Commit d9dcfa5f authored by Alexandre Belloni's avatar Alexandre Belloni
Browse files

rtc: ds1347: properly handle oscillator failures 

The comment in the probe function stating that it disables oscillator stop
detection and glitch filtering is incorrect as it sets bits 3 and 4 while
it should be setting 5 and 6 to achieve that. Then, it is safe to assume
that the oscillator failure detection is actually enabled.

Properly handle oscillator failures by returning -EINVAL when the time and
date are know to be incorrect and reset the flag when the time is set.

Link: https://lore.kernel.org/r/20191007134724.15505-8-alexandre.belloni@bootlin.com


Signed-off-by: default avatarAlexandre Belloni <alexandre.belloni@bootlin.com>
parent 3ce20a23

drivers/rtc/rtc-ds1347.c

+23 −7
Original line number Diff line number Diff line
@@ -29,6 +29,9 @@ 
#define DS1347_STATUS_REG	0x17

#define DS1347_CLOCK_BURST	0x3F



#define DS1347_NEOSC_BIT	BIT(7)

#define DS1347_OSF_BIT		BIT(2)



static const struct regmap_range ds1347_ranges[] = {

	{

		.range_min = DS1347_SECONDS_REG,
@@ -44,9 +47,17 @@ static const struct regmap_access_table ds1347_access_table = { 
static int ds1347_read_time(struct device *dev, struct rtc_time *dt)

{

	struct regmap *map = dev_get_drvdata(dev);

	unsigned int status;

	int err;

	unsigned char buf[8];



	err = regmap_read(map, DS1347_STATUS_REG, &status);

	if (err)

		return err;



	if (status & DS1347_OSF_BIT)

		return -EINVAL;



	err = regmap_bulk_read(map, DS1347_CLOCK_BURST, buf, 8);

	if (err)

		return err;
@@ -66,6 +77,12 @@ static int ds1347_set_time(struct device *dev, struct rtc_time *dt) 
{

	struct regmap *map = dev_get_drvdata(dev);

	unsigned char buf[8];

	int err;



	err = regmap_update_bits(map, DS1347_STATUS_REG,

				 DS1347_NEOSC_BIT, DS1347_NEOSC_BIT);

	if (err)

		return err;



	buf[0] = bin2bcd(dt->tm_sec);

	buf[1] = bin2bcd(dt->tm_min);
@@ -82,7 +99,12 @@ static int ds1347_set_time(struct device *dev, struct rtc_time *dt) 
	buf[7] = bin2bcd(0x00);



	/* write the rtc settings */

	return regmap_bulk_write(map, DS1347_CLOCK_BURST, buf, 8);

	err = regmap_bulk_write(map, DS1347_CLOCK_BURST, buf, 8);

	if (err)

		return err;



	return regmap_update_bits(map, DS1347_STATUS_REG,

				  DS1347_NEOSC_BIT | DS1347_OSF_BIT, 0);

}



static const struct rtc_class_ops ds1347_rtc_ops = {
@@ -123,12 +145,6 @@ static int ds1347_probe(struct spi_device *spi) 
	data = data & ~(1<<7);

	regmap_write(map, DS1347_CONTROL_REG, data);



	/* Enable the oscillator , disable the oscillator stop flag,

	 and glitch filter to reduce current consumption */

	regmap_read(map, DS1347_STATUS_REG, &data);

	data = data & 0x1B;

	regmap_write(map, DS1347_STATUS_REG, data);



	rtc = devm_rtc_allocate_device(&spi->dev);

	if (IS_ERR(rtc))

		return PTR_ERR(rtc);

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