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authorBenoît Thébaudeau <benoit@wsystem.com>2016-07-21 12:41:31 +0200
committerAlexandre Belloni <alexandre.belloni@free-electrons.com>2016-07-28 09:59:41 +0200
commitd3700b6b6479d25c646f7c34a6295872322e6410 (patch)
treef50dc7bde007828d6284a1e79d20d4611da11049 /drivers/rtc/rtc-rv8803.c
parentrtc: rv8803: Always apply the I²C workaround (diff)
downloadlinux-d3700b6b6479d25c646f7c34a6295872322e6410.tar.xz
linux-d3700b6b6479d25c646f7c34a6295872322e6410.zip
rtc: rv8803: Stop the clock while setting the time
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>
Diffstat (limited to 'drivers/rtc/rtc-rv8803.c')
-rw-r--r--drivers/rtc/rtc-rv8803.c18
1 files changed, 17 insertions, 1 deletions
diff --git a/drivers/rtc/rtc-rv8803.c b/drivers/rtc/rtc-rv8803.c
index 09ab5cb1fa8a..24c688eec527 100644
--- a/drivers/rtc/rtc-rv8803.c
+++ b/drivers/rtc/rtc-rv8803.c
@@ -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);