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dma: mmp_pdma: make the controller a DMA provider

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This patch makes the mmp_pdma controller able to provide DMA resources
in DT environments by providing an dma xlate function.

of_dma_simple_xlate() isn't used here, because if fails to handle
multiple different DMA engines or several instances of the same
controller. Instead, a private implementation is provided that makes use
of the newly introduced dma_get_slave_channel() call.

Signed-off-by: Daniel Mack <zonque@gmail.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
This commit is contained in:
Daniel Mack 2013-08-10 18:52:19 +02:00 committed by Vinod Koul
parent 13b3006b8e
commit a9a7cf08bd
1 changed files with 44 additions and 0 deletions
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44
drivers/dma/mmp_pdma.c
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@ -18,6 +18,7 @@
#include <linux/platform_data/mmp_dma.h>
#include <linux/dmapool.h>
#include <linux/of_device.h>
#include <linux/of_dma.h>
#include <linux/of.h>
#include <linux/dma/mmp-pdma.h>
@ -777,6 +778,39 @@ static struct of_device_id mmp_pdma_dt_ids[] = {
};
MODULE_DEVICE_TABLE(of, mmp_pdma_dt_ids);
static struct dma_chan *mmp_pdma_dma_xlate(struct of_phandle_args *dma_spec,
struct of_dma *ofdma)
{
struct mmp_pdma_device *d = ofdma->of_dma_data;
struct dma_chan *chan, *candidate;
retry:
candidate = NULL;
/* walk the list of channels registered with the current instance and
* find one that is currently unused */
list_for_each_entry(chan, &d->device.channels, device_node)
if (chan->client_count == 0) {
candidate = chan;
break;
}
if (!candidate)
return NULL;
/* dma_get_slave_channel will return NULL if we lost a race between
* the lookup and the reservation */
chan = dma_get_slave_channel(candidate);
if (chan) {
struct mmp_pdma_chan *c = to_mmp_pdma_chan(chan);
c->drcmr = dma_spec->args[0];
return chan;
}
goto retry;
}
static int mmp_pdma_probe(struct platform_device *op)
{
struct mmp_pdma_device *pdev;
@ -863,6 +897,16 @@ static int mmp_pdma_probe(struct platform_device *op)
return ret;
}
if (op->dev.of_node) {
/* Device-tree DMA controller registration */
ret = of_dma_controller_register(op->dev.of_node,
mmp_pdma_dma_xlate, pdev);
if (ret < 0) {
dev_err(&op->dev, "of_dma_controller_register failed\n");
return ret;
}
}
dev_info(pdev->device.dev, "initialized\n");
return 0;
}