staging: comedi: dt282x: introduce struct dt282x_dma_desc

For aesthetics, introduce a struct to hold the DMA descriptor data.

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>

diff --git a/drivers/staging/comedi/drivers/dt282x.c b/drivers/staging/comedi/drivers/dt282x.c
index 873aae6..8ee6186 100644 (file)
--- a/drivers/staging/comedi/drivers/dt282x.c
+++ b/drivers/staging/comedi/drivers/dt282x.c
@@ -300,6 +300,12 @@ static const struct dt282x_board boardtypes[] = {
        },
 };
 
+struct dt282x_dma_desc {
+       unsigned int chan;      /* DMA channel */
+       unsigned short *virt_addr;      /* virtual address of DMA buffer */
+       unsigned int size;      /* transfer size (in bytes) */
+};
+
 struct dt282x_private {
        unsigned int ad_2scomp:1;
 
@@ -312,21 +318,16 @@ struct dt282x_private {
        int ntrig;
        int nread;
 
-       struct {
-               int chan;
-               unsigned short *buf;    /* DMA buffer */
-               int size;       /* size of current transfer */
-       } dma[2];
+       struct dt282x_dma_desc dma_desc[2];
        int dma_maxsize;        /* max size of DMA transfer (in bytes) */
-       int current_dma_index;
+       int cur_dma;
        int dma_dir;
 };
 
 static int dt282x_prep_ai_dma(struct comedi_device *dev, int dma_index, int n)
 {
        struct dt282x_private *devpriv = dev->private;
-       int dma_chan;
-       unsigned long dma_ptr;
+       struct dt282x_dma_desc *dma = &devpriv->dma_desc[dma_index];
        unsigned long flags;
 
        if (!devpriv->ntrig)
@@ -338,18 +339,16 @@ static int dt282x_prep_ai_dma(struct comedi_device *dev, int dma_index, int n)
                n = devpriv->ntrig * 2;
        devpriv->ntrig -= n / 2;
 
-       devpriv->dma[dma_index].size = n;
-       dma_chan = devpriv->dma[dma_index].chan;
-       dma_ptr = virt_to_bus(devpriv->dma[dma_index].buf);
+       dma->size = n;
 
-       set_dma_mode(dma_chan, DMA_MODE_READ);
+       set_dma_mode(dma->chan, DMA_MODE_READ);
        flags = claim_dma_lock();
-       clear_dma_ff(dma_chan);
-       set_dma_addr(dma_chan, dma_ptr);
-       set_dma_count(dma_chan, n);
+       clear_dma_ff(dma->chan);
+       set_dma_addr(dma->chan, virt_to_bus(dma->virt_addr));
+       set_dma_count(dma->chan, dma->size);
        release_dma_lock(flags);
 
-       enable_dma(dma_chan);
+       enable_dma(dma->chan);
 
        return n;
 }
@@ -357,22 +356,19 @@ static int dt282x_prep_ai_dma(struct comedi_device *dev, int dma_index, int n)
 static int dt282x_prep_ao_dma(struct comedi_device *dev, int dma_index, int n)
 {
        struct dt282x_private *devpriv = dev->private;
-       int dma_chan;
-       unsigned long dma_ptr;
+       struct dt282x_dma_desc *dma = &devpriv->dma_desc[dma_index];
        unsigned long flags;
 
-       devpriv->dma[dma_index].size = n;
-       dma_chan = devpriv->dma[dma_index].chan;
-       dma_ptr = virt_to_bus(devpriv->dma[dma_index].buf);
+       dma->size = n;
 
-       set_dma_mode(dma_chan, DMA_MODE_WRITE);
+       set_dma_mode(dma->chan, DMA_MODE_WRITE);
        flags = claim_dma_lock();
-       clear_dma_ff(dma_chan);
-       set_dma_addr(dma_chan, dma_ptr);
-       set_dma_count(dma_chan, n);
+       clear_dma_ff(dma->chan);
+       set_dma_addr(dma->chan, virt_to_bus(dma->virt_addr));
+       set_dma_count(dma->chan, dma->size);
        release_dma_lock(flags);
 
-       enable_dma(dma_chan);
+       enable_dma(dma->chan);
 
        return n;
 }
@@ -381,8 +377,8 @@ static void dt282x_disable_dma(struct comedi_device *dev)
 {
        struct dt282x_private *devpriv = dev->private;
 
-       disable_dma(devpriv->dma[0].chan);
-       disable_dma(devpriv->dma[1].chan);
+       disable_dma(devpriv->dma_desc[0].chan);
+       disable_dma(devpriv->dma_desc[1].chan);
 }
 
 static unsigned int dt282x_ns_to_timer(unsigned int *ns, unsigned int flags)
@@ -444,11 +440,11 @@ static unsigned int dt282x_ao_setup_dma(struct comedi_device *dev,
                                        int cur_dma)
 {
        struct dt282x_private *devpriv = dev->private;
-       void *ptr = devpriv->dma[cur_dma].buf;
+       struct dt282x_dma_desc *dma = &devpriv->dma_desc[cur_dma];
        unsigned int nsamples = comedi_bytes_to_samples(s, devpriv->dma_maxsize);
        unsigned int nbytes;
 
-       nbytes = comedi_buf_read_samples(s, ptr, nsamples);
+       nbytes = comedi_buf_read_samples(s, dma->virt_addr, nsamples);
        if (nbytes)
                dt282x_prep_ao_dma(dev, cur_dma, nbytes);
        else
@@ -461,39 +457,35 @@ static void dt282x_ao_dma_interrupt(struct comedi_device *dev,
                                    struct comedi_subdevice *s)
 {
        struct dt282x_private *devpriv = dev->private;
-       int cur_dma = devpriv->current_dma_index;
+       struct dt282x_dma_desc *dma = &devpriv->dma_desc[devpriv->cur_dma];
 
        outw(devpriv->supcsr | DT2821_SUPCSR_CLRDMADNE,
             dev->iobase + DT2821_SUPCSR_REG);
 
-       disable_dma(devpriv->dma[cur_dma].chan);
+       disable_dma(dma->chan);
 
-       devpriv->current_dma_index = 1 - cur_dma;
-
-       if (!dt282x_ao_setup_dma(dev, s, cur_dma))
+       if (!dt282x_ao_setup_dma(dev, s, devpriv->cur_dma))
                s->async->events |= COMEDI_CB_OVERFLOW;
+
+       devpriv->cur_dma = 1 - devpriv->cur_dma;
 }
 
 static void dt282x_ai_dma_interrupt(struct comedi_device *dev,
                                    struct comedi_subdevice *s)
 {
        struct dt282x_private *devpriv = dev->private;
-       int cur_dma = devpriv->current_dma_index;
-       void *ptr = devpriv->dma[cur_dma].buf;
-       int size = devpriv->dma[cur_dma].size;
-       unsigned int nsamples = comedi_bytes_to_samples(s, size);
+       struct dt282x_dma_desc *dma = &devpriv->dma_desc[devpriv->cur_dma];
+       unsigned int nsamples = comedi_bytes_to_samples(s, dma->size);
        int ret;
 
        outw(devpriv->supcsr | DT2821_SUPCSR_CLRDMADNE,
             dev->iobase + DT2821_SUPCSR_REG);
 
-       disable_dma(devpriv->dma[cur_dma].chan);
+       disable_dma(dma->chan);
 
-       devpriv->current_dma_index = 1 - cur_dma;
-
-       dt282x_munge(dev, s, ptr, size);
-       ret = comedi_buf_write_samples(s, ptr, nsamples);
-       if (ret != size)
+       dt282x_munge(dev, s, dma->virt_addr, dma->size);
+       ret = comedi_buf_write_samples(s, dma->virt_addr, nsamples);
+       if (ret != dma->size)
                return;
 
        devpriv->nread -= nsamples;
@@ -514,7 +506,9 @@ static void dt282x_ai_dma_interrupt(struct comedi_device *dev,
        }
 #endif
        /* restart the channel */
-       dt282x_prep_ai_dma(dev, cur_dma, 0);
+       dt282x_prep_ai_dma(dev, devpriv->cur_dma, 0);
+
+       devpriv->cur_dma = 1 - devpriv->cur_dma;
 }
 
 static irqreturn_t dt282x_interrupt(int irq, void *d)
@@ -769,7 +763,7 @@ static int dt282x_ai_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
        devpriv->nread = devpriv->ntrig;
 
        devpriv->dma_dir = DMA_MODE_READ;
-       devpriv->current_dma_index = 0;
+       devpriv->cur_dma = 0;
        dt282x_prep_ai_dma(dev, 0, 0);
        if (devpriv->ntrig) {
                dt282x_prep_ai_dma(dev, 1, 0);
@@ -949,7 +943,7 @@ static int dt282x_ao_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
        devpriv->nread = devpriv->ntrig;
 
        devpriv->dma_dir = DMA_MODE_WRITE;
-       devpriv->current_dma_index = 0;
+       devpriv->cur_dma = 0;
 
        outw(devpriv->divisor, dev->iobase + DT2821_TMRCTR_REG);
 
@@ -1090,10 +1084,11 @@ static int dt282x_alloc_dma(struct comedi_device *dev,
 
        devpriv->dma_maxsize = PAGE_SIZE;
        for (i = 0; i < 2; i++) {
-               devpriv->dma[i].chan = dma_chan[i];
-               devpriv->dma[i].buf =
-                       (void *)__get_free_page(GFP_KERNEL | GFP_DMA);
-               if (!devpriv->dma[i].buf)
+               struct dt282x_dma_desc *dma = &devpriv->dma_desc[i];
+
+               dma->chan = dma_chan[i];
+               dma->virt_addr = (void *)__get_free_page(GFP_KERNEL | GFP_DMA);
+               if (!dma->virt_addr)
                        return -ENOMEM;
        }
 
@@ -1103,18 +1098,18 @@ static int dt282x_alloc_dma(struct comedi_device *dev,
 static void dt282x_free_dma(struct comedi_device *dev)
 {
        struct dt282x_private *devpriv = dev->private;
+       struct dt282x_dma_desc *dma;
        int i;
 
        if (!devpriv)
                return;
 
        for (i = 0; i < 2; i++) {
-               if (devpriv->dma[i].chan)
-                       free_dma(devpriv->dma[i].chan);
-               if (devpriv->dma[i].buf)
-                       free_page((unsigned long)devpriv->dma[i].buf);
-               devpriv->dma[i].chan = 0;
-               devpriv->dma[i].buf = NULL;
+               dma = &devpriv->dma_desc[i];
+               if (dma->chan)
+                       free_dma(dma->chan);
+               if (dma->virt_addr)
+                       free_page((unsigned long)dma->virt_addr);
        }
 }