[PATCH v5 4/6] rtc: s35390a: force 24-hour mode

[Markus Probst]

Instead of trying to remember the current 12/24-hour mode, which could
result in time corruption if out of sync, we force the use of the 24-hour
mode. Set to 24-hour mode if in 12-hour mode on startup and assume
24-hour mode. The 24-hour mode is already forced on reset.

Signed-off-by: Markus Probst <markus.probst@xxxxxxxxx>
---
 drivers/rtc/rtc-s35390a.c | 67 +++++++++++++++++++++--------------------------
 1 file changed, 30 insertions(+), 37 deletions(-)

diff --git a/drivers/rtc/rtc-s35390a.c b/drivers/rtc/rtc-s35390a.c
index 575bb256eb25..b34a3f7e8476 100644
--- a/drivers/rtc/rtc-s35390a.c
+++ b/drivers/rtc/rtc-s35390a.c
@@ -64,7 +64,6 @@ MODULE_DEVICE_TABLE(of, s35390a_of_match);
 
 struct s35390a {
 	struct i2c_client *client[8];
-	int twentyfourhour;
 };
 
 static int s35390a_set_reg(struct s35390a *s35390a, int reg, u8  *buf, int len)
@@ -181,31 +180,6 @@ static int s35390a_disable_test_mode(struct s35390a *s35390a)
 	return s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, buf, sizeof(buf));
 }
 
-static char s35390a_hr2reg(struct s35390a *s35390a, int hour)
-{
-	if (s35390a->twentyfourhour)
-		return bin2bcd(hour);
-
-	if (hour < 12)
-		return bin2bcd(hour);
-
-	return 0x40 | bin2bcd(hour - 12);
-}
-
-static int s35390a_reg2hr(struct s35390a *s35390a, char reg)
-{
-	unsigned hour;
-
-	if (s35390a->twentyfourhour)
-		return bcd2bin(reg & 0x3f);
-
-	hour = bcd2bin(reg & 0x3f);
-	if (reg & 0x40)
-		hour += 12;
-
-	return hour;
-}
-
 static int s35390a_rtc_set_time(struct device *dev, struct rtc_time *tm)
 {
 	struct i2c_client *client = to_i2c_client(dev);
@@ -225,7 +199,7 @@ static int s35390a_rtc_set_time(struct device *dev, struct rtc_time *tm)
 	buf[S35390A_BYTE_MONTH] = bin2bcd(tm->tm_mon + 1);
 	buf[S35390A_BYTE_DAY] = bin2bcd(tm->tm_mday);
 	buf[S35390A_BYTE_WDAY] = bin2bcd(tm->tm_wday);
-	buf[S35390A_BYTE_HOURS] = s35390a_hr2reg(s35390a, tm->tm_hour);
+	buf[S35390A_BYTE_HOURS] = bin2bcd(tm->tm_hour);
 	buf[S35390A_BYTE_MINS] = bin2bcd(tm->tm_min);
 	buf[S35390A_BYTE_SECS] = bin2bcd(tm->tm_sec);
 
@@ -256,7 +230,7 @@ static int s35390a_rtc_read_time(struct device *dev, struct rtc_time *tm)
 
 	tm->tm_sec = bcd2bin(buf[S35390A_BYTE_SECS]);
 	tm->tm_min = bcd2bin(buf[S35390A_BYTE_MINS]);
-	tm->tm_hour = s35390a_reg2hr(s35390a, buf[S35390A_BYTE_HOURS]);
+	tm->tm_hour = bcd2bin(buf[S35390A_BYTE_HOURS] & 0x3f);
 	tm->tm_wday = bcd2bin(buf[S35390A_BYTE_WDAY]);
 	tm->tm_mday = bcd2bin(buf[S35390A_BYTE_DAY]);
 	tm->tm_mon = bcd2bin(buf[S35390A_BYTE_MONTH]) - 1;
@@ -325,8 +299,7 @@ static int s35390a_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
 	else
 		buf[S35390A_ALRM_BYTE_WDAY] = 0;
 
-	buf[S35390A_ALRM_BYTE_HOURS] = s35390a_hr2reg(s35390a,
-			alm->time.tm_hour) | 0x80;
+	buf[S35390A_ALRM_BYTE_HOURS] = bin2bcd(alm->time.tm_hour) | 0x80;
 	buf[S35390A_ALRM_BYTE_MINS] = bin2bcd(alm->time.tm_min) | 0x80;
 
 	if (alm->time.tm_hour >= 12)
@@ -381,8 +354,7 @@ static int s35390a_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
 
 	if (buf[S35390A_ALRM_BYTE_HOURS] & 0x80)
 		alm->time.tm_hour =
-			s35390a_reg2hr(s35390a,
-				       buf[S35390A_ALRM_BYTE_HOURS] & ~0x80);
+			bcd2bin(buf[S35390A_ALRM_BYTE_HOURS] & 0x3f);
 
 	if (buf[S35390A_ALRM_BYTE_MINS] & 0x80)
 		alm->time.tm_min = bcd2bin(buf[S35390A_ALRM_BYTE_MINS] & ~0x80);
@@ -459,7 +431,7 @@ static int s35390a_probe(struct i2c_client *client)
 	unsigned int i;
 	struct s35390a *s35390a;
 	struct rtc_device *rtc;
-	u8 buf, status1;
+	u8 buf, status1, time[7];
 	struct device *dev = &client->dev;
 	struct nvmem_config nvmem_cfg = {
 		.name = "s35390a_nvram",
@@ -503,10 +475,31 @@ static int s35390a_probe(struct i2c_client *client)
 		return err_read;
 	}
 
-	if (status1 & S35390A_FLAG_24H)
-		s35390a->twentyfourhour = 1;
-	else
-		s35390a->twentyfourhour = 0;
+	if (!(status1 & S35390A_FLAG_24H) && err_read != 1) {
+		unsigned int hour;
+
+		status1 |= S35390A_FLAG_24H;
+
+		err = s35390a_get_reg(s35390a, S35390A_CMD_TIME1, time, sizeof(time));
+		if (err < 0)
+			return dev_err_probe(dev, err, "reading 12-hour time failed\n");
+
+		/* converting to 24-hour time */
+		time[S35390A_BYTE_HOURS] = bitrev8(time[S35390A_BYTE_HOURS]);
+		hour = bcd2bin(time[S35390A_BYTE_HOURS] & 0x3f);
+		if (time[S35390A_BYTE_HOURS] & 0x40)
+			hour += 12;
+
+		time[S35390A_BYTE_HOURS] = bitrev8(bin2bcd(hour));
+
+		err = s35390a_set_reg(s35390a, S35390A_CMD_STATUS1, &status1, sizeof(status1));
+		if (err < 0)
+			return dev_err_probe(dev, err, "setting 24-hour mode failed\n");
+
+		err = s35390a_set_reg(s35390a, S35390A_CMD_TIME1, time, sizeof(time));
+		if (err < 0)
+			return dev_err_probe(dev, err, "setting 24-hour time failed\n");
+	}
 
 	if (status1 & S35390A_FLAG_INT2) {
 		/* disable alarm (and maybe test mode) */

-- 
2.54.0