[PATCHv2 3/6] dw_dmac: get number of channels from hardware if possible

Andy Shevchenko
2012-09-21T12:06:50Z

In case the controller has the encoded parameters feature enabled the driver
will use it to get the number of channels. In the future it will be used for
the other important parameters as well.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
drivers/dma/dw_dmac.c | 33 +++++++++++++++++++++++----------
1 file changed, 23 insertions(+), 10 deletions(-)

diff --git a/drivers/dma/dw_dmac.c b/drivers/dma/dw_dmac.c
index 2272f79..c964f6e 100644
--- a/drivers/dma/dw_dmac.c
+++ b/drivers/dma/dw_dmac.c
@@ -1381,6 +1381,10 @@ static int __devinit dw_probe(struct platform_device *pdev)
struct resource *io;
struct dw_dma *dw;
size_t size;
+ void __iomem *regs;
+ bool autocfg;
+ unsigned int dw_params;
+ unsigned int nr_channels;
int irq;
int err;
int i;
@@ -1397,23 +1401,32 @@ static int __devinit dw_probe(struct platform_device *pdev)
if (irq < 0)
return irq;

- size = sizeof(struct dw_dma);
- size += pdata->nr_channels * sizeof(struct dw_dma_chan);
+ regs = devm_request_and_ioremap(&pdev->dev, io);
+ if (!regs)
+ return -EBUSY;
+
+ dw_params = dma_read_byaddr(regs, DW_PARAMS);
+ autocfg = dw_params >> DW_PARAMS_EN & 0x1;
+
+ if (autocfg)
+ nr_channels = (dw_params >> DW_PARAMS_NR_CHAN & 0x7) + 1;
+ else
+ nr_channels = pdata->nr_channels;
+
+ size = sizeof(struct dw_dma) + nr_channels * sizeof(struct dw_dma_chan);
dw = devm_kzalloc(&pdev->dev, size, GFP_KERNEL);
if (!dw)
return -ENOMEM;

- dw->regs = devm_request_and_ioremap(&pdev->dev, io);
- if (!dw->regs)
- return -EBUSY;
-
dw->clk = devm_clk_get(&pdev->dev, "hclk");
if (IS_ERR(dw->clk))
return PTR_ERR(dw->clk);
clk_prepare_enable(dw->clk);

+ dw->regs = regs;
+
/* Calculate all channel mask before DMA setup */
- dw->all_chan_mask = (1 << pdata->nr_channels) - 1;
+ dw->all_chan_mask = (1 << nr_channels) - 1;

/* force dma off, just in case */
dw_dma_off(dw);
@@ -1431,7 +1444,7 @@ static int __devinit dw_probe(struct platform_device *pdev)
tasklet_init(&dw->tasklet, dw_dma_tasklet, (unsigned long)dw);

INIT_LIST_HEAD(&dw->dma.channels);
- for (i = 0; i < pdata->nr_channels; i++) {
+ for (i = 0; i < nr_channels; i++) {
struct dw_dma_chan *dwc = &dw->chan[i];

dwc->chan.device = &dw->dma;
@@ -1444,7 +1457,7 @@ static int __devinit dw_probe(struct platform_device *pdev)

/* 7 is highest priority & 0 is lowest. */
if (pdata->chan_priority == CHAN_PRIORITY_ASCENDING)
- dwc->priority = pdata->nr_channels - i - 1;
+ dwc->priority = nr_channels - i - 1;
else
dwc->priority = i;

@@ -1485,7 +1498,7 @@ static int __devinit dw_probe(struct platform_device *pdev)
dma_writel(dw, CFG, DW_CFG_DMA_EN);

printk(KERN_INFO "%s: DesignWare DMA Controller, %d channels\n",
- dev_name(&pdev->dev), pdata->nr_channels);
+ dev_name(&pdev->dev), nr_channels);

dma_async_device_register(&dw->dma);

--
1.7.10.4