linux-kernel - [PATCH] iommu/arm-smmu: support SMMU module probing from the IORT

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Date:   Fri, 22 Nov 2019 18:41:25 +0100
From:   Ard Biesheuvel <ardb@...nel.org>
To:     will@...nel.org
Cc:     bhelgaas@...gle.com, gregkh@...uxfoundation.org,
        iommu@...ts.linuxfoundation.org, isaacm@...eaurora.org,
        jcrouse@...eaurora.org, jean-philippe@...aro.org,
        john.garry@...wei.com, joro@...tes.org,
        linux-kernel@...r.kernel.org, lorenzo.pieralisi@....com,
        robin.murphy@....com, saravanak@...gle.com,
        Ard Biesheuvel <ardb@...nel.org>
Subject: [PATCH] iommu/arm-smmu: support SMMU module probing from the IORT

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.

Signed-off-by: Ard Biesheuvel <ardb@...nel.org>
---
 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 5a7551d060f2..a696457a9b11 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 7669beafc493..bf6a1e8eb9b0 100644
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -3733,4 +3733,5 @@ module_platform_driver(arm_smmu_driver);
 
 MODULE_DESCRIPTION("IOMMU API for ARM architected SMMUv3 implementations");
 MODULE_AUTHOR("Will Deacon <will@...nel.org>");
+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 d55acc48aee3..db5106b0955b 100644
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c
@@ -2292,4 +2292,5 @@ module_platform_driver(arm_smmu_driver);
 
 MODULE_DESCRIPTION("IOMMU API for ARM architected SMMU implementations");
 MODULE_AUTHOR("Will Deacon <will@...nel.org>");
+MODULE_ALIAS("platform:arm-smmu");
 MODULE_LICENSE("GPL v2");
-- 
2.20.1