[PATCH RFC 1/2] of: property: fw_devlink: Follow GPIO nexus maps

[Ernest Van Hoecke]

From: Ernest Van Hoecke <ernest.vanhoecke@xxxxxxxxxxx>

GPIO consumers use of_parse_phandle_with_args_map() to resolve specifiers
through gpio-map properties. fw_devlink instead parses GPIO properties as
direct phandle references, so it records the nexus node as the supplier
rather than the mapped GPIO provider.

A nexus is a translation node, not the GPIO provider, and need not be
populated as a device. The resulting fwnode link can therefore remain
unresolved and indefinitely defer the consumer while
device_links_check_suppliers() waits for the nexus.

Use the map-aware parser for all supported GPIO property spellings. This
makes fw_devlink resolve the same provider as the GPIO consumer API. Direct
GPIO references continue to work because the map-aware parser returns the
original provider when no gpio-map property is present.

Add OF unittest coverage for mapped and direct GPIO suppliers, including
the deprecated singular and unprefixed property spellings.

Fixes: 7f00be96f125 ("of: property: Add device link support for interrupt-parent, dmas and -gpio(s)")
Reported-by: Leonardo Costa <leonardo.costa@xxxxxxxxxxx>
Link: https://lore.kernel.org/all/juuc4af7ndbajcl7gzf4tg5qz2q2j5tt3rvql4jbauradujrre@gc5nbdhhixaf/
Tested-by: Leonardo Costa <leonardo.costa@xxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Ernest Van Hoecke <ernest.vanhoecke@xxxxxxxxxxx>
---
 drivers/of/property.c                       | 38 +++++++++++-----
 drivers/of/unittest-data/tests-phandle.dtsi | 33 ++++++++++++++
 drivers/of/unittest.c                       | 67 +++++++++++++++++++++++++++++
 3 files changed, 128 insertions(+), 10 deletions(-)

diff --git a/drivers/of/property.c b/drivers/of/property.c
index 72cf12907de0..380df0861ab9 100644
--- a/drivers/of/property.c
+++ b/drivers/of/property.c
@@ -1311,6 +1311,19 @@ static struct device_node *parse_prop_cells(struct device_node *np,
 	return sup_args.np;
 }
 
+static struct device_node *parse_nexus_prop(struct device_node *np,
+					    const char *prop_name, int index,
+					    const char *stem_name)
+{
+	struct of_phandle_args sup_args;
+
+	if (of_parse_phandle_with_args_map(np, prop_name, stem_name, index,
+					   &sup_args))
+		return NULL;
+
+	return sup_args.np;
+}
+
 #define DEFINE_SIMPLE_PROP(fname, name, cells)				  \
 static struct device_node *parse_##fname(struct device_node *np,	  \
 					const char *prop_name, int index) \
@@ -1361,6 +1374,15 @@ static struct device_node *parse_##fname(struct device_node *np,	     \
 	return parse_suffix_prop_cells(np, prop_name, index, suffix, cells); \
 }
 
+#define DEFINE_SUFFIX_NEXUS_PROP(fname, suffix, stem)			     \
+static struct device_node *parse_##fname(struct device_node *np,	     \
+					const char *prop_name, int index)    \
+{									     \
+	if (!strends(prop_name, suffix))				     \
+		return NULL;						     \
+	return parse_nexus_prop(np, prop_name, index, stem);		     \
+}
+
 /**
  * struct supplier_bindings - Property parsing functions for suppliers
  *
@@ -1416,7 +1438,7 @@ DEFINE_SIMPLE_PROP(pses, "pses", "#pse-cells")
 DEFINE_SIMPLE_PROP(power_supplies, "power-supplies", NULL)
 DEFINE_SIMPLE_PROP(mmc_pwrseq, "mmc-pwrseq", NULL)
 DEFINE_SUFFIX_PROP(regulators, "-supply", NULL)
-DEFINE_SUFFIX_PROP(gpio, "-gpio", "#gpio-cells")
+DEFINE_SUFFIX_NEXUS_PROP(gpio, "-gpio", "gpio")
 
 static struct device_node *parse_pinctrl_n(struct device_node *np,
 					   const char *prop_name, int index)
@@ -1436,8 +1458,10 @@ static struct device_node *parse_gpios(struct device_node *np,
 	if (strends(prop_name, ",nr-gpios"))
 		return NULL;
 
-	return parse_suffix_prop_cells(np, prop_name, index, "-gpios",
-				       "#gpio-cells");
+	if (!strends(prop_name, "-gpios"))
+		return NULL;
+
+	return parse_nexus_prop(np, prop_name, index, "gpio");
 }
 
 static struct device_node *parse_iommu_maps(struct device_node *np,
@@ -1452,8 +1476,6 @@ static struct device_node *parse_iommu_maps(struct device_node *np,
 static struct device_node *parse_gpio_compat(struct device_node *np,
 					     const char *prop_name, int index)
 {
-	struct of_phandle_args sup_args;
-
 	if (strcmp(prop_name, "gpio") && strcmp(prop_name, "gpios"))
 		return NULL;
 
@@ -1464,11 +1486,7 @@ static struct device_node *parse_gpio_compat(struct device_node *np,
 	if (of_property_read_bool(np, "gpio-hog"))
 		return NULL;
 
-	if (of_parse_phandle_with_args(np, prop_name, "#gpio-cells", index,
-				       &sup_args))
-		return NULL;
-
-	return sup_args.np;
+	return parse_nexus_prop(np, prop_name, index, "gpio");
 }
 
 static struct device_node *parse_interrupts(struct device_node *np,
diff --git a/drivers/of/unittest-data/tests-phandle.dtsi b/drivers/of/unittest-data/tests-phandle.dtsi
index 554a996b2ef1..163ef07be16d 100644
--- a/drivers/of/unittest-data/tests-phandle.dtsi
+++ b/drivers/of/unittest-data/tests-phandle.dtsi
@@ -79,6 +79,39 @@ consumer-b {
 				phandle-list-bad-args = <&provider2 1 0>,
 							<&provider4 0>;
 			};
+
+			fw-devlink-tests {
+				gpio_provider: gpio-controller {
+					#gpio-cells = <2>;
+				};
+
+				test_nexus: nexus {
+					#gpio-cells = <2>;
+					gpio-map = <0 0 &gpio_provider 1 0>;
+					gpio-map-mask = <0xffffffff 0>;
+					gpio-map-pass-thru = <0 0xffffffff>;
+				};
+
+				gpio-compat-consumer {
+					gpios = <&test_nexus 0 0>;
+				};
+
+				gpio-compat-singular-consumer {
+					gpio = <&test_nexus 0 0>;
+				};
+
+				gpio-consumer {
+					test-gpios = <&test_nexus 0 0>;
+				};
+
+				gpio-direct-consumer {
+					test-gpios = <&gpio_provider 1 0>;
+				};
+
+				gpio-singular-consumer {
+					test-gpio = <&test_nexus 0 0>;
+				};
+			};
 		};
 	};
 };
diff --git a/drivers/of/unittest.c b/drivers/of/unittest.c
index e255f54f4d76..487f3b629a73 100644
--- a/drivers/of/unittest.c
+++ b/drivers/of/unittest.c
@@ -10,6 +10,7 @@
 #include <linux/dma-direct.h> /* to test phys_to_dma/dma_to_phys */
 #include <linux/err.h>
 #include <linux/errno.h>
+#include <linux/fwnode.h>
 #include <linux/hashtable.h>
 #include <linux/libfdt.h>
 #include <linux/of.h>
@@ -710,6 +711,71 @@ static void __init of_unittest_parse_phandle_with_args_map(void)
 	}
 }
 
+static void __init of_unittest_fw_devlink_supplier(struct device_node *tests,
+						   const char *consumer_name,
+						   const char *supplier_name)
+{
+	struct device_node *consumer, *supplier;
+	struct fwnode_handle *consumer_fwnode;
+	struct fwnode_link *link;
+	unsigned int link_count = 0;
+	bool found = false;
+	int rc;
+
+	consumer = of_get_child_by_name(tests, consumer_name);
+	supplier = of_get_child_by_name(tests, supplier_name);
+	if (!consumer || !supplier) {
+		pr_err("missing consumer %s or supplier %s\n", consumer_name, supplier_name);
+		goto put_nodes;
+	}
+
+	consumer_fwnode = of_fwnode_handle(consumer);
+	fwnode_links_purge(consumer_fwnode);
+	rc = fwnode_call_int_op(consumer_fwnode, add_links);
+	if (unittest(!rc, "failed to add links for %pOF: %d\n", consumer, rc))
+		goto purge_links;
+
+	/*
+	 * fwnode_link_lock is private to the driver core. These test nodes are
+	 * isolated and no one should modify their links now, so it is safe to
+	 * inspect the supplier list without the lock here.
+	 */
+	list_for_each_entry(link, &consumer_fwnode->suppliers, c_hook) {
+		link_count++;
+		if (link->supplier == of_fwnode_handle(supplier))
+			found = true;
+	}
+
+	unittest(link_count == 1, "%pOF has %u suppliers, expected 1\n", consumer, link_count);
+	unittest(found, "%pOF is not linked to supplier %pOF\n", consumer, supplier);
+
+purge_links:
+	fwnode_links_purge(consumer_fwnode);
+put_nodes:
+	of_node_put(consumer);
+	of_node_put(supplier);
+}
+
+static void __init of_unittest_fw_devlink(void)
+{
+	const char *gpio_supplier = "gpio-controller";
+	struct device_node *tests;
+
+	tests = of_find_node_by_path("/testcase-data/phandle-tests/fw-devlink-tests");
+	if (!tests) {
+		pr_err("missing fw_devlink test data\n");
+		return;
+	}
+
+	of_unittest_fw_devlink_supplier(tests, "gpio-compat-consumer", gpio_supplier);
+	of_unittest_fw_devlink_supplier(tests, "gpio-compat-singular-consumer", gpio_supplier);
+	of_unittest_fw_devlink_supplier(tests, "gpio-consumer", gpio_supplier);
+	of_unittest_fw_devlink_supplier(tests, "gpio-direct-consumer", gpio_supplier);
+	of_unittest_fw_devlink_supplier(tests, "gpio-singular-consumer", gpio_supplier);
+
+	of_node_put(tests);
+}
+
 static void __init of_unittest_property_string(void)
 {
 	const char *strings[4];
@@ -4533,6 +4599,7 @@ static int __init of_unittest(void)
 	of_unittest_dynamic();
 	of_unittest_parse_phandle_with_args();
 	of_unittest_parse_phandle_with_args_map();
+	of_unittest_fw_devlink();
 	of_unittest_printf();
 	of_unittest_property_string();
 	of_unittest_property_copy();

-- 
2.43.0