[PATCH v2 04/12] media: iris: Add helper to create a context bank device

[Vikash Garodia]

The VPU issues DMA through several SMMU streams, and the hardware does
not give every stream the same addressable range. The non-pixel stream
is restricted to use 0-600MB of IOVA space, while the pixel stream can
address the full range. A stream can only be confined to its range if it
has an IOMMU domain of its own, and the IOMMU core attaches a domain per
struct device, so each stream needs its own device.
Add iris_create_cb_dev(), which looks up a named child of the iris node
and registers it as a platform device parented to the iris core. The
child's fwnode is handed to platform_device_register_full() so the OF
core applies that subnode's "iommus" property and the new device gets
its own IOMMU domain. The DMA mask comes from platform data, and the
segment size and boundary are capped at 32 bits to match the addressing
the VPU performs.
Return NULL when the named child is absent, so callers can treat a
device tree without context bank subnodes as a supported configuration
rather than an error.
Backports are intended since the first DTS of 8550 binding schema.

Fixes: 41661853ae8e ("arm64: dts: qcom: sm8550: add iris DT node")
Cc: stable@xxxxxxxxxxxxxxx
Co-developed-by: Vishnu Reddy <busanna.reddy@xxxxxxxxxxxxxxxx>
Signed-off-by: Vishnu Reddy <busanna.reddy@xxxxxxxxxxxxxxxx>
Tested-by: Daniel J Blueman <daniel@xxxxxxxxx>
Signed-off-by: Vikash Garodia <vikash.garodia@xxxxxxxxxxxxxxxx>
---
 drivers/media/platform/qcom/iris/iris_resources.c | 28 +++++++++++++++++++++++
 drivers/media/platform/qcom/iris/iris_resources.h |  1 +
 2 files changed, 29 insertions(+)

diff --git a/drivers/media/platform/qcom/iris/iris_resources.c b/drivers/media/platform/qcom/iris/iris_resources.c
index 872bd09656b151eb9ed5eda2f9774d3095d3aeeb..9e02a92baae75803c2c12a2ca994006987c69596 100644
--- a/drivers/media/platform/qcom/iris/iris_resources.c
+++ b/drivers/media/platform/qcom/iris/iris_resources.c
@@ -5,6 +5,7 @@
 
 #include <linux/clk.h>
 #include <linux/devfreq.h>
+#include <linux/dma-mapping.h>
 #include <linux/interconnect.h>
 #include <linux/pm_domain.h>
 #include <linux/pm_opp.h>
@@ -137,3 +138,30 @@ int iris_disable_unprepare_clock(struct iris_core *core, enum platform_clk_type
 
 	return 0;
 }
+
+struct device *iris_create_cb_dev(struct iris_core *core, const char *name)
+{
+	struct platform_device_info plat_dev_info = {};
+	struct device_node *child_of_node;
+	struct platform_device *pdev;
+
+	child_of_node = of_get_child_by_name(core->dev->of_node, name);
+	if (!child_of_node)
+		return NULL;
+
+	plat_dev_info.dma_mask = core->iris_platform_data->dma_mask;
+	plat_dev_info.fwnode = &child_of_node->fwnode;
+	plat_dev_info.name = child_of_node->name;
+	plat_dev_info.id = PLATFORM_DEVID_AUTO;
+	plat_dev_info.parent = core->dev;
+
+	pdev = platform_device_register_full(&plat_dev_info);
+	of_node_put(child_of_node);
+	if (IS_ERR(pdev))
+		return ERR_CAST(pdev);
+
+	dma_set_max_seg_size(&pdev->dev, DMA_BIT_MASK(32));
+	dma_set_seg_boundary(&pdev->dev, DMA_BIT_MASK(32));
+
+	return &pdev->dev;
+}
diff --git a/drivers/media/platform/qcom/iris/iris_resources.h b/drivers/media/platform/qcom/iris/iris_resources.h
index 6bfbd2dc6db095ec05e53c894e048285f82446c6..ca53c01f60aef2040002f526b8f1b6a9094d1518 100644
--- a/drivers/media/platform/qcom/iris/iris_resources.h
+++ b/drivers/media/platform/qcom/iris/iris_resources.h
@@ -15,5 +15,6 @@ int iris_unset_icc_bw(struct iris_core *core);
 int iris_set_icc_bw(struct iris_core *core, unsigned long icc_bw);
 int iris_disable_unprepare_clock(struct iris_core *core, enum platform_clk_type clk_type);
 int iris_prepare_enable_clock(struct iris_core *core, enum platform_clk_type clk_type);
+struct device *iris_create_cb_dev(struct iris_core *core, const char *name);
 
 #endif

-- 
2.34.1