[PATCH v2 05/11] dma: mmp_pdma: make the controller a DMA provider
Daniel Mack
zonque at gmail.com
Sat Aug 10 12:52:19 EDT 2013
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 at gmail.com>
---
drivers/dma/mmp_pdma.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 44 insertions(+)
diff --git a/drivers/dma/mmp_pdma.c b/drivers/dma/mmp_pdma.c
index 9dda27e..0ec5c21 100644
--- a/drivers/dma/mmp_pdma.c
+++ b/drivers/dma/mmp_pdma.c
@@ -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>
@@ -784,6 +785,39 @@ 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;
@@ -870,6 +904,16 @@ 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;
}
--
1.8.3.1
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