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

[Ernest Van Hoecke <ernestvanhoecke@gmail.com>]

From: Ernest Van Hoecke <ernest.vanhoecke@toradex.com>

PWM consumers use of_parse_phandle_with_args_map() to resolve specifiers
through pwm-map properties. fw_devlink instead parses the pwms property as
a direct phandle reference, so it records the nexus node as the supplier
rather than the mapped PWM provider.

A nexus is a translation node, not the PWM 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 pwms so fw_devlink resolves the same provider
as the PWM consumer API. Direct PWM references continue to work because the
map-aware parser returns the original provider when no pwm-map property is
present.

Add OF unittest coverage for mapped and direct PWM suppliers.

Fixes: e71e46a6f19c ("pwm: Add support for pwm nexus dt bindings")
Reported-by: Leonardo Costa <leonardo.costa@toradex.com>
Link: https://lore.kernel.org/all/juuc4af7ndbajcl7gzf4tg5qz2q2j5tt3rvql4jbauradujrre@gc5nbdhhixaf/
Tested-by: Leonardo Costa <leonardo.costa@toradex.com>
Cc: stable@vger.kernel.org
Signed-off-by: Ernest Van Hoecke <ernest.vanhoecke@toradex.com>
---
 drivers/of/property.c                       | 11 ++++++++++-
 drivers/of/unittest-data/tests-phandle.dtsi | 16 ++++++++++++++++
 drivers/of/unittest.c                       |  4 ++++
 3 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/drivers/of/property.c b/drivers/of/property.c
index 380df0861ab9..d5e89beb17f9 100644
--- a/drivers/of/property.c
+++ b/drivers/of/property.c
@@ -1331,6 +1331,15 @@ static struct device_node *parse_##fname(struct device_node *np,	  \
 	return parse_prop_cells(np, prop_name, index, name, cells);	  \
 }
 
+#define DEFINE_SIMPLE_NEXUS_PROP(fname, name, stem)			  \
+static struct device_node *parse_##fname(struct device_node *np,	  \
+					const char *prop_name, int index) \
+{									  \
+	if (strcmp(prop_name, name))					  \
+		return NULL;						  \
+	return parse_nexus_prop(np, prop_name, index, stem);		  \
+}
+
 /**
  * parse_suffix_prop_cells - Suffix property parsing function for suppliers
  *
@@ -1426,7 +1435,6 @@ DEFINE_SIMPLE_PROP(extcon, "extcon", NULL)
 DEFINE_SIMPLE_PROP(nvmem_cells, "nvmem-cells", "#nvmem-cell-cells")
 DEFINE_SIMPLE_PROP(phys, "phys", "#phy-cells")
 DEFINE_SIMPLE_PROP(wakeup_parent, "wakeup-parent", NULL)
-DEFINE_SIMPLE_PROP(pwms, "pwms", "#pwm-cells")
 DEFINE_SIMPLE_PROP(resets, "resets", "#reset-cells")
 DEFINE_SIMPLE_PROP(leds, "leds", NULL)
 DEFINE_SIMPLE_PROP(backlight, "backlight", NULL)
@@ -1438,6 +1446,7 @@ 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_SIMPLE_NEXUS_PROP(pwms, "pwms", "pwm")
 DEFINE_SUFFIX_NEXUS_PROP(gpio, "-gpio", "gpio")
 
 static struct device_node *parse_pinctrl_n(struct device_node *np,
diff --git a/drivers/of/unittest-data/tests-phandle.dtsi b/drivers/of/unittest-data/tests-phandle.dtsi
index 163ef07be16d..7cb3e19554b6 100644
--- a/drivers/of/unittest-data/tests-phandle.dtsi
+++ b/drivers/of/unittest-data/tests-phandle.dtsi
@@ -85,11 +85,19 @@ gpio_provider: gpio-controller {
 					#gpio-cells = <2>;
 				};
 
+				pwm_provider: pwm-controller {
+					#pwm-cells = <3>;
+				};
+
 				test_nexus: nexus {
 					#gpio-cells = <2>;
+					#pwm-cells = <3>;
 					gpio-map = <0 0 &gpio_provider 1 0>;
 					gpio-map-mask = <0xffffffff 0>;
 					gpio-map-pass-thru = <0 0xffffffff>;
+					pwm-map = <0 0 0 &pwm_provider 1 0 0>;
+					pwm-map-mask = <0xffffffff 0 0>;
+					pwm-map-pass-thru = <0 0xffffffff 0xffffffff>;
 				};
 
 				gpio-compat-consumer {
@@ -111,6 +119,14 @@ gpio-direct-consumer {
 				gpio-singular-consumer {
 					test-gpio = <&test_nexus 0 0>;
 				};
+
+				pwm-consumer {
+					pwms = <&test_nexus 0 1000 0>;
+				};
+
+				pwm-direct-consumer {
+					pwms = <&pwm_provider 1 1000 0>;
+				};
 			};
 		};
 	};
diff --git a/drivers/of/unittest.c b/drivers/of/unittest.c
index 487f3b629a73..508ebc7581c8 100644
--- a/drivers/of/unittest.c
+++ b/drivers/of/unittest.c
@@ -759,6 +759,7 @@ static void __init of_unittest_fw_devlink_supplier(struct device_node *tests,
 static void __init of_unittest_fw_devlink(void)
 {
 	const char *gpio_supplier = "gpio-controller";
+	const char *pwm_supplier = "pwm-controller";
 	struct device_node *tests;
 
 	tests = of_find_node_by_path("/testcase-data/phandle-tests/fw-devlink-tests");
@@ -773,6 +774,9 @@ static void __init of_unittest_fw_devlink(void)
 	of_unittest_fw_devlink_supplier(tests, "gpio-direct-consumer", gpio_supplier);
 	of_unittest_fw_devlink_supplier(tests, "gpio-singular-consumer", gpio_supplier);
 
+	of_unittest_fw_devlink_supplier(tests, "pwm-consumer", pwm_supplier);
+	of_unittest_fw_devlink_supplier(tests, "pwm-direct-consumer", pwm_supplier);
+
 	of_node_put(tests);
 }
 

-- 
2.43.0