(s, cmd->chanlist[0]);
+
+       /* set clock source to internal or external */
        switch (cmd->scan_begin_src) {
        case TRIG_FOLLOW:       /*  not in burst mode */
                switch (cmd->convert_src) {
@@ -955,25 +962,15 @@ static int das1800_ai_insn_read(struct comedi_device *dev,
 {
        unsigned int chan = CR_CHAN(insn->chanspec);
        unsigned int range = CR_RANGE(insn->chanspec);
-       unsigned int aref = CR_AREF(insn->chanspec);
        bool is_unipolar = comedi_range_is_unipolar(s, range);
        int i, n;
        int chan_range;
        int timeout = 1000;
        unsigned short dpnt;
-       int conv_flags = 0;
        unsigned long irq_flags;
 
-       /* set up analog reference and unipolar / bipolar mode */
-       conv_flags |= UQEN;
-       if (aref != AREF_DIFF)
-               conv_flags |= SD;
-       if (aref == AREF_COMMON)
-               conv_flags |= CMEN;
-       if (is_unipolar)
-               conv_flags |= UB;
-
-       outb(conv_flags, dev->iobase + DAS1800_CONTROL_C);      /* software conversion enabled */
+       outb(das1800_ai_chanspec_bits(s, insn->chanspec),
+            dev->iobase + DAS1800_CONTROL_C);          /* software pacer */
        outb(CVEN, dev->iobase + DAS1800_STATUS);       /* enable conversions */
        outb(0x0, dev->iobase + DAS1800_CONTROL_A);     /* reset fifo */
        outb(FFEN, dev->iobase + DAS1800_CONTROL_A);