Handle the Oscillator Failure (OF) bit on each read of date-time. If the OF is set, an error is returned (-EINVAL) instead of the date-time. The OF bit is cleared each time the date is set.
Signed-off-by: Mylène Josserand <[email protected]> --- drivers/rtc/rtc-m41t80.c | 25 +++++++++++++++++++++++-- 1 file changed, 23 insertions(+), 2 deletions(-) diff --git a/drivers/rtc/rtc-m41t80.c b/drivers/rtc/rtc-m41t80.c index 660a734..64d66a9 100644 --- a/drivers/rtc/rtc-m41t80.c +++ b/drivers/rtc/rtc-m41t80.c @@ -56,6 +56,7 @@ #define M41T80_ALMON_AFE BIT(7) /* AFE: AF Enable Bit */ #define M41T80_ALMON_SQWE BIT(6) /* SQWE: SQW Enable Bit */ #define M41T80_ALHOUR_HT BIT(6) /* HT: Halt Update Bit */ +#define M41T80_FLAGS_OF BIT(2) /* OF: Oscillator Failure Bit */ #define M41T80_FLAGS_AF BIT(6) /* AF: Alarm Flag Bit */ #define M41T80_FLAGS_BATT_LOW BIT(4) /* BL: Battery Low Bit */ #define M41T80_WATCHDOG_RB2 BIT(7) /* RB: Watchdog resolution */ @@ -130,7 +131,16 @@ static int m41t80_get_datetime(struct i2c_client *client, struct rtc_time *tm) { unsigned char buf[8]; - int err; + int err, flags; + + flags = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS); + if (flags < 0) + return flags; + + if (flags & M41T80_FLAGS_OF) { + dev_err(&client->dev, "Oscillator failure, data is invalid.\n"); + return -EINVAL; + } err = i2c_smbus_read_i2c_block_data(client, M41T80_REG_SSEC, sizeof(buf), buf); @@ -155,7 +165,7 @@ static int m41t80_get_datetime(struct i2c_client *client, static int m41t80_set_datetime(struct i2c_client *client, struct rtc_time *tm) { unsigned char buf[8]; - int err; + int err, flags; if (tm->tm_year < 100 || tm->tm_year > 199) return -EINVAL; @@ -176,6 +186,17 @@ static int m41t80_set_datetime(struct i2c_client *client, struct rtc_time *tm) return err; } + /* Clear the OF bit of Flags Register */ + flags = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS); + if (flags < 0) + return flags; + + if (i2c_smbus_write_byte_data(client, M41T80_REG_FLAGS, + flags & ~M41T80_FLAGS_OF)) { + dev_err(&client->dev, "Unable to write flags register\n"); + return -EIO; + } + return err; } -- 2.8.0.rc3
