iommu: of: enforce const-ness of struct iommu_ops

As a set of driver-provided callbacks and static data, there is no
compelling reason for struct iommu_ops to be mutable in core code, so
enforce const-ness throughout.

Acked-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
diff --git a/include/linux/of_iommu.h b/include/linux/of_iommu.h
index ffbe470..bd02b44 100644
--- a/include/linux/of_iommu.h
+++ b/include/linux/of_iommu.h
@@ -12,7 +12,7 @@
 			     size_t *size);
 
 extern void of_iommu_init(void);
-extern struct iommu_ops *of_iommu_configure(struct device *dev,
+extern const struct iommu_ops *of_iommu_configure(struct device *dev,
 					struct device_node *master_np);
 
 #else
@@ -25,7 +25,7 @@
 }
 
 static inline void of_iommu_init(void) { }
-static inline struct iommu_ops *of_iommu_configure(struct device *dev,
+static inline const struct iommu_ops *of_iommu_configure(struct device *dev,
 					 struct device_node *master_np)
 {
 	return NULL;
@@ -33,8 +33,8 @@
 
 #endif	/* CONFIG_OF_IOMMU */
 
-void of_iommu_set_ops(struct device_node *np, struct iommu_ops *ops);
-struct iommu_ops *of_iommu_get_ops(struct device_node *np);
+void of_iommu_set_ops(struct device_node *np, const struct iommu_ops *ops);
+const struct iommu_ops *of_iommu_get_ops(struct device_node *np);
 
 extern struct of_device_id __iommu_of_table;