[RFC 3/3] iommu: arm-smmu: Get reference to memory controller

Thierry Reding thierry.reding at gmail.com
Tue Oct 15 16:29:45 UTC 2019


From: Thierry Reding <treding at nvidia.com>

Use the memory controller framework to obtain a reference to the memory
controller to which the SMMU will make memory requests. This allows the
two drivers to properly order their probes so that the memory controller
can be programmed first.

An example where this is required is Tegra186 where the stream IDs need
to be associated with memory clients before memory requests are emitted
with the correct stream ID.

Signed-off-by: Thierry Reding <treding at nvidia.com>
---
 drivers/iommu/arm-smmu.c | 12 ++++++++++++
 drivers/iommu/arm-smmu.h |  2 ++
 2 files changed, 14 insertions(+)

diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index b18aac4c105e..8dd214244926 100644
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c
@@ -2015,6 +2015,18 @@ static int arm_smmu_device_probe(struct platform_device *pdev)
 	}
 	smmu->dev = dev;
 
+	smmu->mc = memory_controller_get(dev, NULL);
+	if (IS_ERR(smmu->mc)) {
+		err = PTR_ERR(smmu->mc);
+
+		if (err != -ENODEV) {
+			dev_err(dev, "failed to get memory controller: %d\n", err);
+			return err;
+		}
+
+		smmu->mc = NULL;
+	}
+
 	if (dev->of_node)
 		err = arm_smmu_device_dt_probe(pdev, smmu);
 	else
diff --git a/drivers/iommu/arm-smmu.h b/drivers/iommu/arm-smmu.h
index b19b6cae9b5e..40b6d42eb3ab 100644
--- a/drivers/iommu/arm-smmu.h
+++ b/drivers/iommu/arm-smmu.h
@@ -17,6 +17,7 @@
 #include <linux/io-64-nonatomic-hi-lo.h>
 #include <linux/io-pgtable.h>
 #include <linux/iommu.h>
+#include <linux/memory-controller.h>
 #include <linux/mutex.h>
 #include <linux/spinlock.h>
 #include <linux/types.h>
@@ -224,6 +225,7 @@ enum arm_smmu_implementation {
 
 struct arm_smmu_device {
 	struct device			*dev;
+	struct memory_controller	*mc;
 
 	void __iomem			*base;
 	unsigned int			numpage;
-- 
2.23.0



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