rtc: ds1307: fix century bit support
Add an option to properly support the century bit of ds1337 and compatibles and ds1340. Because the driver had a bug until now, it is not possible to switch users to the fixed code directly as RTCs in the field will wrongly have the century bit set. Acked-by: Arnaud Ebalard <arno@natisbad.org> Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
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@ -234,6 +234,20 @@ config RTC_DRV_DS1307_HWMON
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Say Y here if you want to expose temperature sensor data on
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Say Y here if you want to expose temperature sensor data on
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rtc-ds1307 (only DS3231)
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rtc-ds1307 (only DS3231)
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config RTC_DRV_DS1307_CENTURY
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bool "Century bit support for rtc-ds1307"
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depends on RTC_DRV_DS1307
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default n
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help
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The DS1307 driver suffered from a bug where it was enabling the
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century bit inconditionnally but never used it when reading the time.
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It made the driver unable to support dates beyond 2099.
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Setting this option will add proper support for the century bit but if
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the time was previously set using a kernel predating this option,
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reading the date will return a date in the next century.
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To solve that, you could boot a kernel without this option set, set
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the RTC date and then boot a kernel with this option set.
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config RTC_DRV_DS1374
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config RTC_DRV_DS1374
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tristate "Dallas/Maxim DS1374"
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tristate "Dallas/Maxim DS1374"
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help
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help
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@ -382,10 +382,25 @@ static int ds1307_get_time(struct device *dev, struct rtc_time *t)
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t->tm_mday = bcd2bin(ds1307->regs[DS1307_REG_MDAY] & 0x3f);
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t->tm_mday = bcd2bin(ds1307->regs[DS1307_REG_MDAY] & 0x3f);
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tmp = ds1307->regs[DS1307_REG_MONTH] & 0x1f;
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tmp = ds1307->regs[DS1307_REG_MONTH] & 0x1f;
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t->tm_mon = bcd2bin(tmp) - 1;
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t->tm_mon = bcd2bin(tmp) - 1;
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/* assume 20YY not 19YY, and ignore DS1337_BIT_CENTURY */
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t->tm_year = bcd2bin(ds1307->regs[DS1307_REG_YEAR]) + 100;
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t->tm_year = bcd2bin(ds1307->regs[DS1307_REG_YEAR]) + 100;
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#ifdef CONFIG_RTC_DRV_DS1307_CENTURY
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switch (ds1307->type) {
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case ds_1337:
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case ds_1339:
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case ds_3231:
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if (ds1307->regs[DS1307_REG_MONTH] & DS1337_BIT_CENTURY)
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t->tm_year += 100;
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break;
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case ds_1340:
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if (ds1307->regs[DS1307_REG_HOUR] & DS1340_BIT_CENTURY)
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t->tm_year += 100;
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break;
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default:
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break;
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}
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#endif
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dev_dbg(dev, "%s secs=%d, mins=%d, "
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dev_dbg(dev, "%s secs=%d, mins=%d, "
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"hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
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"hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
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"read", t->tm_sec, t->tm_min,
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"read", t->tm_sec, t->tm_min,
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@ -409,6 +424,27 @@ static int ds1307_set_time(struct device *dev, struct rtc_time *t)
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t->tm_hour, t->tm_mday,
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t->tm_hour, t->tm_mday,
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t->tm_mon, t->tm_year, t->tm_wday);
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t->tm_mon, t->tm_year, t->tm_wday);
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#ifdef CONFIG_RTC_DRV_DS1307_CENTURY
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if (t->tm_year < 100)
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return -EINVAL;
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switch (ds1307->type) {
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case ds_1337:
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case ds_1339:
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case ds_3231:
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case ds_1340:
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if (t->tm_year > 299)
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return -EINVAL;
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default:
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if (t->tm_year > 199)
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return -EINVAL;
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break;
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}
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#else
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if (t->tm_year < 100 || t->tm_year > 199)
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return -EINVAL;
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#endif
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buf[DS1307_REG_SECS] = bin2bcd(t->tm_sec);
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buf[DS1307_REG_SECS] = bin2bcd(t->tm_sec);
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buf[DS1307_REG_MIN] = bin2bcd(t->tm_min);
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buf[DS1307_REG_MIN] = bin2bcd(t->tm_min);
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buf[DS1307_REG_HOUR] = bin2bcd(t->tm_hour);
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buf[DS1307_REG_HOUR] = bin2bcd(t->tm_hour);
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@ -424,11 +460,13 @@ static int ds1307_set_time(struct device *dev, struct rtc_time *t)
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case ds_1337:
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case ds_1337:
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case ds_1339:
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case ds_1339:
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case ds_3231:
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case ds_3231:
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buf[DS1307_REG_MONTH] |= DS1337_BIT_CENTURY;
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if (t->tm_year > 199)
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buf[DS1307_REG_MONTH] |= DS1337_BIT_CENTURY;
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break;
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break;
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case ds_1340:
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case ds_1340:
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buf[DS1307_REG_HOUR] |= DS1340_BIT_CENTURY_EN
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buf[DS1307_REG_HOUR] |= DS1340_BIT_CENTURY_EN;
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if (t->tm_year > 199)
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buf[DS1307_REG_HOUR] |= DS1340_BIT_CENTURY;
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break;
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break;
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case mcp794xx:
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case mcp794xx:
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/*
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/*
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