From d03c720e03bd9bf0b784d80b5d3ede7e2daf3b6e Mon Sep 17 00:00:00 2001 From: "davidgow@google.com" Date: Fri, 15 Dec 2023 15:39:08 +0800 Subject: kunit: Add APIs for managing devices Tests for drivers often require a struct device to pass to other functions. While it's possible to create these with root_device_register(), or to use something like a platform device, this is both a misuse of those APIs, and can be difficult to clean up after, for example, a failed assertion. Add some KUnit-specific functions for registering and unregistering a struct device: - kunit_device_register() - kunit_device_register_with_driver() - kunit_device_unregister() These helpers allocate a on a 'kunit' bus which will either probe the driver passed in (kunit_device_register_with_driver), or will create a stub driver (kunit_device_register) which is cleaned up on test shutdown. Devices are automatically unregistered on test shutdown, but can be manually unregistered earlier with kunit_device_unregister() in order to, for example, test device release code. Reviewed-by: Matti Vaittinen Reviewed-by: Maxime Ripard Signed-off-by: David Gow Reviewed-by: Greg Kroah-Hartman Signed-off-by: Shuah Khan --- Documentation/dev-tools/kunit/api/resource.rst | 9 +++++ Documentation/dev-tools/kunit/usage.rst | 50 ++++++++++++++++++++++++++ 2 files changed, 59 insertions(+) (limited to 'Documentation/dev-tools') diff --git a/Documentation/dev-tools/kunit/api/resource.rst b/Documentation/dev-tools/kunit/api/resource.rst index 0a94f831259e..ec6002a6b0db 100644 --- a/Documentation/dev-tools/kunit/api/resource.rst +++ b/Documentation/dev-tools/kunit/api/resource.rst @@ -11,3 +11,12 @@ state on a per-test basis, register custom cleanup actions, and more. .. kernel-doc:: include/kunit/resource.h :internal: + +Managed Devices +--------------- + +Functions for using KUnit-managed struct device and struct device_driver. +Include ``kunit/device.h`` to use these. + +.. kernel-doc:: include/kunit/device.h + :internal: diff --git a/Documentation/dev-tools/kunit/usage.rst b/Documentation/dev-tools/kunit/usage.rst index 9db12e91668e..53c6f7dc8a42 100644 --- a/Documentation/dev-tools/kunit/usage.rst +++ b/Documentation/dev-tools/kunit/usage.rst @@ -797,3 +797,53 @@ structures as shown below: KUnit is not enabled, or if no test is running in the current task, it will do nothing. This compiles down to either a no-op or a static key check, so will have a negligible performance impact when no test is running. + +Managing Fake Devices and Drivers +--------------------------------- + +When testing drivers or code which interacts with drivers, many functions will +require a ``struct device`` or ``struct device_driver``. In many cases, setting +up a real device is not required to test any given function, so a fake device +can be used instead. + +KUnit provides helper functions to create and manage these fake devices, which +are internally of type ``struct kunit_device``, and are attached to a special +``kunit_bus``. These devices support managed device resources (devres), as +described in Documentation/driver-api/driver-model/devres.rst + +To create a KUnit-managed ``struct device_driver``, use ``kunit_driver_create()``, +which will create a driver with the given name, on the ``kunit_bus``. This driver +will automatically be destroyed when the corresponding test finishes, but can also +be manually destroyed with ``driver_unregister()``. + +To create a fake device, use the ``kunit_device_register()``, which will create +and register a device, using a new KUnit-managed driver created with ``kunit_driver_create()``. +To provide a specific, non-KUnit-managed driver, use ``kunit_device_register_with_driver()`` +instead. Like with managed drivers, KUnit-managed fake devices are automatically +cleaned up when the test finishes, but can be manually cleaned up early with +``kunit_device_unregister()``. + +The KUnit devices should be used in preference to ``root_device_register()``, and +instead of ``platform_device_register()`` in cases where the device is not otherwise +a platform device. + +For example: + +.. code-block:: c + + #include + + static void test_my_device(struct kunit *test) + { + struct device *fake_device; + const char *dev_managed_string; + + // Create a fake device. + fake_device = kunit_device_register(test, "my_device"); + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, fake_device) + + // Pass it to functions which need a device. + dev_managed_string = devm_kstrdup(fake_device, "Hello, World!"); + + // Everything is cleaned up automatically when the test ends. + } \ No newline at end of file -- cgit