[PATCH v4 12/16] iommu/arm-smmu: Support SMMU module probing from the IORT

[Will Deacon]

From: Ard Biesheuvel <ardb@xxxxxxxxxx>

Add support for SMMU drivers built as modules to the ACPI/IORT device
probing path, by deferring the probe of the master if the SMMU driver is
known to exist but has not been loaded yet. Given that the IORT code
registers a platform device for each SMMU that it discovers, we can
easily trigger the udev based autoloading of the SMMU drivers by making
the platform device identifier part of the module alias.

Reviewed-by: Robin Murphy <robin.murphy@xxxxxxx>
Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
Tested-by: John Garry <john.garry@xxxxxxxxxx> # only manual smmu ko loading
Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
Signed-off-by: Will Deacon <will@xxxxxxxxxx>
---
 drivers/acpi/arm64/iort.c   | 4 ++--
 drivers/iommu/arm-smmu-v3.c | 1 +
 drivers/iommu/arm-smmu.c    | 1 +
 3 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
index 33f71983e001..4a560fdf7386 100644
--- a/drivers/acpi/arm64/iort.c
+++ b/drivers/acpi/arm64/iort.c
@@ -850,9 +850,9 @@ static inline bool iort_iommu_driver_enabled(u8 type)
 {
 	switch (type) {
 	case ACPI_IORT_NODE_SMMU_V3:
-		return IS_BUILTIN(CONFIG_ARM_SMMU_V3);
+		return IS_ENABLED(CONFIG_ARM_SMMU_V3);
 	case ACPI_IORT_NODE_SMMU:
-		return IS_BUILTIN(CONFIG_ARM_SMMU);
+		return IS_ENABLED(CONFIG_ARM_SMMU);
 	default:
 		pr_warn("IORT node type %u does not describe an SMMU\n", type);
 		return false;
diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index 46160a2fec3e..da9474a02668 100644
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -3734,4 +3734,5 @@ module_platform_driver(arm_smmu_driver);
 
 MODULE_DESCRIPTION("IOMMU API for ARM architected SMMUv3 implementations");
 MODULE_AUTHOR("Will Deacon <will.deacon@xxxxxxx>");
+MODULE_ALIAS("platform:arm-smmu-v3");
 MODULE_LICENSE("GPL v2");
diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index 5cbee88a3b83..5d2f60bb9e50 100644
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c
@@ -2281,4 +2281,5 @@ module_platform_driver(arm_smmu_driver);
 
 MODULE_DESCRIPTION("IOMMU API for ARM architected SMMU implementations");
 MODULE_AUTHOR("Will Deacon <will.deacon@xxxxxxx>");
+MODULE_ALIAS("platform:arm-smmu");
 MODULE_LICENSE("GPL v2");
-- 
2.24.1.735.g03f4e72817-goog