timekeeping: Add CONFIG_HAS_PERSISTENT_CLOCK option
authorFeng Tang <feng.tang@intel.com>
Tue, 15 Jan 2013 16:09:49 +0000 (00:09 +0800)
committerJohn Stultz <john.stultz@linaro.org>
Wed, 16 Jan 2013 02:16:08 +0000 (18:16 -0800)
commit05ad717c77b1b8e98a1dd768c3700036d634629e
treec52d75ca925bcd9b4c7125aad4c1059d7d3a43ee
parent9ecf37eb7a81e3295a1b274eafb6f83d7d2cabf0
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 <tglx@linutronix.de>
Suggested-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Feng Tang <feng.tang@intel.com>
[jstultz: Added dependency for RTC_SYSTOHC as well]
Signed-off-by: John Stultz <john.stultz@linaro.org>
drivers/rtc/Kconfig
include/linux/time.h
kernel/time/Kconfig