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-rw-r--r--drivers/rtc/lib_test.c81
1 files changed, 81 insertions, 0 deletions
diff --git a/drivers/rtc/lib_test.c b/drivers/rtc/lib_test.c
new file mode 100644
index 000000000000..d5caf36c56cd
--- /dev/null
+++ b/drivers/rtc/lib_test.c
@@ -0,0 +1,81 @@
+// SPDX-License-Identifier: LGPL-2.1+
+
+#include <kunit/test.h>
+#include <linux/rtc.h>
+
+/*
+ * Advance a date by one day.
+ */
+static void advance_date(int *year, int *month, int *mday, int *yday)
+{
+ if (*mday != rtc_month_days(*month - 1, *year)) {
+ ++*mday;
+ ++*yday;
+ return;
+ }
+
+ *mday = 1;
+ if (*month != 12) {
+ ++*month;
+ ++*yday;
+ return;
+ }
+
+ *month = 1;
+ *yday = 1;
+ ++*year;
+}
+
+/*
+ * Checks every day in a 160000 years interval starting on 1970-01-01
+ * against the expected result.
+ */
+static void rtc_time64_to_tm_test_date_range(struct kunit *test)
+{
+ /*
+ * 160000 years = (160000 / 400) * 400 years
+ * = (160000 / 400) * 146097 days
+ * = (160000 / 400) * 146097 * 86400 seconds
+ */
+ time64_t total_secs = ((time64_t) 160000) / 400 * 146097 * 86400;
+
+ int year = 1970;
+ int month = 1;
+ int mday = 1;
+ int yday = 1;
+
+ struct rtc_time result;
+ time64_t secs;
+ s64 days;
+
+ for (secs = 0; secs <= total_secs; secs += 86400) {
+
+ rtc_time64_to_tm(secs, &result);
+
+ days = div_s64(secs, 86400);
+
+ #define FAIL_MSG "%d/%02d/%02d (%2d) : %ld", \
+ year, month, mday, yday, days
+
+ KUNIT_ASSERT_EQ_MSG(test, year - 1900, result.tm_year, FAIL_MSG);
+ KUNIT_ASSERT_EQ_MSG(test, month - 1, result.tm_mon, FAIL_MSG);
+ KUNIT_ASSERT_EQ_MSG(test, mday, result.tm_mday, FAIL_MSG);
+ KUNIT_ASSERT_EQ_MSG(test, yday, result.tm_yday, FAIL_MSG);
+
+ advance_date(&year, &month, &mday, &yday);
+ }
+}
+
+static struct kunit_case rtc_lib_test_cases[] = {
+ KUNIT_CASE(rtc_time64_to_tm_test_date_range),
+ {}
+};
+
+static struct kunit_suite rtc_lib_test_suite = {
+ .name = "rtc_lib_test_cases",
+ .test_cases = rtc_lib_test_cases,
+};
+
+kunit_test_suite(rtc_lib_test_suite);
+
+MODULE_LICENSE("GPL");