tests: posix: nanosleep: round up to the nearest microsecond

Here, we include some addtional tests for durations that have
sub-microsecond components.

1ns => k_busy_wait(0). Round to 1us.
1us + 1ns => k_busy_wait(1us). Round to 2us.
1s + 1ns => k_busy_wait(1000000us). Round to 1000001us.
1s + 1us + 1ns => k_busy_wait(1000001us). Round to 1000002us.

Fixes #28483

Signed-off-by: Christopher Friedt <[email protected]>

Author: cfriedt

tests/posix/common/src/main.c

@@ -27,10 +27,13 @@ extern void test_nanosleep_req_is_rem(void);
 extern void test_nanosleep_n1_0(void);
 extern void test_nanosleep_0_n1(void);
 extern void test_nanosleep_n1_n1(void);
-extern void test_nanosleep_0_1000000000(void);
 extern void test_nanosleep_0_1(void);
+extern void test_nanosleep_0_1001(void);
+extern void test_nanosleep_0_1000000000(void);
 extern void test_nanosleep_0_500000000(void);
 extern void test_nanosleep_1_0(void);
+extern void test_nanosleep_1_1(void);
+extern void test_nanosleep_1_1001(void);
 
 void test_main(void)
 {
@@ -55,9 +58,12 @@ void test_main(void)
 			ztest_unit_test(test_nanosleep_n1_0),
 			ztest_unit_test(test_nanosleep_0_n1),
 			ztest_unit_test(test_nanosleep_n1_n1),
-			ztest_unit_test(test_nanosleep_0_1000000000),
+			ztest_unit_test(test_nanosleep_0_1),
+			ztest_unit_test(test_nanosleep_0_1001),
 			ztest_unit_test(test_nanosleep_0_500000000),
-			ztest_unit_test(test_nanosleep_1_0)
+			ztest_unit_test(test_nanosleep_1_0),
+			ztest_unit_test(test_nanosleep_1_1),
+			ztest_unit_test(test_nanosleep_1_1001)
 			);
 	ztest_run_test_suite(posix_apis);
 }

tests/posix/common/src/nanosleep.c

@@ -10,27 +10,6 @@
 #include <stdint.h>
 #include <sys_clock.h>
 
-/* TODO: Upper bounds check when hr timers are available */
-#define NSEC_PER_TICK \
-	(NSEC_PER_SEC / CONFIG_SYS_CLOCK_TICKS_PER_SEC)
-#define NSEC_PER_CYCLE \
-	(NSEC_PER_SEC / CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC)
-
-/* Specify accepted tolerance. On some Zephyr platforms  (e.g. nRF5x) the busy
- * wait loop and the system timer are based on different mechanisms and may not
- * align perfectly. 1 percent base intolerance is to cover CPU processing in the
- * test.
- */
-#if CONFIG_NRF_RTC_TIMER
-/* High frequency clock used for k_busy_wait may have up to 8% tolerance.
- * Additionally, if RC is used for low frequency clock then it has 5% tolerance.
- */
-#define TOLERANCE_PPC \
-	(1 + 8 + (IS_ENABLED(CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC) ? 5 : 0))
-#else
-#define TOLERANCE_PPC 1
-#endif
-
 /** req and rem are both NULL */
 void test_nanosleep_NULL_NULL(void)
 {
@@ -199,23 +178,30 @@ static void common(const uint32_t s, uint32_t ns)
 	zassert_equal(rem.tv_nsec, 0, "actual: %d expected: %d",
 		rem.tv_nsec, 0);
 
+	uint64_t actual_ns = k_cyc_to_ns_ceil64((now - then));
 	uint64_t exp_ns = (uint64_t)s * NSEC_PER_SEC + ns;
-	uint64_t tolerance_ns = MAX(NSEC_PER_CYCLE,
-				    (TOLERANCE_PPC * exp_ns) / 100U);
-	uint64_t tck_ns = k_cyc_to_ns_ceil64((now == then)
-					     ? 1U
-					     : (now - then));
-	int64_t delta_ns = (int64_t)(exp_ns - tck_ns);
-
-	zassert_true((delta_ns < 0)
-		     ? ((uint64_t)-delta_ns <= tolerance_ns)
-		     : ((uint64_t)delta_ns <= tolerance_ns),
-		"error %lld beyond tolerance %llu for %llu vs %llu",
-		     delta_ns, tolerance_ns, exp_ns, tck_ns);
+	/* round up to the nearest microsecond for k_busy_wait() */
+	exp_ns = ceiling_fraction(exp_ns, NSEC_PER_USEC) * NSEC_PER_USEC;
+
+	/* lower bounds check */
+	zassert_true(actual_ns >= exp_ns,
+		"actual: %llu expected: %llu", actual_ns, exp_ns);
 
 	/* TODO: Upper bounds check when hr timers are available */
 }
 
+/** sleep for 1ns */
+void test_nanosleep_0_1(void)
+{
+	common(0, 1);
+}
+
+/** sleep for 1us + 1ns */
+void test_nanosleep_0_1001(void)
+{
+	common(0, 1001);
+}
+
 /** sleep for 500000000ns */
 void test_nanosleep_0_500000000(void)
 {
@@ -227,3 +213,15 @@ void test_nanosleep_1_0(void)
 {
 	common(1, 0);
 }
+
+/** sleep for 1s + 1ns */
+void test_nanosleep_1_1(void)
+{
+	common(1, 1);
+}
+
+/** sleep for 1s + 1us + 1ns */
+void test_nanosleep_1_1001(void)
+{
+	common(1, 1001);
+}