coresight: Add a KUnit test for coresight_find_default_sink()

Add a test to confirm that default sink selection skips over an ETF
and returns an ETR even if it's further away.

This also makes it easier to add new unit tests in the future.

Reviewed-by: Leo Yan <leo.yan@arm.com>
Signed-off-by: James Clark <james.clark@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20250312-james-cs-kunit-test-v4-1-ae3dd718a26a@linaro.org

1 files changed, 74 insertions, 0 deletions

diff --git a/drivers/hwtracing/coresight/coresight-kunit-tests.c b/drivers/hwtracing/coresight/coresight-kunit-tests.c
new file mode 100644
index 000000000000..c8f361767c45
--- /dev/null
+++ b/drivers/hwtracing/coresight/coresight-kunit-tests.c
@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <kunit/test.h>
+#include <kunit/device.h>
+#include <linux/coresight.h>
+
+#include "coresight-priv.h"
+
+static struct coresight_device *coresight_test_device(struct device *dev)
+{
+	struct coresight_device *csdev = devm_kcalloc(dev, 1,
+						     sizeof(struct coresight_device),
+						     GFP_KERNEL);
+	csdev->pdata = devm_kcalloc(dev, 1,
+				   sizeof(struct coresight_platform_data),
+				   GFP_KERNEL);
+	return csdev;
+}
+
+static void test_default_sink(struct kunit *test)
+{
+	/*
+	 * Source -> ETF -> ETR -> CATU
+	 *                   ^
+	 *                   | default
+	 */
+	struct device *dev = kunit_device_register(test, "coresight_kunit");
+	struct coresight_device *src = coresight_test_device(dev),
+				*etf = coresight_test_device(dev),
+				*etr = coresight_test_device(dev),
+				*catu = coresight_test_device(dev);
+	struct coresight_connection conn = {};
+
+	src->type = CORESIGHT_DEV_TYPE_SOURCE;
+	/*
+	 * Don't use CORESIGHT_DEV_SUBTYPE_SOURCE_PROC, that would always return
+	 * a TRBE sink if one is registered.
+	 */
+	src->subtype.source_subtype = CORESIGHT_DEV_SUBTYPE_SOURCE_BUS;
+	etf->type = CORESIGHT_DEV_TYPE_LINKSINK;
+	etf->subtype.sink_subtype = CORESIGHT_DEV_SUBTYPE_SINK_BUFFER;
+	etr->type = CORESIGHT_DEV_TYPE_SINK;
+	etr->subtype.sink_subtype = CORESIGHT_DEV_SUBTYPE_SINK_SYSMEM;
+	catu->type = CORESIGHT_DEV_TYPE_HELPER;
+
+	conn.src_dev = src;
+	conn.dest_dev = etf;
+	coresight_add_out_conn(dev, src->pdata, &conn);
+
+	conn.src_dev = etf;
+	conn.dest_dev = etr;
+	coresight_add_out_conn(dev, etf->pdata, &conn);
+
+	conn.src_dev = etr;
+	conn.dest_dev = catu;
+	coresight_add_out_conn(dev, etr->pdata, &conn);
+
+	KUNIT_ASSERT_PTR_EQ(test, coresight_find_default_sink(src), etr);
+}
+
+static struct kunit_case coresight_testcases[] = {
+	KUNIT_CASE(test_default_sink),
+	{}
+};
+
+static struct kunit_suite coresight_test_suite = {
+	.name = "coresight_test_suite",
+	.test_cases = coresight_testcases,
+};
+
+kunit_test_suites(&coresight_test_suite);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("James Clark <james.clark@linaro.org>");
+MODULE_DESCRIPTION("Arm CoreSight KUnit tests");