In case of empty battery or glitches the oscillator fail bit might be set. This will reset the bit in the reset routine.
Signed-off-by: Sebastian Reichel sebastian.reichel@collabora.com --- drivers/rtc/m41t62.c | 50 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 50 insertions(+)
diff --git a/drivers/rtc/m41t62.c b/drivers/rtc/m41t62.c index 85d6eb02593f..0a4e12d69827 100644 --- a/drivers/rtc/m41t62.c +++ b/drivers/rtc/m41t62.c @@ -23,6 +23,7 @@ #include <rtc.h> #include <i2c.h> #include <linux/log2.h> +#include <linux/delay.h>
#define M41T62_REG_SSEC 0 #define M41T62_REG_SEC 1 @@ -48,6 +49,7 @@ #define M41T62_ALMON_SQWE (1 << 6) /* SQWE: SQW Enable Bit */ #define M41T62_ALHOUR_HT (1 << 6) /* HT: Halt Update Bit */ #define M41T62_FLAGS_AF (1 << 6) /* AF: Alarm Flag Bit */ +#define M41T62_FLAGS_OF (1 << 2) /* OF: Oscillator Flag Bit */ #define M41T62_FLAGS_BATT_LOW (1 << 4) /* BL: Battery Low Bit */
#define M41T62_WDAY_SQW_FREQ_MASK 0xf0 @@ -193,6 +195,50 @@ static int m41t62_sqw_set_rate(struct udevice *dev, unsigned int rate) return dm_i2c_write(dev, M41T62_REG_WDAY, &newval, sizeof(newval)); }
+static int m41t62_rtc_restart_osc(struct udevice *dev) +{ + u8 val; + int ret; + + /* 0. check if oscillator failure happened */ + ret = dm_i2c_read(dev, M41T62_REG_FLAGS, &val, sizeof(val)); + if (ret) + return ret; + if (!(val & M41T62_FLAGS_OF)) + return 0; + + ret = dm_i2c_read(dev, M41T62_REG_SEC, &val, sizeof(val)); + if (ret) + return ret; + + /* 1. Set stop bit */ + val |= M41T62_SEC_ST; + ret = dm_i2c_write(dev, M41T62_REG_ALARM_HOUR, &val, sizeof(val)); + if (ret) + return ret; + + /* 2. Clear stop bit */ + val &= ~M41T62_SEC_ST; + ret = dm_i2c_write(dev, M41T62_REG_ALARM_HOUR, &val, sizeof(val)); + if (ret) + return ret; + + /* 3. wait 4 seconds */ + mdelay(4000); + + ret = dm_i2c_read(dev, M41T62_REG_FLAGS, &val, sizeof(val)); + if (ret) + return ret; + + /* 4. clear M41T62_FLAGS_OF bit */ + val &= ~M41T62_FLAGS_OF; + ret = dm_i2c_write(dev, M41T62_REG_FLAGS, &val, sizeof(val)); + if (ret) + return ret; + + return 0; +} + static int m41t62_rtc_clear_ht(struct udevice *dev) { u8 val; @@ -218,6 +264,10 @@ static int m41t62_rtc_reset(struct udevice *dev) { int ret;
+ ret = m41t62_rtc_restart_osc(dev); + if (ret) + return ret; + ret = m41t62_rtc_clear_ht(dev); if (ret) return ret;