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: Daniel Mack <zonque@gmail.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

diff --git a/drivers/dma/mmp_pdma.c b/drivers/dma/mmp_pdma.c
index dd024d4759e7e77afea11f7f9b79c66ea3898d45..76884c48ea85c4435cbfc61d9968d2b57b582469 100644 (file)
--- 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>
 
@@ -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;
 }