rtc: ds1307: fix century bit support

[cascardo/linux.git] / drivers / rtc / Kconfig

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 7fc11cd..6ce3dad 100644 (file)
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -234,6 +234,20 @@ config RTC_DRV_DS1307_HWMON
          Say Y here if you want to expose temperature sensor data on
          rtc-ds1307 (only DS3231)
 
+config RTC_DRV_DS1307_CENTURY
+       bool "Century bit support for rtc-ds1307"
+       depends on RTC_DRV_DS1307
+       default n
+       help
+         The DS1307 driver suffered from a bug where it was enabling the
+         century bit inconditionnally but never used it when reading the time.
+         It made the driver unable to support dates beyond 2099.
+         Setting this option will add proper support for the century bit but if
+         the time was previously set using a kernel predating this option,
+         reading the date will return a date in the next century.
+         To solve that, you could boot a kernel without this option set, set
+         the RTC date and then boot a kernel with this option set.
+
 config RTC_DRV_DS1374
        tristate "Dallas/Maxim DS1374"
        help