Commit 9c5150b3 authored by Xunlei Pang's avatar Xunlei Pang Committed by Alexandre Belloni
Browse files

rtc: NTP: Add CONFIG_RTC_SYSTOHC_DEVICE for NTP synchronization 



Currently, CONFIG_RTC_SYSTOHC uses CONFIG_RTC_HCTOSYS_DEVICE which
is originally used by CONFIG_RTC_HCTOSYS, but this rtc device has
some limiations, for example, it must be battery-backed, be able
to work with irq off and through system suspension, etc.

So add CONFIG_RTC_SYSTOHC_DEVICE used exclusively for CONFIG_RTC_SYSTOHC,
it is more lenient compared to CONFIG_RTC_HCTOSYS_DEVICE, and could
be assigned any available RTC in the system.

Default value is CONFIG_RTC_HCTOSYS_DEVICE which is "rtc0" by default.
After this patch, NTP will sync up "rtc0" by default.

Cc: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: default avatarXunlei Pang <pang.xunlei@linaro.org>
Signed-off-by: default avatarAlexandre Belloni <alexandre.belloni@free-electrons.com>
parent 9033fd8b

drivers/rtc/Kconfig

+20 −9
Original line number Diff line number Diff line
@@ -25,17 +25,9 @@ config RTC_HCTOSYS 
	  the value read from a specified RTC device. This is useful to avoid

	  unnecessary fsck runs at boot time, and to network better.



config RTC_SYSTOHC

	bool "Set the RTC time based on NTP synchronization"

	default y

	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

	  minutes if userspace reports synchronized NTP status.



config RTC_HCTOSYS_DEVICE

	string "RTC used to set the system time"

	depends on RTC_HCTOSYS = y || RTC_SYSTOHC = y

	depends on RTC_HCTOSYS

	default "rtc0"

	help

	  The RTC device that will be used to (re)initialize the system
@@ -56,6 +48,25 @@ config RTC_HCTOSYS_DEVICE 
	  sleep states. Do not specify an RTC here unless it stays powered

	  during all this system's supported sleep states.



config RTC_SYSTOHC

	bool "Set the RTC time based on NTP synchronization"

	default y

	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

	  minutes if userspace reports synchronized NTP status.



config RTC_SYSTOHC_DEVICE

	string "RTC used to synchronize NTP adjustment"

	depends on RTC_SYSTOHC

	default RTC_HCTOSYS_DEVICE if RTC_HCTOSYS

	default "rtc0"

	help

	  The RTC device used for NTP synchronization. The main difference

	  between RTC_HCTOSYS_DEVICE and RTC_SYSTOHC_DEVICE is that this

	  one can sleep when setting time, because it runs in the workqueue

	  context.



config RTC_DEBUG

	bool "RTC debug support"

	help

drivers/rtc/systohc.c

+1 −1
Original line number Diff line number Diff line
@@ -31,7 +31,7 @@ int rtc_set_ntp_time(struct timespec64 now) 
	else

		rtc_time64_to_tm(now.tv_sec + 1, &tm);



	rtc = rtc_class_open(CONFIG_RTC_HCTOSYS_DEVICE);

	rtc = rtc_class_open(CONFIG_RTC_SYSTOHC_DEVICE);

	if (rtc) {

		/* rtc_hctosys exclusively uses UTC, so we call set_time here,

		 * not set_mmss. */

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