Merge pull request #12610 from kaspar030/pr/add_tests/periph_timer_short_relative_set

tests: add new test periph_timer_short_relative_set

tests/periph_timer_short_relative_set/Makefile

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+include ../Makefile.tests_common
+
+FEATURES_REQUIRED = periph_timer
+
+USEMODULE += core_thread_flags
+
+# optionally configure timer under test. Defaults to xtimer config.
+# TEST_TIMER_DEV takes a 0-based index to the periph_timer instance defined in
+# the board's periph_conf.h. TEST_TIMER_FREQ as an integer number which will
+# be used as "freq" parameter in the timer_init() call.
+# Note: not all implementations support arbitrary frequencies.
+#CFLAGS += -DTEST_TIMER_DEV=foo -DTEST_TIMER_FREQ=bar
+
+# this test currently fails all CI boards and native
+TEST_ON_CI_BLACKLIST += all
+
+include $(RIOTBASE)/Makefile.include

tests/periph_timer_short_relative_set/README.md

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+# Periph Timer Test for short timer_set() values
+
+## About
+
+This test exposes if timer_set() with very low values (down to zero) underflows.
+For each value from 100 to 0, it'll try to set a timer with that length.
+In human terms, that should trigger instantly (It depends on TEST_TIMER_FREQ.
+The default configuration is 1MHz. Some boards configure 32768kHz, which is the
+slowest configuration currently. So each line should trigger after at most
+31us.).
+
+See this example of a timer_set() implementation:
+
+    int timer_set(tim_t dev, int channel, unsigned int timeout)
+    {
+        return timer_set_absolute(dev, channel, timer_read(dev) + timeout);
+    }
+
+This will probably underflow if "timeout" is 0, or if an ISR interrupts
+somewhere between the read and the timerSet_absolute() call.
+Depending on the used frequency of the underlying timer and the time it
+requires for the involved function calls, reading the timer register, doing the
+addition and writing back to the register, this will also fail for higher
+timeouts.
+
+For example, as of this writing (30-Oct-19), samr21-xpro fails for values below
+8, nrf52dk for values below 2.
+
+## Expected Result
+
+After 100 "interval N ok" messages the test should print "TEST SUCCEEDED".
+On failure, the test will print "TEST FAILED".

tests/periph_timer_short_relative_set/main.c

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+/*
+ * Copyright (C) 2019 Kaspar Schleiser <kaspar@schleiser.de>
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+/**
+ * @ingroup     tests
+ * @{
+ *
+ * @file
+ * @brief       Peripheral timer test application
+ *
+ * @author      Kaspar Schleiser <kaspar@schleiser.de>
+ *
+ * @}
+ */
+
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+#include "board.h"
+#include "thread.h"
+#include "thread_flags.h"
+
+#include "periph/timer.h"
+
+#ifndef TEST_TIMER_DEV
+# include "xtimer.h"
+# define TEST_TIMER_DEV      XTIMER_DEV
+# define TEST_TIMER_FREQ     XTIMER_HZ
+#else
+# ifndef TEST_TIMER_FREQ
+#  define TEST_TIMER_FREQ     (1000000LU)
+# endif
+#endif
+
+#ifndef TEST_MAX_DIFF
+#define TEST_MAX_DIFF   (1000LU)
+#endif
+
+static void cb(void *arg, int chan)
+{
+    (void)chan;
+    thread_flags_set(arg, 1);
+}
+
+int main(void)
+{
+    puts("\nTest for peripheral TIMER short timer_set()\n");
+
+    printf("This test tries timer_set() with decreasing intervals down to 0.\n"
+           "You should see lines like 'interval <n> ok', followed by a success"
+           " message.\n"
+           "On failure, this test prints an error message.\n\n");
+
+    printf("testing periph_timer %u, freq %lu\n", TEST_TIMER_DEV, TEST_TIMER_FREQ);
+    timer_init(TEST_TIMER_DEV, TEST_TIMER_FREQ, cb, (thread_t *)sched_active_thread);
+
+    uint32_t interval = 100;
+    while (interval--) {
+        uint32_t before = timer_read(TEST_TIMER_DEV);
+        timer_set(TEST_TIMER_DEV, 0, interval);
+        while(!thread_flags_clear(1)) {
+            uint32_t diff = timer_read(TEST_TIMER_DEV) - before;
+            if (diff > TEST_MAX_DIFF) {
+                printf("ERROR: too long delay, aborted after %" PRIu32
+                        " (TEST_MAX_DIFF=%lu)\n"
+                        "TEST FAILED\n",
+                        diff, TEST_MAX_DIFF);
+                while(1) {}
+            }
+        }
+        printf("interval %" PRIu32 " ok\n", interval);
+    }
+
+    puts("\nTEST SUCCEEDED");
+
+    return 0;
+}

tests/periph_timer_short_relative_set/tests/01-run.py

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+#!/usr/bin/env python3
+
+# Copyright (C) 2019 Kaspar Schleiser <kaspar@schleiser.de>
+#
+# This file is subject to the terms and conditions of the GNU Lesser
+# General Public License v2.1. See the file LICENSE in the top level
+# directory for more details.
+
+import sys
+from testrunner import run
+
+
+def testfunc(child):
+    child.expect_exact('TEST SUCCEEDED')
+
+
+if __name__ == "__main__":
+    sys.exit(run(testfunc))