1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Kunit tests for clk 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 */
clk_fd_test_approximation_max_denominator(struct kunit * test)16 static 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 */
clk_fd_test_approximation_max_numerator(struct kunit * test)45 static 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 */
clk_fd_test_approximation_max_denominator_zero_based(struct kunit * test)74 static 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 */
clk_fd_test_approximation_max_numerator_zero_based(struct kunit * test)104 static 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
128 static 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 */
139 static struct kunit_suite clk_fd_approximation_suite = {
140 .name = "clk-fd-approximation",
141 .test_cases = clk_fd_approximation_test_cases,
142 };
143
144 kunit_test_suites(
145 &clk_fd_approximation_suite
146 );
147 MODULE_DESCRIPTION("Kunit tests for clk fractional divider");
148 MODULE_LICENSE("GPL");
149