[PATCH v2 4/4] irqchip/gic-its: Rework platform MSI deviceID detection

From: Lorenzo Pieralisi <lpieralisi@kernel.org>
Date: 2025-10-14 09:59:08
Also in: linux-arm-kernel, linux-pci, lkml
Reply to: Lorenzo Pieralisi, 2025-10-14

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 triggers an excessive WARN_ON on wrong of_phandle_args count detection
- 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

Implement a helper function that addresses the full set of issues in one go
by consolidating 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>
Cc: Sascha Bischoff <redacted>
Cc: Thomas Gleixner <redacted>
Cc: Rob Herring <robh@kernel.org>
Cc: Frank Li <Frank.Li@nxp.com>
Cc: Marc Zyngier <maz@kernel.org>
---
 drivers/irqchip/irq-gic-its-msi-parent.c | 98 ++++++++----------------
 1 file changed, 33 insertions(+), 65 deletions(-)

diff --git a/drivers/irqchip/irq-gic-its-msi-parent.c b/drivers/irqchip/irq-gic-its-msi-parent.c
index eb1473f1448a..a65f762b7dd4 100644
--- a/drivers/irqchip/irq-gic-its-msi-parent.c
+++ b/drivers/irqchip/irq-gic-its-msi-parent.c

@@ -142,83 +142,51 @@ 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_dev_id(struct irq_domain *domain, struct device *dev, u32 *dev_id,
+				phys_addr_t *pa, bool is_v5)
 {
-	int ret, index = 0;
+	struct of_phandle_iterator it;
+	uint32_t args;
+	int ret;
 
 	/* Suck the DeviceID out of the msi-parent property */
-	do {
-		struct of_phandle_args args;
+	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) = is_v5 ? of_get_parent(it.node)
+							     : of_node_get(it.node);
 
-		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;
+		if (np == irq_domain_get_of_node(domain)) {
+			if (of_phandle_iterator_args(&it, &args, 1) != 1) {
+				dev_warn(dev, "Bogus msi-parent property\n");
+				ret = -EINVAL;
+			}
+
+			if (!ret && is_v5)
+				ret = its_translate_frame_address(it.node, pa);
+
+			if (!ret)
+				*dev_id = args;
+
+			of_node_put(it.node);
+			return ret;
 		}
-		index++;
-	} while (!ret);
-
-	if (ret) {
-		struct device_node *np = NULL;
-
-		ret = of_map_id(dev->of_node, dev->id, "msi-map", "msi-map-mask", &np, dev_id);
-		if (np)
-			of_node_put(np);
 	}
 
-	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);
+}
+
+static int of_pmsi_get_dev_id(struct irq_domain *domain, struct device *dev,
+			      u32 *dev_id)
+{
+	return __of_pmsi_get_dev_id(domain, dev, dev_id, NULL, false);
 }
 
 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) {
-		struct device_node *np = NULL;
-
-		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);
-		}
-	}
-
-	return ret;
+	return __of_pmsi_get_dev_id(domain, dev, dev_id, pa, true);
 }
 
 int __weak iort_pmsi_get_dev_id(struct device *dev, u32 *dev_id)

-- 
2.50.1

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