1 files changed, 71 insertions, 0 deletions
diff --git a/drivers/gpu/drm/tests/drm_fixp_test.c b/drivers/gpu/drm/tests/drm_fixp_test.c
new file mode 100644
index 000000000000..dd77fdedb2a9
--- /dev/null
+++ b/drivers/gpu/drm/tests/drm_fixp_test.c
@@ -0,0 +1,71 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright 2022 Advanced Micro Devices, Inc.
+ */
+
+#include <kunit/test.h>
+#include <drm/drm_fixed.h>
+
+static void drm_test_sm2fixp(struct kunit *test)
+{
+	KUNIT_EXPECT_EQ(test, 0x7fffffffffffffffll, ((1ull << 63) - 1));
+
+	/* 1 */
+	KUNIT_EXPECT_EQ(test, drm_int2fixp(1), drm_sm2fixp(1ull << DRM_FIXED_POINT));
+
+	/* -1 */
+	KUNIT_EXPECT_EQ(test, drm_int2fixp(-1),
+			drm_sm2fixp((1ull << 63) | (1ull << DRM_FIXED_POINT)));
+
+	/* 0.5 */
+	KUNIT_EXPECT_EQ(test, drm_fixp_from_fraction(1, 2),
+			drm_sm2fixp(1ull << (DRM_FIXED_POINT - 1)));
+
+	/* -0.5 */
+	KUNIT_EXPECT_EQ(test, drm_fixp_from_fraction(-1, 2),
+			drm_sm2fixp((1ull << 63) | (1ull << (DRM_FIXED_POINT - 1))));
+}
+
+static void drm_test_int2fixp(struct kunit *test)
+{
+	/* 1 */
+	KUNIT_EXPECT_EQ(test, 1ll << 32, drm_int2fixp(1));
+
+	/* -1 */
+	KUNIT_EXPECT_EQ(test, -(1ll << 32), drm_int2fixp(-1));
+
+	/* 1 + (-1) = 0 */
+	KUNIT_EXPECT_EQ(test, 0, drm_int2fixp(1) + drm_int2fixp(-1));
+
+	/* 1 / 2 */
+	KUNIT_EXPECT_EQ(test, 1ll << 31, drm_fixp_from_fraction(1, 2));
+
+	/* -0.5 */
+	KUNIT_EXPECT_EQ(test, -(1ll << 31), drm_fixp_from_fraction(-1, 2));
+
+	/* (1 / 2) + (-1) = 0.5 */
+	KUNIT_EXPECT_EQ(test, 1ll << 31, drm_fixp_from_fraction(-1, 2) + drm_int2fixp(1));
+
+	/* (1 / 2) - 1) = 0.5 */
+	KUNIT_EXPECT_EQ(test, -(1ll << 31), drm_fixp_from_fraction(1, 2) + drm_int2fixp(-1));
+
+	/* (1 / 2) - 1) = 0.5 */
+	KUNIT_EXPECT_EQ(test, -(1ll << 31), drm_fixp_from_fraction(1, 2) - drm_int2fixp(1));
+}
+
+static struct kunit_case drm_fixp_tests[] = {
+	KUNIT_CASE(drm_test_int2fixp),
+	KUNIT_CASE(drm_test_sm2fixp),
+	{ }
+};
+
+static struct kunit_suite drm_fixp_test_suite = {
+	.name = "drm_fixp",
+	.test_cases = drm_fixp_tests,
+};
+
+kunit_test_suite(drm_fixp_test_suite);
+
+MODULE_AUTHOR("AMD");
+MODULE_LICENSE("Dual MIT/GPL");
+MODULE_DESCRIPTION("Unit tests for drm_fixed.h");