From 501f98266caddd2b76cdf10093105aa2318d1421 Mon Sep 17 00:00:00 2001 From: Uwe Kleine-König Date: Fri, 25 Jan 2019 15:35:57 +0100 Subject: rtc: ds1307: rx8130: honor Voltage Loss Flag when reading the time 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 Signed-off-by: Alexandre Belloni --- drivers/rtc/rtc-ds1307.c | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) (limited to 'drivers') diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c index 81e20653700d..974eafda9de4 100644 --- a/drivers/rtc/rtc-ds1307.c +++ b/drivers/rtc/rtc-ds1307.c @@ -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, ®flag); + 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; } -- cgit v1.2.3