iommu: Move dev_iommu_ops() to private header

dev_iommu_ops() is essentially only used in iommu subsystem, so move to a
private header to avoid being abused by other drivers.

Link: https://lore.kernel.org/r/20230818101033.4100-2-yi.l.liu@intel.com
Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

Author: yiliu1765

drivers/iommu/iommu-priv.h

@@ -6,6 +6,17 @@
 
 #include <linux/iommu.h>
 
+static inline const struct iommu_ops *dev_iommu_ops(struct device *dev)
+{
+	/*
+	 * Assume that valid ops must be installed if iommu_probe_device()
+	 * has succeeded. The device ops are essentially for internal use
+	 * within the IOMMU subsystem itself, so we should be able to trust
+	 * ourselves not to misuse the helper.
+	 */
+	return dev->iommu->iommu_dev->ops;
+}
+
 int iommu_group_replace_domain(struct iommu_group *group,
 			       struct iommu_domain *new_domain);
 

include/linux/iommu.h

@@ -450,17 +450,6 @@ static inline void iommu_iotlb_gather_init(struct iommu_iotlb_gather *gather)
 	};
 }
 
-static inline const struct iommu_ops *dev_iommu_ops(struct device *dev)
-{
-	/*
-	 * Assume that valid ops must be installed if iommu_probe_device()
-	 * has succeeded. The device ops are essentially for internal use
-	 * within the IOMMU subsystem itself, so we should be able to trust
-	 * ourselves not to misuse the helper.
-	 */
-	return dev->iommu->iommu_dev->ops;
-}
-
 extern int bus_iommu_probe(const struct bus_type *bus);
 extern bool iommu_present(const struct bus_type *bus);
 extern bool device_iommu_capable(struct device *dev, enum iommu_cap cap);