linux-kernel - [PATCH] Convert m32r to use arch

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Message-Id: <1244760744.7192.29.camel@localhost.localdomain>
Date:	Thu, 11 Jun 2009 15:52:24 -0700
From:	john stultz <johnstul@...ibm.com>
To:	takata@...ux-m32r.org
Cc:	lkml <linux-kernel@...r.kernel.org>, linux-m32r@...linux-m32r.org
Subject: [PATCH] Convert m32r to use arch_gettimeoffset()

This patch converts m32r to use GENERIC_TIME via the arch_getoffset()
infrastructure, reducing the amount of arch specific code we need to
maintain.

I also noted that m32r doesn't seem to be taking the xtime write lock
before calling do_timer()!  That looks like a pretty bad bug to me. If
folks agree, let me know and I can move the lock grab to the correct
spot.

This patch applies on top of Linus' current -git tree (pre 2.6.31-rc1).

I've taken my best swing at converting this, but I'm not 100% confident
I got it right. It does cross compile, so that's hopefully a good sign.
Any assistance from arch maintainers or testers to get this merged would
be great.

thanks
-john

Signed-off-by: John Stultz <johnstul@...ibm.com>
---
 Kconfig       |    6 ++++
 kernel/time.c |   74 ++--------------------------------------------------------
 2 files changed, 9 insertions(+), 71 deletions(-)

diff --git a/arch/m32r/Kconfig b/arch/m32r/Kconfig
index cabba33..c41234f 100644
--- a/arch/m32r/Kconfig
+++ b/arch/m32r/Kconfig
@@ -41,6 +41,12 @@ config HZ
 	int
 	default 100
 
+config GENERIC_TIME
+	def_bool y
+
+config ARCH_USES_GETTIMEOFFSET
+	def_bool y
+
 source "init/Kconfig"
 
 source "kernel/Kconfig.freezer"
diff --git a/arch/m32r/kernel/time.c b/arch/m32r/kernel/time.c
index cada3ba..ba61c4c 100644
--- a/arch/m32r/kernel/time.c
+++ b/arch/m32r/kernel/time.c
@@ -48,7 +48,7 @@ extern void smp_local_timer_interrupt(void);
 
 static unsigned long latch;
 
-static unsigned long do_gettimeoffset(void)
+u32 arch_gettimeoffset(void)
 {
 	unsigned long  elapsed_time = 0;  /* [us] */
 
@@ -93,79 +93,10 @@ static unsigned long do_gettimeoffset(void)
 #error no chip configuration
 #endif
 
-	return elapsed_time;
+	return elapsed_time * 1000;
 }
 
 /*
- * This version of gettimeofday has near microsecond resolution.
- */
-void do_gettimeofday(struct timeval *tv)
-{
-	unsigned long seq;
-	unsigned long usec, sec;
-	unsigned long max_ntp_tick = tick_usec - tickadj;
-
-	do {
-		seq = read_seqbegin(&xtime_lock);
-
-		usec = do_gettimeoffset();
-
-		/*
-		 * If time_adjust is negative then NTP is slowing the clock
-		 * so make sure not to go into next possible interval.
-		 * Better to lose some accuracy than have time go backwards..
-		 */
-		if (unlikely(time_adjust < 0))
-			usec = min(usec, max_ntp_tick);
-
-		sec = xtime.tv_sec;
-		usec += (xtime.tv_nsec / 1000);
-	} while (read_seqretry(&xtime_lock, seq));
-
-	while (usec >= 1000000) {
-		usec -= 1000000;
-		sec++;
-	}
-
-	tv->tv_sec = sec;
-	tv->tv_usec = usec;
-}
-
-EXPORT_SYMBOL(do_gettimeofday);
-
-int do_settimeofday(struct timespec *tv)
-{
-	time_t wtm_sec, sec = tv->tv_sec;
- 	long wtm_nsec, nsec = tv->tv_nsec;
-
-	if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
-		return -EINVAL;
-
-	write_seqlock_irq(&xtime_lock);
-	/*
-	 * This is revolting. We need to set "xtime" correctly. However, the
-	 * value in this location is the value at the most recent update of
-	 * wall time.  Discover what correction gettimeofday() would have
-	 * made, and then undo it!
-	 */
-	nsec -= do_gettimeoffset() * NSEC_PER_USEC;
-
-	wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
-	wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
-
-	set_normalized_timespec(&xtime, sec, nsec);
-	set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
-
-	ntp_clear();
-	write_sequnlock_irq(&xtime_lock);
-	clock_was_set();
-
-	return 0;
-}
-
-EXPORT_SYMBOL(do_settimeofday);
-
-/*
  * In order to set the CMOS clock precisely, set_rtc_mmss has to be
  * called 500 ms after the second nowtime has started, because when
  * nowtime is written into the registers of the CMOS clock, it will
@@ -192,6 +123,7 @@ static irqreturn_t timer_interrupt(int irq, void *dev_id)
 #ifndef CONFIG_SMP
 	profile_tick(CPU_PROFILING);
 #endif
+	/* XXX FIXME. Uh, the xtime_lock should be held here, no? */
 	do_timer(1);
 
 #ifndef CONFIG_SMP


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