linux-kernel - [PATCH v1 3/3] rtc: mt6359: Use RTC_TC

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Message-ID: <20240923100010.97470-4-angelogioacchino.delregno@collabora.com>
Date: Mon, 23 Sep 2024 12:00:10 +0200
From: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
To: lee@...nel.org
Cc: robh@...nel.org,
	krzk+dt@...nel.org,
	conor+dt@...nel.org,
	matthias.bgg@...il.com,
	angelogioacchino.delregno@...labora.com,
	eddie.huang@...iatek.com,
	sean.wang@...iatek.com,
	alexandre.belloni@...tlin.com,
	sen.chu@...iatek.com,
	macpaul.lin@...iatek.com,
	devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-mediatek@...ts.infradead.org,
	linux-rtc@...r.kernel.org,
	kernel@...labora.com
Subject: [PATCH v1 3/3] rtc: mt6359: Use RTC_TC_DOW hardware register for wday

Instead of calculating the number of full days since Sunday with
(days + 4) % 7, read (and write) that to the RTC Day-of-week Time
Counter register (RTC_TC_DOW).

Some transformation (addition and subtraction for set/get) is
still done, as this register's range is [1..7], while the tm_wday
in struct tm's range is [0..6].

Please note that this was added only to set_time() and read_time()
callbacks because set_alarm() and read_alarm() are setting a bit
in RTC_AL_MASK to ignore DOW for RTC HW alarms for unknown reasons.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
---
 drivers/rtc/rtc-mt6397.c | 16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/drivers/rtc/rtc-mt6397.c b/drivers/rtc/rtc-mt6397.c
index 4785af123a7f..152699219a2b 100644
--- a/drivers/rtc/rtc-mt6397.c
+++ b/drivers/rtc/rtc-mt6397.c
@@ -75,6 +75,7 @@ static int __mtk_rtc_read_time(struct mt6397_rtc *rtc,
 	tm->tm_min = data[RTC_OFFSET_MIN];
 	tm->tm_hour = data[RTC_OFFSET_HOUR];
 	tm->tm_mday = data[RTC_OFFSET_DOM];
+	tm->tm_wday = data[RTC_OFFSET_DOW];
 	tm->tm_mon = data[RTC_OFFSET_MTH] & RTC_TC_MTH_MASK;
 	tm->tm_year = data[RTC_OFFSET_YEAR];
 
@@ -86,9 +87,8 @@ static int __mtk_rtc_read_time(struct mt6397_rtc *rtc,
 
 static int mtk_rtc_read_time(struct device *dev, struct rtc_time *tm)
 {
-	time64_t time;
 	struct mt6397_rtc *rtc = dev_get_drvdata(dev);
-	int days, sec, ret;
+	int sec, ret;
 
 	do {
 		ret = __mtk_rtc_read_time(rtc, tm, &sec);
@@ -96,15 +96,9 @@ static int mtk_rtc_read_time(struct device *dev, struct rtc_time *tm)
 			goto exit;
 	} while (sec < tm->tm_sec);
 
-	/* HW register start mon from one, but tm_mon start from zero. */
+	/* HW register start mon/wday from one, but tm_mon/tm_wday start from zero. */
 	tm->tm_mon--;
-	time = rtc_tm_to_time64(tm);
-
-	/* rtc_tm_to_time64 covert Gregorian date to seconds since
-	 * 01-01-1970 00:00:00, and this date is Thursday.
-	 */
-	days = div_s64(time, 86400);
-	tm->tm_wday = (days + 4) % 7;
+	tm->tm_wday--;
 
 exit:
 	return ret;
@@ -117,11 +111,13 @@ static int mtk_rtc_set_time(struct device *dev, struct rtc_time *tm)
 	u16 data[RTC_OFFSET_COUNT];
 
 	tm->tm_mon++;
+	tm->tm_wday++;
 
 	data[RTC_OFFSET_SEC] = tm->tm_sec;
 	data[RTC_OFFSET_MIN] = tm->tm_min;
 	data[RTC_OFFSET_HOUR] = tm->tm_hour;
 	data[RTC_OFFSET_DOM] = tm->tm_mday;
+	data[RTC_OFFSET_DOW] = tm->tm_wday;
 	data[RTC_OFFSET_MTH] = tm->tm_mon;
 	data[RTC_OFFSET_YEAR] = tm->tm_year;
 
-- 
2.46.0