iommu: Make of_iommu_set/get_ops() DT agnostic

The of_iommu_{set/get}_ops() API is used to associate a device
tree node with a specific set of IOMMU operations. The same
kernel interface is required on systems booting with ACPI, where
devices are not associated with a device tree node, therefore
the interface requires generalization.

The struct device fwnode member represents the fwnode token associated
with the device and the struct it points at is firmware specific;
regardless, it is initialized on both ACPI and DT systems and makes an
ideal candidate to use it to associate a set of IOMMU operations to a
given device, through its struct device.fwnode member pointer, paving
the way for representing per-device iommu_ops (ie an iommu instance
associated with a device).

Convert the DT specific of_iommu_{set/get}_ops() interface to
use struct device.fwnode as a look-up token, making the interface
usable on ACPI systems and rename the data structures and the
registration API so that they are made to represent their usage
more clearly.

Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: Tomasz Nowicki <tn@semihalf.com>
Tested-by: Hanjun Guo <hanjun.guo@linaro.org>
Tested-by: Tomasz Nowicki <tn@semihalf.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Hanjun Guo <hanjun.guo@linaro.org>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Joerg Roedel <joro@8bytes.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>

drivers/iommu/iommu.c

@@ -1615,6 +1615,46 @@ int iommu_request_dm_for_dev(struct device *dev)
 	return ret;
 }
 
+struct iommu_instance {
+	struct list_head list;
+	struct fwnode_handle *fwnode;
+	const struct iommu_ops *ops;
+};
+static LIST_HEAD(iommu_instance_list);
+static DEFINE_SPINLOCK(iommu_instance_lock);
+
+void iommu_register_instance(struct fwnode_handle *fwnode,
+			     const struct iommu_ops *ops)
+{
+	struct iommu_instance *iommu = kzalloc(sizeof(*iommu), GFP_KERNEL);
+
+	if (WARN_ON(!iommu))
+		return;
+
+	of_node_get(to_of_node(fwnode));
+	INIT_LIST_HEAD(&iommu->list);
+	iommu->fwnode = fwnode;
+	iommu->ops = ops;
+	spin_lock(&iommu_instance_lock);
+	list_add_tail(&iommu->list, &iommu_instance_list);
+	spin_unlock(&iommu_instance_lock);
+}
+
+const struct iommu_ops *iommu_get_instance(struct fwnode_handle *fwnode)
+{
+	struct iommu_instance *instance;
+	const struct iommu_ops *ops = NULL;
+
+	spin_lock(&iommu_instance_lock);
+	list_for_each_entry(instance, &iommu_instance_list, list)
+		if (instance->fwnode == fwnode) {
+			ops = instance->ops;
+			break;
+		}
+	spin_unlock(&iommu_instance_lock);
+	return ops;
+}
+
 int iommu_fwspec_init(struct device *dev, struct fwnode_handle *iommu_fwnode,
 		      const struct iommu_ops *ops)
 {

drivers/iommu/of_iommu.c

@@ -96,45 +96,6 @@ int of_get_dma_window(struct device_node *dn, const char *prefix, int index,
 }
 EXPORT_SYMBOL_GPL(of_get_dma_window);
 
-struct of_iommu_node {
-	struct list_head list;
-	struct device_node *np;
-	const struct iommu_ops *ops;
-};
-static LIST_HEAD(of_iommu_list);
-static DEFINE_SPINLOCK(of_iommu_lock);
-
-void of_iommu_set_ops(struct device_node *np, const struct iommu_ops *ops)
-{
-	struct of_iommu_node *iommu = kzalloc(sizeof(*iommu), GFP_KERNEL);
-
-	if (WARN_ON(!iommu))
-		return;
-
-	of_node_get(np);
-	INIT_LIST_HEAD(&iommu->list);
-	iommu->np = np;
-	iommu->ops = ops;
-	spin_lock(&of_iommu_lock);
-	list_add_tail(&iommu->list, &of_iommu_list);
-	spin_unlock(&of_iommu_lock);
-}
-
-const struct iommu_ops *of_iommu_get_ops(struct device_node *np)
-{
-	struct of_iommu_node *node;
-	const struct iommu_ops *ops = NULL;
-
-	spin_lock(&of_iommu_lock);
-	list_for_each_entry(node, &of_iommu_list, list)
-		if (node->np == np) {
-			ops = node->ops;
-			break;
-		}
-	spin_unlock(&of_iommu_lock);
-	return ops;
-}
-
 static int __get_pci_rid(struct pci_dev *pdev, u16 alias, void *data)
 {
 	struct of_phandle_args *iommu_spec = data;

include/linux/iommu.h

@@ -351,6 +351,9 @@ int iommu_fwspec_init(struct device *dev, struct fwnode_handle *iommu_fwnode,
 		      const struct iommu_ops *ops);
 void iommu_fwspec_free(struct device *dev);
 int iommu_fwspec_add_ids(struct device *dev, u32 *ids, int num_ids);
+void iommu_register_instance(struct fwnode_handle *fwnode,
+			     const struct iommu_ops *ops);
+const struct iommu_ops *iommu_get_instance(struct fwnode_handle *fwnode);
 
 #else /* CONFIG_IOMMU_API */
 
@@ -580,6 +583,17 @@ static inline int iommu_fwspec_add_ids(struct device *dev, u32 *ids,
 	return -ENODEV;
 }
 
+static inline void iommu_register_instance(struct fwnode_handle *fwnode,
+					   const struct iommu_ops *ops)
+{
+}
+
+static inline
+const struct iommu_ops *iommu_get_instance(struct fwnode_handle *fwnode)
+{
+	return NULL;
+}
+
 #endif /* CONFIG_IOMMU_API */
 
 #endif /* __LINUX_IOMMU_H */

include/linux/of_iommu.h

@@ -31,8 +31,16 @@ static inline const struct iommu_ops *of_iommu_configure(struct device *dev,
 
 #endif	/* CONFIG_OF_IOMMU */
 
-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);
+static inline void of_iommu_set_ops(struct device_node *np,
+				    const struct iommu_ops *ops)
+{
+	iommu_register_instance(&np->fwnode, ops);
+}
+
+static inline const struct iommu_ops *of_iommu_get_ops(struct device_node *np)
+{
+	return iommu_get_instance(&np->fwnode);
+}
 
 extern struct of_device_id __iommu_of_table;