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authorJason Gunthorpe <jgunthorpe@obsidianresearch.com>2012-12-18 01:30:53 +0400
committerJohn Stultz <john.stultz@linaro.org>2013-01-16 06:16:06 +0400
commit023f333a99cee9b5cd3268ff87298eb01a31f78e (patch)
treebf1d316ac4f4ad6ccd9f98206debece6f24a7a4f /kernel/time/ntp.c
parent503637375269e33f368fd3484a199beace01f36e (diff)
downloadlinux-023f333a99cee9b5cd3268ff87298eb01a31f78e.tar.xz
NTP: Add a CONFIG_RTC_SYSTOHC configuration
The purpose of this option is to allow ARM/etc systems that rely on the class RTC subsystem to have the same kind of automatic NTP based synchronization that we have on PC platforms. Today ARM does not implement update_persistent_clock and makes extensive use of the class RTC system. When enabled CONFIG_RTC_SYSTOHC will provide a generic rtc_update_persistent_clock that stores the current time in the RTC and is intended complement the existing CONFIG_RTC_HCTOSYS option that loads the RTC at boot. Like with RTC_HCTOSYS the platform's update_persistent_clock is used first, if it works. Platforms with mixed class RTC and non-RTC drivers need to return ENODEV when class RTC should be used. Such an update for PPC is included in this patch. Long term, implementations of update_persistent_clock should migrate to proper class RTC drivers and use CONFIG_RTC_SYSTOHC instead. Tested on ARM kirkwood and PPC405 Signed-off-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com> Signed-off-by: John Stultz <john.stultz@linaro.org>
Diffstat (limited to 'kernel/time/ntp.c')
-rw-r--r--kernel/time/ntp.c16
1 files changed, 12 insertions, 4 deletions
diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
index 24174b4d669b..313b161504b7 100644
--- a/kernel/time/ntp.c
+++ b/kernel/time/ntp.c
@@ -15,6 +15,7 @@
#include <linux/time.h>
#include <linux/mm.h>
#include <linux/module.h>
+#include <linux/rtc.h>
#include "tick-internal.h"
@@ -483,8 +484,7 @@ out:
return leap;
}
-#ifdef CONFIG_GENERIC_CMOS_UPDATE
-
+#if defined(CONFIG_GENERIC_CMOS_UPDATE) || defined(CONFIG_RTC_SYSTOHC)
static void sync_cmos_clock(struct work_struct *work);
static DECLARE_DELAYED_WORK(sync_cmos_work, sync_cmos_clock);
@@ -510,14 +510,22 @@ static void sync_cmos_clock(struct work_struct *work)
}
getnstimeofday(&now);
- if (abs(now.tv_nsec - (NSEC_PER_SEC / 2)) <= tick_nsec / 2)
+ if (abs(now.tv_nsec - (NSEC_PER_SEC / 2)) <= tick_nsec / 2) {
+ fail = -ENODEV;
+#ifdef CONFIG_GENERIC_CMOS_UPDATE
fail = update_persistent_clock(now);
+#endif
+#ifdef CONFIG_RTC_SYSTOHC
+ if (fail == -ENODEV)
+ fail = rtc_set_ntp_time(now);
+#endif
+ }
next.tv_nsec = (NSEC_PER_SEC / 2) - now.tv_nsec - (TICK_NSEC / 2);
if (next.tv_nsec <= 0)
next.tv_nsec += NSEC_PER_SEC;
- if (!fail)
+ if (!fail || fail == -ENODEV)
next.tv_sec = 659;
else
next.tv_sec = 0;