staging: comedi: dmm32at: cleanup dmm32at_ao_winsn()

For aesthetics, rename the function and tidy it up a bit. Also rename the
registers used by this function and add a macro to set the 'chan' bits in
the MSB data register.

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 e9cd251..cfe3234 100644 (file)
--- a/drivers/staging/comedi/drivers/dmm32at.c
+++ b/drivers/staging/comedi/drivers/dmm32at.c
@@ -47,9 +47,10 @@ Configuration Options:
 #define DMM32AT_AILOW 0x02
 #define DMM32AT_AIHIGH 0x03
 
-#define DMM32AT_DACLSB 0x04
 #define DMM32AT_DACSTAT 0x04
-#define DMM32AT_DACMSB 0x05
+#define DMM32AT_DACLSB_REG     0x04
+#define DMM32AT_DACMSB_REG     0x05
+#define DMM32AT_DACMSB_CHAN(x) ((x) << 6)
 
 #define DMM32AT_FIFOCNTRL 0x07
 #define DMM32AT_FIFOSTAT 0x07
@@ -540,42 +541,37 @@ static int dmm32at_ao_eoc(struct comedi_device *dev,
        return -EBUSY;
 }
 
-static int dmm32at_ao_winsn(struct comedi_device *dev,
-                           struct comedi_subdevice *s,
-                           struct comedi_insn *insn, unsigned int *data)
+static int dmm32at_ao_insn_write(struct comedi_device *dev,
+                                struct comedi_subdevice *s,
+                                struct comedi_insn *insn,
+                                unsigned int *data)
 {
        struct dmm32at_private *devpriv = dev->private;
-       int i;
-       int chan = CR_CHAN(insn->chanspec);
-       unsigned char hi, lo, status;
+       unsigned int chan = CR_CHAN(insn->chanspec);
+       unsigned int val;
        int ret;
+       int i;
 
-       /* Writing a list of values to an AO channel is probably not
-        * very useful, but that's how the interface is defined. */
        for (i = 0; i < insn->n; i++) {
+               val = data[i];
 
-               devpriv->ao_readback[chan] = data[i];
-
-               /* get the low byte */
-               lo = data[i] & 0x00ff;
-               /* high byte also contains channel number */
-               hi = (data[i] >> 8) + chan * (1 << 6);
-               /* write the low and high values to the board */
-               outb(lo, dev->iobase + DMM32AT_DACLSB);
-               outb(hi, dev->iobase + DMM32AT_DACMSB);
+               /* write LSB then MSB + chan to load DAC */
+               outb(val & 0xff, dev->iobase + DMM32AT_DACLSB_REG);
+               outb((val >> 8) | DMM32AT_DACMSB_CHAN(chan),
+                    dev->iobase + DMM32AT_DACMSB_REG);
 
                /* wait for circuit to settle */
                ret = comedi_timeout(dev, s, insn, dmm32at_ao_eoc, 0);
                if (ret)
                        return ret;
 
-               /* dummy read to update trigger the output */
-               status = inb(dev->iobase + DMM32AT_DACMSB);
+               /* dummy read to update DAC */
+               inb(dev->iobase + DMM32AT_DACMSB_REG);
 
+               devpriv->ao_readback[chan] = val;
        }
 
-       /* return the number of samples read/written */
-       return i;
+       return insn->n;
 }
 
 static int dmm32at_ao_rinsn(struct comedi_device *dev,
@@ -764,7 +760,7 @@ static int dmm32at_attach(struct comedi_device *dev,
        s->n_chan = 4;
        s->maxdata = 0x0fff;
        s->range_table = &dmm32at_aoranges;
-       s->insn_write = dmm32at_ao_winsn;
+       s->insn_write = dmm32at_ao_insn_write;
        s->insn_read = dmm32at_ao_rinsn;
 
        s = &dev->subdevices[2];