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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: Alexandre Belloni <alexandre.belloni@bootlin.com>
This commit is contained in:
Alexandre Belloni 2019-10-07 15:47:22 +02:00
parent 3ce20a23e2
commit d9dcfa5f70
1 changed files with 23 additions and 7 deletions
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30
drivers/rtc/rtc-ds1347.c
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@ -29,6 +29,9 @@
#define DS1347_STATUS_REG 0x17 #define DS1347_STATUS_REG 0x17
#define DS1347_CLOCK_BURST 0x3F #define DS1347_CLOCK_BURST 0x3F
#define DS1347_NEOSC_BIT BIT(7)
#define DS1347_OSF_BIT BIT(2)
static const struct regmap_range ds1347_ranges[] = { static const struct regmap_range ds1347_ranges[] = {
{ {
.range_min = DS1347_SECONDS_REG, .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) static int ds1347_read_time(struct device *dev, struct rtc_time *dt)
{ {
struct regmap *map = dev_get_drvdata(dev); struct regmap *map = dev_get_drvdata(dev);
unsigned int status;
int err; int err;
unsigned char buf[8]; 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); err = regmap_bulk_read(map, DS1347_CLOCK_BURST, buf, 8);
if (err) if (err)
return 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); struct regmap *map = dev_get_drvdata(dev);
unsigned char buf[8]; 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[0] = bin2bcd(dt->tm_sec);
buf[1] = bin2bcd(dt->tm_min); 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); buf[7] = bin2bcd(0x00);
/* write the rtc settings */ /* 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 = { 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); data = data & ~(1<<7);
regmap_write(map, DS1347_CONTROL_REG, data); 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); rtc = devm_rtc_allocate_device(&spi->dev);
if (IS_ERR(rtc)) if (IS_ERR(rtc))
return PTR_ERR(rtc); return PTR_ERR(rtc);