[PATCH V7 05/11] ACPI/IORT: Add function to check SMMUs drivers presence

Sricharan R sricharan at codeaurora.org
Mon Jan 23 08:18:07 PST 2017

From: Lorenzo Pieralisi <lorenzo.pieralisi at arm.com>

The IOMMU probe deferral implementation requires a mechanism to detect
if drivers for SMMU components are built-in in the kernel to detect
whether IOMMU configuration for a given device should be deferred (ie
SMMU drivers present but still not probed) or not (drivers not present).

Add a simple function to IORT to detect if SMMU drivers for SMMU
components managed by IORT are built-in in the kernel.

Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi at arm.com>
Cc: Robin Murphy <robin.murphy at arm.com>
Cc: Sricharan R <sricharan at codeaurora.org>
 drivers/acpi/arm64/iort.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
index e0d2e6e..bf0ed09 100644
--- a/drivers/acpi/arm64/iort.c
+++ b/drivers/acpi/arm64/iort.c
@@ -523,6 +523,19 @@ static int arm_smmu_iort_xlate(struct device *dev, u32 streamid,
 	return ret;
+static inline bool iort_iommu_driver_enabled(u8 type)
+	switch (type) {
+	default:
+		pr_warn("IORT node type %u does not describe an SMMU\n", type);
+		return false;
+	}
 static const struct iommu_ops *iort_iommu_xlate(struct device *dev,
 					struct acpi_iort_node *node,
 					u32 streamid)
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