staging: comedi: addi_apci_3120: fix apci3120_ai_insn_read()

Now that the scanning and interrupt support have been removed from this
function it can be refactored to work correctly.

The comedi core expects (*insn_read) functions to read insn->n values
from the hardware and return the number of samples read. This function
currently just reads one sample but it returns insn->n.

Fix this function to work like the core expects.

Use comedi_timeout() to prevent a possible deadlock in the loop that
waits for the end-of-conversion.

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/addi-data/hwdrv_apci3120.c b/drivers/staging/comedi/drivers/addi-data/hwdrv_apci3120.c
index 51cdecb..5fb8848 100644 (file)
--- a/drivers/staging/comedi/drivers/addi-data/hwdrv_apci3120.c
+++ b/drivers/staging/comedi/drivers/addi-data/hwdrv_apci3120.c
@@ -139,6 +139,19 @@ static int apci3120_setup_chan_list(struct comedi_device *dev,
        return 1;               /*  we can serve this with scan logic */
 }
 
+static int apci3120_ai_eoc(struct comedi_device *dev,
+                          struct comedi_subdevice *s,
+                          struct comedi_insn *insn,
+                          unsigned long context)
+{
+       unsigned int status;
+
+       status = inw(dev->iobase + APCI3120_RD_STATUS);
+       if ((status & APCI3120_EOC) == 0)
+               return 0;
+       return -EBUSY;
+}
+
 static int apci3120_ai_insn_read(struct comedi_device *dev,
                                 struct comedi_subdevice *s,
                                 struct comedi_insn *insn,
@@ -146,67 +159,44 @@ static int apci3120_ai_insn_read(struct comedi_device *dev,
 {
        struct apci3120_private *devpriv = dev->private;
        unsigned int divisor;
-       unsigned int ns;
-       unsigned short us_TmpValue;
-
-       /*  fix conversion time to 10 us */
-       ns = 10000;
-
-       /*  Clear software registers */
-       devpriv->timer_mode = 0;
-       devpriv->mode = 0;
-
-       if (insn->unused[0] == 222) {   /*  second insn read */
-       } else {
-               devpriv->tsk_Current = current; /*  Save the current process task structure */
-
-               divisor = apci3120_ns_to_timer(dev, 0, ns, CMDF_ROUND_NEAREST);
-
-               us_TmpValue = (unsigned short) devpriv->b_InterruptMode;
-
-               switch (us_TmpValue) {
-
-               case APCI3120_EOC_MODE:
-                       apci3120_ai_reset_fifo(dev);
-
-                       /*  Initialize the sequence array */
-                       if (!apci3120_setup_chan_list(dev, s, 1,
-                                       &insn->chanspec))
-                               return -EINVAL;
-
-                       /* Initialize Timer 0 mode 4 */
-                       apci3120_timer_set_mode(dev, 0, APCI3120_TIMER_MODE4);
+       int ret;
+       int i;
 
-                       outb(devpriv->mode, dev->iobase + APCI3120_MODE_REG);
+       /* set mode for A/D conversions by software trigger with timer 0 */
+       devpriv->mode = APCI3120_MODE_TIMER2_CLK_OSC |
+                       APCI3120_MODE_TIMER2_AS_TIMER;
+       outb(devpriv->mode, dev->iobase + APCI3120_MODE_REG);
 
-                       apci3120_timer_enable(dev, 0, true);
+       /* load chanlist for single channel scan */
+       if (!apci3120_setup_chan_list(dev, s, 1, &insn->chanspec))
+               return -EINVAL;
 
-                       /* Set the conversion time */
-                       apci3120_timer_write(dev, 0, divisor);
+       /*
+        * Timer 0 is used in MODE4 (software triggered strobe) to set the
+        * conversion time for each acquisition. Each conversion is triggered
+        * when the divisor is written to the timer, The conversion is done
+        * when the EOC bit in the status register is '0'.
+        */
+       apci3120_timer_set_mode(dev, 0, APCI3120_TIMER_MODE4);
+       apci3120_timer_enable(dev, 0, true);
 
-                       us_TmpValue =
-                               (unsigned short) inw(dev->iobase + APCI3120_RD_STATUS);
+       /* fixed conversion time of 10 us */
+       divisor = apci3120_ns_to_timer(dev, 0, 10000, CMDF_ROUND_NEAREST);
 
-                       do {
-                               /*  Waiting for the end of conversion */
-                               us_TmpValue = inw(dev->iobase +
-                                                 APCI3120_RD_STATUS);
-                       } while ((us_TmpValue & APCI3120_EOC) == APCI3120_EOC);
+       apci3120_ai_reset_fifo(dev);
 
-                       /* Read the result in FIFO  and put it in insn data pointer */
-                       us_TmpValue = inw(dev->iobase + 0);
-                       *data = us_TmpValue;
+       for (i = 0; i < insn->n; i++) {
+               /* trigger conversion */
+               apci3120_timer_write(dev, 0, divisor);
 
-                       apci3120_ai_reset_fifo(dev);
-                       break;
-               default:
-                       dev_err(dev->class_dev, "inputs wrong\n");
+               ret = comedi_timeout(dev, s, insn, apci3120_ai_eoc, 0);
+               if (ret)
+                       return ret;
 
-               }
+               data[i] = inw(dev->iobase + 0);
        }
 
        return insn->n;
-
 }
 
 static int apci3120_reset(struct comedi_device *dev)