1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Kunit test for clock fractional divider
4 */
5#include <linux/clk-provider.h>
6#include <kunit/test.h>
7
8#include "clk-fractional-divider.h"
9
10/*
11 * Test the maximum denominator case for fd clock without flags.
12 *
13 * Expect the highest possible denominator to be used in order to get as close as possible to the
14 * requested rate.
15 */
16static void clk_fd_test_approximation_max_denominator(struct kunit *test)
17{
18	struct clk_fractional_divider *fd;
19	unsigned long rate, parent_rate, parent_rate_before, m, n, max_n;
20
21	fd = kunit_kzalloc(test, sizeof(*fd), GFP_KERNEL);
22	KUNIT_ASSERT_NOT_NULL(test, fd);
23
24	fd->mwidth = 3;
25	fd->nwidth = 3;
26	max_n = 7;
27
28	rate = 240000000;
29	parent_rate = (max_n + 1) * rate; /* so that it exceeds the maximum divisor */
30	parent_rate_before = parent_rate;
31
32	clk_fractional_divider_general_approximation(&fd->hw, rate, &parent_rate, &m, &n);
33	KUNIT_ASSERT_EQ(test, parent_rate, parent_rate_before);
34
35	KUNIT_EXPECT_EQ(test, m, 1);
36	KUNIT_EXPECT_EQ(test, n, max_n);
37}
38
39/*
40 * Test the maximum numerator case for fd clock without flags.
41 *
42 * Expect the highest possible numerator to be used in order to get as close as possible to the
43 * requested rate.
44 */
45static void clk_fd_test_approximation_max_numerator(struct kunit *test)
46{
47	struct clk_fractional_divider *fd;
48	unsigned long rate, parent_rate, parent_rate_before, m, n, max_m;
49
50	fd = kunit_kzalloc(test, sizeof(*fd), GFP_KERNEL);
51	KUNIT_ASSERT_NOT_NULL(test, fd);
52
53	fd->mwidth = 3;
54	max_m = 7;
55	fd->nwidth = 3;
56
57	rate = 240000000;
58	parent_rate = rate / (max_m + 1); /* so that it exceeds the maximum numerator */
59	parent_rate_before = parent_rate;
60
61	clk_fractional_divider_general_approximation(&fd->hw, rate, &parent_rate, &m, &n);
62	KUNIT_ASSERT_EQ(test, parent_rate, parent_rate_before);
63
64	KUNIT_EXPECT_EQ(test, m, max_m);
65	KUNIT_EXPECT_EQ(test, n, 1);
66}
67
68/*
69 * Test the maximum denominator case for zero based fd clock.
70 *
71 * Expect the highest possible denominator to be used in order to get as close as possible to the
72 * requested rate.
73 */
74static void clk_fd_test_approximation_max_denominator_zero_based(struct kunit *test)
75{
76	struct clk_fractional_divider *fd;
77	unsigned long rate, parent_rate, parent_rate_before, m, n, max_n;
78
79	fd = kunit_kzalloc(test, sizeof(*fd), GFP_KERNEL);
80	KUNIT_ASSERT_NOT_NULL(test, fd);
81
82	fd->flags = CLK_FRAC_DIVIDER_ZERO_BASED;
83	fd->mwidth = 3;
84	fd->nwidth = 3;
85	max_n = 8;
86
87	rate = 240000000;
88	parent_rate = (max_n + 1) * rate; /* so that it exceeds the maximum divisor */
89	parent_rate_before = parent_rate;
90
91	clk_fractional_divider_general_approximation(&fd->hw, rate, &parent_rate, &m, &n);
92	KUNIT_ASSERT_EQ(test, parent_rate, parent_rate_before);
93
94	KUNIT_EXPECT_EQ(test, m, 1);
95	KUNIT_EXPECT_EQ(test, n, max_n);
96}
97
98/*
99 * Test the maximum numerator case for zero based fd clock.
100 *
101 * Expect the highest possible numerator to be used in order to get as close as possible to the
102 * requested rate.
103 */
104static void clk_fd_test_approximation_max_numerator_zero_based(struct kunit *test)
105{
106	struct clk_fractional_divider *fd;
107	unsigned long rate, parent_rate, parent_rate_before, m, n, max_m;
108
109	fd = kunit_kzalloc(test, sizeof(*fd), GFP_KERNEL);
110	KUNIT_ASSERT_NOT_NULL(test, fd);
111
112	fd->flags = CLK_FRAC_DIVIDER_ZERO_BASED;
113	fd->mwidth = 3;
114	max_m = 8;
115	fd->nwidth = 3;
116
117	rate = 240000000;
118	parent_rate = rate / (max_m + 1); /* so that it exceeds the maximum numerator */
119	parent_rate_before = parent_rate;
120
121	clk_fractional_divider_general_approximation(&fd->hw, rate, &parent_rate, &m, &n);
122	KUNIT_ASSERT_EQ(test, parent_rate, parent_rate_before);
123
124	KUNIT_EXPECT_EQ(test, m, max_m);
125	KUNIT_EXPECT_EQ(test, n, 1);
126}
127
128static struct kunit_case clk_fd_approximation_test_cases[] = {
129	KUNIT_CASE(clk_fd_test_approximation_max_denominator),
130	KUNIT_CASE(clk_fd_test_approximation_max_numerator),
131	KUNIT_CASE(clk_fd_test_approximation_max_denominator_zero_based),
132	KUNIT_CASE(clk_fd_test_approximation_max_numerator_zero_based),
133	{}
134};
135
136/*
137 * Test suite for clk_fractional_divider_general_approximation().
138 */
139static struct kunit_suite clk_fd_approximation_suite = {
140	.name = "clk-fd-approximation",
141	.test_cases = clk_fd_approximation_test_cases,
142};
143
144kunit_test_suites(
145	&clk_fd_approximation_suite
146);
147MODULE_LICENSE("GPL");
148