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Commit a9a7cf08 authored by Daniel Mack's avatar Daniel Mack Committed by Vinod Koul
Browse files

dma: mmp_pdma: make the controller a DMA provider 



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: default avatarDaniel Mack <zonque@gmail.com>
Acked-by: default avatarArnd Bergmann <arnd@arndb.de>
Signed-off-by: default avatarVinod Koul <vinod.koul@intel.com>
parent 13b3006b

drivers/dma/mmp_pdma.c

+44 −0
Original line number Diff line number Diff line
@@ -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;

}