powerpc/time: Use clockevents_register_device(), fixing an issue with large decrementer

We currently cap the decrementer clockevent at 4 seconds, even on systems
with large decrementer support. Fix this by converting the code to use
clockevents_register_device() which calculates the upper bound based on
the max_delta passed in.

Signed-off-by: Anton Blanchard <anton@ozlabs.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/kernel/time.c

@@ -984,10 +984,10 @@ static void register_decrementer_clockevent(int cpu)
 	*dec = decrementer_clockevent;
 	dec->cpumask = cpumask_of(cpu);
 
+	clockevents_config_and_register(dec, ppc_tb_freq, 2, decrementer_max);
+
 	printk_once(KERN_DEBUG "clockevent: %s mult[%x] shift[%d] cpu[%d]\n",
 		    dec->name, dec->mult, dec->shift, cpu);
-
-	clockevents_register_device(dec);
 }
 
 static void enable_large_decrementer(void)
@@ -1035,18 +1035,7 @@ static void __init set_decrementer_max(void)
 
 static void __init init_decrementer_clockevent(void)
 {
-	int cpu = smp_processor_id();
-
-	clockevents_calc_mult_shift(&decrementer_clockevent, ppc_tb_freq, 4);
-
-	decrementer_clockevent.max_delta_ns =
-		clockevent_delta2ns(decrementer_max, &decrementer_clockevent);
-	decrementer_clockevent.max_delta_ticks = decrementer_max;
-	decrementer_clockevent.min_delta_ns =
-		clockevent_delta2ns(2, &decrementer_clockevent);
-	decrementer_clockevent.min_delta_ticks = 2;
-
-	register_decrementer_clockevent(cpu);
+	register_decrementer_clockevent(smp_processor_id());
 }
 
 void secondary_cpu_time_init(void)