[PATCH v2 7/9] dmaengine: tegra: Use iommu-map for stream ID

[Akhil R]

Use 'iommu-map', when provided, to get the stream ID to be programmed
for each channel. Iterate over the channels registered and configure
each channel device separately using of_dma_configure_id() to allow
it to use a separate IOMMU domain for the transfer. But do this
in a second loop since the first loop populates the dma device channels
list and async_device_register() registers the channels. Both are
prerequisite for using the channel device in the next loop.

Channels will continue to use the same global stream ID if the
'iommu-map' property is not present in the device tree.

Signed-off-by: Akhil R <akhilrajeev@xxxxxxxxxx>
---
 drivers/dma/tegra186-gpc-dma.c | 64 +++++++++++++++++++++++++++++-----
 1 file changed, 55 insertions(+), 9 deletions(-)

diff --git a/drivers/dma/tegra186-gpc-dma.c b/drivers/dma/tegra186-gpc-dma.c
index 5997edaba28e..9af509ecf495 100644
--- a/drivers/dma/tegra186-gpc-dma.c
+++ b/drivers/dma/tegra186-gpc-dma.c
@@ -15,6 +15,7 @@
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/of_dma.h>
+#include <linux/of_device.h>
 #include <linux/platform_device.h>
 #include <linux/reset.h>
 #include <linux/slab.h>
@@ -1390,9 +1391,13 @@ static int tegra_dma_program_sid(struct tegra_dma_channel *tdc, int stream_id)
 static int tegra_dma_probe(struct platform_device *pdev)
 {
 	const struct tegra_dma_chip_data *cdata = NULL;
+	struct tegra_dma_channel *tdc;
+	struct tegra_dma *tdma;
+	struct dma_chan *chan;
+	struct device *chdev;
+	bool use_iommu_map = false;
 	unsigned int i;
 	u32 stream_id;
-	struct tegra_dma *tdma;
 	int ret;
 
 	cdata = of_device_get_match_data(&pdev->dev);
@@ -1420,9 +1425,12 @@ static int tegra_dma_probe(struct platform_device *pdev)
 
 	tdma->dma_dev.dev = &pdev->dev;
 
-	if (!tegra_dev_iommu_get_stream_id(&pdev->dev, &stream_id)) {
-		dev_err(&pdev->dev, "Missing iommu stream-id\n");
-		return -EINVAL;
+	use_iommu_map = of_property_present(pdev->dev.of_node, "iommu-map");
+	if (!use_iommu_map) {
+		if (!tegra_dev_iommu_get_stream_id(&pdev->dev, &stream_id)) {
+			dev_err(&pdev->dev, "Missing iommu stream-id\n");
+			return -EINVAL;
+		}
 	}
 
 	ret = device_property_read_u32(&pdev->dev, "dma-channel-mask",
@@ -1434,9 +1442,10 @@ static int tegra_dma_probe(struct platform_device *pdev)
 		tdma->chan_mask = TEGRA_GPCDMA_DEFAULT_CHANNEL_MASK;
 	}
 
+	/* Initialize vchan for each channel and populate the channels list */
 	INIT_LIST_HEAD(&tdma->dma_dev.channels);
 	for (i = 0; i < cdata->nr_channels; i++) {
-		struct tegra_dma_channel *tdc = &tdma->channels[i];
+		tdc = &tdma->channels[i];
 
 		/* Check for channel mask */
 		if (!(tdma->chan_mask & BIT(i)))
@@ -1456,10 +1465,6 @@ static int tegra_dma_probe(struct platform_device *pdev)
 
 		vchan_init(&tdc->vc, &tdma->dma_dev);
 		tdc->vc.desc_free = tegra_dma_desc_free;
-
-		/* program stream-id for this channel */
-		tegra_dma_program_sid(tdc, stream_id);
-		tdc->stream_id = stream_id;
 	}
 
 	ret = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(cdata->addr_bits));
@@ -1497,6 +1502,7 @@ static int tegra_dma_probe(struct platform_device *pdev)
 	tdma->dma_dev.device_synchronize = tegra_dma_chan_synchronize;
 	tdma->dma_dev.residue_granularity = DMA_RESIDUE_GRANULARITY_BURST;
 
+	/* Register the DMA device and the channels */
 	ret = dmaenginem_async_device_register(&tdma->dma_dev);
 	if (ret < 0) {
 		dev_err_probe(&pdev->dev, ret,
@@ -1504,6 +1510,46 @@ static int tegra_dma_probe(struct platform_device *pdev)
 		return ret;
 	}
 
+	/*
+	 * Configure stream ID for each channel from the channels registered
+	 * above. This is done in a separate iteration to ensure that only
+	 * the channels available and registered for the DMA device are used.
+	 */
+	list_for_each_entry(chan, &tdma->dma_dev.channels, device_node) {
+		chdev = &chan->dev->device;
+		tdc = to_tegra_dma_chan(chan);
+
+		if (use_iommu_map) {
+			chdev->bus = pdev->dev.bus;
+			ret = dma_coerce_mask_and_coherent(chdev, DMA_BIT_MASK(cdata->addr_bits));
+			if (ret) {
+				dev_err(chdev, "Failed to set DMA mask for channel %d: %d\n",
+					tdc->id, ret);
+				return ret;
+			}
+
+			ret = of_dma_configure_id(chdev, pdev->dev.of_node,
+						  true, &tdc->id);
+			if (ret) {
+				dev_err(chdev, "Failed to configure IOMMU for channel %d: %d\n",
+					tdc->id, ret);
+				return ret;
+			}
+
+			if (!tegra_dev_iommu_get_stream_id(chdev, &stream_id)) {
+				dev_err(chdev, "Failed to get stream ID for channel %d\n",
+					tdc->id);
+				return -EINVAL;
+			}
+
+			chan->dev->chan_dma_dev = true;
+		}
+
+		/* program stream-id for this channel */
+		tegra_dma_program_sid(tdc, stream_id);
+		tdc->stream_id = stream_id;
+	}
+
 	ret = of_dma_controller_register(pdev->dev.of_node,
 					 tegra_dma_of_xlate, tdma);
 	if (ret < 0) {
-- 
2.50.1