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rtc: m41t80: handle oscillator failure bit 

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 <mylene.josserand@free-electrons.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
hifive-unleashed-5.1
Mylène Josserand 2016-03-29 08:56:05 +02:00 committed by Alexandre Belloni
parent 3726a21833
commit 05a7f27a88
1 changed files with 23 additions and 2 deletions
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25
drivers/rtc/rtc-m41t80.c
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@ -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 */
@ -134,7 +135,16 @@ 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);
@ -159,7 +169,7 @@ 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;
@ -180,6 +190,17 @@ 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;
}