According to the datasheet, the "oscillator failure" bit is set
> ...on a power on reset, when both the system and battery voltages have
> dropped below acceptable levels. It is also set if an Oscillator Failure
> occurs....
>From testing, this bit is also set if a software reset is initiated.
This bit has a confusing name; it really tells us whether the time data
is valid. We clear it when writing the time. If it is still set, that
means there is a persistent issue (such as an oscillator failure),
instead of a transient one (such as power loss).
Because there are several other reasons which might cause this bit
to be set (including booting for the first time or a battery failure),
do not warn about oscillator failures willy-nilly. This may cause system
integrators to waste time looking into the wrong line of investigation.
Signed-off-by: Sean Anderson <sean.anderson@xxxxxxxx>
---
drivers/rtc/rtc-abx80x.c | 17 ++++++++++++++++-
1 file changed, 16 insertions(+), 1 deletion(-)
diff --git a/drivers/rtc/rtc-abx80x.c b/drivers/rtc/rtc-abx80x.c
index 9b0138d07232..1eb752e4e39d 100644
--- a/drivers/rtc/rtc-abx80x.c
+++ b/drivers/rtc/rtc-abx80x.c
@@ -115,6 +115,7 @@ struct abx80x_priv {
struct rtc_device *rtc;
struct i2c_client *client;
struct watchdog_device wdog;
+ bool wrote_time;
};
static int abx80x_write_config_key(struct i2c_client *client, u8 key)
@@ -167,6 +168,7 @@ static int abx80x_enable_trickle_charger(struct i2c_client *client,
static int abx80x_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
struct i2c_client *client = to_i2c_client(dev);
+ struct abx80x_priv *priv = i2c_get_clientdata(client);
unsigned char buf[8];
int err, flags, rc_mode = 0;
@@ -181,7 +183,18 @@ static int abx80x_rtc_read_time(struct device *dev, struct rtc_time *tm)
return flags;
if (flags & ABX8XX_OSS_OF) {
- dev_err(dev, "Oscillator failure, data is invalid.\n");
+ /*
+ * The OF bit can be set either because of a reset
+ * (PoR/Software reset) or because of an oscillator
+ * failure. Effectively, it indicates that the stored
+ * time is invalid. When we write the time, we clear
+ * this bit. If it stays set, then this indicates an
+ * oscillator failure.
+ */
+ if (priv->wrote_time)
+ dev_err(dev, "Oscillator failure\n");
+ else
+ dev_info(dev, "Time data invalid\n");
return -EINVAL;
}
}
@@ -207,6 +220,7 @@ static int abx80x_rtc_read_time(struct device *dev, struct rtc_time *tm)
static int abx80x_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
struct i2c_client *client = to_i2c_client(dev);
+ struct abx80x_priv *priv = i2c_get_clientdata(client);
unsigned char buf[8];
int err, flags;
@@ -240,6 +254,7 @@ static int abx80x_rtc_set_time(struct device *dev, struct rtc_time *tm)
dev_err(&client->dev, "Unable to write oscillator status register\n");
return err;
}
+ priv->wrote_time = true;
return 0;
}
--
2.35.1.1320.gc452695387.dirty
