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 #ifdef CONFIG_X86_64
  28 __visible volatile unsigned long jiffies __cacheline_aligned = INITIAL_JIFFIES;
  29 #endif
  30
  31 unsigned long profile_pc(struct pt_regs *regs)
  32 {
  33         unsigned long pc = instruction_pointer(regs);
  34
  35         if (!user_mode(regs) && in_lock_functions(pc)) {
  36 #ifdef CONFIG_FRAME_POINTER
  37                 return *(unsigned long *)(regs->bp + sizeof(long));
  38 #else
  39                 unsigned long *sp =
  40                         (unsigned long *)kernel_stack_pointer(regs);
  41                 /*
  42                  * Return address is either directly at stack pointer
  43                  * or above a saved flags. Eflags has bits 22-31 zero,
  44                  * kernel addresses don't.
  45                  */
  46                 if (sp[0] >> 22)
  47                         return sp[0];
  48                 if (sp[1] >> 22)
  49                         return sp[1];
  50 #endif
  51         }
  52         return pc;
  53 }
  54 EXPORT_SYMBOL(profile_pc);
  55
  56 /*
  57  * Default timer interrupt handler for PIT/HPET
  58  */
  59 static irqreturn_t timer_interrupt(int irq, void *dev_id)
  60 {
  61         global_clock_event->event_handler(global_clock_event);
  62         return IRQ_HANDLED;
  63 }
  64
  65 static struct irqaction irq0  = {
  66         .handler = timer_interrupt,
  67         .flags = IRQF_NOBALANCING | IRQF_IRQPOLL | IRQF_TIMER,
  68         .name = "timer"
  69 };
  70
  71 static void __init setup_default_timer_irq(void)
  72 {
  73         /*
  74          * Unconditionally register the legacy timer; even without legacy
  75          * PIC/PIT we need this for the HPET0 in legacy replacement mode.
  76          */
  77         if (setup_irq(0, &irq0))
  78                 pr_info("Failed to register legacy timer interrupt\n");
  79 }
  80
  81 /* Default timer init function */
  82 void __init hpet_time_init(void)
  83 {
  84         if (!hpet_enable())
  85                 setup_pit_timer();
  86         setup_default_timer_irq();
  87 }
  88
  89 static __init void x86_late_time_init(void)
  90 {
  91         x86_init.timers.timer_init();
  92         /*
  93          * After PIT/HPET timers init, select and setup
  94          * the final interrupt mode for delivering IRQs.
  95          */
  96         x86_init.irqs.intr_mode_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 }