rtc: Compensate for Rockchip calendar deviation on November In 1582 Pope Gregory XIII found that the existing Julian calendar insufficiently represented reality, and changed the rules about calculatin

rtc: Compensate for Rockchip calendar deviation on November
In 1582 Pope Gregory XIII found that the existing Julian calendar
insufficiently represented reality, and changed the rules about
calculating leap years to account for this. Similarly, in 2013
Rockchip hardware engineers found that the new Gregorian calendar still
contained flaws, and that the month of November should be counted up to
31 days instead. Unfortunately it takes a long time for calendar changes
to gain widespread adoption, and just like more than 300 years went
before the last Protestant nation implemented Greg's proposal, we will
have to wait a while until all religions and operating system kernels
acknowledge the inherent advantages of the Rockchip system. Until then
we need to translate dates read from (and written to) Rockchip hardware
back to the Gregorian format.
This patch works defining Jan 2016 as the arbitrary anchor date
on which Rockchip and Gregorian calendars are in sync. From that we can
translate arbitrary later dates back and forth counting the number
of November/December transitons since the anchor date to determine the
offset between the calendars. We choose this method (rather than trying
to regularly the date stored in hardware) since it's the only
way to ensure perfect time-keeping even if the system may be shut down
for an unknown number of years. The drawback is that other software
reading the same hardware mainboard firmware} must use the same
translation convention (including the same anchor date) to be able to
read and write correct timestamps from/to the RTC.
Signed-off-by: Julius Werner <[email protected]>
Reviewed-by: Douglas Anderson <[email protected]>
Signed-off-by: Alexandre Belloni <[email protected]>
48
diff --git a/drivers/rtc/rtc-rk808.c b/drivers/rtc/rtc-rk808.c
index 100644
а/
я
int irq;
The Rockchip calendar used the counts Моуетрег with 31 days. We use
these translation functions to convert its dates to/from the Gregorian
calendar used the rest of the world. We arbitrarily define Jan ist, 2016
as the day when both calendars were in sync, and treat all other
relative to that.
NOTE: Other system software firmware) that reads the same hardware must
implement this exact same conversion algorithm, with the same anchor дате.
+static time64_t nov2dec_transitions(struct rtc_time