staging: comedi: dmm32at: introduce dmm32at_ai_set_chanspec()

Introduce a helper function to set the analog input channel scan and range
control registers. Use the new helper in the analog input (*insn_read) and
(*do_cmd) functions.

The extra sanity checks in the (*do_cmd) are not necessary. The cmd->chanlist
will always be valid and the (*do_cmdtest) validates the channel list in
Step 5.

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/dmm32at.c b/drivers/staging/comedi/drivers/dmm32at.c
index 6413f60c6f6bc699a303f6b35244f6d70106748e..dc222d13e318d45d5399f4573859a6ac2542c6ea 100644 (file)
--- a/drivers/staging/comedi/drivers/dmm32at.c
+++ b/drivers/staging/comedi/drivers/dmm32at.c
@@ -154,6 +154,24 @@ struct dmm32at_private {
        unsigned char dio_config;
 };
 
+static void dmm32at_ai_set_chanspec(struct comedi_device *dev,
+                                   struct comedi_subdevice *s,
+                                   unsigned int chanspec, int nchan)
+{
+       unsigned int chan = CR_CHAN(chanspec);
+       unsigned int range = CR_RANGE(chanspec);
+       unsigned int last_chan = (chan + nchan - 1) % s->n_chan;
+
+       outb(DMM32AT_FIFORESET, dev->iobase + DMM32AT_FIFOCNTRL);
+
+       if (nchan > 1)
+               outb(DMM32AT_SCANENABLE, dev->iobase + DMM32AT_FIFOCNTRL);
+
+       outb(chan, dev->iobase + DMM32AT_AILOW);
+       outb(last_chan, dev->iobase + DMM32AT_AIHIGH);
+       outb(dmm32at_rangebits[range], dev->iobase + DMM32AT_AICONF);
+}
+
 static unsigned int dmm32at_ai_get_sample(struct comedi_device *dev,
                                          struct comedi_subdevice *s)
 {
@@ -184,18 +202,10 @@ static int dmm32at_ai_insn_read(struct comedi_device *dev,
                                struct comedi_insn *insn,
                                unsigned int *data)
 {
-       unsigned int chan = CR_CHAN(insn->chanspec);
-       unsigned int range = CR_RANGE(insn->chanspec);
        int ret;
        int i;
 
-       /* zero scan and fifo control and reset fifo */
-       outb(DMM32AT_FIFORESET, dev->iobase + DMM32AT_FIFOCNTRL);
-
-       /* set the channel and range */
-       outb(chan, dev->iobase + DMM32AT_AILOW);
-       outb(chan, dev->iobase + DMM32AT_AIHIGH);
-       outb(dmm32at_rangebits[range], dev->iobase + DMM32AT_AICONF);
+       dmm32at_ai_set_chanspec(dev, s, insn->chanspec, 1);
 
        /* wait for circuit to settle */
        ret = comedi_timeout(dev, s, insn, dmm32at_ai_status, DMM32AT_AIRBACK);
@@ -347,32 +357,9 @@ static void dmm32at_setaitimer(struct comedi_device *dev, unsigned int nansec)
 static int dmm32at_ai_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
 {
        struct comedi_cmd *cmd = &s->async->cmd;
-       int range;
-       unsigned char chanlo, chanhi;
        int ret;
 
-       if (!cmd->chanlist)
-               return -EINVAL;
-
-       /* get the channel list and range */
-       chanlo = CR_CHAN(cmd->chanlist[0]) & (s->n_chan - 1);
-       chanhi = chanlo + cmd->chanlist_len - 1;
-       if (chanhi >= s->n_chan)
-               return -EINVAL;
-       range = CR_RANGE(cmd->chanlist[0]);
-
-       /* reset fifo */
-       outb(DMM32AT_FIFORESET, dev->iobase + DMM32AT_FIFOCNTRL);
-
-       /* set scan enable */
-       outb(DMM32AT_SCANENABLE, dev->iobase + DMM32AT_FIFOCNTRL);
-
-       /* write the ai channel range regs */
-       outb(chanlo, dev->iobase + DMM32AT_AILOW);
-       outb(chanhi, dev->iobase + DMM32AT_AIHIGH);
-
-       /* set the range bits */
-       outb(dmm32at_rangebits[range], dev->iobase + DMM32AT_AICONF);
+       dmm32at_ai_set_chanspec(dev, s, cmd->chanlist[0], cmd->chanlist_len);
 
        /* reset the interrupt just in case */
        outb(DMM32AT_INTRESET, dev->iobase + DMM32AT_CNTRL);