From aa16bea929aed6ea854b55d2be8306a9fb40e694 Mon Sep 17 00:00:00 2001 From: Alexey Kardashevskiy Date: Mon, 25 Mar 2013 10:23:49 +1100 Subject: iommu: Add a function to find an iommu group by id As IOMMU groups are exposed to the user space by their numbers, the user space can use them in various kernel APIs so the kernel might need an API to find a group by its ID. As an example, QEMU VFIO on PPC64 platform needs it to associate a logical bus number (LIOBN) with a specific IOMMU group in order to support in-kernel handling of DMA map/unmap requests. The patch adds the iommu_group_get_by_id(id) function which performs such search. v2: fixed reference counting. Signed-off-by: Alexey Kardashevskiy Acked-by: Alex Williamson Signed-off-by: Joerg Roedel --- drivers/iommu/iommu.c | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) (limited to 'drivers/iommu/iommu.c') diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index b972d430d92b..db01af01ce0a 100644 --- 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 -- cgit v1.2.3