From b3a50169762b14102a296a410d785f9ec1132ae1 Mon Sep 17 00:00:00 2001 From: Alexandre Belloni Date: Thu, 11 Apr 2019 00:16:29 +0200 Subject: rtc: ds1307: properly handle oscillator failure flags 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 Signed-off-by: Alexandre Belloni --- drivers/rtc/rtc-ds1307.c | 129 +++++++++++++++++++++-------------------------- 1 file changed, 58 insertions(+), 71 deletions(-) (limited to 'drivers/rtc') diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c index 07530fe1da2a..7f8b236c935c 100644 --- a/drivers/rtc/rtc-ds1307.c +++ b/drivers/rtc/rtc-ds1307.c @@ -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 @@ read_rtc: 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]; -- cgit v1.2.3-59-g8ed1b