ARM: dma-mapping: Add arm_iommu_detach_device()

A counter part of arm_iommu_attach_device().

Signed-off-by: Hiroshi Doyu <hdoyu@nvidia.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>

2 files changed, 26 insertions, 0 deletions

diff --git a/arch/arm/include/asm/dma-iommu.h b/arch/arm/include/asm/dma-iommu.h
index 666d8a8c3a2b..a8c56acc8c98 100644
--- a/arch/arm/include/asm/dma-iommu.h
+++ b/arch/arm/include/asm/dma-iommu.h
@@ -30,6 +30,7 @@ void arm_iommu_release_mapping(struct dma_iommu_mapping *mapping);
 
 int arm_iommu_attach_device(struct device *dev,
                                         struct dma_iommu_mapping *mapping);
+void arm_iommu_detach_device(struct device *dev);
 
 #endif /* __KERNEL__ */
 #endif
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index d91c4880f559..6563e3872659 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -1848,4 +1848,29 @@ int arm_iommu_attach_device(struct device *dev,
         return 0;
 }
 
+/**
+ * arm_iommu_detach_device
+ * @dev: valid struct device pointer
+ *
+ * Detaches the provided device from a previously attached map.
+ * This voids the dma operations (dma_map_ops pointer)
+ */
+void arm_iommu_detach_device(struct device *dev)
+{
+        struct dma_iommu_mapping *mapping;
+
+        mapping = to_dma_iommu_mapping(dev);
+        if (!mapping) {
+                dev_warn(dev, "Not attached\n");
+                return;
+        }
+
+        iommu_detach_device(mapping->domain, dev);
+        kref_put(&mapping->kref, release_iommu_mapping);
+        mapping = NULL;
+        set_dma_ops(dev, NULL);
+
+        pr_debug("Detached IOMMU controller from %s device.\n", dev_name(dev));
+}
+
 #endif