summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorJason Gunthorpe <jgunthorpe@obsidianresearch.com>2012-12-17 14:30:53 -0700
committerJohn Stultz <john.stultz@linaro.org>2013-01-15 18:16:06 -0800
commit023f333a99cee9b5cd3268ff87298eb01a31f78e (patch)
treebf1d316ac4f4ad6ccd9f98206debece6f24a7a4f
parent503637375269e33f368fd3484a199beace01f36e (diff)
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>
-rw-r--r--arch/powerpc/kernel/time.c2
-rw-r--r--drivers/rtc/Kconfig10
-rw-r--r--drivers/rtc/Makefile1
-rw-r--r--drivers/rtc/systohc.c44
-rw-r--r--include/linux/rtc.h1
-rw-r--r--kernel/time/ntp.c16
6 files changed, 68 insertions, 6 deletions
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index ce4cb772dc78..bc844a857e05 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -667,7 +667,7 @@ int update_persistent_clock(struct timespec now)
struct rtc_time tm;
if (!ppc_md.set_rtc_time)
- return 0;
+ return -ENODEV;
to_tm(now.tv_sec + 1 + timezone_offset, &tm);
tm.tm_year -= 1900;
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 19c03ab2bdcb..b377e9672497 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -25,9 +25,17 @@ 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
+ depends on RTC_HCTOSYS = y || RTC_SYSTOHC = y
default "rtc0"
help
The RTC device that will be used to (re)initialize the system
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 56297f0fd388..69d11f1d76e4 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -6,6 +6,7 @@ ccflags-$(CONFIG_RTC_DEBUG) := -DDEBUG
obj-$(CONFIG_RTC_LIB) += rtc-lib.o
obj-$(CONFIG_RTC_HCTOSYS) += hctosys.o
+obj-$(CONFIG_RTC_SYSTOHC) += systohc.o
obj-$(CONFIG_RTC_CLASS) += rtc-core.o
rtc-core-y := class.o interface.o
diff --git a/drivers/rtc/systohc.c b/drivers/rtc/systohc.c
new file mode 100644
index 000000000000..bf3e242ccc5c
--- /dev/null
+++ b/drivers/rtc/systohc.c
@@ -0,0 +1,44 @@
+/*
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ */
+#include <linux/rtc.h>
+#include <linux/time.h>
+
+/**
+ * rtc_set_ntp_time - Save NTP synchronized time to the RTC
+ * @now: Current time of day
+ *
+ * Replacement for the NTP platform function update_persistent_clock
+ * that stores time for later retrieval by rtc_hctosys.
+ *
+ * Returns 0 on successful RTC update, -ENODEV if a RTC update is not
+ * possible at all, and various other -errno for specific temporary failure
+ * cases.
+ *
+ * If temporary failure is indicated the caller should try again 'soon'
+ */
+int rtc_set_ntp_time(struct timespec now)
+{
+ struct rtc_device *rtc;
+ struct rtc_time tm;
+ int err = -ENODEV;
+
+ if (now.tv_nsec < (NSEC_PER_SEC >> 1))
+ rtc_time_to_tm(now.tv_sec, &tm);
+ else
+ rtc_time_to_tm(now.tv_sec + 1, &tm);
+
+ rtc = rtc_class_open(CONFIG_RTC_HCTOSYS_DEVICE);
+ if (rtc) {
+ /* rtc_hctosys exclusively uses UTC, so we call set_time here,
+ * not set_mmss. */
+ if (rtc->ops && (rtc->ops->set_time || rtc->ops->set_mmss))
+ err = rtc_set_time(rtc, &tm);
+ rtc_class_close(rtc);
+ }
+
+ return err;
+}
diff --git a/include/linux/rtc.h b/include/linux/rtc.h
index 9531845c419f..11d05f9fe8b6 100644
--- a/include/linux/rtc.h
+++ b/include/linux/rtc.h
@@ -138,6 +138,7 @@ extern void rtc_device_unregister(struct rtc_device *rtc);
extern int rtc_read_time(struct rtc_device *rtc, struct rtc_time *tm);
extern int rtc_set_time(struct rtc_device *rtc, struct rtc_time *tm);
extern int rtc_set_mmss(struct rtc_device *rtc, unsigned long secs);
+extern int rtc_set_ntp_time(struct timespec now);
int __rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm);
extern int rtc_read_alarm(struct rtc_device *rtc,
struct rtc_wkalrm *alrm);
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;