staging: comedi: me4000: fix me4000_ai_insn_read()

The coemdi (*insn_read) functions are supposed to read insn->n values
from the hardware. Make this function work like the core expects.

Use the comedi_offset_munge() helper to munge the two's complement
values to offset binary.

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/me4000.c b/drivers/staging/comedi/drivers/me4000.c
index 4231e393c5778cf84c8003f7cc37de1ab1133fab..c15e731db6c00cebcbe80214dcccd9a71e8cce74 100644 (file)
--- a/drivers/staging/comedi/drivers/me4000.c
+++ b/drivers/staging/comedi/drivers/me4000.c
@@ -456,16 +456,8 @@ static int me4000_ai_insn_read(struct comedi_device *dev,
        int aref = CR_AREF(insn->chanspec);
        unsigned int entry = 0;
        unsigned int tmp;
-       unsigned int lval;
        int ret;
-
-       if (insn->n == 0) {
-               return 0;
-       } else if (insn->n > 1) {
-               dev_err(dev->class_dev, "Invalid instruction length %d\n",
-                       insn->n);
-               return -EINVAL;
-       }
+       int i;
 
        entry |= ME4000_AI_LIST_RANGE(rang);
        entry |= chan;
@@ -515,18 +507,22 @@ static int me4000_ai_insn_read(struct comedi_device *dev,
        outl(ME4000_AI_MIN_TICKS, dev->iobase + ME4000_AI_CHAN_TIMER_REG);
        outl(ME4000_AI_MIN_TICKS, dev->iobase + ME4000_AI_CHAN_PRE_TIMER_REG);
 
-       /* Start conversion by dummy read */
-       inl(dev->iobase + ME4000_AI_START_REG);
+       for (i = 0; i < insn->n; i++) {
+               unsigned int val;
 
-       ret = comedi_timeout(dev, s, insn, me4000_ai_eoc, 0);
-       if (ret)
-               return ret;
+               /* start conversion by dummy read */
+               inl(dev->iobase + ME4000_AI_START_REG);
 
-       /* Read value from data fifo */
-       lval = inl(dev->iobase + ME4000_AI_DATA_REG) & 0xFFFF;
-       data[0] = lval ^ 0x8000;
+               ret = comedi_timeout(dev, s, insn, me4000_ai_eoc, 0);
+               if (ret)
+                       return ret;
 
-       return 1;
+               /* read two's complement value and munge to offset binary */
+               val = inl(dev->iobase + ME4000_AI_DATA_REG);
+               data[i] = comedi_offset_munge(s, val);
+       }
+
+       return insn->n;
 }
 
 static int me4000_ai_cancel(struct comedi_device *dev,