dmaengine: tegra: Use iommu-map for stream ID

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. However, 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
prerequisites 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@nvidia.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Link: https://patch.msgid.link/20260331102303.33181-9-akhilrajeev@nvidia.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

diff --git a/drivers/dma/tegra186-gpc-dma.c b/drivers/dma/tegra186-gpc-dma.c
index 9bea2ffb3b9e5bd3e01d8fa70db09c6301b05b2a..939eb5462d0a8e963122a1df95826bd2e9841f9e 100644 (file)
--- 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>
@@ -1380,9 +1381,13 @@ 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);
@@ -1410,9 +1415,10 @@ 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))
+                       return dev_err_probe(&pdev->dev, -EINVAL, "Missing iommu stream-id\n");
        }
 
        ret = device_property_read_u32(&pdev->dev, "dma-channel-mask",
@@ -1424,9 +1430,10 @@ 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)))
@@ -1446,10 +1453,6 @@ 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;
        }
 
        dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(cdata->addr_bits));
@@ -1483,6 +1486,7 @@ 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,
@@ -1490,6 +1494,37 @@ 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;
+                       dma_coerce_mask_and_coherent(chdev, DMA_BIT_MASK(cdata->addr_bits));
+
+                       ret = of_dma_configure_id(chdev, pdev->dev.of_node,
+                                                 true, &tdc->id);
+                       if (ret)
+                               return dev_err_probe(chdev, ret,
+                                          "Failed to configure IOMMU for channel %d\n", tdc->id);
+
+                       if (!tegra_dev_iommu_get_stream_id(chdev, &stream_id))
+                               return dev_err_probe(chdev, -EINVAL,
+                                          "Failed to get stream ID for channel %d\n", tdc->id);
+
+                       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 = devm_of_dma_controller_register(&pdev->dev, pdev->dev.of_node,
                                              tegra_dma_of_xlate, tdma);
        if (ret < 0) {