[PATCH v3 3/3] gpio: add kunit test cases for the GPIO subsystem

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

Add a module containing kunit test cases for GPIO core. The idea is to
use it to test functionalities that can't easily be tested from
user-space with kernel selftests or GPIO character device test suites
provided by the libgpiod package.

For now add test cases that verify software node based lookup and ensure
that a GPIO provider unbinding with active consumers does not cause a
crash.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
---
 drivers/gpio/Kconfig         |   8 +
 drivers/gpio/Makefile        |   1 +
 drivers/gpio/gpiolib-kunit.c | 358 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 367 insertions(+)

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 00fcab5d09a4294ed778cea78af5867a0f6e481b..0306005fb7d65ae85905e967b9065fd74db753db 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -102,6 +102,14 @@ config GPIO_CDEV_V1
 	  This ABI version is deprecated.
 	  Please use the latest ABI for new developments.
 
+config GPIO_KUNIT
+	tristate "Build GPIO Kunit test cases"
+	depends on KUNIT
+	default KUNIT_ALL_TESTS
+	help
+	  Say Y here to build the module containing Kunit test cases verifying
+	  the functionality of the GPIO subsystem.
+
 config GPIO_GENERIC
 	depends on HAS_IOMEM # Only for IOMEM drivers
 	tristate
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index 2ea47d9d3dca948e1cdc46965e83b0e1b6de5f70..c66b6dd659b16b80b6bb6b15fac3e3f462dec596 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -13,6 +13,7 @@ obj-$(CONFIG_GPIO_ACPI)		+= gpiolib-acpi.o
 gpiolib-acpi-y			:= gpiolib-acpi-core.o gpiolib-acpi-quirks.o
 obj-$(CONFIG_GPIOLIB)		+= gpiolib-swnode.o
 obj-$(CONFIG_GPIO_SHARED)	+= gpiolib-shared.o
+obj-$(CONFIG_GPIO_KUNIT)	+= gpiolib-kunit.o
 
 # Device drivers. Generally keep list sorted alphabetically
 obj-$(CONFIG_GPIO_REGMAP)	+= gpio-regmap.o
diff --git a/drivers/gpio/gpiolib-kunit.c b/drivers/gpio/gpiolib-kunit.c
new file mode 100644
index 0000000000000000000000000000000000000000..380b68f879e55433668353bb88067d561142a5bc
--- /dev/null
+++ b/drivers/gpio/gpiolib-kunit.c
@@ -0,0 +1,358 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) Qualcomm Technologies, Inc. and/or its subsidiaries
+ */
+
+#include <linux/fwnode.h>
+#include <linux/gpio/consumer.h>
+#include <linux/gpio/driver.h>
+#include <linux/gpio/machine.h>
+#include <linux/gpio/property.h>
+#include <linux/notifier.h>
+#include <linux/platform_device.h>
+#include <linux/property.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_UNBIND_TEST_CONSUMER	"gpio-unbind-test-consumer"
+
+static int gpio_test_provider_get_direction(struct gpio_chip *gc, unsigned int offset)
+{
+	return GPIO_LINE_DIRECTION_OUT;
+}
+
+static int gpio_test_provider_set(struct gpio_chip *gc, unsigned int offset, int value)
+{
+	return 0;
+}
+
+static int gpio_test_provider_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct gpio_chip *gc;
+
+	gc = devm_kzalloc(dev, sizeof(*gc), GFP_KERNEL);
+	if (!gc)
+		return -ENOMEM;
+
+	gc->base = -1;
+	gc->ngpio = 4;
+	gc->label = "gpio-swnode-consumer-test-device";
+	gc->parent = dev;
+	gc->owner = THIS_MODULE;
+
+	gc->get_direction = gpio_test_provider_get_direction;
+	gc->set = gpio_test_provider_set;
+
+	return devm_gpiochip_add_data(dev, gc, NULL);
+}
+
+static struct platform_driver gpio_test_provider_driver = {
+	.probe = gpio_test_provider_probe,
+	.driver = {
+		.name = GPIO_TEST_PROVIDER,
+	},
+};
+
+static const struct software_node gpio_test_provider_swnode = {
+	.name = "gpio-test-provider-primary",
+};
+
+struct gpio_swnode_consumer_pdata {
+	bool gpio_ok;
+};
+
+static const struct gpio_swnode_consumer_pdata gpio_swnode_pdata_template = {
+	.gpio_ok = false,
+};
+
+static int gpio_swnode_consumer_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct gpio_swnode_consumer_pdata *pdata = dev_get_platdata(dev);
+	struct gpio_desc *desc;
+
+	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_swnode_consumer_driver = {
+	.probe = gpio_swnode_consumer_probe,
+	.driver = {
+		.name = GPIO_SWNODE_TEST_CONSUMER,
+	},
+};
+
+static void gpio_swnode_lookup_by_primary(struct kunit *test)
+{
+	struct gpio_swnode_consumer_pdata *pdata;
+	struct platform_device_info pdevinfo;
+	struct property_entry properties[2];
+	struct platform_device *pdev;
+	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_swnode_consumer_driver);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	pdevinfo = (struct platform_device_info){
+		.name = GPIO_TEST_PROVIDER,
+		.id = PLATFORM_DEVID_NONE,
+		.swnode = &gpio_test_provider_swnode,
+	};
+
+	pdev = kunit_platform_device_register_full(test, &pdevinfo);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, pdev);
+
+	properties[0] = PROPERTY_ENTRY_GPIO("foo-gpios",
+					    &gpio_test_provider_swnode,
+					    0, GPIO_ACTIVE_HIGH);
+	properties[1] = (struct property_entry){ };
+
+	pdevinfo = (struct platform_device_info){
+		.name = GPIO_SWNODE_TEST_CONSUMER,
+		.id = PLATFORM_DEVID_NONE,
+		.data = &gpio_swnode_pdata_template,
+		.size_data = sizeof(gpio_swnode_pdata_template),
+		.properties = properties,
+	};
+
+	pdev = kunit_platform_device_register_full(test, &pdevinfo);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, pdev);
+
+	wait_for_device_probe();
+	scoped_guard(device, &pdev->dev)
+		bound = device_is_bound(&pdev->dev);
+
+	KUNIT_ASSERT_TRUE(test, bound);
+
+	pdata = dev_get_platdata(&pdev->dev);
+	KUNIT_ASSERT_TRUE(test, pdata->gpio_ok);
+}
+
+static void gpio_swnode_lookup_by_secondary(struct kunit *test)
+{
+	struct gpio_swnode_consumer_pdata *pdata;
+	struct platform_device_info pdevinfo;
+	struct property_entry properties[2];
+	struct fwnode_handle *primary;
+	struct platform_device *pdev;
+	bool bound = false;
+	int ret;
+
+	/*
+	 * Can't live on the stack as it will still get referenced in cleanup
+	 * path after this function returns.
+	 */
+	primary = kunit_kzalloc(test, sizeof(*primary), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, primary);
+
+	ret = kunit_platform_driver_register(test, &gpio_test_provider_driver);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	ret = kunit_platform_driver_register(test, &gpio_swnode_consumer_driver);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	fwnode_init(primary, NULL);
+
+	pdevinfo = (struct platform_device_info){
+		.name = GPIO_TEST_PROVIDER,
+		.id = PLATFORM_DEVID_NONE,
+		.fwnode = primary,
+		.swnode = &gpio_test_provider_swnode,
+	};
+
+	pdev = kunit_platform_device_register_full(test, &pdevinfo);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, pdev);
+
+	properties[0] = PROPERTY_ENTRY_GPIO("foo-gpios",
+					    &gpio_test_provider_swnode,
+					    0, GPIO_ACTIVE_HIGH);
+	properties[1] = (struct property_entry){ };
+
+	pdevinfo = (struct platform_device_info){
+		.name = GPIO_SWNODE_TEST_CONSUMER,
+		.id = PLATFORM_DEVID_NONE,
+		.data = &gpio_swnode_pdata_template,
+		.size_data = sizeof(gpio_swnode_pdata_template),
+		.properties = properties,
+	};
+
+	pdev = kunit_platform_device_register_full(test, &pdevinfo);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, pdev);
+
+	wait_for_device_probe();
+	scoped_guard(device, &pdev->dev)
+		bound = device_is_bound(&pdev->dev);
+
+	KUNIT_ASSERT_TRUE(test, bound);
+
+	pdata = dev_get_platdata(&pdev->dev);
+	KUNIT_ASSERT_TRUE(test, pdata->gpio_ok);
+}
+
+static struct kunit_case gpio_swnode_lookup_tests[] = {
+	KUNIT_CASE(gpio_swnode_lookup_by_primary),
+	KUNIT_CASE(gpio_swnode_lookup_by_secondary),
+	{ }
+};
+
+static struct kunit_suite gpio_swnode_lookup_test_suite = {
+	.name = "gpio-swnode-lookup",
+	.test_cases = gpio_swnode_lookup_tests,
+};
+
+static BLOCKING_NOTIFIER_HEAD(gpio_unbind_notifier);
+
+struct gpio_unbind_consumer_drvdata {
+	struct device *dev;
+	struct gpio_desc *desc;
+	struct notifier_block nb;
+	int set_retval;
+};
+
+static int gpio_unbind_notify(struct notifier_block *nb, unsigned long action,
+			      void *data)
+{
+	struct gpio_unbind_consumer_drvdata *drvdata =
+		container_of(nb, struct gpio_unbind_consumer_drvdata, nb);
+	struct device *dev = data;
+
+	if (dev != drvdata->dev)
+		return NOTIFY_DONE;
+
+	drvdata->set_retval = gpiod_set_value_cansleep(drvdata->desc, 0);
+
+	return NOTIFY_OK;
+}
+
+static void gpio_unbind_unregister_notifier(void *data)
+{
+	struct notifier_block *nb = data;
+
+	blocking_notifier_chain_unregister(&gpio_unbind_notifier, nb);
+}
+
+static int gpio_unbind_consumer_probe(struct platform_device *pdev)
+{
+	struct gpio_unbind_consumer_drvdata *data;
+	struct device *dev = &pdev->dev;
+	int ret;
+
+	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->dev = dev;
+
+	data->desc = devm_gpiod_get(dev, "foo", GPIOD_OUT_HIGH);
+	if (IS_ERR(data->desc))
+		return PTR_ERR(data->desc);
+
+	data->nb.notifier_call = gpio_unbind_notify;
+	ret = blocking_notifier_chain_register(&gpio_unbind_notifier, &data->nb);
+	if (ret)
+		return ret;
+
+	ret = devm_add_action_or_reset(dev, gpio_unbind_unregister_notifier, &data->nb);
+	if (ret)
+		return ret;
+
+	platform_set_drvdata(pdev, data);
+
+	return 0;
+}
+
+static struct platform_driver gpio_unbind_consumer_driver = {
+	.probe = gpio_unbind_consumer_probe,
+	.driver = {
+		.name = GPIO_UNBIND_TEST_CONSUMER,
+	},
+};
+
+static void gpio_unbind_with_consumers(struct kunit *test)
+{
+	struct gpio_unbind_consumer_drvdata *cons_data;
+	struct platform_device_info pdevinfo;
+	struct property_entry properties[2];
+	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_unbind_consumer_driver);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	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);
+
+	properties[0] = PROPERTY_ENTRY_GPIO("foo-gpios",
+					    &gpio_test_provider_swnode,
+					    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);
+	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_TRUE(test, bound);
+
+	kunit_platform_device_unregister(test, prvd);
+
+	ret = blocking_notifier_call_chain(&gpio_unbind_notifier, 0, &cons->dev);
+	KUNIT_ASSERT_EQ(test, ret, NOTIFY_OK);
+
+	scoped_guard(device, &cons->dev) {
+		cons_data = platform_get_drvdata(cons);
+		ret = cons_data->set_retval;
+	}
+
+	KUNIT_ASSERT_EQ(test, ret, -ENODEV);
+}
+
+static struct kunit_case gpio_unbind_with_consumers_tests[] = {
+	KUNIT_CASE(gpio_unbind_with_consumers),
+	{ }
+};
+
+static struct kunit_suite gpio_unbind_with_consumers_test_suite = {
+	.name = "gpio-unbind-with-consumers",
+	.test_cases = gpio_unbind_with_consumers_tests,
+};
+
+kunit_test_suites(
+	&gpio_swnode_lookup_test_suite,
+	&gpio_unbind_with_consumers_test_suite,
+);
+
+MODULE_DESCRIPTION("Test module for the GPIO subsystem");
+MODULE_AUTHOR("Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>");
+MODULE_LICENSE("GPL");

-- 
2.47.3