[PATCH 5/5] iommu: Add iommu_get_domain_for_dev function

[Joerg Roedel <joro@8bytes.org>]

From: Joerg Roedel <jroedel@suse.de>

This function can be used to request the current domain a
device is attached to.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
 drivers/iommu/iommu.c | 18 ++++++++++++++++++
 include/linux/iommu.h |  6 ++++++
 2 files changed, 24 insertions(+)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 5080759..824442e 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1022,6 +1022,24 @@ out_unlock:
 }
 EXPORT_SYMBOL_GPL(iommu_detach_device);
 
+struct iommu_domain *iommu_get_domain_for_dev(struct device *dev)
+{
+	struct iommu_domain *domain;
+	struct iommu_group *group;
+
+	group = iommu_group_get(dev);
+	/* FIXME: Remove this when groups a mandatory for iommu drivers */
+	if (group == NULL)
+		return NULL;
+
+	domain = group->domain;
+
+	iommu_group_put(group);
+
+	return domain;
+}
+EXPORT_SYMBOL_GPL(iommu_get_domain_for_dev);
+
 /*
  * IOMMU groups are really the natrual working unit of the IOMMU, but
  * the IOMMU API works on domains and devices.  Bridge that gap by
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 2951dca..dc102ad 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -177,6 +177,7 @@ extern int iommu_attach_device(struct iommu_domain *domain,
 			       struct device *dev);
 extern void iommu_detach_device(struct iommu_domain *domain,
 				struct device *dev);
+extern struct iommu_domain *iommu_get_domain_for_dev(struct device *dev);
 extern int iommu_map(struct iommu_domain *domain, unsigned long iova,
 		     phys_addr_t paddr, size_t size, int prot);
 extern size_t iommu_unmap(struct iommu_domain *domain, unsigned long iova,
@@ -316,6 +317,11 @@ static inline void iommu_detach_device(struct iommu_domain *domain,
 {
 }
 
+static inline struct iommu_domain *iommu_get_domain_for_dev(struct device *dev)
+{
+	return NULL;
+}
+
 static inline int iommu_map(struct iommu_domain *domain, unsigned long iova,
 			    phys_addr_t paddr, int gfp_order, int prot)
 {
-- 
1.9.1