[PATCH v6 5/8] platform: Add test managed platform_device/driver APIs

Stephen Boyd
2024-07-06T04:55:01Z

Introduce KUnit resource wrappers around platform_driver_register(),
platform_device_alloc(), and platform_device_add() so that test authors
can register platform drivers/devices from their tests and have the
drivers/devices automatically be unregistered when the test is done.

This makes test setup code simpler when a platform driver or platform
device is needed. Add a few test cases at the same time to make sure the
APIs work as intended.

Cc: Brendan Higgins <brendan.higgins@linux.dev>
Reviewed-by: David Gow <davidgow@google.com>
Cc: Rae Moar <rmoar@google.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
---
Documentation/dev-tools/kunit/api/index.rst | 5 +
.../dev-tools/kunit/api/platformdevice.rst | 10 +
include/kunit/platform_device.h | 20 ++
lib/kunit/Makefile | 4 +-
lib/kunit/platform-test.c | 223 +++++++++++++
lib/kunit/platform.c | 302 ++++++++++++++++++
6 files changed, 563 insertions(+), 1 deletion(-)
create mode 100644 Documentation/dev-tools/kunit/api/platformdevice.rst
create mode 100644 include/kunit/platform_device.h
create mode 100644 lib/kunit/platform-test.c
create mode 100644 lib/kunit/platform.c

diff --git a/Documentation/dev-tools/kunit/api/index.rst b/Documentation/dev-tools/kunit/api/index.rst
index 282befa17edf..02b26f5e8750 100644
--- a/Documentation/dev-tools/kunit/api/index.rst
+++ b/Documentation/dev-tools/kunit/api/index.rst
@@ -10,6 +10,7 @@ API Reference
resource
functionredirection
of
+ platformdevice

This page documents the KUnit kernel testing API. It is divided into the
@@ -36,3 +37,7 @@ Driver KUnit API
Documentation/dev-tools/kunit/api/of.rst

- Documents the KUnit device tree (OF) API
+
+Documentation/dev-tools/kunit/api/platformdevice.rst
+
+ - Documents the KUnit platform device API
diff --git a/Documentation/dev-tools/kunit/api/platformdevice.rst b/Documentation/dev-tools/kunit/api/platformdevice.rst
new file mode 100644
index 000000000000..49ddd5729003
--- /dev/null
+++ b/Documentation/dev-tools/kunit/api/platformdevice.rst
@@ -0,0 +1,10 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+===================
+Platform Device API
+===================
+
+The KUnit platform device API is used to test platform devices.
+
+.. kernel-doc:: lib/kunit/platform.c
+ :export:
diff --git a/include/kunit/platform_device.h b/include/kunit/platform_device.h
new file mode 100644
index 000000000000..0fc0999d2420
--- /dev/null
+++ b/include/kunit/platform_device.h
@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _KUNIT_PLATFORM_DRIVER_H
+#define _KUNIT_PLATFORM_DRIVER_H
+
+struct kunit;
+struct platform_device;
+struct platform_driver;
+
+struct platform_device *
+kunit_platform_device_alloc(struct kunit *test, const char *name, int id);
+int kunit_platform_device_add(struct kunit *test, struct platform_device *pdev);
+
+int kunit_platform_device_prepare_wait_for_probe(struct kunit *test,
+ struct platform_device *pdev,
+ struct completion *x);
+
+int kunit_platform_driver_register(struct kunit *test,
+ struct platform_driver *drv);
+
+#endif
diff --git a/lib/kunit/Makefile b/lib/kunit/Makefile
index 309659a32a78..a980ae62eff6 100644
--- a/lib/kunit/Makefile
+++ b/lib/kunit/Makefile
@@ -8,7 +8,8 @@ kunit-objs += test.o \
try-catch.o \
executor.o \
attributes.o \
- device.o
+ device.o \
+ platform.o

ifeq ($(CONFIG_KUNIT_DEBUGFS),y)
kunit-objs += debugfs.o
@@ -18,6 +19,7 @@ endif
obj-y += hooks.o

obj-$(CONFIG_KUNIT_TEST) += kunit-test.o
+obj-$(CONFIG_KUNIT_TEST) += platform-test.o

# string-stream-test compiles built-in only.
ifeq ($(CONFIG_KUNIT_TEST),y)
diff --git a/lib/kunit/platform-test.c b/lib/kunit/platform-test.c
new file mode 100644
index 000000000000..b4fbedadc55e
--- /dev/null
+++ b/lib/kunit/platform-test.c
@@ -0,0 +1,223 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * KUnit test for platform driver infrastructure.
+ */
+
+#include <linux/platform_device.h>
+
+#include <kunit/platform_device.h>
+#include <kunit/test.h>
+
+/*
+ * Test that kunit_platform_device_alloc() creates a platform device.
+ */
+static void kunit_platform_device_alloc_test(struct kunit *test)
+{
+ KUNIT_EXPECT_NOT_ERR_OR_NULL(test,
+ kunit_platform_device_alloc(test, "kunit-platform", 1));
+}
+
+/*
+ * Test that kunit_platform_device_add() registers a platform device on the
+ * platform bus with the proper name and id.
+ */
+static void kunit_platform_device_add_test(struct kunit *test)
+{
+ struct platform_device *pdev;
+ const char *name = "kunit-platform-add";
+ const int id = -1;
+
+ pdev = kunit_platform_device_alloc(test, name, id);
+ KUNIT_ASSERT_NOT_ERR_OR_NULL(test, pdev);
+
+ KUNIT_EXPECT_EQ(test, 0, kunit_platform_device_add(test, pdev));
+ KUNIT_EXPECT_TRUE(test, dev_is_platform(&pdev->dev));
+ KUNIT_EXPECT_STREQ(test, pdev->name, name);
+ KUNIT_EXPECT_EQ(test, pdev->id, id);
+}
+
+/*
+ * Test that kunit_platform_device_add() called twice with the same device name
+ * and id fails the second time and properly cleans up.
+ */
+static void kunit_platform_device_add_twice_fails_test(struct kunit *test)
+{
+ struct platform_device *pdev;
+ const char *name = "kunit-platform-add-2";
+ const int id = -1;
+
+ pdev = kunit_platform_device_alloc(test, name, id);
+ KUNIT_ASSERT_NOT_ERR_OR_NULL(test, pdev);
+ KUNIT_ASSERT_EQ(test, 0, kunit_platform_device_add(test, pdev));
+
+ pdev = kunit_platform_device_alloc(test, name, id);
+ KUNIT_ASSERT_NOT_ERR_OR_NULL(test, pdev);
+
+ KUNIT_EXPECT_NE(test, 0, kunit_platform_device_add(test, pdev));
+}
+
+static int kunit_platform_device_find_by_name(struct device *dev, const void *data)
+{
+ return strcmp(dev_name(dev), data) == 0;
+}
+
+/*
+ * Test that kunit_platform_device_add() cleans up by removing the platform
+ * device when the test finishes. */
+static void kunit_platform_device_add_cleans_up(struct kunit *test)
+{
+ struct platform_device *pdev;
+ const char *name = "kunit-platform-clean";
+ const int id = -1;
+ struct kunit fake;
+ struct device *dev;
+
+ kunit_init_test(&fake, "kunit_platform_device_add_fake_test", NULL);
+ KUNIT_ASSERT_EQ(test, fake.status, KUNIT_SUCCESS);
+
+ pdev = kunit_platform_device_alloc(&fake, name, id);
+ KUNIT_ASSERT_NOT_ERR_OR_NULL(test, pdev);
+ KUNIT_ASSERT_EQ(test, 0, kunit_platform_device_add(&fake, pdev));
+ dev = bus_find_device(&platform_bus_type, NULL, name,
+ kunit_platform_device_find_by_name);
+ KUNIT_ASSERT_NOT_ERR_OR_NULL(test, dev);
+ put_device(dev);
+
+ /* Remove pdev */
+ kunit_cleanup(&fake);
+
+ /*
+ * Failing to migrate the kunit_resource would lead to an extra
+ * put_device() call on the platform device. The best we can do here is
+ * make sure the device no longer exists on the bus, but if something
+ * is wrong we'll see a refcount underflow here. We can't test for a
+ * refcount underflow because the kref matches the lifetime of the
+ * device which should already be freed and could be used by something
+ * else.
+ */
+ dev = bus_find_device(&platform_bus_type, NULL, name,
+ kunit_platform_device_find_by_name);
+ KUNIT_EXPECT_PTR_EQ(test, NULL, dev);
+ put_device(dev);
+}
+
+/*
+ * Test suite for struct platform_device kunit APIs
+ */
+static struct kunit_case kunit_platform_device_test_cases[] = {
+ KUNIT_CASE(kunit_platform_device_alloc_test),
+ KUNIT_CASE(kunit_platform_device_add_test),
+ KUNIT_CASE(kunit_platform_device_add_twice_fails_test),
+ KUNIT_CASE(kunit_platform_device_add_cleans_up),
+ {}
+};
+
+static struct kunit_suite kunit_platform_device_suite = {
+ .name = "kunit_platform_device",
+ .test_cases = kunit_platform_device_test_cases,
+};
+
+struct kunit_platform_driver_test_context {
+ struct platform_driver pdrv;
+ const char *data;
+};
+
+static const char * const test_data = "test data";
+
+static inline struct kunit_platform_driver_test_context *
+to_test_context(struct platform_device *pdev)
+{
+ return container_of(to_platform_driver(pdev->dev.driver),
+ struct kunit_platform_driver_test_context,
+ pdrv);
+}
+
+static int kunit_platform_driver_probe(struct platform_device *pdev)
+{
+ struct kunit_platform_driver_test_context *ctx;
+
+ ctx = to_test_context(pdev);
+ ctx->data = test_data;
+
+ return 0;
+}
+
+/* Test that kunit_platform_driver_register() registers a driver that probes. */
+static void kunit_platform_driver_register_test(struct kunit *test)
+{
+ struct platform_device *pdev;
+ struct kunit_platform_driver_test_context *ctx;
+ DECLARE_COMPLETION_ONSTACK(comp);
+ const char *name = "kunit-platform-register";
+
+ ctx = kunit_kzalloc(test, sizeof(*ctx), GFP_KERNEL);
+ KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ctx);
+
+ pdev = kunit_platform_device_alloc(test, name, -1);
+ KUNIT_ASSERT_NOT_ERR_OR_NULL(test, pdev);
+ KUNIT_ASSERT_EQ(test, 0, kunit_platform_device_add(test, pdev));
+
+ ctx->pdrv.probe = kunit_platform_driver_probe;
+ ctx->pdrv.driver.name = name;
+ ctx->pdrv.driver.owner = THIS_MODULE;
+
+ KUNIT_ASSERT_EQ(test, 0, kunit_platform_device_prepare_wait_for_probe(test, pdev, &comp));
+
+ KUNIT_EXPECT_EQ(test, 0, kunit_platform_driver_register(test, &ctx->pdrv));
+ KUNIT_EXPECT_NE(test, 0, wait_for_completion_timeout(&comp, 3 * HZ));
+ KUNIT_EXPECT_STREQ(test, ctx->data, test_data);
+}
+
+/*
+ * Test that kunit_platform_device_prepare_wait_for_probe() completes the completion
+ * when the device is already probed.
+ */
+static void kunit_platform_device_prepare_wait_for_probe_completes_when_already_probed(struct kunit *test)
+{
+ struct platform_device *pdev;
+ struct kunit_platform_driver_test_context *ctx;
+ DECLARE_COMPLETION_ONSTACK(comp);
+ const char *name = "kunit-platform-wait";
+
+ ctx = kunit_kzalloc(test, sizeof(*ctx), GFP_KERNEL);
+ KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ctx);
+
+ pdev = kunit_platform_device_alloc(test, name, -1);
+ KUNIT_ASSERT_NOT_ERR_OR_NULL(test, pdev);
+ KUNIT_ASSERT_EQ(test, 0, kunit_platform_device_add(test, pdev));
+
+ ctx->pdrv.probe = kunit_platform_driver_probe;
+ ctx->pdrv.driver.name = name;
+ ctx->pdrv.driver.owner = THIS_MODULE;
+
+ /* Make sure driver has actually probed */
+ KUNIT_ASSERT_EQ(test, 0, kunit_platform_device_prepare_wait_for_probe(test, pdev, &comp));
+ KUNIT_ASSERT_EQ(test, 0, kunit_platform_driver_register(test, &ctx->pdrv));
+ KUNIT_ASSERT_NE(test, 0, wait_for_completion_timeout(&comp, 3 * HZ));
+
+ reinit_completion(&comp);
+ KUNIT_ASSERT_EQ(test, 0, kunit_platform_device_prepare_wait_for_probe(test, pdev, &comp));
+
+ KUNIT_EXPECT_NE(test, 0, wait_for_completion_timeout(&comp, HZ));
+}
+
+static struct kunit_case kunit_platform_driver_test_cases[] = {
+ KUNIT_CASE(kunit_platform_driver_register_test),
+ KUNIT_CASE(kunit_platform_device_prepare_wait_for_probe_completes_when_already_probed),
+ {}
+};
+
+/*
+ * Test suite for struct platform_driver kunit APIs
+ */
+static struct kunit_suite kunit_platform_driver_suite = {
+ .name = "kunit_platform_driver",
+ .test_cases = kunit_platform_driver_test_cases,
+};
+
+kunit_test_suites(
+ &kunit_platform_device_suite,
+ &kunit_platform_driver_suite,
+);
+
+MODULE_LICENSE("GPL");
diff --git a/lib/kunit/platform.c b/lib/kunit/platform.c
new file mode 100644
index 000000000000..ba1b0006dc45
--- /dev/null
+++ b/lib/kunit/platform.c
@@ -0,0 +1,302 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Test managed platform driver
+ */
+
+#include <linux/completion.h>
+#include <linux/device/bus.h>
+#include <linux/device/driver.h>
+#include <linux/platform_device.h>
+
+#include <kunit/platform_device.h>
+#include <kunit/resource.h>
+
+struct kunit_platform_device_alloc_params {
+ const char *name;
+ int id;
+};
+
+static int kunit_platform_device_alloc_init(struct kunit_resource *res, void *context)
+{
+ struct kunit_platform_device_alloc_params *params = context;
+ struct platform_device *pdev;
+
+ pdev = platform_device_alloc(params->name, params->id);
+ if (!pdev)
+ return -ENOMEM;
+
+ res->data = pdev;
+
+ return 0;
+}
+
+static void kunit_platform_device_alloc_exit(struct kunit_resource *res)
+{
+ struct platform_device *pdev = res->data;
+
+ platform_device_put(pdev);
+}
+
+/**
+ * kunit_platform_device_alloc() - Allocate a KUnit test managed platform device
+ * @test: test context
+ * @name: device name of platform device to alloc
+ * @id: identifier of platform device to alloc.
+ *
+ * Allocate a test managed platform device. The device is put when the test completes.
+ *
+ * Return: Allocated platform device on success, NULL on failure.
+ */
+struct platform_device *
+kunit_platform_device_alloc(struct kunit *test, const char *name, int id)
+{
+ struct kunit_platform_device_alloc_params params = {
+ .name = name,
+ .id = id,
+ };
+
+ return kunit_alloc_resource(test,
+ kunit_platform_device_alloc_init,
+ kunit_platform_device_alloc_exit,
+ GFP_KERNEL, &params);
+}
+EXPORT_SYMBOL_GPL(kunit_platform_device_alloc);
+
+static void kunit_platform_device_add_exit(struct kunit_resource *res)
+{
+ struct platform_device *pdev = res->data;
+
+ platform_device_unregister(pdev);
+}
+
+static bool
+kunit_platform_device_alloc_match(struct kunit *test,
+ struct kunit_resource *res, void *match_data)
+{
+ struct platform_device *pdev = match_data;
+
+ return res->data == pdev && res->free != kunit_platform_device_alloc_exit;
+}
+
+KUNIT_DEFINE_ACTION_WRAPPER(platform_device_unregister_wrapper,
+ platform_device_unregister, struct platform_device *);
+/**
+ * kunit_platform_device_add() - Register a KUnit test managed platform device
+ * @test: test context
+ * @pdev: platform device to add
+ *
+ * Register a test managed platform device. The device is unregistered when the
+ * test completes.
+ *
+ * Return: 0 on success, negative errno on failure.
+ */
+int kunit_platform_device_add(struct kunit *test, struct platform_device *pdev)
+{
+ struct kunit_resource *res;
+ int ret;
+
+ ret = platform_device_add(pdev);
+ if (ret)
+ return ret;
+
+ res = kunit_find_resource(test, kunit_platform_device_alloc_match, pdev);
+ if (res) {
+ /*
+ * Transfer the reference count of the platform device if it
+ * was allocated with kunit_platform_device_alloc(). In this
+ * case, calling platform_device_put() when the test exits from
+ * kunit_platform_device_alloc_exit() would lead to reference
+ * count underflow because platform_device_unregister_wrapper()
+ * calls platform_device_unregister() which also calls
+ * platform_device_put().
+ *
+ * Usually callers transfer the refcount initialized in
+ * platform_device_alloc() to platform_device_add() by calling
+ * platform_device_unregister() when platform_device_add()
+ * succeeds or platform_device_put() when it fails. KUnit has to
+ * keep this straight by redirecting the free routine for the
+ * resource to the right function. Luckily this only has to
+ * account for the success scenario.
+ */
+ res->free = kunit_platform_device_add_exit;
+ kunit_put_resource(res);
+ } else {
+ ret = kunit_add_action_or_reset(test, platform_device_unregister_wrapper, pdev);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(kunit_platform_device_add);
+
+struct kunit_platform_device_probe_nb {
+ struct completion *x;
+ struct device *dev;
+ struct notifier_block nb;
+};
+
+static int kunit_platform_device_probe_notify(struct notifier_block *nb,
+ unsigned long event, void *data)
+{
+ struct kunit_platform_device_probe_nb *knb;
+ struct device *dev = data;
+
+ knb = container_of(nb, struct kunit_platform_device_probe_nb, nb);
+ if (event != BUS_NOTIFY_BOUND_DRIVER || knb->dev != dev)
+ return NOTIFY_DONE;
+
+ complete(knb->x);
+
+ return NOTIFY_OK;
+}
+
+static void kunit_platform_device_probe_nb_remove(void *nb)
+{
+ bus_unregister_notifier(&platform_bus_type, nb);
+}
+
+/**
+ * kunit_platform_device_prepare_wait_for_probe() - Prepare a completion
+ * variable to wait for a platform device to probe
+ * @test: test context
+ * @pdev: platform device to prepare to wait for probe of
+ * @x: completion variable completed when @dev has probed
+ *
+ * Prepare a completion variable @x to wait for @pdev to probe. Waiting on the
+ * completion forces a preemption, allowing the platform driver to probe.
+ *
+ * Example
+ *
+ * .. code-block:: c
+ *
+ * static int kunit_platform_driver_probe(struct platform_device *pdev)
+ * {
+ * return 0;
+ * }
+ *
+ * static void kunit_platform_driver_test(struct kunit *test)
+ * {
+ * struct platform_device *pdev;
+ * struct platform_driver *pdrv;
+ * DECLARE_COMPLETION_ONSTACK(comp);
+ *
+ * pdev = kunit_platform_device_alloc(test, "kunit-platform", -1);
+ * KUNIT_ASSERT_NOT_ERR_OR_NULL(test, pdev);
+ * KUNIT_ASSERT_EQ(test, 0, kunit_platform_device_add(test, pdev));
+ *
+ * pdrv = kunit_kzalloc(test, sizeof(*pdrv), GFP_KERNEL);
+ * KUNIT_ASSERT_NOT_ERR_OR_NULL(test, pdrv);
+ *
+ * pdrv->probe = kunit_platform_driver_probe;
+ * pdrv->driver.name = "kunit-platform";
+ * pdrv->driver.owner = THIS_MODULE;
+ *
+ * KUNIT_ASSERT_EQ(test, 0, kunit_platform_device_prepare_wait_for_probe(test, pdev, &comp));
+ * KUNIT_ASSERT_EQ(test, 0, kunit_platform_driver_register(test, pdrv));
+ *
+ * KUNIT_EXPECT_NE(test, 0, wait_for_completion_timeout(&comp, 3 * HZ));
+ * }
+ *
+ * Return: 0 on success, negative errno on failure.
+ */
+int kunit_platform_device_prepare_wait_for_probe(struct kunit *test,
+ struct platform_device *pdev,
+ struct completion *x)
+{
+ struct device *dev = &pdev->dev;
+ struct kunit_platform_device_probe_nb *knb;
+ bool bound;
+
+ knb = kunit_kzalloc(test, sizeof(*knb), GFP_KERNEL);
+ if (!knb)
+ return -ENOMEM;
+
+ knb->nb.notifier_call = kunit_platform_device_probe_notify;
+ knb->dev = dev;
+ knb->x = x;
+
+ device_lock(dev);
+ bound = device_is_bound(dev);
+ if (bound) {
+ device_unlock(dev);
+ complete(x);
+ kunit_kfree(test, knb);
+ return 0;
+ }
+
+ bus_register_notifier(&platform_bus_type, &knb->nb);
+ device_unlock(&pdev->dev);
+
+ return kunit_add_action_or_reset(test, kunit_platform_device_probe_nb_remove, &knb->nb);
+}
+EXPORT_SYMBOL_GPL(kunit_platform_device_prepare_wait_for_probe);
+
+KUNIT_DEFINE_ACTION_WRAPPER(platform_driver_unregister_wrapper,
+ platform_driver_unregister, struct platform_driver *);
+/**
+ * kunit_platform_driver_register() - Register a KUnit test managed platform driver
+ * @test: test context
+ * @drv: platform driver to register
+ *
+ * Register a test managed platform driver. This allows callers to embed the
+ * @drv in a container structure and use container_of() in the probe function
+ * to pass information to KUnit tests.
+ *
+ * Example
+ *
+ * .. code-block:: c
+ *
+ * struct kunit_test_context {
+ * struct platform_driver pdrv;
+ * const char *data;
+ * };
+ *
+ * static inline struct kunit_test_context *
+ * to_test_context(struct platform_device *pdev)
+ * {
+ * return container_of(to_platform_driver(pdev->dev.driver),
+ * struct kunit_test_context,
+ * pdrv);
+ * }
+ *
+ * static int kunit_platform_driver_probe(struct platform_device *pdev)
+ * {
+ * struct kunit_test_context *ctx;
+ *
+ * ctx = to_test_context(pdev);
+ * ctx->data = "test data";
+ *
+ * return 0;
+ * }
+ *
+ * static void kunit_platform_driver_test(struct kunit *test)
+ * {
+ * struct kunit_test_context *ctx;
+ *
+ * ctx = kunit_kzalloc(test, sizeof(*ctx), GFP_KERNEL);
+ * KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ctx);
+ *
+ * ctx->pdrv.probe = kunit_platform_driver_probe;
+ * ctx->pdrv.driver.name = "kunit-platform";
+ * ctx->pdrv.driver.owner = THIS_MODULE;
+ *
+ * KUNIT_EXPECT_EQ(test, 0, kunit_platform_driver_register(test, &ctx->pdrv));
+ * <... wait for driver to probe ...>
+ * KUNIT_EXPECT_STREQ(test, ctx->data, "test data");
+ * }
+ *
+ * Return: 0 on success, negative errno on failure.
+ */
+int kunit_platform_driver_register(struct kunit *test,
+ struct platform_driver *drv)
+{
+ int ret;
+
+ ret = platform_driver_register(drv);
+ if (ret)
+ return ret;
+
+ return kunit_add_action_or_reset(test, platform_driver_unregister_wrapper, drv);
+}
+EXPORT_SYMBOL_GPL(kunit_platform_driver_register);