drivers/rtc/rtc-isl12057.c: add support for century bit

The month register of ISL12057 RTC chip includes a century bit which
reports overflow of year register from 99 to 0.  This bit can also be
written, which allows using it to extend the time interval the chip can
support from 99 to 199 years.

This patch adds support for century overflow bit in tm to regs and regs to
tm helpers in ISL12057 driver.

This was tested by putting a device 100 years in the future (using a
specific kernel due to the inability of userland tools such as date or
hwclock to pass year 2038), rebooting on a kernel w/ this patch applied
and verifying the device was still 100 years in the future.

Signed-off-by: Arnaud Ebalard <[email protected]>
Suggested-by: Uwe Kleine-König <[email protected]>
Acked-by: Uwe Kleine-König <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Alessandro Zummo <[email protected]>
Cc: Peter Huewe <[email protected]>
Cc: Linus Walleij <[email protected]>
Cc: Thierry Reding <[email protected]>
Cc: Mark Brown <[email protected]>
Cc: Grant Likely <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions