1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright �� 2020 Intel Corporation
4 */
5
6static struct intel_ring *mock_ring(unsigned long sz)
7{
8	struct intel_ring *ring;
9
10	ring = kzalloc(sizeof(*ring) + sz, GFP_KERNEL);
11	if (!ring)
12		return NULL;
13
14	kref_init(&ring->ref);
15	ring->size = sz;
16	ring->wrap = BITS_PER_TYPE(ring->size) - ilog2(sz);
17	ring->effective_size = sz;
18	ring->vaddr = (void *)(ring + 1);
19	atomic_set(&ring->pin_count, 1);
20
21	intel_ring_update_space(ring);
22
23	return ring;
24}
25
26static void mock_ring_free(struct intel_ring *ring)
27{
28	kfree(ring);
29}
30
31static int check_ring_direction(struct intel_ring *ring,
32				u32 next, u32 prev,
33				int expected)
34{
35	int result;
36
37	result = intel_ring_direction(ring, next, prev);
38	if (result < 0)
39		result = -1;
40	else if (result > 0)
41		result = 1;
42
43	if (result != expected) {
44		pr_err("intel_ring_direction(%u, %u):%d != %d\n",
45		       next, prev, result, expected);
46		return -EINVAL;
47	}
48
49	return 0;
50}
51
52static int check_ring_step(struct intel_ring *ring, u32 x, u32 step)
53{
54	u32 prev = x, next = intel_ring_wrap(ring, x + step);
55	int err = 0;
56
57	err |= check_ring_direction(ring, next, next,  0);
58	err |= check_ring_direction(ring, prev, prev,  0);
59	err |= check_ring_direction(ring, next, prev,  1);
60	err |= check_ring_direction(ring, prev, next, -1);
61
62	return err;
63}
64
65static int check_ring_offset(struct intel_ring *ring, u32 x, u32 step)
66{
67	int err = 0;
68
69	err |= check_ring_step(ring, x, step);
70	err |= check_ring_step(ring, intel_ring_wrap(ring, x + 1), step);
71	err |= check_ring_step(ring, intel_ring_wrap(ring, x - 1), step);
72
73	return err;
74}
75
76static int igt_ring_direction(void *dummy)
77{
78	struct intel_ring *ring;
79	unsigned int half = 2048;
80	int step, err = 0;
81
82	ring = mock_ring(2 * half);
83	if (!ring)
84		return -ENOMEM;
85
86	GEM_BUG_ON(ring->size != 2 * half);
87
88	/* Precision of wrap detection is limited to ring->size / 2 */
89	for (step = 1; step < half; step <<= 1) {
90		err |= check_ring_offset(ring, 0, step);
91		err |= check_ring_offset(ring, half, step);
92	}
93	err |= check_ring_step(ring, 0, half - 64);
94
95	/* And check unwrapped handling for good measure */
96	err |= check_ring_offset(ring, 0, 2 * half + 64);
97	err |= check_ring_offset(ring, 3 * half, 1);
98
99	mock_ring_free(ring);
100	return err;
101}
102
103int intel_ring_mock_selftests(void)
104{
105	static const struct i915_subtest tests[] = {
106		SUBTEST(igt_ring_direction),
107	};
108
109	return i915_subtests(tests, NULL);
110}
111