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 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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/rtc') 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