staging: comedi: pcl818: introduce pcl818_ai_get_sample()

Introduce a helper function to read the 12-bit analog input data
sample and optionally return the channel that the sample was for.
The channel is only used in the interrupt routine to check for
dropped samples.

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/pcl818.c b/drivers/staging/comedi/drivers/pcl818.c
index 2b8e7e0d2c75e89bc0761941f88f68d9afebbf75..d5709edd679999f4001a9aee8207eec1d5c080f9 100644 (file)
--- a/drivers/staging/comedi/drivers/pcl818.c
+++ b/drivers/staging/comedi/drivers/pcl818.c
@@ -372,6 +372,21 @@ static int pcl818_ai_cancel(struct comedi_device *dev,
 static void start_pacer(struct comedi_device *dev, int mode,
                        unsigned int divisor1, unsigned int divisor2);
 
+static unsigned int pcl818_ai_get_sample(struct comedi_device *dev,
+                                        struct comedi_subdevice *s,
+                                        unsigned int *chan)
+{
+       unsigned int val;
+
+       val = inb(dev->iobase + PCL818_AD_HI) << 8;
+       val |= inb(dev->iobase + PCL818_AD_LO);
+
+       if (chan)
+               *chan = val & 0xf;
+
+       return (val >> 4) & s->maxdata;
+}
+
 static int pcl818_ai_eoc(struct comedi_device *dev,
                         struct comedi_subdevice *s,
                         struct comedi_insn *insn,
@@ -416,8 +431,7 @@ static int pcl818_ai_insn_read(struct comedi_device *dev,
                        return ret;
                }
 
-               data[n] = ((inb(dev->iobase + PCL818_AD_HI) << 4) |
-                          (inb(dev->iobase + PCL818_AD_LO) >> 4));
+               data[n] = pcl818_ai_get_sample(dev, s, NULL);
        }
 
        return n;
@@ -502,7 +516,7 @@ static irqreturn_t interrupt_pcl818_ai_mode13_int(int irq, void *d)
        struct comedi_device *dev = d;
        struct pcl818_private *devpriv = dev->private;
        struct comedi_subdevice *s = dev->read_subdev;
-       unsigned char low;
+       unsigned int chan;
        int timeout = 50;       /* wait max 50us */
 
        while (timeout--) {
@@ -518,14 +532,13 @@ static irqreturn_t interrupt_pcl818_ai_mode13_int(int irq, void *d)
        return IRQ_HANDLED;
 
 conv_finish:
-       low = inb(dev->iobase + PCL818_AD_LO);
-       comedi_buf_put(s->async, ((inb(dev->iobase + PCL818_AD_HI) << 4) | (low >> 4)));        /*  get one sample */
+       comedi_buf_put(s->async, pcl818_ai_get_sample(dev, s, &chan));
        outb(0, dev->iobase + PCL818_CLRINT);   /* clear INT request */
 
-       if ((low & 0xf) != devpriv->act_chanlist[devpriv->act_chanlist_pos]) {  /*  dropout! */
+       if (chan != devpriv->act_chanlist[devpriv->act_chanlist_pos]) {
                dev_dbg(dev->class_dev,
                        "A/D mode1/3 IRQ - channel dropout %x!=%x !\n",
-                       (low & 0xf),
+                       chan,
                        devpriv->act_chanlist[devpriv->act_chanlist_pos]);
                pcl818_ai_cancel(dev, s);
                s->async->events |= COMEDI_CB_EOA | COMEDI_CB_ERROR;
@@ -1166,8 +1179,7 @@ static int pcl818_ai_cancel(struct comedi_device *dev,
                        udelay(1);
                        start_pacer(dev, -1, 0, 0);
                        outb(0, dev->iobase + PCL818_AD_LO);
-                       inb(dev->iobase + PCL818_AD_LO);
-                       inb(dev->iobase + PCL818_AD_HI);
+                       pcl818_ai_get_sample(dev, s, NULL);
                        outb(0, dev->iobase + PCL818_CLRINT);   /* clear INT request */
                        outb(0, dev->iobase + PCL818_CONTROL);  /* Stop A/D */
                        if (devpriv->usefifo) { /*  FIFO shutdown */