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/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 #ifdef CONFIG_X86_64
  27 __visible volatile unsigned long jiffies __cacheline_aligned = 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(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 /*
  56  * Default timer interrupt handler for PIT/HPET
  57  */
  58 static irqreturn_t timer_interrupt(int irq, void *dev_id)
  59 {
  60         global_clock_event->event_handler(global_clock_event);
  61         return IRQ_HANDLED;
  62 }
  63
  64 static struct irqaction irq0  = {
  65         .handler = timer_interrupt,
  66         .flags = IRQF_NOBALANCING | IRQF_IRQPOLL | IRQF_TIMER,
  67         .name = "timer"
  68 };
  69
  70 static void __init setup_default_timer_irq(void)
  71 {
  72         /*
  73          * Unconditionally register the legacy timer; even without legacy
  74          * PIC/PIT we need this for the HPET0 in legacy replacement mode.
  75          */
  76         if (setup_irq(0, &irq0))
  77                 pr_info("Failed to register legacy timer interrupt\n");
  78 }
  79
  80 /* Default timer init function */
  81 void __init hpet_time_init(void)
  82 {
  83         if (!hpet_enable())
  84                 setup_pit_timer();
  85         setup_default_timer_irq();
  86 }
  87
  88 static __init void x86_late_time_init(void)
  89 {
  90         x86_init.timers.timer_init();
  91         /*
  92          * After PIT/HPET timers init, select and setup
  93          * the final interrupt mode for delivering IRQs.
  94          */
  95         x86_init.irqs.intr_mode_init();
  96         tsc_init();
  97 }
  98
  99 /*
 100  * Initialize TSC and delay the periodic timer init to
 101  * late x86_late_time_init() so ioremap works.
 102  */
 103 void __init time_init(void)
 104 {
 105         late_time_init = x86_late_time_init;
 106 }