Commit 501f9826 authored by Uwe Kleine-König's avatar Uwe Kleine-König Committed by Alexandre Belloni
Browse files

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: default avatarUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: default avatarAlexandre Belloni <alexandre.belloni@bootlin.com>
parent 3ffd4a2f

drivers/rtc/rtc-ds1307.c

+25 −0
Original line number Diff line number Diff line
@@ -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;

}