iommu/arm-smmu: Play nice on non-ARM/SMMU systems
Currently the driver registers IOMMU bus operations for all busses even
if no ARM SMMU is present on a system. Depending on the driver probing
order this prevents the driver for the real IOMMU to register itself as
the bus-wide IOMMU.
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index c8fc02f..2175814 100644
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c
@@ -2075,8 +2075,20 @@
static int __init arm_smmu_init(void)
{
+ struct device_node *np;
int ret;
+ /*
+ * Play nice with systems that don't have an ARM SMMU by checking that
+ * an ARM SMMU exists in the system before proceeding with the driver
+ * and IOMMU bus operation registration.
+ */
+ np = of_find_matching_node(NULL, arm_smmu_of_match);
+ if (!np)
+ return 0;
+
+ of_node_put(np);
+
ret = platform_driver_register(&arm_smmu_driver);
if (ret)
return ret;