staging: comedi: ni_at_a2150: introduce a2150_isadma_program()

Introduce a helper function to program the ISA DMA controller. Program
the ISA DMA 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/ni_at_a2150.c b/drivers/staging/comedi/drivers/ni_at_a2150.c
index 3905097..23c59cb 100644 (file)
--- a/drivers/staging/comedi/drivers/ni_at_a2150.c
+++ b/drivers/staging/comedi/drivers/ni_at_a2150.c
@@ -159,6 +159,19 @@ struct a2150_private {
        int config_bits;        /*  config register bits */
 };
 
+static void a2150_isadma_program(struct a2150_dma_desc *dma)
+{
+       unsigned long flags;
+
+       flags = claim_dma_lock();
+       clear_dma_ff(dma->chan);
+       set_dma_mode(dma->chan, DMA_MODE_READ);
+       set_dma_addr(dma->chan, dma->hw_addr);
+       set_dma_count(dma->chan, dma->size);
+       enable_dma(dma->chan);
+       release_dma_lock(flags);
+}
+
 /* interrupt service routine */
 static irqreturn_t a2150_interrupt(int irq, void *d)
 {
@@ -217,6 +230,7 @@ static irqreturn_t a2150_interrupt(int irq, void *d)
         * the stop_src is set to external triggering.
         */
        residue = comedi_bytes_to_samples(s, get_dma_residue(dma->chan));
+       release_dma_lock(flags);
        num_points = max_points - residue;
        if (devpriv->count < num_points && cmd->stop_src == TRIG_COUNT)
                num_points = devpriv->count;
@@ -250,14 +264,11 @@ static irqreturn_t a2150_interrupt(int irq, void *d)
                        }
                }
        }
-       /*  re-enable  dma */
+       /* re-enable dma */
        if (leftover) {
-               set_dma_addr(dma->chan, dma->hw_addr);
-               set_dma_count(dma->chan,
-                             comedi_samples_to_bytes(s, leftover));
-               enable_dma(dma->chan);
+               dma->size = comedi_samples_to_bytes(s, leftover);
+               a2150_isadma_program(dma);
        }
-       release_dma_lock(flags);
 
        comedi_handle_events(dev, s);
 
@@ -549,13 +560,10 @@ static int a2150_ai_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
        /*  initialize number of samples remaining */
        devpriv->count = cmd->stop_arg * cmd->chanlist_len;
 
-       /*  enable computer's dma */
        lock_flags = claim_dma_lock();
        disable_dma(dma->chan);
-       /* clear flip-flop to make sure 2-byte registers for
-        * count and address get set correctly */
-       clear_dma_ff(dma->chan);
-       set_dma_addr(dma->chan, dma->hw_addr);
+       release_dma_lock(lock_flags);
+
        /*  set size of transfer to fill in 1/3 second */
 #define ONE_THIRD_SECOND 333333333
        dma->size = comedi_bytes_per_sample(s) * cmd->chanlist_len *
@@ -565,9 +573,8 @@ static int a2150_ai_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
        if (dma->size < comedi_bytes_per_sample(s))
                dma->size = comedi_bytes_per_sample(s);
        dma->size -= dma->size % comedi_bytes_per_sample(s);
-       set_dma_count(dma->chan, dma->size);
-       enable_dma(dma->chan);
-       release_dma_lock(lock_flags);
+
+       a2150_isadma_program(dma);
 
        /* clear dma interrupt before enabling it, to try and get rid of that
         * one spurious interrupt that has been happening */
@@ -724,7 +731,6 @@ static void a2150_alloc_irq_dma(struct comedi_device *dev,
        devpriv->irq_dma_bits = IRQ_LVL_BITS(irq_num) | DMA_CHAN_BITS(dma_chan);
 
        disable_dma(dma_chan);
-       set_dma_mode(dma_chan, DMA_MODE_READ);
 }
 
 static void a2150_free_dma(struct comedi_device *dev)