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/*
* Copyright (c) 2019 Intel Corp.
*
* SPDX-License-Identifier: Apache-2.0
*/
#include <ztest.h>
#include <zephyr.h>
/*
* precision timing tests in an emulation environment are not reliable.
* if the test passes at least once, we know it works properly, so we
* attempt to repeat the test RETRIES times before reporting failure.
*/
#define RETRIES 10
/*
* We need to know how many ticks will elapse when we ask for the
* shortest possible tick timeout. That's generally 1, but in some
* cases it may be more. On Nordic paths that take 5 or 6 ticks may
* be observed depending on clock stability and alignment. The base
* rate assumes 3 ticks for non-timeout effects so increase the
* maximum effect of timeout to 3 ticks on this platform.
*/
#if defined(CONFIG_NRF_RTC_TIMER) && (CONFIG_SYS_CLOCK_TICKS_PER_SEC > 16384)
/* The overhead of k_usleep() adds three ticks per loop iteration on
* nRF51, which has a slow CPU clock.
*/
#define MAXIMUM_SHORTEST_TICKS (IS_ENABLED(CONFIG_SOC_SERIES_NRF51X) ? 6 : 3)
/*
* Similar situation for TI CC13X2/CC26X2 RTC due to the limitation
* that a value too close to the current time cannot be loaded to
* its comparator.
*/
#elif defined(CONFIG_CC13X2_CC26X2_RTC_TIMER) && \
(CONFIG_SYS_CLOCK_TICKS_PER_SEC > 16384)
#define MAXIMUM_SHORTEST_TICKS 3
#else
#define MAXIMUM_SHORTEST_TICKS 1
#endif
/*
* Theory of operation: we can't use absolute units (e.g., "sleep for
* 10us") in testing k_usleep() because the granularity of sleeps is
* highly dependent on the hardware's capabilities and kernel
* configuration. Instead, we test that k_usleep() actually sleeps for
* the minimum possible duration, which is nominally two ticks. So,
* we loop k_usleep()ing for as many iterations as should comprise a
* second, and check to see that a total of one second has elapsed.
*/
#define LOOPS (CONFIG_SYS_CLOCK_TICKS_PER_SEC / 2)
/* It should never iterate faster than the tick rate. However the
* app, sleep, and timeout layers may each add a tick alignment with
* fast tick rates, and cycle layer may inject another to guarantee
* the timeout deadline is met.
*/
#define LOWER_BOUND_MS ((1000 * LOOPS) / CONFIG_SYS_CLOCK_TICKS_PER_SEC)
#define UPPER_BOUND_MS (((3 + MAXIMUM_SHORTEST_TICKS) * 1000 * LOOPS) \
/ CONFIG_SYS_CLOCK_TICKS_PER_SEC)
void test_usleep(void)
{
int retries = 0;
int64_t elapsed_ms;
while (retries < RETRIES) {
int64_t start_ms;
int64_t end_ms;
int i;
++retries;
start_ms = k_uptime_get();
for (i = 0; i < LOOPS; ++i) {
k_usleep(1);
}
end_ms = k_uptime_get();
elapsed_ms = end_ms - start_ms;
/* if at first you don't succeed, keep sucking. */
if ((elapsed_ms >= LOWER_BOUND_MS) &&
(elapsed_ms <= UPPER_BOUND_MS)) {
break;
}
}
printk("elapsed_ms = %" PRId64 "\n", elapsed_ms);
zassert_true(elapsed_ms >= LOWER_BOUND_MS, "short sleep");
zassert_true(elapsed_ms <= UPPER_BOUND_MS, "overslept");
}
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