staging: comedi: me4000: introduce me4000_ai_reset()

Introduce a helper function to stop any ai conversions and reset the
ai control register. This consolidates the common code in me4000_reset()
and me4000_ai_cancel().

Use the new helper in the ai (*insn_read) to ensure that the ai control
register is set to a known state after reading the samples.

The ai control register will now always be '0' after the (*cancel) of
a command or doing an (*insn_read). Knowing this the programming of
the register for single acquisition mode in the (*insn_read) can be
simplified.

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 3d4a9c841192bf547fe25bc8c5885c9a44458027..da0075b926a51f453b113518997b7ed76859b18a 100644 (file)
--- a/drivers/staging/comedi/drivers/me4000.c
+++ b/drivers/staging/comedi/drivers/me4000.c
@@ -393,6 +393,19 @@ static int me4000_xilinx_download(struct comedi_device *dev,
        return 0;
 }
 
+static void me4000_ai_reset(struct comedi_device *dev)
+{
+       unsigned int ctrl;
+
+       /* Stop any running conversion */
+       ctrl = inl(dev->iobase + ME4000_AI_CTRL_REG);
+       ctrl |= ME4000_AI_CTRL_STOP | ME4000_AI_CTRL_IMMEDIATE_STOP;
+       outl(ctrl, dev->iobase + ME4000_AI_CTRL_REG);
+
+       /* Clear the control register */
+       outl(0x0, dev->iobase + ME4000_AI_CTRL_REG);
+}
+
 static void me4000_reset(struct comedi_device *dev)
 {
        struct me4000_private *devpriv = dev->private;
@@ -410,12 +423,7 @@ static void me4000_reset(struct comedi_device *dev)
        for (chan = 0; chan < 4; chan++)
                outl(0x8000, dev->iobase + ME4000_AO_SINGLE_REG(chan));
 
-       /* Set both stop bits in the analog input control register */
-       outl(ME4000_AI_CTRL_IMMEDIATE_STOP | ME4000_AI_CTRL_STOP,
-            dev->iobase + ME4000_AI_CTRL_REG);
-
-       /* Clear the analog input control register */
-       outl(0x0, dev->iobase + ME4000_AI_CTRL_REG);
+       me4000_ai_reset(dev);
 
        /* Set both stop bits in the analog output control register */
        val = ME4000_AO_CTRL_IMMEDIATE_STOP | ME4000_AO_CTRL_STOP;
@@ -461,8 +469,7 @@ static int me4000_ai_insn_read(struct comedi_device *dev,
        unsigned int range = CR_RANGE(insn->chanspec);
        unsigned int aref = CR_AREF(insn->chanspec);
        unsigned int entry;
-       unsigned int tmp;
-       int ret;
+       int ret = 0;
        int i;
 
        entry = chan | ME4000_AI_LIST_RANGE(range);
@@ -489,20 +496,9 @@ static int me4000_ai_insn_read(struct comedi_device *dev,
 
        entry |= ME4000_AI_LIST_LAST_ENTRY;
 
-       /* Clear channel list, data fifo and both stop bits */
-       tmp = inl(dev->iobase + ME4000_AI_CTRL_REG);
-       tmp &= ~(ME4000_AI_CTRL_CHANNEL_FIFO | ME4000_AI_CTRL_DATA_FIFO |
-                ME4000_AI_CTRL_STOP | ME4000_AI_CTRL_IMMEDIATE_STOP);
-       outl(tmp, dev->iobase + ME4000_AI_CTRL_REG);
-
-       /* Set the acquisition mode to single */
-       tmp &= ~(ME4000_AI_CTRL_MODE_0 | ME4000_AI_CTRL_MODE_1 |
-                ME4000_AI_CTRL_MODE_2);
-       outl(tmp, dev->iobase + ME4000_AI_CTRL_REG);
-
-       /* Enable channel list and data fifo */
-       tmp |= ME4000_AI_CTRL_CHANNEL_FIFO | ME4000_AI_CTRL_DATA_FIFO;
-       outl(tmp, dev->iobase + ME4000_AI_CTRL_REG);
+       /* Enable channel list and data fifo for single acquisition mode */
+       outl(ME4000_AI_CTRL_CHANNEL_FIFO | ME4000_AI_CTRL_DATA_FIFO,
+            dev->iobase + ME4000_AI_CTRL_REG);
 
        /* Generate channel list entry */
        outl(entry, dev->iobase + ME4000_AI_CHANNEL_LIST_REG);
@@ -519,28 +515,22 @@ static int me4000_ai_insn_read(struct comedi_device *dev,
 
                ret = comedi_timeout(dev, s, insn, me4000_ai_eoc, 0);
                if (ret)
-                       return ret;
+                       break;
 
                /* 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;
+       me4000_ai_reset(dev);
+
+       return ret ? ret : insn->n;
 }
 
 static int me4000_ai_cancel(struct comedi_device *dev,
                            struct comedi_subdevice *s)
 {
-       unsigned int ctrl;
-
-       /* Stop any running conversion */
-       ctrl = inl(dev->iobase + ME4000_AI_CTRL_REG);
-       ctrl |= ME4000_AI_CTRL_STOP | ME4000_AI_CTRL_IMMEDIATE_STOP;
-       outl(ctrl, dev->iobase + ME4000_AI_CTRL_REG);
-
-       /* Clear the control register */
-       outl(0x0, dev->iobase + ME4000_AI_CTRL_REG);
+       me4000_ai_reset(dev);
 
        return 0;
 }