1 files changed, 106 insertions, 0 deletions
diff --git a/drivers/rtc/test_rtc_lib.c b/drivers/rtc/test_rtc_lib.c
new file mode 100644
index 000000000000..0eebad1fe2a0
--- /dev/null
+++ b/drivers/rtc/test_rtc_lib.c
@@ -0,0 +1,106 @@
+// 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, int *wday)
+{
+	*wday = (*wday + 1) % 7;
+
+	if (*mday != rtc_month_days(*month - 1, *year)) {
+		++*mday;
+		++*yday;
+		return;
+	}
+
+	*mday = 1;
+	if (*month != 12) {
+		++*month;
+		++*yday;
+		return;
+	}
+
+	*month = 1;
+	*yday  = 1;
+	++*year;
+}
+
+/*
+ * Check every day in specified number of years interval starting on 1970-01-01
+ * against the expected result.
+ */
+static void rtc_time64_to_tm_test_date_range(struct kunit *test, int years)
+{
+	/*
+	 * years	= (years / 400) * 400 years
+	 *		= (years / 400) * 146097 days
+	 *		= (years / 400) * 146097 * 86400 seconds
+	 */
+	time64_t total_secs = ((time64_t)years) / 400 * 146097 * 86400;
+
+	int year	= 1900;
+	int month	= 1;
+	int mday	= 1;
+	int yday	= 1;
+	int wday	= 1; /* Jan 1st 1900 was a Monday */
+
+	struct rtc_time result;
+	time64_t secs;
+	const time64_t sec_offset = RTC_TIMESTAMP_BEGIN_1900 + ((1 * 60) + 2) * 60 + 3;
+
+	for (secs = 0; secs <= total_secs; secs += 86400) {
+
+		rtc_time64_to_tm(secs + sec_offset, &result);
+
+		#define FAIL_MSG "%d/%02d/%02d (%2d, %d) : %lld", \
+			year, month, mday, yday, wday, secs + sec_offset
+
+		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);
+		KUNIT_ASSERT_EQ_MSG(test, 1, result.tm_hour, FAIL_MSG);
+		KUNIT_ASSERT_EQ_MSG(test, 2, result.tm_min, FAIL_MSG);
+		KUNIT_ASSERT_EQ_MSG(test, 3, result.tm_sec, FAIL_MSG);
+		KUNIT_ASSERT_EQ_MSG(test, wday, result.tm_wday, FAIL_MSG);
+
+		advance_date(&year, &month, &mday, &yday, &wday);
+	}
+}
+
+/*
+ * Checks every day in a 160000 years interval starting on 1900-01-01
+ * against the expected result.
+ */
+static void rtc_time64_to_tm_test_date_range_160000(struct kunit *test)
+{
+	rtc_time64_to_tm_test_date_range(test, 160000);
+}
+
+/*
+ * Checks every day in a 1000 years interval starting on 1900-01-01
+ * against the expected result.
+ */
+static void rtc_time64_to_tm_test_date_range_1000(struct kunit *test)
+{
+	rtc_time64_to_tm_test_date_range(test, 1000);
+}
+
+static struct kunit_case rtc_lib_test_cases[] = {
+	KUNIT_CASE(rtc_time64_to_tm_test_date_range_1000),
+	KUNIT_CASE_SLOW(rtc_time64_to_tm_test_date_range_160000),
+	{}
+};
+
+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_DESCRIPTION("KUnit test for RTC lib functions");
+MODULE_LICENSE("GPL");