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staging: comedi: ni_labpc_isadma: introduce labpc_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.

The DMA will always be disabled when labpc_setup_dma() is called. Remove
the unnecessary disable in that function.

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>
This commit is contained in:
H Hartley Sweeten 2015-01-13 10:16:39 -07:00 committed by Greg Kroah-Hartman
parent afd8f40f6f
commit 0f02b081da
1 changed files with 24 additions and 17 deletions
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41
drivers/staging/comedi/drivers/ni_labpc_isadma.c
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@ -31,6 +31,19 @@
/* size in bytes of dma buffer */ /* size in bytes of dma buffer */
#define LABPC_ISADMA_BUFFER_SIZE 0xff00 #define LABPC_ISADMA_BUFFER_SIZE 0xff00
static unsigned int labpc_isadma_disable(struct labpc_dma_desc *dma)
{
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;
}
/* utility function that suggests a dma transfer size in bytes */ /* utility function that suggests a dma transfer size in bytes */
static unsigned int labpc_suggest_transfer_size(struct comedi_device *dev, static unsigned int labpc_suggest_transfer_size(struct comedi_device *dev,
struct comedi_subdevice *s) struct comedi_subdevice *s)
@ -67,10 +80,10 @@ void labpc_setup_dma(struct comedi_device *dev, struct comedi_subdevice *s)
unsigned long irq_flags; unsigned long irq_flags;
irq_flags = claim_dma_lock(); irq_flags = claim_dma_lock();
disable_dma(dma->chan);
/* clear flip-flop to make sure 2-byte registers for /* clear flip-flop to make sure 2-byte registers for
* count and address get set correctly */ * count and address get set correctly */
clear_dma_ff(dma->chan); clear_dma_ff(dma->chan);
set_dma_mode(dma->chan, DMA_MODE_READ);
set_dma_addr(dma->chan, dma->hw_addr); set_dma_addr(dma->chan, dma->hw_addr);
/* set appropriate size of transfer */ /* set appropriate size of transfer */
dma->size = labpc_suggest_transfer_size(dev, s); dma->size = labpc_suggest_transfer_size(dev, s);
@ -99,20 +112,16 @@ void labpc_drain_dma(struct comedi_device *dev)
status = devpriv->stat1; status = devpriv->stat1;
flags = claim_dma_lock(); /*
disable_dma(dma->chan); * residue is the number of bytes left to be done on the dma
/* clear flip-flop to make sure 2-byte registers for
* count and address get set correctly */
clear_dma_ff(dma->chan);
/* figure out how many points to read */
max_points = dma->size / sample_size;
/* residue is the number of points left to be done on the dma
* transfer. It should always be zero at this point unless * transfer. It should always be zero at this point unless
* the stop_src is set to external triggering. * the stop_src is set to external triggering.
*/ */
residue = get_dma_residue(dma->chan) / sample_size; residue = labpc_isadma_disable(dma);
num_points = max_points - residue;
/* figure out how many points to read */
max_points = dma->size / sample_size;
num_points = max_points - comedi_bytes_to_samples(s, residue);
if (cmd->stop_src == TRIG_COUNT && devpriv->count < num_points) if (cmd->stop_src == TRIG_COUNT && devpriv->count < num_points)
num_points = devpriv->count; num_points = devpriv->count;
@ -132,6 +141,8 @@ void labpc_drain_dma(struct comedi_device *dev)
devpriv->count -= num_points; devpriv->count -= num_points;
/* set address and count for next transfer */ /* set address and count for next transfer */
flags = claim_dma_lock();
set_dma_mode(dma->chan, DMA_MODE_READ);
set_dma_addr(dma->chan, dma->hw_addr); set_dma_addr(dma->chan, dma->hw_addr);
set_dma_count(dma->chan, leftover * sample_size); set_dma_count(dma->chan, leftover * sample_size);
release_dma_lock(flags); release_dma_lock(flags);
@ -170,7 +181,6 @@ void labpc_init_dma_chan(struct comedi_device *dev, unsigned int dma_chan)
{ {
struct labpc_private *devpriv = dev->private; struct labpc_private *devpriv = dev->private;
struct labpc_dma_desc *dma = &devpriv->dma_desc; struct labpc_dma_desc *dma = &devpriv->dma_desc;
unsigned long dma_flags;
if (dma_chan != 1 && dma_chan != 3) if (dma_chan != 1 && dma_chan != 3)
return; return;
@ -187,10 +197,7 @@ void labpc_init_dma_chan(struct comedi_device *dev, unsigned int dma_chan)
dma->chan = dma_chan; dma->chan = dma_chan;
dma_flags = claim_dma_lock(); labpc_isadma_disable(dma);
disable_dma(dma->chan);
set_dma_mode(dma->chan, DMA_MODE_READ);
release_dma_lock(dma_flags);
} }
EXPORT_SYMBOL_GPL(labpc_init_dma_chan); EXPORT_SYMBOL_GPL(labpc_init_dma_chan);