Commit 4f543fa4 authored by john stultz's avatar john stultz Committed by Linus Torvalds
Browse files

alpha: convert to use arch_gettimeoffset() 



Converts alpha to use GENERIC_TIME via the arch_getoffset()
infrastructure, reducing the amount of arch specific code we need to
maintain.

I suspect the alpha arch could even be further improved to provide and
rpcc() based clocksource, but not having the hardware, I don't feel
comfortable attempting the more complicated conversion (but I'd be glad to
help if anyone else is interested).

[akpm@linux-foundation.org: fix build]
Signed-off-by: default avatarJohn Stultz <johnstul@us.ibm.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 6e0c9e77

arch/alpha/Kconfig

+8 −0
Original line number Diff line number Diff line
@@ -45,6 +45,14 @@ config GENERIC_CALIBRATE_DELAY 
	bool

	default y



config GENERIC_TIME

	bool

	default y



config ARCH_USES_GETTIMEOFFSET

	bool

	default y



config ZONE_DMA

	bool

	default y

arch/alpha/kernel/time.c

+7 −72
Original line number Diff line number Diff line
@@ -408,28 +408,17 @@ time_init(void) 
 * part.  So we can't do the "find absolute time in terms of cycles" thing

 * that the other ports do.

 */

void

do_gettimeofday(struct timeval *tv)

u32 arch_gettimeoffset(void)

{

	unsigned long flags;

	unsigned long sec, usec, seq;

	unsigned long delta_cycles, delta_usec, partial_tick;



	do {

		seq = read_seqbegin_irqsave(&xtime_lock, flags);



		delta_cycles = rpcc() - state.last_time;

		sec = xtime.tv_sec;

		usec = (xtime.tv_nsec / 1000);

		partial_tick = state.partial_tick;



	} while (read_seqretry_irqrestore(&xtime_lock, seq, flags));



#ifdef CONFIG_SMP

	/* Until and unless we figure out how to get cpu cycle counters

	   in sync and keep them there, we can't use the rpcc tricks.  */

	delta_usec = 0;

	return 0;

#else

	unsigned long delta_cycles, delta_usec, partial_tick;



	delta_cycles = rpcc() - state.last_time;

	partial_tick = state.partial_tick;

	/*

	 * usec = cycles * ticks_per_cycle * 2**48 * 1e6 / (2**48 * ticks)

	 *	= cycles * (s_t_p_c) * 1e6 / (2**48 * ticks)
@@ -446,64 +435,10 @@ do_gettimeofday(struct timeval *tv) 
	delta_usec = (delta_cycles * state.scaled_ticks_per_cycle 

		      + partial_tick) * 15625;

	delta_usec = ((delta_usec / ((1UL << (FIX_SHIFT-6-1)) * HZ)) + 1) / 2;

	return delta_usec * 1000;

#endif



	usec += delta_usec;

	if (usec >= 1000000) {

		sec += 1;

		usec -= 1000000;

}



	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;

	unsigned long delta_nsec;



	if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)

		return -EINVAL;



	write_seqlock_irq(&xtime_lock);



	/* The offset that is added into time in do_gettimeofday above

	   must be subtracted out here to keep a coherent view of the

	   time.  Without this, a full-tick error is possible.  */



#ifdef CONFIG_SMP

	delta_nsec = 0;

#else

	delta_nsec = rpcc() - state.last_time;

	delta_nsec = (delta_nsec * state.scaled_ticks_per_cycle 

		      + state.partial_tick) * 15625;

	delta_nsec = ((delta_nsec / ((1UL << (FIX_SHIFT-6-1)) * HZ)) + 1) / 2;

	delta_nsec *= 1000;

#endif



	nsec -= delta_nsec;



	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

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