[PATCH 5.10.y 0/3] rtc: backport support for handling dates before 1970

["Uwe Kleine-König" <u.kleine-koenig@baylibre.com>]

Hello,

this is a followup to
https://lore.kernel.org/stable/cover.1749223334.git.u.kleine-koenig@baylibre.com
that handled backporting the two patches by Alexandre to the active
stable kernels between 6.15 and 5.15. Here comes a backport to 5.10.y, git
am handles application to 5.4.y just fine.

Compared to the backport for later kernels I included a major rework of
rtc_time64_to_tm() by Cassio Neri. (FTR: I checked, that commit by
Cassio Neri isn't the reason we need to fix rtc_time64_to_tm(), the
actual problem is older.)

Now that I completed the backport and did some final checks on it I
noticed that the problem fixed here is (TTBOMK) a theoretic one because
only drivers with .start_secs < 0 are known to have issues and in 5.10
and before there is no such driver. I'm uncertain if this should result
in not backporting the changes. I would tend to pick them anyhow, but
I won't argue on a veto.

Best regards
Uwe

Alexandre Mergnat (2):
  rtc: Make rtc_time64_to_tm() support dates before 1970
  rtc: Fix offset calculation for .start_secs < 0

Cassio Neri (1):
  rtc: Improve performance of rtc_time64_to_tm(). Add tests.

 drivers/rtc/Kconfig    |  10 ++++
 drivers/rtc/Makefile   |   1 +
 drivers/rtc/class.c    |   2 +-
 drivers/rtc/lib.c      | 121 ++++++++++++++++++++++++++++++++---------
 drivers/rtc/lib_test.c |  79 +++++++++++++++++++++++++++
 5 files changed, 185 insertions(+), 28 deletions(-)
 create mode 100644 drivers/rtc/lib_test.c


base-commit: 01e7e36b8606e5d4fddf795938010f7bfa3aa277
-- 
2.49.0