ia64: convert to legacy_timer_tick

ia64 is the only architecture that calls xtime_update() in a loop, once for each jiffie that has passed since the last event. Before commit 3171a03 ("[PATCH] simplify update_times (avoid jiffies/jiffies_64 aliasing problem)") in 2006, it could not actually do this any differently, but now it seems simpler to just pass the number of jiffies that passed in the meantime. While this loses the ability process interrupts in the middle of the timer tick by calling local_irq_enable(), doing so is fairly peculiar anyway and it seems better to just do what everyone else does here. Reviewed-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Author: arndb

arch/ia64/Kconfig

@@ -46,6 +46,7 @@ config IA64
 select ARCH_THREAD_STACK_ALLOCATOR
 select ARCH_CLOCKSOURCE_DATA
 select GENERIC_TIME_VSYSCALL
+select LEGACY_TIMER_TICK
 select SWIOTLB
 select SYSCTL_ARCH_UNALIGN_NO_WARN
 select HAVE_MOD_ARCH_SPECIFIC

arch/ia64/kernel/time.c

@@ -161,39 +161,29 @@ void vtime_account_idle(struct task_struct *tsk)
 static irqreturn_t
 timer_interrupt (int irq, void *dev_id)
 {
-unsigned long new_itm;
+unsigned long cur_itm, new_itm, ticks;
 
 if (cpu_is_offline(smp_processor_id())) {
 return IRQ_HANDLED;
 }
 
 new_itm = local_cpu_data->itm_next;
+cur_itm = ia64_get_itc();
 
-if (!time_after(ia64_get_itc(), new_itm))
+if (!time_after(cur_itm, new_itm)) {
 printk(KERN_ERR "Oops: timer tick before it's due (itc=%lx,itm=%lx)\n",
- ia64_get_itc(), new_itm);
-
-profile_tick(CPU_PROFILING);
-
-while (1) {
-update_process_times(user_mode(get_irq_regs()));
-
-new_itm += local_cpu_data->itm_delta;
-
-if (smp_processor_id() == time_keeper_id)
-xtime_update(1);
-
-local_cpu_data->itm_next = new_itm;
+ cur_itm, new_itm);
+ticks = 1;
+} else {
+ticks = DIV_ROUND_UP(cur_itm - new_itm,
+ local_cpu_data->itm_delta);
+new_itm += ticks * local_cpu_data->itm_delta;
+}
 
-if (time_after(new_itm, ia64_get_itc()))
-break;
+if (smp_processor_id() != time_keeper_id)
+ticks = 0;
 
-/*
- * Allow IPIs to interrupt the timer loop.
- */
-local_irq_enable();
-local_irq_disable();
-}
+legacy_timer_tick(ticks);
 
 do {
 /*