Blackfin: convert to use arch_gettimeoffset()

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

I've taken my best swing at converting this, but I'm not 100% confident
I got it right.  My cross-compiler is now out of date (gcc4.2) so I
wasn't able to check if it compiled. Any assistance from arch
maintainers or testers to get this merged would be great.
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>

arch/blackfin/Kconfig

@@ -229,7 +229,7 @@ endchoice
 
 config SMP
 	depends on BF561
-	select GENERIC_TIME
+	select GENERIC_CLOCKEVENTS
 	bool "Symmetric multi-processing support"
 	---help---
 	  This enables support for systems with more than one CPU,
@@ -613,12 +613,10 @@ comment "Kernel Timer/Scheduler"
 source kernel/Kconfig.hz
 
 config GENERIC_TIME
-	bool "Generic time"
-	default y
+	def_bool y
 
 config GENERIC_CLOCKEVENTS
 	bool "Generic clock events"
-	depends on GENERIC_TIME
 	default y
 
 choice
@@ -653,6 +651,10 @@ config GPTMR0_CLOCKSOURCE
 	depends on GENERIC_CLOCKEVENTS
 	depends on !TICKSOURCE_GPTMR0
 
+config ARCH_USES_GETTIMEOFFSET
+	depends on !GENERIC_CLOCKEVENTS
+	def_bool y
+
 source kernel/time/Kconfig
 
 comment "Misc"

arch/blackfin/kernel/time.c

@@ -81,11 +81,11 @@ time_sched_init(irqreturn_t(*timer_routine) (int, void *))
 #endif
 }
 
+#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
 /*
  * Should return useconds since last timer tick
  */
-#ifndef CONFIG_GENERIC_TIME
-static unsigned long gettimeoffset(void)
+u32 arch_gettimeoffset(void)
 {
 	unsigned long offset;
 	unsigned long clocks_per_jiffy;
@@ -184,65 +184,6 @@ void __init time_init(void)
 	time_sched_init(timer_interrupt);
 }
 
-#ifndef CONFIG_GENERIC_TIME
-void do_gettimeofday(struct timeval *tv)
-{
-	unsigned long flags;
-	unsigned long seq;
-	unsigned long usec, sec;
-
-	do {
-		seq = read_seqbegin_irqsave(&xtime_lock, flags);
-		usec = gettimeoffset();
-		sec = xtime.tv_sec;
-		usec += (xtime.tv_nsec / NSEC_PER_USEC);
-	}
-	while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
-
-	while (usec >= USEC_PER_SEC) {
-		usec -= USEC_PER_SEC;
-		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 the xtime.tv_usec
-	 * correctly. However, the value in this location is
-	 * is value at the last tick.
-	 * Discover what correction gettimeofday
-	 * would have done, and then undo it!
-	 */
-	nsec -= (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);
-#endif /* !CONFIG_GENERIC_TIME */
-
 /*
  * Scheduler clock - returns current time in nanosec units.
  */