arch/x86/kernel/time.c

   1 /*
   2  *  Copyright (c) 1991,1992,1995  Linus Torvalds
   3  *  Copyright (c) 1994  Alan Modra
   4  *  Copyright (c) 1995  Markus Kuhn
   5  *  Copyright (c) 1996  Ingo Molnar
   6  *  Copyright (c) 1998  Andrea Arcangeli
   7  *  Copyright (c) 2002,2006  Vojtech Pavlik
   8  *  Copyright (c) 2003  Andi Kleen
   9  *
  10  */
  11
  12 #include <linux/clockchips.h>
  13 #include <linux/interrupt.h>
  14 #include <linux/irq.h>
  15 #include <linux/i8253.h>
  16 #include <linux/time.h>
  17 #include <linux/export.h>
  18
  19 #include <asm/vsyscall.h>
  20 #include <asm/x86_init.h>
  21 #include <asm/i8259.h>
  22 #include <asm/timer.h>
  23 #include <asm/hpet.h>
  24 #include <asm/time.h>
  25
  26 unsigned long profile_pc(struct pt_regs *regs)
  27 {
  28         unsigned long pc = instruction_pointer(regs);
  29
  30         if (!user_mode(regs) && in_lock_functions(pc)) {
  31 #ifdef CONFIG_FRAME_POINTER
  32                 return *(unsigned long *)(regs->bp + sizeof(long));
  33 #else
  34                 unsigned long *sp =
  35                         (unsigned long *)kernel_stack_pointer(regs);
  36                 /*
  37                  * Return address is either directly at stack pointer
  38                  * or above a saved flags. Eflags has bits 22-31 zero,
  39                  * kernel addresses don't.
  40                  */
  41                 if (sp[0] >> 22)
  42                         return sp[0];
  43                 if (sp[1] >> 22)
  44                         return sp[1];
  45 #endif
  46         }
  47         return pc;
  48 }
  49 EXPORT_SYMBOL(profile_pc);
  50
  51 /*
  52  * Default timer interrupt handler for PIT/HPET
  53  */
  54 static irqreturn_t timer_interrupt(int irq, void *dev_id)
  55 {
  56         global_clock_event->event_handler(global_clock_event);
  57         return IRQ_HANDLED;
  58 }
  59
  60 static struct irqaction irq0  = {
  61         .handler = timer_interrupt,
  62         .flags = IRQF_NOBALANCING | IRQF_IRQPOLL | IRQF_TIMER,
  63         .name = "timer"
  64 };
  65
  66 void __init setup_default_timer_irq(void)
  67 {
  68         if (!nr_legacy_irqs())
  69                 return;
  70         setup_irq(0, &irq0);
  71 }
  72
  73 /* Default timer init function */
  74 void __init hpet_time_init(void)
  75 {
  76         if (!hpet_enable())
  77                 setup_pit_timer();
  78         setup_default_timer_irq();
  79 }
  80
  81 static __init void x86_late_time_init(void)
  82 {
  83         x86_init.timers.timer_init();
  84         tsc_init();
  85 }
  86
  87 /*
  88  * Initialize TSC and delay the periodic timer init to
  89  * late x86_late_time_init() so ioremap works.
  90  */
  91 void __init time_init(void)
  92 {
  93         late_time_init = x86_late_time_init;
  94 }