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Commit 05a7f27a authored by Mylène Josserand's avatar Mylène Josserand Committed by Alexandre Belloni
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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: default avatarMylène Josserand <mylene.josserand@free-electrons.com>
Signed-off-by: default avatarAlexandre Belloni <alexandre.belloni@free-electrons.com>
parent 3726a218

drivers/rtc/rtc-m41t80.c

+23 −2
Original line number Diff line number Diff line
@@ -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;

}