diff options
Diffstat (limited to 'drivers/rtc/rtc-ds1307.c')
| -rw-r--r-- | drivers/rtc/rtc-ds1307.c | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c index aa705bb4748c..097ca2a8565f 100644 --- a/drivers/rtc/rtc-ds1307.c +++ b/drivers/rtc/rtc-ds1307.c @@ -34,6 +34,7 @@ enum ds_type { ds_1340, ds_1388, ds_3231, + m41t0, m41t00, mcp794xx, rx_8025, @@ -48,6 +49,7 @@ enum ds_type { # define DS1340_BIT_nEOSC 0x80 # define MCP794XX_BIT_ST 0x80 #define DS1307_REG_MIN 0x01 /* 00-59 */ +# define M41T0_BIT_OF 0x80 #define DS1307_REG_HOUR 0x02 /* 00-23, or 1-12{am,pm} */ # define DS1307_BIT_12HR 0x40 /* in REG_HOUR */ # define DS1307_BIT_PM 0x20 /* in REG_HOUR */ @@ -174,6 +176,7 @@ static const struct i2c_device_id ds1307_id[] = { { "ds1388", ds_1388 }, { "ds1340", ds_1340 }, { "ds3231", ds_3231 }, + { "m41t0", m41t0 }, { "m41t00", m41t00 }, { "mcp7940x", mcp794xx }, { "mcp7941x", mcp794xx }, @@ -363,6 +366,13 @@ static int ds1307_get_time(struct device *dev, struct rtc_time *t) dev_dbg(dev, "%s: %7ph\n", "read", ds1307->regs); + /* if oscillator fail bit is set, no data can be trusted */ + if (ds1307->type == m41t0 && + ds1307->regs[DS1307_REG_MIN] & M41T0_BIT_OF) { + dev_warn_once(dev, "oscillator failed, set time!\n"); + return -EINVAL; + } + t->tm_sec = bcd2bin(ds1307->regs[DS1307_REG_SECS] & 0x7f); t->tm_min = bcd2bin(ds1307->regs[DS1307_REG_MIN] & 0x7f); tmp = ds1307->regs[DS1307_REG_HOUR] & 0x3f; @@ -1044,6 +1054,7 @@ read_rtc: tmp = ds1307->regs[DS1307_REG_SECS]; switch (ds1307->type) { case ds_1307: + case m41t0: case m41t00: /* clock halted? turn it on, so clock can tick. */ if (tmp & DS1307_BIT_CH) { @@ -1108,6 +1119,7 @@ read_rtc: tmp = ds1307->regs[DS1307_REG_HOUR]; switch (ds1307->type) { case ds_1340: + case m41t0: case m41t00: /* * NOTE: ignores century bits; fix before deploying |