drm/xe/tests: Add helpers for use in live tests

Instead of iterating over available Xe devices within a testcase,
without being able to distinguish potential failures from different
devices on system with many Xe devices, introduce helpers that will
allow to treat each Xe device as a parameter for the testcase like:

static void bar(struct kunit *test)
{
struct xe_device *xe = test->priv;
...
}

struct kunit_case foo_live_tests[] = {
KUNIT_CASE_PARAM(bar, xe_pci_live_device_gen_param),
{}
};

struct kunit_suite foo_suite = {
.name = "foo_live",
.test_cases = foo_live_tests,
.init = xe_kunit_helper_xe_device_live_test_init,
};

Signed-off-by: Michal Wajdeczko <[e-mail]>
Reviewed-by: Jonathan Cavitt <[e-mail]>
Reviewed-by: Lucas De Marchi <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/xe/tests/xe_kunit_helpers.c

···
 
 #include "tests/xe_kunit_helpers.h"
 #include "tests/xe_pci_test.h"
+#include "xe_device.h"
 #include "xe_device_types.h"
+#include "xe_pm.h"
 
 /**
  * xe_kunit_helper_alloc_xe_device - Allocate a &xe_device for a KUnit test.
···
 	return 0;
 }
 EXPORT_SYMBOL_IF_KUNIT(xe_kunit_helper_xe_device_test_init);
+
+KUNIT_DEFINE_ACTION_WRAPPER(put_xe_pm_runtime, xe_pm_runtime_put, struct xe_device *);
+
+/**
+ * xe_kunit_helper_xe_device_live_test_init - Prepare a &xe_device for
+ *                                            use in a live KUnit test.
+ * @test: the &kunit where live &xe_device will be used
+ *
+ * This function expects pointer to the &xe_device in the &test.param_value,
+ * like it is prepared by the &xe_pci_live_device_gen_param and stores that
+ * pointer as &kunit.priv to allow the test code to access it.
+ *
+ * This function makes sure that device is not wedged and then resumes it
+ * to avoid waking up the device inside the test. It uses deferred cleanup
+ * action to release a runtime_pm reference.
+ *
+ * This function can be used as custom implementation of &kunit_suite.init.
+ *
+ * This function uses KUNIT_ASSERT to detect any failures.
+ *
+ * Return: Always 0.
+ */
+int xe_kunit_helper_xe_device_live_test_init(struct kunit *test)
+{
+	struct xe_device *xe = xe_device_const_cast(test->param_value);
+
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, xe);
+	kunit_info(test, "running on %s device\n", xe->info.platform_name);
+
+	KUNIT_ASSERT_FALSE(test, xe_device_wedged(xe));
+	xe_pm_runtime_get(xe);
+	KUNIT_ASSERT_EQ(test, 0, kunit_add_action_or_reset(test, put_xe_pm_runtime, xe));
+
+	test->priv = xe;
+	return 0;
+}
+EXPORT_SYMBOL_IF_KUNIT(xe_kunit_helper_xe_device_live_test_init);

drivers/gpu/drm/xe/tests/xe_kunit_helpers.h

···
 						  struct device *dev);
 int xe_kunit_helper_xe_device_test_init(struct kunit *test);
 
+int xe_kunit_helper_xe_device_live_test_init(struct kunit *test);
+
 #endif

drivers/gpu/drm/xe/tests/xe_pci.c

···
 	return 0;
 }
 EXPORT_SYMBOL_IF_KUNIT(xe_pci_fake_device_init);
+
+/**
+ * xe_pci_live_device_gen_param - Helper to iterate Xe devices as KUnit parameters
+ * @prev: the previously returned value, or NULL for the first iteration
+ * @desc: the buffer for a parameter name
+ *
+ * Iterates over the available Xe devices on the system. Uses the device name
+ * as the parameter name.
+ *
+ * To be used only as a parameter generator function in &KUNIT_CASE_PARAM.
+ *
+ * Return: pointer to the next &struct xe_device ready to be used as a parameter
+ *         or NULL if there are no more Xe devices on the system.
+ */
+const void *xe_pci_live_device_gen_param(const void *prev, char *desc)
+{
+	const struct xe_device *xe = prev;
+	struct device *dev = xe ? xe->drm.dev : NULL;
+	struct device *next;
+
+	next = driver_find_next_device(&xe_pci_driver.driver, dev);
+	if (dev)
+		put_device(dev);
+	if (!next)
+		return NULL;
+
+	snprintf(desc, KUNIT_PARAM_DESC_SIZE, "%s", dev_name(next));
+	return pdev_to_xe_device(to_pci_dev(next));
+}
+EXPORT_SYMBOL_IF_KUNIT(xe_pci_live_device_gen_param);

drivers/gpu/drm/xe/tests/xe_pci_test.h

···
 
 int xe_pci_fake_device_init(struct xe_device *xe);
 
+const void *xe_pci_live_device_gen_param(const void *prev, char *desc);
+
 #endif