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Subject[PATCH] Convert m32r to use arch_gettimeoffset()
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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@us.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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