arch/x86/kernel/time.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  Copyright (c) 1991,1992,1995  Linus Torvalds
   4  *  Copyright (c) 1994  Alan Modra
   5  *  Copyright (c) 1995  Markus Kuhn
   6  *  Copyright (c) 1996  Ingo Molnar
   7  *  Copyright (c) 1998  Andrea Arcangeli
   8  *  Copyright (c) 2002,2006  Vojtech Pavlik
   9  *  Copyright (c) 2003  Andi Kleen
  10  *
  11  */
  12
  13 #include <linux/clockchips.h>
  14 #include <linux/interrupt.h>
  15 #include <linux/irq.h>
  16 #include <linux/i8253.h>
  17 #include <linux/time.h>
  18 #include <linux/export.h>
  19
  20 #include <asm/vsyscall.h>
  21 #include <asm/x86_init.h>
  22 #include <asm/i8259.h>
  23 #include <asm/timer.h>
  24 #include <asm/hpet.h>
  25 #include <asm/time.h>
  26
  27 unsigned long profile_pc(struct pt_regs *regs)
  28 {
  29         unsigned long pc = instruction_pointer(regs);
  30
  31         if (!user_mode(regs) && in_lock_functions(pc)) {
  32 #ifdef CONFIG_FRAME_POINTER
  33                 return *(unsigned long *)(regs->bp + sizeof(long));
  34 #else
  35                 unsigned long *sp =
  36                         (unsigned long *)kernel_stack_pointer(regs);
  37                 /*
  38                  * Return address is either directly at stack pointer
  39                  * or above a saved flags. Eflags has bits 22-31 zero,
  40                  * kernel addresses don't.
  41                  */
  42                 if (sp[0] >> 22)
  43                         return sp[0];
  44                 if (sp[1] >> 22)
  45                         return sp[1];
  46 #endif
  47         }
  48         return pc;
  49 }
  50 EXPORT_SYMBOL(profile_pc);
  51
  52 /*
  53  * Default timer interrupt handler for PIT/HPET
  54  */
  55 static irqreturn_t timer_interrupt(int irq, void *dev_id)
  56 {
  57         global_clock_event->event_handler(global_clock_event);
  58         return IRQ_HANDLED;
  59 }
  60
  61 static struct irqaction irq0  = {
  62         .handler = timer_interrupt,
  63         .flags = IRQF_NOBALANCING | IRQF_IRQPOLL | IRQF_TIMER,
  64         .name = "timer"
  65 };
  66
  67 static void __init setup_default_timer_irq(void)
  68 {
  69         if (!nr_legacy_irqs())
  70                 return;
  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 }