irqchip/gic-its: Rework platform MSI deviceID detection

Current code retrieving platform devices MSI devID in the GIC ITS MSI
parent helpers suffers from some minor issues:

- It leaks a struct device_node reference
- It is duplicated between GICv3 and GICv5 for no good reason
- It does not use the OF phandle iterator code that simplifies
  the msi-parent property parsing

Consolidate GIC v3 and v5 deviceID retrieval in a function that addresses
the full set of issues in one go by merging GIC v3 and v5 code and
converting the msi-parent parsing loop to the more modern OF phandle
iterator API, fixing the struct device_node reference leak in the process.

Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://patch.msgid.link/20251021124103.198419-6-lpieralisi@kernel.org

Author: Lorenzo Pieralisi

drivers/irqchip/irq-gic-its-msi-parent.c

@@ -142,83 +142,38 @@ static int its_v5_pci_msi_prepare(struct irq_domain *domain, struct device *dev,
 #define its_v5_pci_msi_prepare	NULL
 #endif /* !CONFIG_PCI_MSI */
 
-static int of_pmsi_get_dev_id(struct irq_domain *domain, struct device *dev,
-				  u32 *dev_id)
+static int of_pmsi_get_msi_info(struct irq_domain *domain, struct device *dev, u32 *dev_id,
+				phys_addr_t *pa)
 {
-	int ret, index = 0;
+	struct of_phandle_iterator it;
+	int ret;
 
 	/* Suck the DeviceID out of the msi-parent property */
-	do {
-		struct of_phandle_args args;
-
-		ret = of_parse_phandle_with_args(dev->of_node,
-						 "msi-parent", "#msi-cells",
-						 index, &args);
-		if (args.np == irq_domain_get_of_node(domain)) {
-			if (WARN_ON(args.args_count != 1))
-				return -EINVAL;
-			*dev_id = args.args[0];
-			break;
-		}
-		index++;
-	} while (!ret);
-
-	if (ret) {
-		struct device_node *np = NULL;
+	of_for_each_phandle(&it, ret, dev->of_node, "msi-parent", "#msi-cells", -1) {
+		/* GICv5 ITS domain matches the MSI controller node parent */
+		struct device_node *np __free(device_node) = pa ? of_get_parent(it.node)
+								: of_node_get(it.node);
 
-		ret = of_map_id(dev->of_node, dev->id, "msi-map", "msi-map-mask", &np, dev_id);
-		if (np)
-			of_node_put(np);
-	}
+		if (np == irq_domain_get_of_node(domain)) {
+			u32 args;
 
-	return ret;
-}
+			if (WARN_ON(of_phandle_iterator_args(&it, &args, 1) != 1))
+				ret = -EINVAL;
 
-static int of_v5_pmsi_get_msi_info(struct irq_domain *domain, struct device *dev,
-				   u32 *dev_id, phys_addr_t *pa)
-{
-	int ret, index = 0;
-	/*
-	 * Retrieve the DeviceID and the ITS translate frame node pointer
-	 * out of the msi-parent property.
-	 */
-	do {
-		struct of_phandle_args args;
-
-		ret = of_parse_phandle_with_args(dev->of_node,
-						 "msi-parent", "#msi-cells",
-						 index, &args);
-		if (ret)
-			break;
-		/*
-		 * The IRQ domain fwnode is the msi controller parent
-		 * in GICv5 (where the msi controller nodes are the
-		 * ITS translate frames).
-		 */
-		if (args.np->parent == irq_domain_get_of_node(domain)) {
-			if (WARN_ON(args.args_count != 1))
-				return -EINVAL;
-			*dev_id = args.args[0];
-
-			ret = its_translate_frame_address(args.np, pa);
-			if (ret)
-				return -ENODEV;
-			break;
-		}
-		index++;
-	} while (!ret);
+			if (!ret && pa)
+				ret = its_translate_frame_address(it.node, pa);
 
-	if (ret) {
-		struct device_node *np = NULL;
+			if (!ret)
+				*dev_id = args;
 
-		ret = of_map_id(dev->of_node, dev->id, "msi-map", "msi-map-mask", &np, dev_id);
-		if (np) {
-			ret = its_translate_frame_address(np, pa);
-			of_node_put(np);
+			of_node_put(it.node);
+			return ret;
 		}
 	}
 
-	return ret;
+	struct device_node *msi_ctrl __free(device_node) = NULL;
+
+	return of_map_id(dev->of_node, dev->id, "msi-map", "msi-map-mask", &msi_ctrl, dev_id);
 }
 
 int __weak iort_pmsi_get_dev_id(struct device *dev, u32 *dev_id)
@@ -234,7 +189,7 @@ static int its_pmsi_prepare(struct irq_domain *domain, struct device *dev,
 	int ret;
 
 	if (dev->of_node)
-		ret = of_pmsi_get_dev_id(domain->parent, dev, &dev_id);
+		ret = of_pmsi_get_msi_info(domain->parent, dev, &dev_id, NULL);
 	else
 		ret = iort_pmsi_get_dev_id(dev, &dev_id);
 	if (ret)
@@ -262,7 +217,7 @@ static int its_v5_pmsi_prepare(struct irq_domain *domain, struct device *dev,
 	if (!dev->of_node)
 		return -ENODEV;
 
-	ret = of_v5_pmsi_get_msi_info(domain->parent, dev, &dev_id, &pa);
+	ret = of_pmsi_get_msi_info(domain->parent, dev, &dev_id, &pa);
 	if (ret)
 		return ret;