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.reic...@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;
--
2.28.0
