staging: comedi: pcl818: clarify dma channel request in pcl818_attach()

All the board types that can do DMA can use DMA channels 3 or 1. Remove
the 'DMAbits', which is a mask of the valid channels, from the boardinfo
and replace it with a bit-field flag 'has_dma'.

Refactor pcl818_attach() to use the new flag and remove the need for the
goto.

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/pcl818.c b/drivers/staging/comedi/drivers/pcl818.c
index a000f74..9cb3e46 100644 (file)
--- a/drivers/staging/comedi/drivers/pcl818.c
+++ b/drivers/staging/comedi/drivers/pcl818.c
@@ -267,9 +267,9 @@ struct pcl818_board {
        int n_dochan;
        const struct comedi_lrange *ai_range_type;
        unsigned int IRQbits;
-       unsigned int DMAbits;
        int ai_maxdata;
        int ao_maxdata;
+       unsigned int has_dma:1;
        unsigned int has_fifo:1;
        int is_818;
 };
@@ -286,9 +286,9 @@ static const struct pcl818_board boardtypes[] = {
                .n_dochan       = 16,
                .ai_range_type  = &range_pcl818l_l_ai,
                .IRQbits        = 0x00fc,
-               .DMAbits        = 0x0a,
                .ai_maxdata     = 0xfff,
                .ao_maxdata     = 0xfff,
+               .has_dma        = 1,
                .is_818         = 1,
        }, {
                .name           = "pcl818h",
@@ -301,9 +301,9 @@ static const struct pcl818_board boardtypes[] = {
                .n_dochan       = 16,
                .ai_range_type  = &range_pcl818h_ai,
                .IRQbits        = 0x00fc,
-               .DMAbits        = 0x0a,
                .ai_maxdata     = 0xfff,
                .ao_maxdata     = 0xfff,
+               .has_dma        = 1,
                .is_818         = 1,
        }, {
                .name           = "pcl818hd",
@@ -316,9 +316,9 @@ static const struct pcl818_board boardtypes[] = {
                .n_dochan       = 16,
                .ai_range_type  = &range_pcl818h_ai,
                .IRQbits        = 0x00fc,
-               .DMAbits        = 0x0a,
                .ai_maxdata     = 0xfff,
                .ao_maxdata     = 0xfff,
+               .has_dma        = 1,
                .has_fifo       = 1,
                .is_818         = 1,
        }, {
@@ -332,9 +332,9 @@ static const struct pcl818_board boardtypes[] = {
                .n_dochan       = 16,
                .ai_range_type  = &range_pcl818hg_ai,
                .IRQbits        = 0x00fc,
-               .DMAbits        = 0x0a,
                .ai_maxdata     = 0xfff,
                .ao_maxdata     = 0xfff,
+               .has_dma        = 1,
                .has_fifo       = 1,
                .is_818         = 1,
        }, {
@@ -348,9 +348,9 @@ static const struct pcl818_board boardtypes[] = {
                .n_dochan       = 16,
                .ai_range_type  = &range_pcl818h_ai,
                .IRQbits        = 0x00fc,
-               .DMAbits        = 0x0a,
                .ai_maxdata     = 0xfff,
                .ao_maxdata     = 0xfff,
+               .has_dma        = 1,
                .is_818         = 1,
        }, {
                .name           = "pcl718",
@@ -363,9 +363,9 @@ static const struct pcl818_board boardtypes[] = {
                .n_dochan       = 16,
                .ai_range_type  = &range_unipolar5,
                .IRQbits        = 0x00fc,
-               .DMAbits        = 0x0a,
                .ai_maxdata     = 0xfff,
                .ao_maxdata     = 0xfff,
+               .has_dma        = 1,
        }, {
                .name           = "pcm3718",
                .n_ranges       = 9,
@@ -376,9 +376,9 @@ static const struct pcl818_board boardtypes[] = {
                .n_dochan       = 16,
                .ai_range_type  = &range_pcl818h_ai,
                .IRQbits        = 0x00fc,
-               .DMAbits        = 0x0a,
                .ai_maxdata     = 0xfff,
                .ao_maxdata     = 0xfff,
+               .has_dma        = 1,
                .is_818         = 1,
        },
 };
@@ -1315,7 +1315,6 @@ static int pcl818_attach(struct comedi_device *dev, struct comedi_devconfig *it)
        const struct pcl818_board *board = comedi_board(dev);
        struct pcl818_private *devpriv;
        int ret;
-       int dma;
        unsigned long pages;
        struct comedi_subdevice *s;
 
@@ -1347,24 +1346,18 @@ static int pcl818_attach(struct comedi_device *dev, struct comedi_devconfig *it)
        devpriv->irq_blocked = 0;       /* number of subdevice which use IRQ */
        devpriv->ai_mode = 0;   /* mode of irq */
 
-       /* grab our DMA */
-       dma = 0;
-       devpriv->dma = dma;
-       if (!dev->irq)
-               goto no_dma;    /* if we haven't IRQ, we can't use DMA */
-       if (board->DMAbits != 0) {      /* board support DMA */
-               dma = it->options[2];
-               if (dma < 1)
-                       goto no_dma;    /* DMA disabled */
-               if (((1 << dma) & board->DMAbits) == 0) {
+       /* we need an IRQ to do DMA on channel 3 or 1 */
+       if (dev->irq && board->has_dma &&
+           (it->options[2] == 3 || it->options[2] == 1)) {
+               ret = request_dma(it->options[2], dev->board_name);
+               if (ret) {
                        dev_err(dev->class_dev,
-                               "DMA is out of allowed range, FAIL!\n");
-                       return -EINVAL; /* Bad DMA */
+                               "unable to request DMA channel %d\n",
+                               it->options[2]);
+                       return -EBUSY;
                }
-               ret = request_dma(dma, dev->board_name);
-               if (ret)
-                       return -EBUSY;  /* DMA isn't free */
-               devpriv->dma = dma;
+               devpriv->dma = it->options[2];
+
                pages = 2;      /* we need 16KB */
                devpriv->dmabuf[0] = __get_dma_pages(GFP_KERNEL, pages);
                if (!devpriv->dmabuf[0])
@@ -1381,8 +1374,6 @@ static int pcl818_attach(struct comedi_device *dev, struct comedi_devconfig *it)
                devpriv->hwdmasize[1] = (1 << pages) * PAGE_SIZE;
        }
 
-no_dma:
-
        ret = comedi_alloc_subdevices(dev, 4);
        if (ret)
                return ret;