From 0f546b058b86ea2f661cc7a6e931cee5a29959ef Mon Sep 17 00:00:00 2001 From: Gary Bisson Date: Tue, 25 Apr 2017 16:45:15 +0200 Subject: [PATCH] rtc: m41t80: fix SQW dividers override when setting a date This patch is only relevant for RTC with the SQ_ALT feature which means the clock output frequency divider is stored in the weekday register. Current implementation discards the previous dividers value and clear them as soon as the time is set. Signed-off-by: Gary Bisson Signed-off-by: Alexandre Belloni --- drivers/rtc/rtc-m41t80.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/drivers/rtc/rtc-m41t80.c b/drivers/rtc/rtc-m41t80.c index b0749645aa48..1e8ba7a469ac 100644 --- a/drivers/rtc/rtc-m41t80.c +++ b/drivers/rtc/rtc-m41t80.c @@ -227,6 +227,7 @@ static int m41t80_get_datetime(struct i2c_client *client, /* Sets the given date and time to the real time clock. */ static int m41t80_set_datetime(struct i2c_client *client, struct rtc_time *tm) { + struct m41t80_data *clientdata = i2c_get_clientdata(client); unsigned char buf[8]; int err, flags; @@ -242,6 +243,17 @@ static int m41t80_set_datetime(struct i2c_client *client, struct rtc_time *tm) buf[M41T80_REG_YEAR] = bin2bcd(tm->tm_year - 100); buf[M41T80_REG_WDAY] = tm->tm_wday; + /* If the square wave output is controlled in the weekday register */ + if (clientdata->features & M41T80_FEATURE_SQ_ALT) { + int val; + + val = i2c_smbus_read_byte_data(client, M41T80_REG_WDAY); + if (val < 0) + return val; + + buf[M41T80_REG_WDAY] |= (val & 0xf0); + } + err = i2c_smbus_write_i2c_block_data(client, M41T80_REG_SSEC, sizeof(buf), buf); if (err < 0) { -- 2.20.1