linux-kernel - [PATCH 2/2] of/address: Fix WARN when attempting translating non-translatable addresses

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Message-ID: <20250110215030.3637845-2-robh@kernel.org>
Date: Fri, 10 Jan 2025 15:50:29 -0600
From: "Rob Herring (Arm)" <robh@...nel.org>
To: Michael Ellerman <mpe@...erman.id.au>,
	Saravana Kannan <saravanak@...gle.com>
Cc: linuxppc-dev@...ts.ozlabs.org,
	devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] of/address: Fix WARN when attempting translating non-translatable addresses

The recently added WARN() for deprecated #address-cells and #size-cells
triggered a WARN when of_platform_populate() (which calls
of_address_to_resource()) is used on nodes with non-translatable
addresses. This case is expected to return an error.

Rework the bus matching to allow no match and make the default require
an #address-cells property. That should be safe to do as any platform
missing #address-cells would have a warning already.

Fixes: 045b14ca5c36 ("of: WARN on deprecated #address-cells/#size-cells handling")
Signed-off-by: Rob Herring (Arm) <robh@...nel.org>
---
 drivers/of/address.c | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/drivers/of/address.c b/drivers/of/address.c
index c1f1c810e810..8770004d9b08 100644
--- a/drivers/of/address.c
+++ b/drivers/of/address.c
@@ -340,6 +340,15 @@ static int of_bus_default_flags_match(struct device_node *np)
 	return of_property_present(np, "#address-cells") && (of_bus_n_addr_cells(np) == 3);
 }
 
+static int of_bus_default_match(struct device_node *np)
+{
+	/*
+	 * Check for presence first since of_bus_n_addr_cells() will warn when
+	 * walking parent nodes.
+	 */
+	return of_property_present(np, "#address-cells");
+}
+
 /*
  * Array of bus specific translators
  */
@@ -384,7 +393,7 @@ static const struct of_bus of_busses[] = {
 	{
 		.name = "default",
 		.addresses = "reg",
-		.match = NULL,
+		.match = of_bus_default_match,
 		.count_cells = of_bus_default_count_cells,
 		.map = of_bus_default_map,
 		.translate = of_bus_default_translate,
@@ -399,7 +408,6 @@ static const struct of_bus *of_match_bus(struct device_node *np)
 	for (i = 0; i < ARRAY_SIZE(of_busses); i++)
 		if (!of_busses[i].match || of_busses[i].match(np))
 			return &of_busses[i];
-	BUG();
 	return NULL;
 }
 
@@ -521,6 +529,8 @@ static u64 __of_translate_address(struct device_node *node,
 	if (parent == NULL)
 		return OF_BAD_ADDR;
 	bus = of_match_bus(parent);
+	if (!bus)
+		return OF_BAD_ADDR;
 
 	/* Count address cells & copy address locally */
 	bus->count_cells(dev, &na, &ns);
@@ -564,6 +574,8 @@ static u64 __of_translate_address(struct device_node *node,
 
 		/* Get new parent bus and counts */
 		pbus = of_match_bus(parent);
+		if (!pbus)
+			return OF_BAD_ADDR;
 		pbus->count_cells(dev, &pna, &pns);
 		if (!OF_CHECK_COUNTS(pna, pns)) {
 			pr_err("Bad cell count for %pOF\n", dev);
@@ -703,7 +715,7 @@ const __be32 *__of_get_address(struct device_node *dev, int index, int bar_no,
 
 	/* match the parent's bus type */
 	bus = of_match_bus(parent);
-	if (strcmp(bus->name, "pci") && (bar_no >= 0))
+	if (!bus || (strcmp(bus->name, "pci") && (bar_no >= 0)))
 		return NULL;
 
 	/* Get "reg" or "assigned-addresses" property */
-- 
2.45.2