Commit 05ad717c authored by Feng Tang's avatar Feng Tang Committed by John Stultz
Browse files

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: default avatarJohn Stultz <john.stultz@linaro.org>
Signed-off-by: default avatarFeng Tang <feng.tang@intel.com>
[jstultz: Added dependency for RTC_SYSTOHC as well]
Signed-off-by: default avatarJohn Stultz <john.stultz@linaro.org>
parent 9ecf37eb

drivers/rtc/Kconfig

+2 −0
Original line number Diff line number Diff line
@@ -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

include/linux/time.h

+5 −0
Original line number Diff line number Diff line
@@ -116,10 +116,15 @@ static inline bool timespec_valid_strict(const struct timespec *ts) 
}



extern bool persistent_clock_exist;



#ifdef CONFIG_HAS_PERSISTENT_CLOCK

#define has_persistent_clock()	true

#else

static inline bool has_persistent_clock(void)

{

	return persistent_clock_exist;

}

#endif



extern void read_persistent_clock(struct timespec *ts);

extern void read_boot_clock(struct timespec *ts);

kernel/time/Kconfig

+5 −0
Original line number Diff line number Diff line
@@ -12,6 +12,11 @@ config CLOCKSOURCE_WATCHDOG 
config ARCH_CLOCKSOURCE_DATA

	bool



# Platforms has a persistent clock

config HAS_PERSISTENT_CLOCK

	bool

	default n



# Timekeeping vsyscall support

config GENERIC_TIME_VSYSCALL

	bool

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