staging: comedi: das16: introduce das16_isadma_disable()

Introduce a helper function to disable and the ISA DMA controller and
return the residue as described in Documentation/DMA-ISA-LPC.txt.

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/das16.c b/drivers/staging/comedi/drivers/das16.c
index f997966849784cf723bf5314a89a59e0e9e8affe..09d65fcebd0bfee6c18eec0cd0796788b9151064 100644 (file)
--- a/drivers/staging/comedi/drivers/das16.c
+++ b/drivers/staging/comedi/drivers/das16.c
@@ -475,6 +475,19 @@ static void das16_isadma_program(unsigned int dma_chan,
        release_dma_lock(flags);
 }
 
+static unsigned int das16_isadma_disable(unsigned int dma_chan)
+{
+       unsigned long flags;
+       unsigned int residue;
+
+       flags = claim_dma_lock();
+       disable_dma(dma_chan);
+       residue = get_dma_residue(dma_chan);
+       release_dma_lock(flags);
+
+       return residue;
+}
+
 static void das16_ai_enable(struct comedi_device *dev,
                            unsigned int mode, unsigned int src)
 {
@@ -514,23 +527,24 @@ static int disable_dma_on_even(struct comedi_device *dev)
        struct das16_private_struct *devpriv = dev->private;
        static const int disable_limit = 100;
        static const int enable_timeout = 100;
-       int residue;
+       unsigned long flags;
+       unsigned int residue;
        int new_residue;
        int i;
        int j;
 
-       disable_dma(devpriv->dma_chan);
-       residue = get_dma_residue(devpriv->dma_chan);
+       residue = das16_isadma_disable(devpriv->dma_chan);
        for (i = 0; i < disable_limit && (residue % 2); ++i) {
+               flags = claim_dma_lock();
                enable_dma(devpriv->dma_chan);
                for (j = 0; j < enable_timeout; ++j) {
                        udelay(2);
                        new_residue = get_dma_residue(devpriv->dma_chan);
+                       release_dma_lock(flags);
                        if (new_residue != residue)
                                break;
                }
-               disable_dma(devpriv->dma_chan);
-               residue = get_dma_residue(devpriv->dma_chan);
+               residue = das16_isadma_disable(devpriv->dma_chan);
        }
        if (i == disable_limit) {
                dev_err(dev->class_dev,
@@ -548,7 +562,6 @@ static void das16_interrupt(struct comedi_device *dev)
        struct das16_dma_desc *dma = &devpriv->dma_desc[devpriv->cur_dma];
        struct das16_dma_desc *nxt_dma;
        unsigned long spin_flags;
-       unsigned long dma_flags;
        unsigned int nsamples;
        int num_bytes, residue;
 
@@ -558,10 +571,7 @@ static void das16_interrupt(struct comedi_device *dev)
                return;
        }
 
-       dma_flags = claim_dma_lock();
-       clear_dma_ff(devpriv->dma_chan);
        residue = disable_dma_on_even(dev);
-       release_dma_lock(dma_flags);
 
        /*  figure out how many points to read */
        if (residue > dma->size) {
@@ -1001,7 +1011,6 @@ static int das16_alloc_dma(struct comedi_device *dev, unsigned int dma_chan)
 {
        struct das16_private_struct *devpriv = dev->private;
        struct das16_dma_desc *dma;
-       unsigned long flags;
        int i;
 
        if (!(dma_chan == 1 || dma_chan == 3))
@@ -1020,9 +1029,7 @@ static int das16_alloc_dma(struct comedi_device *dev, unsigned int dma_chan)
                        return -ENOMEM;
        }
 
-       flags = claim_dma_lock();
-       disable_dma(devpriv->dma_chan);
-       release_dma_lock(flags);
+       das16_isadma_disable(devpriv->dma_chan);
 
        init_timer(&devpriv->timer);
        devpriv->timer.function = das16_timer_interrupt;