For PL330 dma controllers instantiated from device tree, the channel
lookup is based on phandle of the dma controller and dma request id
specified by the client node. During probe, the private data of each
channel of the controller is set to point to the device node of the
dma controller. The 'chan_id' of the each channel is used as the
dma request id.

Client driver requesting dma channels specify the phandle of the
dma controller and the request id. The pl330 filter function
converts the phandle to the device node pointer and matches that
with channel's private data. If a match is found, the request id
from the client node and the 'chan_id' of the channel is matched.
A channel is found if both the values match.

Signed-off-by: Thomas Abraham <redacted>
---
 .../devicetree/bindings/dma/arm-pl330.txt          |   42 +++++++++++++
 drivers/dma/pl330.c                                |   63 +++++++++++++++++++-
 2 files changed, 103 insertions(+), 2 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/dma/arm-pl330.txt

diff --git a/Documentation/devicetree/bindings/dma/arm-pl330.txt b/Documentation/devicetree/bindings/dma/arm-pl330.txt
new file mode 100644
index 0000000..46a8307
--- /dev/null
+++ b/Documentation/devicetree/bindings/dma/arm-pl330.txt

@@ -0,0 +1,42 @@
+* ARM PrimeCell PL330 DMA Controller
+
+The ARM PrimeCell PL330 DMA controller can move blocks of memory contents
+between memory and peripherals or memory to memory.
+
+Required properties:
+  - compatible: should one or more of the following
+    - arm,pl330-pdma - For controllers that support mem-to-dev and dev-to-mem
+      transfers.
+    - arm,pl330-mdma - For controllers that support mem-to-mem transfers only.

diff --git a/drivers/dma/pl330.c b/drivers/dma/pl330.c
index 9732995..984dc18 100644
--- a/drivers/dma/pl330.c
+++ b/drivers/dma/pl330.c

@@ -19,6 +19,7 @@
 #include <linux/amba/pl330.h>
 #include <linux/pm_runtime.h>
 #include <linux/scatterlist.h>
+#include <linux/of.h>
 
 #define NR_DEFAULT_DESC	16
 

@@ -277,6 +278,20 @@ bool pl330_filter(struct dma_chan *chan, void *param)
 	if (chan->device->dev->driver != &pl330_driver.drv)
 		return false;
 
+#ifdef CONFIG_OF
+	if (chan->device->dev->of_node) {
+		const __be32 *prop_value;
+		phandle phandle;
+		struct device_node *node;
+
+		prop_value = ((struct property *)param)->value;
+		phandle = be32_to_cpup(prop_value++);
+		node = of_find_node_by_phandle(phandle);
+		return ((chan->private == node) &&
+				(chan->chan_id == be32_to_cpup(prop_value)));
+	}
+#endif
+
 	peri_id = chan->private;
 	return *peri_id == (unsigned)param;
 }

@@ -777,6 +792,40 @@ static irqreturn_t pl330_irq_handler(int irq, void *data)
 		return IRQ_NONE;
 }
 
+#ifdef CONFIG_OF
+static struct dma_pl330_platdata *pl330_parse_dt(struct device *dev)
+{
+	struct dma_pl330_platdata *pdat;
+	const void *value;
+
+	pdat = devm_kzalloc(dev, sizeof(*pdat), GFP_KERNEL);
+	if (!pdat)
+		return NULL;

+		dma_cap_set(DMA_SLAVE, pdat->cap_mask);
+		dma_cap_set(DMA_CYCLIC, pdat->cap_mask);
+		dma_cap_set(DMA_MEMCPY, pdat->cap_mask);
+	}
+
+	return pdat;
+}
+#else
+static struct dma_pl330_platdata *pl330_parse_dt(struct device *dev)
+{
+	return NULL;
+}
+#endif
+
 static int __devinit
 pl330_probe(struct amba_device *adev, const struct amba_id *id)
 {

@@ -789,7 +838,13 @@ pl330_probe(struct amba_device *adev, const struct amba_id *id)
 	int i, ret, irq;
 	int num_chan;
 
-	pdat = adev->dev.platform_data;
+	if (adev->dev.of_node) {
+		pdat = pl330_parse_dt(&adev->dev);
+		if (!pdat)
+			return -ENOMEM;
+	} else {
+		pdat = adev->dev.platform_data;
+	}
 
 	/* Allocate a new DMAC and its Channels */
 	pdmac = kzalloc(sizeof(*pdmac), GFP_KERNEL);

@@ -862,7 +917,11 @@ pl330_probe(struct amba_device *adev, const struct amba_id *id)
 
 	for (i = 0; i < num_chan; i++) {
 		pch = &pdmac->peripherals[i];
-		pch->chan.private = pdat ? &pdat->peri_id[i] : NULL;
+		if (!adev->dev.of_node)
+			pch->chan.private = pdat ? &pdat->peri_id[i] : NULL;
+		else
+			pch->chan.private = adev->dev.of_node;
+
 		INIT_LIST_HEAD(&pch->work_list);
 		spin_lock_init(&pch->lock);
 		pch->pl330_chid = NULL;