drm/tests: helpers: Allow for a custom device struct to be allocated

The current helper to allocate a DRM device doesn't allow for any
subclassing by drivers, which is going to be troublesome as we work on
getting some kunit testing on atomic modesetting code.

Let's use a similar pattern to the other allocation helpers by providing
the structure size and offset as arguments.

Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://lore.kernel.org/r/20221123-rpi-kunit-tests-v3-10-4615a663a84a@cerno.tech
Signed-off-by: Maxime Ripard <maxime@cerno.tech>

1 files changed, 30 insertions, 2 deletions

diff --git a/include/drm/drm_kunit_helpers.h b/include/drm/drm_kunit_helpers.h
index b4277fe92c38..df99fda95e89 100644
--- a/include/drm/drm_kunit_helpers.h
+++ b/include/drm/drm_kunit_helpers.h
@@ -10,7 +10,35 @@ struct device *drm_kunit_helper_alloc_device(struct kunit *test);
 void drm_kunit_helper_free_device(struct kunit *test, struct device *dev);
 
 struct drm_device *
-drm_kunit_helper_alloc_drm_device(struct kunit *test, struct device *dev,
-				  u32 features);
+__drm_kunit_helper_alloc_drm_device(struct kunit *test, struct device *dev,
+				    size_t size, size_t offset,
+				    u32 features);
+
+/**
+ * drm_kunit_helper_alloc_drm_device - Allocates a mock DRM device for KUnit tests
+ * @_test: The test context object
+ * @_dev: The parent device object
+ * @_type: the type of the struct which contains struct &drm_device
+ * @_member: the name of the &drm_device within @_type.
+ * @_features: Mocked DRM device driver features
+ *
+ * This function creates a struct &drm_driver and will create a struct
+ * &drm_device from @_dev and that driver.
+ *
+ * @_dev should be allocated using drm_kunit_helper_alloc_device().
+ *
+ * The driver is tied to the @_test context and will get cleaned at the
+ * end of the test. The drm_device is allocated through
+ * devm_drm_dev_alloc() and will thus be freed through a device-managed
+ * resource.
+ *
+ * Returns:
+ * A pointer to the new drm_device, or an ERR_PTR() otherwise.
+ */
+#define drm_kunit_helper_alloc_drm_device(_test, _dev, _type, _member, _feat)	\
+	((_type *)__drm_kunit_helper_alloc_drm_device(_test, _dev,		\
+						      sizeof(_type),		\
+						      offsetof(_type, _member),	\
+						      _feat))
 
 #endif // DRM_KUNIT_HELPERS_H_