[PATCH 10/25] staging: comedi: das1800: introduce das1800_isadma_disable()
H Hartley Sweeten
hsweeten at visionengravers.com
Tue Jan 13 17:16:29 UTC 2015
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 at visionengravers.com>
Cc: Ian Abbott <abbotti at mev.co.uk>
Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
---
drivers/staging/comedi/drivers/das1800.c | 40 ++++++++++++++------------------
1 file changed, 18 insertions(+), 22 deletions(-)
diff --git a/drivers/staging/comedi/drivers/das1800.c b/drivers/staging/comedi/drivers/das1800.c
index 6df58cd..6359fe6 100644
--- a/drivers/staging/comedi/drivers/das1800.c
+++ b/drivers/staging/comedi/drivers/das1800.c
@@ -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;
--
2.0.3
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