[PATCH v2 1/4] NTP: rtc: Add CONFIG_RTC_SYSTOHC_DEVICE for NTP synchronization

[PATCH v2 1/4] NTP: rtc: Add CONFIG_RTC_SYSTOHC_DEVICE for NTP synchronization

[Xunlei Pang]

From: Xunlei Pang <pang.xunlei@linaro.org>

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 "rtc0".

After this patch, NTP will sync up "rtc0" by default.

Cc: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: Xunlei Pang <pang.xunlei@linaro.org>
---
v1->v2:
Change "depends on RTC_XX = y" to "depends on RTC_XXX".

 drivers/rtc/Kconfig   | 28 +++++++++++++++++++---------
 drivers/rtc/systohc.c |  2 +-
 2 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 0fe4ad8..f422a46 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -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 +48,24 @@ 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 "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
diff --git a/drivers/rtc/systohc.c b/drivers/rtc/systohc.c
index 7728d5e..b4a68ff 100644
--- a/drivers/rtc/systohc.c
+++ b/drivers/rtc/systohc.c
@@ -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. */
-- 
1.9.1

[PATCH v2 2/4] sparc: time: Replace update_persistent_clock() with CONFIG_RTC_SYSTOHC

[Xunlei Pang]

From: Xunlei Pang <pang.xunlei@linaro.org>

On Sparc systems, update_persistent_clock() uses RTC drivers to do
the job, it makes more sense to hand it over to CONFIG_RTC_SYSTOHC.

In the long run, all the update_persistent_clock() should migrate to
proper class RTC drivers if any and use CONFIG_RTC_SYSTOHC instead.

Signed-off-by: Xunlei Pang <pang.xunlei@linaro.org>
---
 arch/sparc/Kconfig          |  2 +-
 arch/sparc/kernel/time_32.c | 21 ---------------------
 arch/sparc/kernel/time_64.c | 14 --------------
 3 files changed, 1 insertion(+), 36 deletions(-)

diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index e49502a..56442d2 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -25,6 +25,7 @@ config SPARC
 	select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
 	select RTC_CLASS
 	select RTC_DRV_M48T59
+	select RTC_SYSTOHC
 	select HAVE_DMA_ATTRS
 	select HAVE_DMA_API_DEBUG
 	select HAVE_ARCH_JUMP_LABEL if SPARC64
@@ -35,7 +36,6 @@ config SPARC
 	select HAVE_BPF_JIT
 	select HAVE_DEBUG_BUGVERBOSE
 	select GENERIC_SMP_IDLE_THREAD
-	select GENERIC_CMOS_UPDATE
 	select GENERIC_CLOCKEVENTS
 	select GENERIC_STRNCPY_FROM_USER
 	select GENERIC_STRNLEN_USER
diff --git a/arch/sparc/kernel/time_32.c b/arch/sparc/kernel/time_32.c
index 8caf45e..c9692f3 100644
--- a/arch/sparc/kernel/time_32.c
+++ b/arch/sparc/kernel/time_32.c
@@ -23,7 +23,6 @@
 #include <linux/mm.h>
 #include <linux/interrupt.h>
 #include <linux/time.h>
-#include <linux/rtc.h>
 #include <linux/rtc/m48t59.h>
 #include <linux/timex.h>
 #include <linux/clocksource.h>
@@ -65,8 +64,6 @@ DEFINE_PER_CPU(struct clock_event_device, sparc32_clockevent);
 DEFINE_SPINLOCK(rtc_lock);
 EXPORT_SYMBOL(rtc_lock);
 
-static int set_rtc_mmss(unsigned long);
-
 unsigned long profile_pc(struct pt_regs *regs)
 {
 	extern char __copy_user_begin[], __copy_user_end[];
@@ -87,11 +84,6 @@ EXPORT_SYMBOL(profile_pc);
 
 volatile u32 __iomem *master_l10_counter;
 
-int update_persistent_clock(struct timespec now)
-{
-	return set_rtc_mmss(now.tv_sec);
-}
-
 irqreturn_t notrace timer_interrupt(int dummy, void *dev_id)
 {
 	if (timer_cs_enabled) {
@@ -362,16 +354,3 @@ void __init time_init(void)
 		sbus_time_init();
 }
 
-
-static int set_rtc_mmss(unsigned long secs)
-{
-	struct rtc_device *rtc = rtc_class_open("rtc0");
-	int err = -1;
-
-	if (rtc) {
-		err = rtc_set_mmss(rtc, secs);
-		rtc_class_close(rtc);
-	}
-
-	return err;
-}
diff --git a/arch/sparc/kernel/time_64.c b/arch/sparc/kernel/time_64.c
index edbbeb1..2e6035c 100644
--- a/arch/sparc/kernel/time_64.c
+++ b/arch/sparc/kernel/time_64.c
@@ -28,7 +28,6 @@
 #include <linux/cpufreq.h>
 #include <linux/percpu.h>
 #include <linux/miscdevice.h>
-#include <linux/rtc.h>
 #include <linux/rtc/m48t59.h>
 #include <linux/kernel_stat.h>
 #include <linux/clockchips.h>
@@ -394,19 +393,6 @@ static struct sparc64_tick_ops hbtick_operations __read_mostly = {
 
 static unsigned long timer_ticks_per_nsec_quotient __read_mostly;
 
-int update_persistent_clock(struct timespec now)
-{
-	struct rtc_device *rtc = rtc_class_open("rtc0");
-	int err = -1;
-
-	if (rtc) {
-		err = rtc_set_mmss(rtc, now.tv_sec);
-		rtc_class_close(rtc);
-	}
-
-	return err;
-}
-
 unsigned long cmos_regs;
 EXPORT_SYMBOL(cmos_regs);
 
-- 
1.9.1

Re: [PATCH v2 2/4] sparc: time: Replace update_persistent_clock() with CONFIG_RTC_SYSTOHC

[Alexandre Belloni]

On 02/06/2015 at 17:14:35 +0800, Xunlei Pang wrote :
> From: Xunlei Pang <pang.xunlei@linaro.org>
> 
> On Sparc systems, update_persistent_clock() uses RTC drivers to do
> the job, it makes more sense to hand it over to CONFIG_RTC_SYSTOHC.
> 
> In the long run, all the update_persistent_clock() should migrate to
> proper class RTC drivers if any and use CONFIG_RTC_SYSTOHC instead.
> 
> Signed-off-by: Xunlei Pang <pang.xunlei@linaro.org>

I could take that patch but you should probably get an ack for the sparc
maintainer:
"David S. Miller" <davem@davemloft.net> (maintainer:SPARC + UltraSPAR...,commit_signer:2/4=50%)
sparclinux@vger.kernel.org (open list:SPARC + UltraSPAR...)

-- 
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

[PATCH v2 3/4] drivers/rtc/interface.c: Remove rtc_set_mmss()

[Xunlei Pang]

From: Xunlei Pang <pang.xunlei@linaro.org>

Now rtc_set_mmss() has no users, just remove it.

We still have rtc_set_time() doing similar things.

Signed-off-by: Xunlei Pang <pang.xunlei@linaro.org>
---
 drivers/rtc/interface.c | 45 ---------------------------------------------
 include/linux/rtc.h     |  1 -
 2 files changed, 46 deletions(-)

diff --git a/drivers/rtc/interface.c b/drivers/rtc/interface.c
index 166fc60..b511aa1 100644
--- a/drivers/rtc/interface.c
+++ b/drivers/rtc/interface.c
@@ -91,51 +91,6 @@ int rtc_set_time(struct rtc_device *rtc, struct rtc_time *tm)
 }
 EXPORT_SYMBOL_GPL(rtc_set_time);
 
-int rtc_set_mmss(struct rtc_device *rtc, unsigned long secs)
-{
-	int err;
-
-	err = mutex_lock_interruptible(&rtc->ops_lock);
-	if (err)
-		return err;
-
-	if (!rtc->ops)
-		err = -ENODEV;
-	else if (rtc->ops->set_mmss64)
-		err = rtc->ops->set_mmss64(rtc->dev.parent, secs);
-	else if (rtc->ops->set_mmss)
-		err = rtc->ops->set_mmss(rtc->dev.parent, secs);
-	else if (rtc->ops->read_time && rtc->ops->set_time) {
-		struct rtc_time new, old;
-
-		err = rtc->ops->read_time(rtc->dev.parent, &old);
-		if (err == 0) {
-			rtc_time64_to_tm(secs, &new);
-
-			/*
-			 * avoid writing when we're going to change the day of
-			 * the month. We will retry in the next minute. This
-			 * basically means that if the RTC must not drift
-			 * by more than 1 minute in 11 minutes.
-			 */
-			if (!((old.tm_hour == 23 && old.tm_min == 59) ||
-				(new.tm_hour == 23 && new.tm_min == 59)))
-				err = rtc->ops->set_time(rtc->dev.parent,
-						&new);
-		}
-	} else {
-		err = -EINVAL;
-	}
-
-	pm_stay_awake(rtc->dev.parent);
-	mutex_unlock(&rtc->ops_lock);
-	/* A timer might have just expired */
-	schedule_work(&rtc->irqwork);
-
-	return err;
-}
-EXPORT_SYMBOL_GPL(rtc_set_mmss);
-
 static int rtc_read_alarm_internal(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 {
 	int err;
diff --git a/include/linux/rtc.h b/include/linux/rtc.h
index 13e4138..2e9b0e2 100644
--- a/include/linux/rtc.h
+++ b/include/linux/rtc.h
@@ -163,7 +163,6 @@ extern void devm_rtc_device_unregister(struct device *dev,
 
 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 timespec64 now);
 int __rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm);
 extern int rtc_read_alarm(struct rtc_device *rtc,
-- 
1.9.1

[PATCH v2 4/4] cris: time: Cleanup of persistent clock stuff

[Xunlei Pang]

From: Xunlei Pang <pang.xunlei@linaro.org>

- Remove update_persistent_clock(), as it does nothing now.
- Remove read_persistent_clock(), let it fall back to the weak version.

Signed-off-by: Xunlei Pang <pang.xunlei@linaro.org>
---
 arch/cris/Kconfig       |  1 -
 arch/cris/kernel/time.c | 25 -------------------------
 2 files changed, 26 deletions(-)

diff --git a/arch/cris/Kconfig b/arch/cris/Kconfig
index 0314e32..982d562 100644
--- a/arch/cris/Kconfig
+++ b/arch/cris/Kconfig
@@ -46,7 +46,6 @@ config CRIS
 	select ARCH_WANT_IPC_PARSE_VERSION
 	select GENERIC_IRQ_SHOW
 	select GENERIC_IOMAP
-	select GENERIC_CMOS_UPDATE
 	select MODULES_USE_ELF_RELA
 	select CLONE_BACKWARDS2
 	select OLD_SIGSUSPEND
diff --git a/arch/cris/kernel/time.c b/arch/cris/kernel/time.c
index 7780d37..2dda6da 100644
--- a/arch/cris/kernel/time.c
+++ b/arch/cris/kernel/time.c
@@ -39,31 +39,6 @@
 extern unsigned long loops_per_jiffy; /* init/main.c */
 unsigned long loops_per_usec;
 
-int set_rtc_mmss(unsigned long nowtime)
-{
-	D(printk(KERN_DEBUG "set_rtc_mmss(%lu)\n", nowtime));
-	return 0;
-}
-
-/* grab the time from the RTC chip */
-unsigned long get_cmos_time(void)
-{
-	return 0;
-}
-
-
-int update_persistent_clock(struct timespec now)
-{
-	return set_rtc_mmss(now.tv_sec);
-}
-
-void read_persistent_clock(struct timespec *ts)
-{
-	ts->tv_sec = 0;
-	ts->tv_nsec = 0;
-}
-
-
 extern void cris_profile_sample(struct pt_regs* regs);
 
 void
-- 
1.9.1

Re: [PATCH v2 4/4] cris: time: Cleanup of persistent clock stuff

[Alexandre Belloni]

On 02/06/2015 at 17:14:37 +0800, Xunlei Pang wrote :
> From: Xunlei Pang <pang.xunlei@linaro.org>
> 
> - Remove update_persistent_clock(), as it does nothing now.
> - Remove read_persistent_clock(), let it fall back to the weak version.
> 
> Signed-off-by: Xunlei Pang <pang.xunlei@linaro.org>

That patch doesn't seem to have any dependencies, it should go through
the cris maintainers tree:
Mikael Starvik <starvik@axis.com> (maintainer:CRIS PORT)
Jesper Nilsson <jesper.nilsson@axis.com> (maintainer:CRIS PORT)
linux-cris-kernel@axis.com (open list:CRIS PORT)

-- 
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

Re: [PATCH v2 1/4] NTP: rtc: Add CONFIG_RTC_SYSTOHC_DEVICE for NTP synchronization

[Alexandre Belloni]

Hi,

On 02/06/2015 at 17:14:34 +0800, Xunlei Pang wrote :
> +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 "rtc0"

To make that working nicely with current configurations, I would use:
default RTC_HCTOSYS_DEVICE


-- 
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

[PATCH v2 1/4] NTP: rtc: Add CONFIG_RTC_SYSTOHC_DEVICE for NTP synchronization

[Xunlei Pang]

From: Xunlei Pang <pang.xunlei@linaro.org>

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 "rtc0".

After this patch, NTP will sync up "rtc0" by default.

Signed-off-by: Xunlei Pang <pang.xunlei@linaro.org>
---
 drivers/rtc/Kconfig   | 28 +++++++++++++++++++---------
 drivers/rtc/systohc.c |  2 +-
 2 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 0fe4ad8..f429e9a 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -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 = y
 	default "rtc0"
 	help
 	  The RTC device that will be used to (re)initialize the system
@@ -56,6 +48,24 @@ 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 = y
+	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
diff --git a/drivers/rtc/systohc.c b/drivers/rtc/systohc.c
index 7728d5e..b4a68ff 100644
--- a/drivers/rtc/systohc.c
+++ b/drivers/rtc/systohc.c
@@ -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. */
-- 
1.9.1

[PATCH v2 2/4] sparc: time: Replace update_persistent_clock() with CONFIG_RTC_SYSTOHC

[Xunlei Pang]

From: Xunlei Pang <pang.xunlei@linaro.org>

On Sparc systems, update_persistent_clock() uses RTC drivers to do
the job, it makes more sense to hand it over to CONFIG_RTC_SYSTOHC.

In the long run, all the update_persistent_clock() should migrate to
proper class RTC drivers if any and use CONFIG_RTC_SYSTOHC instead.

Signed-off-by: Xunlei Pang <pang.xunlei@linaro.org>
---
 arch/sparc/Kconfig          |  2 +-
 arch/sparc/kernel/time_32.c | 21 ---------------------
 arch/sparc/kernel/time_64.c | 14 --------------
 3 files changed, 1 insertion(+), 36 deletions(-)

diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index e49502a..56442d2 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -25,6 +25,7 @@ config SPARC
 	select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
 	select RTC_CLASS
 	select RTC_DRV_M48T59
+	select RTC_SYSTOHC
 	select HAVE_DMA_ATTRS
 	select HAVE_DMA_API_DEBUG
 	select HAVE_ARCH_JUMP_LABEL if SPARC64
@@ -35,7 +36,6 @@ config SPARC
 	select HAVE_BPF_JIT
 	select HAVE_DEBUG_BUGVERBOSE
 	select GENERIC_SMP_IDLE_THREAD
-	select GENERIC_CMOS_UPDATE
 	select GENERIC_CLOCKEVENTS
 	select GENERIC_STRNCPY_FROM_USER
 	select GENERIC_STRNLEN_USER
diff --git a/arch/sparc/kernel/time_32.c b/arch/sparc/kernel/time_32.c
index 8caf45e..c9692f3 100644
--- a/arch/sparc/kernel/time_32.c
+++ b/arch/sparc/kernel/time_32.c
@@ -23,7 +23,6 @@
 #include <linux/mm.h>
 #include <linux/interrupt.h>
 #include <linux/time.h>
-#include <linux/rtc.h>
 #include <linux/rtc/m48t59.h>
 #include <linux/timex.h>
 #include <linux/clocksource.h>
@@ -65,8 +64,6 @@ DEFINE_PER_CPU(struct clock_event_device, sparc32_clockevent);
 DEFINE_SPINLOCK(rtc_lock);
 EXPORT_SYMBOL(rtc_lock);
 
-static int set_rtc_mmss(unsigned long);
-
 unsigned long profile_pc(struct pt_regs *regs)
 {
 	extern char __copy_user_begin[], __copy_user_end[];
@@ -87,11 +84,6 @@ EXPORT_SYMBOL(profile_pc);
 
 volatile u32 __iomem *master_l10_counter;
 
-int update_persistent_clock(struct timespec now)
-{
-	return set_rtc_mmss(now.tv_sec);
-}
-
 irqreturn_t notrace timer_interrupt(int dummy, void *dev_id)
 {
 	if (timer_cs_enabled) {
@@ -362,16 +354,3 @@ void __init time_init(void)
 		sbus_time_init();
 }
 
-
-static int set_rtc_mmss(unsigned long secs)
-{
-	struct rtc_device *rtc = rtc_class_open("rtc0");
-	int err = -1;
-
-	if (rtc) {
-		err = rtc_set_mmss(rtc, secs);
-		rtc_class_close(rtc);
-	}
-
-	return err;
-}
diff --git a/arch/sparc/kernel/time_64.c b/arch/sparc/kernel/time_64.c
index edbbeb1..2e6035c 100644
--- a/arch/sparc/kernel/time_64.c
+++ b/arch/sparc/kernel/time_64.c
@@ -28,7 +28,6 @@
 #include <linux/cpufreq.h>
 #include <linux/percpu.h>
 #include <linux/miscdevice.h>
-#include <linux/rtc.h>
 #include <linux/rtc/m48t59.h>
 #include <linux/kernel_stat.h>
 #include <linux/clockchips.h>
@@ -394,19 +393,6 @@ static struct sparc64_tick_ops hbtick_operations __read_mostly = {
 
 static unsigned long timer_ticks_per_nsec_quotient __read_mostly;
 
-int update_persistent_clock(struct timespec now)
-{
-	struct rtc_device *rtc = rtc_class_open("rtc0");
-	int err = -1;
-
-	if (rtc) {
-		err = rtc_set_mmss(rtc, now.tv_sec);
-		rtc_class_close(rtc);
-	}
-
-	return err;
-}
-
 unsigned long cmos_regs;
 EXPORT_SYMBOL(cmos_regs);
 
-- 
1.9.1