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rtc: ds1307: rx8130: honor Voltage Loss Flag when reading the time

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When voltage dropped since the RTC was last set the reported time is not
reliable. In this case return an error indicator instead of a bogus
time.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
This commit is contained in:
Uwe Kleine-König 2019-01-25 15:35:57 +01:00 committed by Alexandre Belloni
parent 3ffd4a2fcf
commit 501f98266c
1 changed files with 25 additions and 0 deletions
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25
drivers/rtc/rtc-ds1307.c
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@ -194,6 +194,20 @@ static int ds1307_get_time(struct device *dev, struct rtc_time *t)
const struct chip_desc *chip = &chips[ds1307->type];
u8 regs[7];
if (ds1307->type == rx_8130) {
unsigned int regflag;
ret = regmap_read(ds1307->regmap, RX8130_REG_FLAG, &regflag);
if (ret) {
dev_err(dev, "%s error %d\n", "read", ret);
return ret;
}
if (regflag & RX8130_REG_FLAG_VLF) {
dev_warn_once(dev, "oscillator failed, set time!\n");
return -EINVAL;
}
}
/* read the RTC date and time registers all at once */
ret = regmap_bulk_read(ds1307->regmap, chip->offset, regs,
sizeof(regs));
@ -293,6 +307,17 @@ static int ds1307_set_time(struct device *dev, struct rtc_time *t)
dev_err(dev, "%s error %d\n", "write", result);
return result;
}
if (ds1307->type == rx_8130) {
/* clear Voltage Loss Flag as data is available now */
result = regmap_write(ds1307->regmap, RX8130_REG_FLAG,
~(u8)RX8130_REG_FLAG_VLF);
if (result) {
dev_err(dev, "%s error %d\n", "write", result);
return result;
}
}
return 0;
}