timekeeping: Add CONFIG_HAS_PERSISTENT_CLOCK option

Make the persistent clock check a kernel config option, so that some
platform can explicitely select it, also make CONFIG_RTC_HCTOSYS and
RTC_SYSTOHC depend on its non-existence, which could prevent the
persistent clock and RTC code from doing similar thing twice during
system's init/suspend/resume phases.

If the CONFIG_HAS_PERSISTENT_CLOCK=n, then no change happens for kernel
which still does the persistent clock check in timekeeping_init().

Cc: Thomas Gleixner <[email protected]>
Suggested-by: John Stultz <[email protected]>
Signed-off-by: Feng Tang <[email protected]>
[jstultz: Added dependency for RTC_SYSTOHC as well]
Signed-off-by: John Stultz <[email protected]>
This commit is contained in:
Feng Tang 2013-01-16 00:09:49 +08:00 • committed by John Stultz
commit 05ad717c77
3 changed files with 12 additions and 0 deletions

View file

@ -20,6 +20,7 @@ if RTC_CLASS
config RTC_HCTOSYS
bool "Set system time from RTC on startup and resume"
default y
depends on !HAS_PERSISTENT_CLOCK
help
If you say yes here, the system time (wall clock) will be set using
the value read from a specified RTC device. This is useful to avoid
@ -28,6 +29,7 @@ config RTC_HCTOSYS
config RTC_SYSTOHC
bool "Set the RTC time based on NTP synchronization"
default y
depends on !HAS_PERSISTENT_CLOCK
help
If you say yes here, the system time (wall clock) will be stored
in the RTC specified by RTC_HCTOSYS_DEVICE approximately every 11