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Commit 0f02b081 authored by H Hartley Sweeten's avatar H Hartley Sweeten Committed by Greg Kroah-Hartman
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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: default avatarH Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: default avatarIan Abbott <abbotti@mev.co.uk>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent afd8f40f

drivers/staging/comedi/drivers/ni_labpc_isadma.c

+24 −17
Original line number Diff line number Diff line
@@ -31,6 +31,19 @@ 
/* size in bytes of dma buffer */

#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 */

static unsigned int labpc_suggest_transfer_size(struct comedi_device *dev,

						struct comedi_subdevice *s)
@@ -67,10 +80,10 @@ void labpc_setup_dma(struct comedi_device *dev, struct comedi_subdevice *s) 
	unsigned long irq_flags;



	irq_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_mode(dma->chan, DMA_MODE_READ);

	set_dma_addr(dma->chan, dma->hw_addr);

	/* set appropriate size of transfer */

	dma->size = labpc_suggest_transfer_size(dev, s);
@@ -99,20 +112,16 @@ void labpc_drain_dma(struct comedi_device *dev) 


	status = devpriv->stat1;



	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);



	/* 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

	/*

	 * residue is the number of bytes left to be done on the dma

	 * transfer.  It should always be zero at this point unless

	 * the stop_src is set to external triggering.

	 */

	residue = get_dma_residue(dma->chan) / sample_size;

	num_points = max_points - residue;

	residue = labpc_isadma_disable(dma);



	/* 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)

		num_points = devpriv->count;
@@ -132,6 +141,8 @@ void labpc_drain_dma(struct comedi_device *dev) 
		devpriv->count -= num_points;



	/* 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_count(dma->chan, leftover * sample_size);

	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_dma_desc *dma = &devpriv->dma_desc;

	unsigned long dma_flags;



	if (dma_chan != 1 && dma_chan != 3)

		return;
@@ -187,10 +197,7 @@ void labpc_init_dma_chan(struct comedi_device *dev, unsigned int dma_chan) 


	dma->chan = dma_chan;



	dma_flags = claim_dma_lock();

	disable_dma(dma->chan);

	set_dma_mode(dma->chan, DMA_MODE_READ);

	release_dma_lock(dma_flags);

	labpc_isadma_disable(dma);

}

EXPORT_SYMBOL_GPL(labpc_init_dma_chan);