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/clocksource.h>
  14 #include <linux/clockchips.h>
  15 #include <linux/interrupt.h>
  16 #include <linux/irq.h>
  17 #include <linux/i8253.h>
  18 #include <linux/time.h>
  19 #include <linux/export.h>
  20
  21 #include <asm/vsyscall.h>
  22 #include <asm/x86_init.h>
  23 #include <asm/i8259.h>
  24 #include <asm/timer.h>
  25 #include <asm/hpet.h>
  26 #include <asm/time.h>
  27
  28 unsigned long profile_pc(struct pt_regs *regs)
  29 {
  30         unsigned long pc = instruction_pointer(regs);
  31
  32         if (!user_mode(regs) && in_lock_functions(pc)) {
  33 #ifdef CONFIG_FRAME_POINTER
  34                 return *(unsigned long *)(regs->bp + sizeof(long));
  35 #else
  36                 unsigned long *sp = (unsigned long *)regs->sp;
  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 void __init setup_default_timer_irq(void)
  62 {
  63         unsigned long flags = IRQF_NOBALANCING | IRQF_IRQPOLL | IRQF_TIMER;
  64
  65         /*
  66          * Unconditionally register the legacy timer interrupt; even
  67          * without legacy PIC/PIT we need this for the HPET0 in legacy
  68          * replacement mode.
  69          */
  70         if (request_irq(0, timer_interrupt, flags, "timer", NULL))
  71                 pr_info("Failed to register legacy timer interrupt\n");
  72 }
  73
  74 /* Default timer init function */
  75 void __init hpet_time_init(void)
  76 {
  77         if (!hpet_enable()) {
  78                 if (!pit_timer_init())
  79                         return;
  80         }
  81
  82         setup_default_timer_irq();
  83 }
  84
  85 static __init void x86_late_time_init(void)
  86 {
  87         /*
  88          * Before PIT/HPET init, select the interrupt mode. This is required
  89          * to make the decision whether PIT should be initialized correct.
  90          */
  91         x86_init.irqs.intr_mode_select();
  92
  93         /* Setup the legacy timers */
  94         x86_init.timers.timer_init();
  95
  96         /*
  97          * After PIT/HPET timers init, set up the final interrupt mode for
  98          * delivering IRQs.
  99          */
 100         x86_init.irqs.intr_mode_init();
 101         tsc_init();
 102 }
 103
 104 /*
 105  * Initialize TSC and delay the periodic timer init to
 106  * late x86_late_time_init() so ioremap works.
 107  */
 108 void __init time_init(void)
 109 {
 110         late_time_init = x86_late_time_init;
 111 }
 112
 113 /*
 114  * Sanity check the vdso related archdata content.
 115  */
 116 void clocksource_arch_init(struct clocksource *cs)
 117 {
 118         if (cs->vdso_clock_mode == VDSO_CLOCKMODE_NONE)
 119                 return;
 120
 121         if (cs->mask != CLOCKSOURCE_MASK(64)) {
 122                 pr_warn("clocksource %s registered with invalid mask %016llx for VDSO. Disabling VDSO support.\n",
 123                         cs->name, cs->mask);
 124                 cs->vdso_clock_mode = VDSO_CLOCKMODE_NONE;
 125         }
 126 }