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rtc: ds1307: properly handle oscillator failure flags

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Stop enabling the oscillator and removing the oscillator failure flags in
probe. Instead, return -EINVAL in .read_time when the oscillaotr is not
start or when it failed at some point. The oscillator gets enabled on the
first .set_time after failure and the failure flags are cleared.

This also removes the possibility of an infinite loop at probe where a
failing RTC will make the goto read_rtc to be taken every time.

Tested on mcp79411.

Reported-by: Mastro Gippo <gipmad@gmail.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
This commit is contained in:
Alexandre Belloni 2019-04-11 00:16:29 +02:00
parent 097aa24b5d
commit b3a5016976
1 changed files with 58 additions and 71 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

129
drivers/rtc/rtc-ds1307.c
View file

@ -225,6 +225,45 @@ static int ds1307_get_time(struct device *dev, struct rtc_time *t)
return -EINVAL;
}
tmp = regs[DS1307_REG_SECS];
switch (ds1307->type) {
case ds_1307:
case m41t0:
case m41t00:
case m41t11:
if (tmp & DS1307_BIT_CH)
return -EINVAL;
break;
case ds_1308:
case ds_1338:
if (tmp & DS1307_BIT_CH)
return -EINVAL;
ret = regmap_read(ds1307->regmap, DS1307_REG_CONTROL, &tmp);
if (ret)
return ret;
if (tmp & DS1338_BIT_OSF)
return -EINVAL;
break;
case ds_1340:
if (tmp & DS1340_BIT_nEOSC)
return -EINVAL;
ret = regmap_read(ds1307->regmap, DS1340_REG_FLAG, &tmp);
if (ret)
return ret;
if (tmp & DS1340_BIT_OSF)
return -EINVAL;
break;
case mcp794xx:
if (!(tmp & MCP794XX_BIT_ST))
return -EINVAL;
break;
default:
break;
}
t->tm_sec = bcd2bin(regs[DS1307_REG_SECS] & 0x7f);
t->tm_min = bcd2bin(regs[DS1307_REG_MIN] & 0x7f);
tmp = regs[DS1307_REG_HOUR] & 0x3f;
@ -289,7 +328,17 @@ static int ds1307_set_time(struct device *dev, struct rtc_time *t)
if (t->tm_year > 199 && chip->century_bit)
regs[chip->century_reg] |= chip->century_bit;
if (ds1307->type == mcp794xx) {
switch (ds1307->type) {
case ds_1308:
case ds_1338:
regmap_update_bits(ds1307->regmap, DS1307_REG_CONTROL,
DS1338_BIT_OSF, 0);
break;
case ds_1340:
regmap_update_bits(ds1307->regmap, DS1340_REG_FLAG,
DS1340_BIT_OSF, 0);
break;
case mcp794xx:
/*
* these bits were cleared when preparing the date/time
* values and need to be set again before writing the
@ -297,6 +346,9 @@ static int ds1307_set_time(struct device *dev, struct rtc_time *t)
*/
regs[DS1307_REG_SECS] |= MCP794XX_BIT_ST;
regs[DS1307_REG_WDAY] |= MCP794XX_BIT_VBATEN;
break;
default:
break;
}
dev_dbg(dev, "%s: %7ph\n", "write", regs);
@ -1705,7 +1757,6 @@ static int ds1307_probe(struct i2c_client *client,
break;
}
read_rtc:
/* read RTC registers */
err = regmap_bulk_read(ds1307->regmap, chip->offset, regs,
sizeof(regs));
@ -1714,75 +1765,11 @@ static int ds1307_probe(struct i2c_client *client,
goto exit;
}
/*
* minimal sanity checking; some chips (like DS1340) don't
* specify the extra bits as must-be-zero, but there are
* still a few values that are clearly out-of-range.
*/
tmp = regs[DS1307_REG_SECS];
switch (ds1307->type) {
case ds_1307:
case m41t0:
case m41t00:
case m41t11:
/* clock halted? turn it on, so clock can tick. */
if (tmp & DS1307_BIT_CH) {
regmap_write(ds1307->regmap, DS1307_REG_SECS, 0);
dev_warn(ds1307->dev, "SET TIME!\n");
goto read_rtc;
}
break;
case ds_1308:
case ds_1338:
/* clock halted? turn it on, so clock can tick. */
if (tmp & DS1307_BIT_CH)
regmap_write(ds1307->regmap, DS1307_REG_SECS, 0);
/* oscillator fault? clear flag, and warn */
if (regs[DS1307_REG_CONTROL] & DS1338_BIT_OSF) {
regmap_write(ds1307->regmap, DS1307_REG_CONTROL,
regs[DS1307_REG_CONTROL] &
~DS1338_BIT_OSF);
dev_warn(ds1307->dev, "SET TIME!\n");
goto read_rtc;
}
break;
case ds_1340:
/* clock halted? turn it on, so clock can tick. */
if (tmp & DS1340_BIT_nEOSC)
regmap_write(ds1307->regmap, DS1307_REG_SECS, 0);
err = regmap_read(ds1307->regmap, DS1340_REG_FLAG, &tmp);
if (err) {
dev_dbg(ds1307->dev, "read error %d\n", err);
goto exit;
}
/* oscillator fault? clear flag, and warn */
if (tmp & DS1340_BIT_OSF) {
regmap_write(ds1307->regmap, DS1340_REG_FLAG, 0);
dev_warn(ds1307->dev, "SET TIME!\n");
}
break;
case mcp794xx:
/* make sure that the backup battery is enabled */
if (!(regs[DS1307_REG_WDAY] & MCP794XX_BIT_VBATEN)) {
regmap_write(ds1307->regmap, DS1307_REG_WDAY,
regs[DS1307_REG_WDAY] |
MCP794XX_BIT_VBATEN);
}
/* clock halted? turn it on, so clock can tick. */
if (!(tmp & MCP794XX_BIT_ST)) {
regmap_write(ds1307->regmap, DS1307_REG_SECS,
MCP794XX_BIT_ST);
dev_warn(ds1307->dev, "SET TIME!\n");
goto read_rtc;
}
break;
default:
break;
if (ds1307->type == mcp794xx &&
!(regs[DS1307_REG_WDAY] & MCP794XX_BIT_VBATEN)) {
regmap_write(ds1307->regmap, DS1307_REG_WDAY,
regs[DS1307_REG_WDAY] |
MCP794XX_BIT_VBATEN);
}
tmp = regs[DS1307_REG_HOUR];