1 /*
2 * Copyright (c) 2019 Intel Corp.
3 *
4 * SPDX-License-Identifier: Apache-2.0
5 */
6
7 #include <zephyr/ztest.h>
8 #include <zephyr/kernel.h>
9
10 /*
11 * precision timing tests in an emulation environment are not reliable.
12 * if the test passes at least once, we know it works properly, so we
13 * attempt to repeat the test RETRIES times before reporting failure.
14 */
15
16 #define RETRIES 10
17
18 /*
19 * We need to know how many ticks will elapse when we ask for the
20 * shortest possible tick timeout. That's generally 1, but in some
21 * cases it may be more. On Nordic paths that take 5 or 6 ticks may
22 * be observed depending on clock stability and alignment. The base
23 * rate assumes 3 ticks for non-timeout effects so increase the
24 * maximum effect of timeout to 3 ticks on this platform.
25 */
26
27 #if defined(CONFIG_NRF_RTC_TIMER) && (CONFIG_SYS_CLOCK_TICKS_PER_SEC > 16384)
28 /* The overhead of k_usleep() adds three ticks per loop iteration on
29 * nRF51, which has a slow CPU clock.
30 */
31 #define MAXIMUM_SHORTEST_TICKS (IS_ENABLED(CONFIG_SOC_SERIES_NRF51X) ? 6 : 3)
32 /* Similar situation for TI CC13XX/CC26XX RTC kernel timer due to the
33 * limitation that a value too close to the current time cannot be
34 * loaded to its comparator.
35 */
36 #elif defined(CONFIG_CC13XX_CC26XX_RTC_TIMER) && \
37 (CONFIG_SYS_CLOCK_TICKS_PER_SEC > 16384)
38 #define MAXIMUM_SHORTEST_TICKS 3
39 #elif defined(CONFIG_SILABS_SLEEPTIMER_TIMER) && (CONFIG_SYS_CLOCK_TICKS_PER_SEC > 16384)
40 /* Similar situation for Silabs devices using sleeptimer due to the
41 * limitation that a value too close to the current time cannot be
42 * loaded to its comparator.
43 */
44 #define MAXIMUM_SHORTEST_TICKS 2
45 #else
46 #define MAXIMUM_SHORTEST_TICKS 1
47 #endif
48
49 /*
50 * Theory of operation: we can't use absolute units (e.g., "sleep for
51 * 10us") in testing k_usleep() because the granularity of sleeps is
52 * highly dependent on the hardware's capabilities and kernel
53 * configuration. Instead, we test that k_usleep() actually sleeps for
54 * the minimum possible duration, which is nominally two ticks. So,
55 * we loop k_usleep()ing for as many iterations as should comprise a
56 * second, and check to see that a total of one second has elapsed.
57 */
58
59 #define LOOPS (CONFIG_SYS_CLOCK_TICKS_PER_SEC / 2)
60
61 /* It should never iterate faster than the tick rate. However the
62 * app, sleep, and timeout layers may each add a tick alignment with
63 * fast tick rates, and cycle layer may inject another to guarantee
64 * the timeout deadline is met.
65 */
66 #define LOWER_BOUND_MS ((1000 * LOOPS) / CONFIG_SYS_CLOCK_TICKS_PER_SEC)
67 #define UPPER_BOUND_MS (((3 + MAXIMUM_SHORTEST_TICKS) * 1000 * LOOPS) \
68 / CONFIG_SYS_CLOCK_TICKS_PER_SEC)
69
ZTEST_USER(sleep,test_usleep)70 ZTEST_USER(sleep, test_usleep)
71 {
72 int retries = 0;
73 int64_t elapsed_ms = 0;
74
75 while (retries < RETRIES) {
76 int64_t start_ms;
77 int64_t end_ms;
78 int i;
79
80 ++retries;
81 start_ms = k_uptime_get();
82
83 for (i = 0; i < LOOPS; ++i) {
84 k_usleep(1);
85 }
86
87 end_ms = k_uptime_get();
88 elapsed_ms = end_ms - start_ms;
89
90 /* if at first you don't succeed, keep sucking. */
91
92 if ((elapsed_ms >= LOWER_BOUND_MS) &&
93 (elapsed_ms <= UPPER_BOUND_MS)) {
94 break;
95 }
96 }
97
98 zassert_true(elapsed_ms >= LOWER_BOUND_MS, "short sleep");
99 zassert_true(elapsed_ms <= UPPER_BOUND_MS, "overslept");
100 }
101