iommu: Enable debugfs exposure of IOMMU driver internals

Provide base enablement for using debugfs to expose internal data of an
IOMMU driver. When called, create the /sys/kernel/debug/iommu directory.

Emit a strong warning at boot time to indicate that this feature is
enabled.

This function is called from iommu_init, and creates the initial DebugFS
directory. Drivers may then call iommu_debugfs_new_driver_dir() to
instantiate a device-specific directory to expose internal data.
It will return a pointer to the new dentry structure created in
/sys/kernel/debug/iommu, or NULL in the event of a failure.

Since the IOMMU driver can not be removed from the running system, there
is no need for an "off" function.

Signed-off-by: Gary R Hook <gary.hook@amd.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 63b37563db7e..d227b864a109 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1748,6 +1748,8 @@ static int __init iommu_init(void)
                                                NULL, kernel_kobj);
         BUG_ON(!iommu_group_kset);
 
+        iommu_debugfs_setup();
+
         return 0;
 }
 core_initcall(iommu_init);