[PATCH v2 5/5] gpio: kunit: add test cases verifying swnode devlink support

[Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>]

The software node fw_devlink support already has its own kunit suite, but
that verifies the fwnode links in isolation. Add GPIO tests that prove
the ordering works in a real-life use-case: a GPIO consumer that
references its provider via a software node.

The first suite registers the provider's software node, adds the consumer
device first and checks that fw_devlink defers its probe until the
provider has been added and bound. The second covers the fallback:
with the provider's software node not yet registered no supplier link is
created, so the consumer probes, devm_gpiod_get() returns -EPROBE_DEFER
and the consumer only binds once the provider shows up.

While at it: the existing gpio_unbind_with_consumers() test keeps the
consumer bound while the provider goes away and then operates the orphaned
descriptor. With software nodes now being covered by fw_devlink that would
instead force-unbind the consumer along with the provider, so opt it out
by setting FWNODE_FLAG_LINKS_ADDED.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
---
 drivers/gpio/gpiolib-kunit.c | 273 +++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 266 insertions(+), 7 deletions(-)

diff --git a/drivers/gpio/gpiolib-kunit.c b/drivers/gpio/gpiolib-kunit.c
index 380b68f879e55433668353bb88067d561142a5bc..fe984a283318849df26ced1c1e572734f7e154ae 100644
--- a/drivers/gpio/gpiolib-kunit.c
+++ b/drivers/gpio/gpiolib-kunit.c
@@ -3,6 +3,8 @@
  * Copyright (C) Qualcomm Technologies, Inc. and/or its subsidiaries
  */
 
+#include <linux/cleanup.h>
+#include <linux/err.h>
 #include <linux/fwnode.h>
 #include <linux/gpio/consumer.h>
 #include <linux/gpio/driver.h>
@@ -11,12 +13,16 @@
 #include <linux/notifier.h>
 #include <linux/platform_device.h>
 #include <linux/property.h>
+#include <linux/types.h>
 
+#include <kunit/fwnode.h>
 #include <kunit/platform_device.h>
 #include <kunit/test.h>
 
 #define GPIO_TEST_PROVIDER		"gpio-test-provider"
 #define GPIO_SWNODE_TEST_CONSUMER	"gpio-swnode-test-consumer"
+#define GPIO_PROBE_ORDER_TEST_CONSUMER	"gpio-probe-order-test-consumer"
+#define GPIO_PROBE_DEFER_TEST_CONSUMER	"gpio-probe-defer-test-consumer"
 #define GPIO_UNBIND_TEST_CONSUMER	"gpio-unbind-test-consumer"
 
 static int gpio_test_provider_get_direction(struct gpio_chip *gc, unsigned int offset)
@@ -213,6 +219,249 @@ static struct kunit_suite gpio_swnode_lookup_test_suite = {
 	.test_cases = gpio_swnode_lookup_tests,
 };
 
+static void gpio_swnode_unregister_swnode(void *data)
+{
+	software_node_unregister(data);
+}
+
+struct gpio_probe_order_pdata {
+	unsigned int probe_count;
+	bool gpio_ok;
+};
+
+static const struct gpio_probe_order_pdata gpio_probe_order_pdata_template = {
+	.probe_count = 0,
+	.gpio_ok = false,
+};
+
+static int gpio_probe_order_consumer_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct gpio_probe_order_pdata *pdata = dev_get_platdata(dev);
+	struct gpio_desc *desc;
+
+	pdata->probe_count++;
+
+	desc = devm_gpiod_get(dev, "foo", GPIOD_OUT_HIGH);
+	if (IS_ERR(desc))
+		return PTR_ERR(desc);
+
+	pdata->gpio_ok = true;
+
+	return 0;
+}
+
+static struct platform_driver gpio_probe_order_consumer_driver = {
+	.probe = gpio_probe_order_consumer_probe,
+	.driver = {
+		.name = GPIO_PROBE_ORDER_TEST_CONSUMER,
+	},
+};
+
+/*
+ * Verify that fw_devlink orders the probe of a GPIO consumer after its
+ * provider. The consumer references the provider through a software node and
+ * is registered first. fw_devlink must defer it before its driver's probe()
+ * is ever entered, so the consumer probes exactly once - only after the
+ * provider is added and bound.
+ */
+static void gpio_swnode_probe_order(struct kunit *test)
+{
+	struct property_entry properties[2] = { };
+	struct gpio_probe_order_pdata *pdata;
+	struct platform_device_info pdevinfo;
+	struct platform_device *prvd, *cons;
+	bool bound = false;
+	int ret;
+
+	ret = kunit_platform_driver_register(test, &gpio_test_provider_driver);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	ret = kunit_platform_driver_register(test, &gpio_probe_order_consumer_driver);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	ret = software_node_register(&gpio_test_provider_swnode);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	ret = kunit_add_action_or_reset(test, gpio_swnode_unregister_swnode,
+					(void *)&gpio_test_provider_swnode);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	properties[0] = PROPERTY_ENTRY_GPIO("foo-gpios",
+					    &gpio_test_provider_swnode,
+					    0, GPIO_ACTIVE_HIGH);
+
+	pdevinfo = (struct platform_device_info){
+		.name = GPIO_PROBE_ORDER_TEST_CONSUMER,
+		.id = PLATFORM_DEVID_NONE,
+		.data = &gpio_probe_order_pdata_template,
+		.size_data = sizeof(gpio_probe_order_pdata_template),
+		.properties = properties,
+	};
+
+	cons = kunit_platform_device_register_full(test, &pdevinfo);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, cons);
+
+	wait_for_device_probe();
+	scoped_guard(device, &cons->dev)
+		bound = device_is_bound(&cons->dev);
+
+	KUNIT_ASSERT_FALSE(test, bound);
+
+	pdata = dev_get_platdata(&cons->dev);
+	KUNIT_ASSERT_EQ(test, pdata->probe_count, 0);
+	KUNIT_ASSERT_FALSE(test, pdata->gpio_ok);
+
+	pdevinfo = (struct platform_device_info){
+		.name = GPIO_TEST_PROVIDER,
+		.id = PLATFORM_DEVID_NONE,
+		.swnode = &gpio_test_provider_swnode,
+	};
+
+	prvd = kunit_platform_device_register_full(test, &pdevinfo);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, prvd);
+
+	wait_for_device_probe();
+
+	scoped_guard(device, &prvd->dev)
+		bound = device_is_bound(&prvd->dev);
+	KUNIT_ASSERT_TRUE(test, bound);
+
+	scoped_guard(device, &cons->dev)
+		bound = device_is_bound(&cons->dev);
+	KUNIT_ASSERT_TRUE(test, bound);
+
+	pdata = dev_get_platdata(&cons->dev);
+	KUNIT_ASSERT_EQ(test, pdata->probe_count, 1);
+	KUNIT_ASSERT_TRUE(test, pdata->gpio_ok);
+}
+
+struct gpio_probe_defer_pdata {
+	unsigned int probe_count;
+	int gpio_err;
+};
+
+static const struct gpio_probe_defer_pdata gpio_probe_defer_pdata_template = {
+	.probe_count = 0,
+	.gpio_err = 0,
+};
+
+static int gpio_probe_defer_consumer_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct gpio_probe_defer_pdata *pdata = dev_get_platdata(dev);
+	struct gpio_desc *desc;
+
+	pdata->probe_count++;
+
+	desc = devm_gpiod_get(dev, "foo", GPIOD_OUT_HIGH);
+	if (IS_ERR(desc)) {
+		pdata->gpio_err = PTR_ERR(desc);
+		return pdata->gpio_err;
+	}
+
+	pdata->gpio_err = 0;
+
+	return 0;
+}
+
+static struct platform_driver gpio_probe_defer_consumer_driver = {
+	.probe = gpio_probe_defer_consumer_probe,
+	.driver = {
+		.name = GPIO_PROBE_DEFER_TEST_CONSUMER,
+	},
+};
+
+/*
+ * Verify that a GPIO consumer referencing a provider whose software node is
+ * not registered yet, defers its probe instead of failing.
+ *
+ * The provider software node is deliberately left unregistered when the
+ * consumer is added. fw_devlink cannot resolve the reference, so it creates no
+ * supplier link and does not order the consumer - the consumer's probe() runs
+ * and reaches devm_gpiod_get(). The swnode GPIO lookup returns -ENOTCONN for a
+ * reference to an unregistered node, which gpiolib maps to -EPROBE_DEFER. Once
+ * the provider software node and device appear, the deferred consumer probes
+ * again and binds.
+ */
+static void gpio_swnode_probe_defer_on_unregistered(struct kunit *test)
+{
+	struct property_entry properties[2] = { };
+	struct gpio_probe_defer_pdata *pdata;
+	struct platform_device_info pdevinfo;
+	struct platform_device *prvd, *cons;
+	struct fwnode_handle *fwnode;
+	bool bound = false;
+	int ret;
+
+	ret = kunit_platform_driver_register(test, &gpio_test_provider_driver);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	ret = kunit_platform_driver_register(test, &gpio_probe_defer_consumer_driver);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	properties[0] = PROPERTY_ENTRY_GPIO("foo-gpios",
+					    &gpio_test_provider_swnode,
+					    0, GPIO_ACTIVE_HIGH);
+
+	pdevinfo = (struct platform_device_info){
+		.name = GPIO_PROBE_DEFER_TEST_CONSUMER,
+		.id = PLATFORM_DEVID_NONE,
+		.data = &gpio_probe_defer_pdata_template,
+		.size_data = sizeof(gpio_probe_defer_pdata_template),
+		.properties = properties,
+	};
+
+	cons = kunit_platform_device_register_full(test, &pdevinfo);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, cons);
+
+	wait_for_device_probe();
+	scoped_guard(device, &cons->dev)
+		bound = device_is_bound(&cons->dev);
+
+	KUNIT_ASSERT_FALSE(test, bound);
+
+	pdata = dev_get_platdata(&cons->dev);
+	KUNIT_ASSERT_GT(test, pdata->probe_count, 0);
+	KUNIT_ASSERT_EQ(test, pdata->gpio_err, -EPROBE_DEFER);
+
+	fwnode = kunit_software_node_register(test, &gpio_test_provider_swnode);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, fwnode);
+
+	pdevinfo = (struct platform_device_info){
+		.name = GPIO_TEST_PROVIDER,
+		.id = PLATFORM_DEVID_NONE,
+		.swnode = &gpio_test_provider_swnode,
+	};
+
+	prvd = kunit_platform_device_register_full(test, &pdevinfo);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, prvd);
+
+	wait_for_device_probe();
+
+	scoped_guard(device, &prvd->dev)
+		bound = device_is_bound(&prvd->dev);
+	KUNIT_ASSERT_TRUE(test, bound);
+
+	scoped_guard(device, &cons->dev)
+		bound = device_is_bound(&cons->dev);
+	KUNIT_ASSERT_TRUE(test, bound);
+
+	pdata = dev_get_platdata(&cons->dev);
+	KUNIT_ASSERT_EQ(test, pdata->gpio_err, 0);
+}
+
+static struct kunit_case gpio_swnode_probe_order_tests[] = {
+	KUNIT_CASE(gpio_swnode_probe_order),
+	KUNIT_CASE(gpio_swnode_probe_defer_on_unregistered),
+	{ }
+};
+
+static struct kunit_suite gpio_swnode_probe_order_test_suite = {
+	.name = "gpio-swnode-probe-order",
+	.test_cases = gpio_swnode_probe_order_tests,
+};
+
 static BLOCKING_NOTIFIER_HEAD(gpio_unbind_notifier);
 
 struct gpio_unbind_consumer_drvdata {
@@ -310,15 +559,24 @@ static void gpio_unbind_with_consumers(struct kunit *test)
 					    0, GPIO_ACTIVE_HIGH);
 	properties[1] = (struct property_entry){ };
 
-	pdevinfo = (struct platform_device_info){
-		.name = GPIO_UNBIND_TEST_CONSUMER,
-		.id = PLATFORM_DEVID_NONE,
-		.properties = properties,
-	};
-
-	cons = kunit_platform_device_register_full(test, &pdevinfo);
+	/*
+	 * This test deliberately keeps the consumer bound while the provider
+	 * is unregistered. fw_devlink would force-unbind the consumer before
+	 * the provider so use the FWNODE_FLAG_LINKS_ADDED flag to opt out of
+	 * it as a workaround.
+	 */
+	cons = kunit_platform_device_alloc(test, GPIO_UNBIND_TEST_CONSUMER,
+					   PLATFORM_DEVID_NONE);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, cons);
 
+	ret = device_create_managed_software_node(&cons->dev, properties, NULL);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	fwnode_set_flag(dev_fwnode(&cons->dev), FWNODE_FLAG_LINKS_ADDED);
+
+	ret = kunit_platform_device_add(test, cons);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
 	wait_for_device_probe();
 	scoped_guard(device, &cons->dev)
 		bound = device_is_bound(&cons->dev);
@@ -350,6 +608,7 @@ static struct kunit_suite gpio_unbind_with_consumers_test_suite = {
 
 kunit_test_suites(
 	&gpio_swnode_lookup_test_suite,
+	&gpio_swnode_probe_order_test_suite,
 	&gpio_unbind_with_consumers_test_suite,
 );
 

-- 
2.47.3