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authorAlexandre Belloni <alexandre.belloni@bootlin.com>2018-02-24 01:08:53 +0100
committerAlexandre Belloni <alexandre.belloni@bootlin.com>2018-03-17 14:20:49 +0100
commit188306ac9536ec47674ffa9dd330f69927679aeb (patch)
tree1f236c578142e0f542d2226fc1d7eca733c1881e /drivers/rtc/rtc-pcf85363.c
parente5aac267a10a8fd571032ffba42ccb61ea16ca80 (diff)
rtc: pcf85363: set time accurately
As per 8.2.6 Setting and reading the time in RTC mode, first stop the clok, then reset it before setting the date and time registers. Finally, start the clock. This uses register address wrap around from 0x2f to 0x00 for efficiency. This allows to set the clock with a millisecond accuracy (drift is not corrected in this example): RTC System 1325388767 1325388767.000029180 1325388768 1325388768.000018362 1325388769 1325388769.000006544 1325388770 1325388769.999992725 1325388771 1325388770.999974544 Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Diffstat (limited to 'drivers/rtc/rtc-pcf85363.c')
-rw-r--r--drivers/rtc/rtc-pcf85363.c20
1 files changed, 16 insertions, 4 deletions
diff --git a/drivers/rtc/rtc-pcf85363.c b/drivers/rtc/rtc-pcf85363.c
index 3fa5bda59987..c04a1edcd571 100644
--- a/drivers/rtc/rtc-pcf85363.c
+++ b/drivers/rtc/rtc-pcf85363.c
@@ -106,6 +106,10 @@
#define PIN_IO_INTA_OUT 2
#define PIN_IO_INTA_HIZ 3
+#define STOP_EN_STOP BIT(0)
+
+#define RESET_CPR 0xa4
+
#define NVRAM_SIZE 0x40
static struct i2c_driver pcf85363_driver;
@@ -148,8 +152,12 @@ static int pcf85363_rtc_read_time(struct device *dev, struct rtc_time *tm)
static int pcf85363_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
struct pcf85363 *pcf85363 = dev_get_drvdata(dev);
- unsigned char buf[DT_YEARS + 1];
- int len = sizeof(buf);
+ unsigned char tmp[11];
+ unsigned char *buf = &tmp[2];
+ int ret;
+
+ tmp[0] = STOP_EN_STOP;
+ tmp[1] = RESET_CPR;
buf[DT_100THS] = 0;
buf[DT_SECS] = bin2bcd(tm->tm_sec);
@@ -160,8 +168,12 @@ static int pcf85363_rtc_set_time(struct device *dev, struct rtc_time *tm)
buf[DT_MONTHS] = bin2bcd(tm->tm_mon + 1);
buf[DT_YEARS] = bin2bcd(tm->tm_year % 100);
- return regmap_bulk_write(pcf85363->regmap, DT_100THS,
- buf, len);
+ ret = regmap_bulk_write(pcf85363->regmap, CTRL_STOP_EN,
+ tmp, sizeof(tmp));
+ if (ret)
+ return ret;
+
+ return regmap_write(pcf85363->regmap, CTRL_STOP_EN, 0);
}
static int pcf85363_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)