iommu: Add a function to find an iommu group by id

[deliverable/linux.git] / drivers / iommu / iommu.c

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index b972d430d92b946eb16e98a41a2e23441b17f93e..db01af01ce0af6d60671d0ffbcf8982fd62f8367 100644 (file)
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -204,6 +204,35 @@ again:
 }
 EXPORT_SYMBOL_GPL(iommu_group_alloc);
 
+struct iommu_group *iommu_group_get_by_id(int id)
+{
+       struct kobject *group_kobj;
+       struct iommu_group *group;
+       const char *name;
+
+       if (!iommu_group_kset)
+               return NULL;
+
+       name = kasprintf(GFP_KERNEL, "%d", id);
+       if (!name)
+               return NULL;
+
+       group_kobj = kset_find_obj(iommu_group_kset, name);
+       kfree(name);
+
+       if (!group_kobj)
+               return NULL;
+
+       group = container_of(group_kobj, struct iommu_group, kobj);
+       BUG_ON(group->id != id);
+
+       kobject_get(group->devices_kobj);
+       kobject_put(&group->kobj);
+
+       return group;
+}
+EXPORT_SYMBOL_GPL(iommu_group_get_by_id);
+
 /**
  * iommu_group_get_iommudata - retrieve iommu_data registered for a group
  * @group: the group