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staging: comedi: das1800: introduce das1800_isadma_disable()

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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>
This commit is contained in:
H Hartley Sweeten 2015-01-13 10:16:29 -07:00 committed by Greg Kroah-Hartman
parent dec3aa4fff
commit ae4e131e0b
1 changed files with 18 additions and 22 deletions
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40
drivers/staging/comedi/drivers/das1800.c
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@ -465,6 +465,19 @@ static void das1800_isadma_program(struct das1800_dma_desc *dma)
release_dma_lock(flags);
}
static unsigned int das1800_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 inline uint16_t munge_bipolar_sample(const struct comedi_device *dev,
uint16_t sample)
{
@ -524,23 +537,16 @@ static void das1800_handle_fifo_not_empty(struct comedi_device *dev,
}
}
/* Utility function used by das1800_flush_dma() and das1800_handle_dma().
* Assumes dma lock is held */
/* Utility function used by das1800_flush_dma() and das1800_handle_dma() */
static void das1800_flush_dma_channel(struct comedi_device *dev,
struct comedi_subdevice *s,
struct das1800_dma_desc *dma)
{
unsigned int nbytes;
unsigned int residue = das1800_isadma_disable(dma->chan);
unsigned int nbytes = dma->size - residue;
unsigned int nsamples;
disable_dma(dma->chan);
/* clear flip-flop to make sure 2-byte registers
* get set correctly */
clear_dma_ff(dma->chan);
/* figure out how many points to read */
nbytes = dma->size - get_dma_residue(dma->chan);
nsamples = comedi_bytes_to_samples(s, nbytes);
nsamples = comedi_nsamples_left(s, nsamples);
@ -555,10 +561,8 @@ static void das1800_flush_dma(struct comedi_device *dev,
{
struct das1800_private *devpriv = dev->private;
struct das1800_dma_desc *dma = &devpriv->dma_desc[devpriv->cur_dma];
unsigned long flags;
const int dual_dma = devpriv->irq_dma_bits & DMA_DUAL;
flags = claim_dma_lock();
das1800_flush_dma_channel(dev, s, dma);
if (dual_dma) {
@ -568,8 +572,6 @@ static void das1800_flush_dma(struct comedi_device *dev,
das1800_flush_dma_channel(dev, s, dma);
}
release_dma_lock(flags);
/* get any remaining samples in fifo */
das1800_handle_fifo_not_empty(dev, s);
}
@ -579,12 +581,9 @@ static void das1800_handle_dma(struct comedi_device *dev,
{
struct das1800_private *devpriv = dev->private;
struct das1800_dma_desc *dma = &devpriv->dma_desc[devpriv->cur_dma];
unsigned long flags;
const int dual_dma = devpriv->irq_dma_bits & DMA_DUAL;
flags = claim_dma_lock();
das1800_flush_dma_channel(dev, s, dma);
release_dma_lock(flags);
/* re-enable dma channel */
das1800_isadma_program(dma);
@ -611,7 +610,7 @@ static int das1800_cancel(struct comedi_device *dev, struct comedi_subdevice *s)
for (i = 0; i < 2; i++) {
dma = &devpriv->dma_desc[i];
if (dma->chan)
disable_dma(dma->chan);
das1800_isadma_disable(dma->chan);
}
return 0;
@ -1233,7 +1232,6 @@ static int das1800_init_dma(struct comedi_device *dev,
struct das1800_private *devpriv = dev->private;
struct das1800_dma_desc *dma;
unsigned int *dma_chan;
unsigned long flags;
int i;
/*
@ -1292,9 +1290,7 @@ static int das1800_init_dma(struct comedi_device *dev,
if (!dma->virt_addr)
return -ENOMEM;
flags = claim_dma_lock();
disable_dma(dma->chan);
release_dma_lock(flags);
das1800_isadma_disable(dma->chan);
}
return 0;