linux-kernel - [PATCH v4 5/5] rtc: test: Test date conversion for dates starting in 1900

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Message-Id: <20250428-enable-rtc-v4-5-2b2f7e3f9349@baylibre.com>
Date: Mon, 28 Apr 2025 12:06:51 +0200
From: amergnat@...libre.com
To: Alexandre Belloni <alexandre.belloni@...tlin.com>, 
 Baolin Wang <baolin.wang@...ux.alibaba.com>
Cc: Uwe Kleine-König <u.kleine-koenig@...libre.com>, 
 linux-rtc@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Alexandre Mergnat <amergnat@...libre.com>
Subject: [PATCH v4 5/5] rtc: test: Test date conversion for dates starting
 in 1900

From: Uwe Kleine-König <u.kleine-koenig@...libre.com>

While the RTC framework intends to only handle dates after 1970 for
consumers, time conversion must also work for earlier dates to cover
e.g. storing dates beyond an RTC's range_max. This is most relevant for
the rtc-mt6397 driver that has

	range_min = RTC_TIMESTAMP_BEGIN_1900;
	range_max = mktime64(2027, 12, 31, 23, 59, 59);

and so needs working support for timestamps in 1900 starting in less than
three years.

So shift the tested interval of timestamps to also cover years 1900 to
1970.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@...libre.com>
Signed-off-by: Alexandre Mergnat <amergnat@...libre.com>
---
 drivers/rtc/lib_test.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/rtc/lib_test.c b/drivers/rtc/lib_test.c
index b1ac0701d42e5562b8eae5b191012c8b56a06902..0eebad1fe2a0983c0009626dac526fa07d27f6b6 100644
--- a/drivers/rtc/lib_test.c
+++ b/drivers/rtc/lib_test.c
@@ -41,15 +41,15 @@ static void rtc_time64_to_tm_test_date_range(struct kunit *test, int years)
 	 */
 	time64_t total_secs = ((time64_t)years) / 400 * 146097 * 86400;
 
-	int year	= 1970;
+	int year	= 1900;
 	int month	= 1;
 	int mday	= 1;
 	int yday	= 1;
-	int wday	= 4; /* Jan 1st 1970 was a Thursday */
+	int wday	= 1; /* Jan 1st 1900 was a Monday */
 
 	struct rtc_time result;
 	time64_t secs;
-	const time64_t sec_offset = ((1 * 60) + 2) * 60 + 3;
+	const time64_t sec_offset = RTC_TIMESTAMP_BEGIN_1900 + ((1 * 60) + 2) * 60 + 3;
 
 	for (secs = 0; secs <= total_secs; secs += 86400) {
 
@@ -72,7 +72,7 @@ static void rtc_time64_to_tm_test_date_range(struct kunit *test, int years)
 }
 
 /*
- * Checks every day in a 160000 years interval starting on 1970-01-01
+ * 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)
@@ -81,7 +81,7 @@ static void rtc_time64_to_tm_test_date_range_160000(struct kunit *test)
 }
 
 /*
- * Checks every day in a 1000 years interval starting on 1970-01-01
+ * 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)

-- 
2.25.1