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 #include <linux/mca.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 #ifdef CONFIG_X86_64
  27 DEFINE_VVAR(volatile unsigned long, jiffies) = INITIAL_JIFFIES;
  28 #endif
  29
  30 unsigned long profile_pc(struct pt_regs *regs)
  31 {
  32         unsigned long pc = instruction_pointer(regs);
  33
  34         if (!user_mode_vm(regs) && in_lock_functions(pc)) {
  35 #ifdef CONFIG_FRAME_POINTER
  36                 return *(unsigned long *)(regs->bp + sizeof(long));
  37 #else
  38                 unsigned long *sp =
  39                         (unsigned long *)kernel_stack_pointer(regs);
  40                 /*
  41                  * Return address is either directly at stack pointer
  42                  * or above a saved flags. Eflags has bits 22-31 zero,
  43                  * kernel addresses don't.
  44                  */
  45                 if (sp[0] >> 22)
  46                         return sp[0];
  47                 if (sp[1] >> 22)
  48                         return sp[1];
  49 #endif
  50         }
  51         return pc;
  52 }
  53 EXPORT_SYMBOL(profile_pc);
  54
  55 static irqreturn_t timer_interrupt(int irq, void *dev_id);
  56 static struct irqaction irq0  = {
  57         .handler = timer_interrupt,
  58         .flags = IRQF_DISABLED | IRQF_NOBALANCING | IRQF_IRQPOLL | IRQF_TIMER,
  59         .name = "timer"
  60 };
  61
  62 /*
  63  * Default timer interrupt handler for PIT/HPET
  64  */
  65 static irqreturn_t timer_interrupt(int irq, void *dev_id)
  66 {
  67         /* Keep nmi watchdog up to date */
  68         inc_irq_stat(irq0_irqs);
  69
  70         trace_irq_handler_entry(irq, &irq0);
  71         global_clock_event->event_handler(global_clock_event);
  72         trace_irq_handler_exit(irq, &irq0, 1);
  73
  74         /* MCA bus quirk: Acknowledge irq0 by setting bit 7 in port 0x61 */
  75         if (MCA_bus)
  76                 outb_p(inb_p(0x61)| 0x80, 0x61);
  77
  78         return IRQ_HANDLED;
  79 }
  80
  81 void __init setup_default_timer_irq(void)
  82 {
  83         setup_irq(0, &irq0);
  84 }
  85
  86 /* Default timer init function */
  87 void __init hpet_time_init(void)
  88 {
  89         if (!hpet_enable())
  90                 setup_pit_timer();
  91         setup_default_timer_irq();
  92 }
  93
  94 static __init void x86_late_time_init(void)
  95 {
  96         x86_init.timers.timer_init();
  97         tsc_init();
  98 }
  99
 100 /*
 101  * Initialize TSC and delay the periodic timer init to
 102  * late x86_late_time_init() so ioremap works.
 103  */
 104 void __init time_init(void)
 105 {
 106         late_time_init = x86_late_time_init;
 107 }