1 files changed, 95 insertions, 31 deletions

diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c
index 2683e9fc0dcf..9f44ee8ea1bc 100644
--- a/drivers/iommu/of_iommu.c
+++ b/drivers/iommu/of_iommu.c
@@ -96,6 +96,49 @@ int of_get_dma_window(struct device_node *dn, const char *prefix, int index,
 }
 EXPORT_SYMBOL_GPL(of_get_dma_window);
 
+static bool of_iommu_driver_present(struct device_node *np)
+{
+	/*
+	 * If the IOMMU still isn't ready by the time we reach init, assume
+	 * it never will be. We don't want to defer indefinitely, nor attempt
+	 * to dereference __iommu_of_table after it's been freed.
+	 */
+	if (system_state > SYSTEM_BOOTING)
+		return false;
+
+	return of_match_node(&__iommu_of_table, np);
+}
+
+static const struct iommu_ops
+*of_iommu_xlate(struct device *dev, struct of_phandle_args *iommu_spec)
+{
+	const struct iommu_ops *ops;
+	struct fwnode_handle *fwnode = &iommu_spec->np->fwnode;
+	int err;
+
+	ops = iommu_ops_from_fwnode(fwnode);
+	if ((ops && !ops->of_xlate) ||
+	    (!ops && !of_iommu_driver_present(iommu_spec->np)))
+		return NULL;
+
+	err = iommu_fwspec_init(dev, &iommu_spec->np->fwnode, ops);
+	if (err)
+		return ERR_PTR(err);
+	/*
+	 * The otherwise-empty fwspec handily serves to indicate the specific
+	 * IOMMU device we're waiting for, which will be useful if we ever get
+	 * a proper probe-ordering dependency mechanism in future.
+	 */
+	if (!ops)
+		return ERR_PTR(-EPROBE_DEFER);
+
+	err = ops->of_xlate(dev, iommu_spec);
+	if (err)
+		return ERR_PTR(err);
+
+	return ops;
+}
+
 static int __get_pci_rid(struct pci_dev *pdev, u16 alias, void *data)
 {
 	struct of_phandle_args *iommu_spec = data;
@@ -105,10 +148,11 @@ static int __get_pci_rid(struct pci_dev *pdev, u16 alias, void *data)
 }
 
 static const struct iommu_ops
-*of_pci_iommu_configure(struct pci_dev *pdev, struct device_node *bridge_np)
+*of_pci_iommu_init(struct pci_dev *pdev, struct device_node *bridge_np)
 {
 	const struct iommu_ops *ops;
 	struct of_phandle_args iommu_spec;
+	int err;
 
 	/*
 	 * Start by tracing the RID alias down the PCI topology as
@@ -123,56 +167,76 @@ static const struct iommu_ops
 	 * bus into the system beyond, and which IOMMU it ends up at.
 	 */
 	iommu_spec.np = NULL;
-	if (of_pci_map_rid(bridge_np, iommu_spec.args[0], "iommu-map",
-			   "iommu-map-mask", &iommu_spec.np, iommu_spec.args))
-		return NULL;
+	err = of_pci_map_rid(bridge_np, iommu_spec.args[0], "iommu-map",
+			     "iommu-map-mask", &iommu_spec.np,
+			     iommu_spec.args);
+	if (err)
+		return err == -ENODEV ? NULL : ERR_PTR(err);
 
-	ops = iommu_ops_from_fwnode(&iommu_spec.np->fwnode);
-	if (!ops || !ops->of_xlate ||
-	    iommu_fwspec_init(&pdev->dev, &iommu_spec.np->fwnode, ops) ||
-	    ops->of_xlate(&pdev->dev, &iommu_spec))
-		ops = NULL;
+	ops = of_iommu_xlate(&pdev->dev, &iommu_spec);
 
 	of_node_put(iommu_spec.np);
 	return ops;
 }
 
-const struct iommu_ops *of_iommu_configure(struct device *dev,
-					   struct device_node *master_np)
+static const struct iommu_ops
+*of_platform_iommu_init(struct device *dev, struct device_node *np)
 {
 	struct of_phandle_args iommu_spec;
-	struct device_node *np;
 	const struct iommu_ops *ops = NULL;
 	int idx = 0;
 
-	if (dev_is_pci(dev))
-		return of_pci_iommu_configure(to_pci_dev(dev), master_np);
-
 	/*
 	 * We don't currently walk up the tree looking for a parent IOMMU.
 	 * See the `Notes:' section of
 	 * Documentation/devicetree/bindings/iommu/iommu.txt
 	 */
-	while (!of_parse_phandle_with_args(master_np, "iommus",
-					   "#iommu-cells", idx,
-					   &iommu_spec)) {
-		np = iommu_spec.np;
-		ops = iommu_ops_from_fwnode(&np->fwnode);
-
-		if (!ops || !ops->of_xlate ||
-		    iommu_fwspec_init(dev, &np->fwnode, ops) ||
-		    ops->of_xlate(dev, &iommu_spec))
-			goto err_put_node;
-
-		of_node_put(np);
+	while (!of_parse_phandle_with_args(np, "iommus", "#iommu-cells",
+					   idx, &iommu_spec)) {
+		ops = of_iommu_xlate(dev, &iommu_spec);
+		of_node_put(iommu_spec.np);
 		idx++;
+		if (IS_ERR_OR_NULL(ops))
+			break;
 	}
 
 	return ops;
+}
+
+const struct iommu_ops *of_iommu_configure(struct device *dev,
+					   struct device_node *master_np)
+{
+	const struct iommu_ops *ops;
+	struct iommu_fwspec *fwspec = dev->iommu_fwspec;
+
+	if (!master_np)
+		return NULL;
+
+	if (fwspec) {
+		if (fwspec->ops)
+			return fwspec->ops;
+
+		/* In the deferred case, start again from scratch */
+		iommu_fwspec_free(dev);
+	}
 
-err_put_node:
-	of_node_put(np);
-	return NULL;
+	if (dev_is_pci(dev))
+		ops = of_pci_iommu_init(to_pci_dev(dev), master_np);
+	else
+		ops = of_platform_iommu_init(dev, master_np);
+	/*
+	 * If we have reason to believe the IOMMU driver missed the initial
+	 * add_device callback for dev, replay it to get things in order.
+	 */
+	if (!IS_ERR_OR_NULL(ops) && ops->add_device &&
+	    dev->bus && !dev->iommu_group) {
+		int err = ops->add_device(dev);
+
+		if (err)
+			ops = ERR_PTR(err);
+	}
+
+	return ops;
 }
 
 static int __init of_iommu_init(void)
@@ -183,7 +247,7 @@ static int __init of_iommu_init(void)
 	for_each_matching_node_and_match(np, matches, &match) {
 		const of_iommu_init_fn init_fn = match->data;
 
-		if (init_fn(np))
+		if (init_fn && init_fn(np))
 			pr_err("Failed to initialise IOMMU %s\n",
 				of_node_full_name(np));
 	}