From ae4e131e0b5ab57313371aa7d773ac8b01fdb2c7 Mon Sep 17 00:00:00 2001 From: H Hartley Sweeten Date: Tue, 13 Jan 2015 10:16:29 -0700 Subject: [PATCH] staging: comedi: das1800: introduce das1800_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. Signed-off-by: H Hartley Sweeten Reviewed-by: Ian Abbott Signed-off-by: Greg Kroah-Hartman --- 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 6df58cda7d32..6359fe665ed6 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; -- 2.34.1