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rtc: rv8803: Stop the clock while setting the time

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According to the application manual of the RX8900, the RESET bit must be
set to 1 to prevent a timer update while setting the time. This also
resets the subsecond counter. The application manual of the RV-8803 does
not mention such a requirement, and it says that the 100th Seconds
register is cleared when writing to the Seconds register, but using the
RESET bit for the RV-8803 too should not be an issue and is probably
safer.

This change also ensures that the RESET bit is initialized properly in
all cases. Indeed, all the registers must be initialized if the voltage
has been lower than VLOW2 (triggering V2F), but not low enough to
trigger a POR.

Signed-off-by: Benoît Thébaudeau <benoit@wsystem.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
This commit is contained in:
Benoît Thébaudeau 2016-07-21 12:41:31 +02:00 committed by Alexandre Belloni
parent d522649e26
commit d3700b6b64
1 changed files with 17 additions and 1 deletions
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18
drivers/rtc/rtc-rv8803.c
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@ -223,11 +223,21 @@ static int rv8803_set_time(struct device *dev, struct rtc_time *tm)
{
struct rv8803_data *rv8803 = dev_get_drvdata(dev);
u8 date[7];
int flags, ret;
int ctrl, flags, ret;
if ((tm->tm_year < 100) || (tm->tm_year > 199))
return -EINVAL;
ctrl = rv8803_read_reg(rv8803->client, RV8803_CTRL);
if (ctrl < 0)
return ctrl;
/* Stop the clock */
ret = rv8803_write_reg(rv8803->client, RV8803_CTRL,
ctrl | RV8803_CTRL_RESET);
if (ret)
return ret;
date[RV8803_SEC] = bin2bcd(tm->tm_sec);
date[RV8803_MIN] = bin2bcd(tm->tm_min);
date[RV8803_HOUR] = bin2bcd(tm->tm_hour);
@ -240,6 +250,12 @@ static int rv8803_set_time(struct device *dev, struct rtc_time *tm)
if (ret)
return ret;
/* Restart the clock */
ret = rv8803_write_reg(rv8803->client, RV8803_CTRL,
ctrl & ~RV8803_CTRL_RESET);
if (ret)
return ret;
mutex_lock(&rv8803->flags_lock);
flags = rv8803_read_reg(rv8803->client, RV8803_FLAG);