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/i8253.h>
  15 #include <linux/time.h>
  16 #include <linux/export.h>
  17
  18 #include <asm/vsyscall.h>
  19 #include <asm/x86_init.h>
  20 #include <asm/i8259.h>
  21 #include <asm/timer.h>
  22 #include <asm/hpet.h>
  23 #include <asm/time.h>
  24
  25 #ifdef CONFIG_X86_64
  26 DEFINE_VVAR(volatile unsigned long, jiffies) = INITIAL_JIFFIES;
  27 #endif
  28
  29 unsigned long profile_pc(struct pt_regs *regs)
  30 {
  31         unsigned long pc = instruction_pointer(regs);
  32
  33         if (!user_mode_vm(regs) && in_lock_functions(pc)) {
  34 #ifdef CONFIG_FRAME_POINTER
  35                 return *(unsigned long *)(regs->bp + sizeof(long));
  36 #else
  37                 unsigned long *sp =
  38                         (unsigned long *)kernel_stack_pointer(regs);
  39                 /*
  40                  * Return address is either directly at stack pointer
  41                  * or above a saved flags. Eflags has bits 22-31 zero,
  42                  * kernel addresses don't.
  43                  */
  44                 if (sp[0] >> 22)
  45                         return sp[0];
  46                 if (sp[1] >> 22)
  47                         return sp[1];
  48 #endif
  49         }
  50         return pc;
  51 }
  52 EXPORT_SYMBOL(profile_pc);
  53
  54 /*
  55  * Default timer interrupt handler for PIT/HPET
  56  */
  57 static irqreturn_t timer_interrupt(int irq, void *dev_id)
  58 {
  59         global_clock_event->event_handler(global_clock_event);
  60         return IRQ_HANDLED;
  61 }
  62
  63 static struct irqaction irq0  = {
  64         .handler = timer_interrupt,
  65         .flags = IRQF_DISABLED | IRQF_NOBALANCING | IRQF_IRQPOLL | IRQF_TIMER,
  66         .name = "timer"
  67 };
  68
  69 void __init setup_default_timer_irq(void)
  70 {
  71         setup_irq(0, &irq0);
  72 }
  73
  74 /* Default timer init function */
  75 void __init hpet_time_init(void)
  76 {
  77         if (!hpet_enable())
  78                 setup_pit_timer();
  79         setup_default_timer_irq();
  80 }
  81
  82 static __init void x86_late_time_init(void)
  83 {
  84         x86_init.timers.timer_init();
  85         tsc_init();
  86 }
  87
  88 /*
  89  * Initialize TSC and delay the periodic timer init to
  90  * late x86_late_time_init() so ioremap works.
  91  */
  92 void __init time_init(void)
  93 {
  94         late_time_init = x86_late_time_init;
  95 }