Message-ID: <CABVgOSm=R2-SvCRLsep_2Zk20eq7rg_RBvXK4ZYWvjWnmpboKA@mail.gmail.com>
Date: Thu, 13 Jun 2024 15:50:18 +0800
From: David Gow <davidgow@...gle.com>
To: Stephen Boyd <sboyd@...nel.org>
Cc: Michael Turquette <mturquette@...libre.com>, linux-kernel@...r.kernel.org, 
	linux-clk@...r.kernel.org, patches@...ts.linux.dev, 
	kunit-dev@...glegroups.com, linux-kselftest@...r.kernel.org, 
	devicetree@...r.kernel.org, Brendan Higgins <brendan.higgins@...ux.dev>, 
	Rae Moar <rmoar@...gle.com>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
	"Rafael J . Wysocki" <rafael@...nel.org>, Rob Herring <robh@...nel.org>, 
	Saravana Kannan <saravanak@...gle.com>, Daniel Latypov <dlatypov@...gle.com>, 
	Christian Marangi <ansuelsmth@...il.com>, 
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>, Conor Dooley <conor+dt@...nel.org>, 
	Maxime Ripard <maxime@...no.tech>
Subject: Re: [PATCH v5 06/11] platform: Add test managed platform_device/driver
 APIs

On Tue, 4 Jun 2024 at 06:38, Stephen Boyd <sboyd@...nel.org> wrote:
>
> 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@...ux.dev>
> Cc: David Gow <davidgow@...gle.com>
> Cc: Rae Moar <rmoar@...gle.com>
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Cc: "Rafael J. Wysocki" <rafael@...nel.org>
> Signed-off-by: Stephen Boyd <sboyd@...nel.org>
> ---

This looks great, thanks!

Reviewed-by: David Gow <davidgow@...gle.com>

Cheers,
-- David


>  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);
> --
> https://git.kernel.org/pub/scm/linux/kernel/git/clk/linux.git/
> https://git.kernel.org/pub/scm/linux/kernel/git/sboyd/spmi.git
>

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