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Date: Mon, 05 Mar 2007 21:37:52 -0800 (PST)
From: David Miller <davem@...emloft.net>
To: tglx@...utronix.de
CC: linux-kernel@...r.kernel.org, sparclinux@...r.kernel.org
Subject: [PATCH 1/4]: [SPARC64]: Synchronize RTC clock via timer just like
x86.
>From 8c59ccd3f9906c95a62b3157285093d203881ae4 Mon Sep 17 00:00:00 2001
From: David S. Miller <davem@...set.davemloft.net>
Date: Thu, 22 Feb 2007 04:16:21 -0800
Subject: [PATCH] [SPARC64]: Synchronize RTC clock via timer just like x86.
Signed-off-by: David S. Miller <davem@...emloft.net>
---
arch/sparc64/kernel/time.c | 66 ++++++++++++++++++++++++++++++++------------
1 files changed, 48 insertions(+), 18 deletions(-)
diff --git a/arch/sparc64/kernel/time.c b/arch/sparc64/kernel/time.c
index f84da4f..d457079 100644
--- a/arch/sparc64/kernel/time.c
+++ b/arch/sparc64/kernel/time.c
@@ -435,22 +435,56 @@ static unsigned long timer_ticks_per_nsec_quotient __read_mostly;
#define TICK_SIZE (tick_nsec / 1000)
-static inline void timer_check_rtc(void)
+#define USEC_AFTER 500000
+#define USEC_BEFORE 500000
+
+static void sync_cmos_clock(unsigned long dummy);
+
+static DEFINE_TIMER(sync_cmos_timer, sync_cmos_clock, 0, 0);
+
+static void sync_cmos_clock(unsigned long dummy)
{
- /* last time the cmos clock got updated */
- static long last_rtc_update;
-
- /* Determine when to update the Mostek clock. */
- if (ntp_synced() &&
- xtime.tv_sec > last_rtc_update + 660 &&
- (xtime.tv_nsec / 1000) >= 500000 - ((unsigned) TICK_SIZE) / 2 &&
- (xtime.tv_nsec / 1000) <= 500000 + ((unsigned) TICK_SIZE) / 2) {
- if (set_rtc_mmss(xtime.tv_sec) == 0)
- last_rtc_update = xtime.tv_sec;
- else
- last_rtc_update = xtime.tv_sec - 600;
- /* do it again in 60 s */
+ struct timeval now, next;
+ int fail = 1;
+
+ /*
+ * If we have an externally synchronized Linux clock, then update
+ * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
+ * called as close as possible to 500 ms before the new second starts.
+ * This code is run on a timer. If the clock is set, that timer
+ * may not expire at the correct time. Thus, we adjust...
+ */
+ if (!ntp_synced())
+ /*
+ * Not synced, exit, do not restart a timer (if one is
+ * running, let it run out).
+ */
+ return;
+
+ do_gettimeofday(&now);
+ if (now.tv_usec >= USEC_AFTER - ((unsigned) TICK_SIZE) / 2 &&
+ now.tv_usec <= USEC_BEFORE + ((unsigned) TICK_SIZE) / 2)
+ fail = set_rtc_mmss(now.tv_sec);
+
+ next.tv_usec = USEC_AFTER - now.tv_usec;
+ if (next.tv_usec <= 0)
+ next.tv_usec += USEC_PER_SEC;
+
+ if (!fail)
+ next.tv_sec = 659;
+ else
+ next.tv_sec = 0;
+
+ if (next.tv_usec >= USEC_PER_SEC) {
+ next.tv_sec++;
+ next.tv_usec -= USEC_PER_SEC;
}
+ mod_timer(&sync_cmos_timer, jiffies + timeval_to_jiffies(&next));
+}
+
+void notify_arch_cmos_timer(void)
+{
+ mod_timer(&sync_cmos_timer, jiffies + 1);
}
irqreturn_t timer_interrupt(int irq, void *dev_id)
@@ -483,8 +517,6 @@ irqreturn_t timer_interrupt(int irq, void *dev_id)
: "r" (pstate));
} while (time_after_eq(ticks, compare));
- timer_check_rtc();
-
write_sequnlock(&xtime_lock);
return IRQ_HANDLED;
@@ -497,8 +529,6 @@ void timer_tick_interrupt(struct pt_regs *regs)
do_timer(1);
- timer_check_rtc();
-
write_sequnlock(&xtime_lock);
}
#endif
--
1.5.0
-
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