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git.proxmox.com Git - mirror_ubuntu-artful-kernel.git/blob - arch/x86/kernel/time_32.c
2 * Copyright (C) 1991, 1992, 1995 Linus Torvalds
4 * This file contains the PC-specific time handling details:
5 * reading the RTC at bootup, etc..
6 * 1994-07-02 Alan Modra
7 * fixed set_rtc_mmss, fixed time.year for >= 2000, new mktime
8 * 1995-03-26 Markus Kuhn
9 * fixed 500 ms bug at call to set_rtc_mmss, fixed DS12887
10 * precision CMOS clock update
11 * 1996-05-03 Ingo Molnar
12 * fixed time warps in do_[slow|fast]_gettimeoffset()
13 * 1997-09-10 Updated NTP code according to technical memorandum Jan '96
14 * "A Kernel Model for Precision Timekeeping" by Dave Mills
15 * 1998-09-05 (Various)
16 * More robust do_fast_gettimeoffset() algorithm implemented
17 * (works with APM, Cyrix 6x86MX and Centaur C6),
18 * monotonic gettimeofday() with fast_get_timeoffset(),
19 * drift-proof precision TSC calibration on boot
20 * (C. Scott Ananian <cananian@alumni.princeton.edu>, Andrew D.
21 * Balsa <andrebalsa@altern.org>, Philip Gladstone <philip@raptor.com>;
22 * ported from 2.0.35 Jumbo-9 by Michael Krause <m.krause@tu-harburg.de>).
23 * 1998-12-16 Andrea Arcangeli
24 * Fixed Jumbo-9 code in 2.1.131: do_gettimeofday was missing 1 jiffy
25 * because was not accounting lost_ticks.
26 * 1998-12-24 Copyright (C) 1998 Andrea Arcangeli
27 * Fixed a xtime SMP race (we need the xtime_lock rw spinlock to
28 * serialize accesses to xtime/lost_ticks).
31 #include <linux/init.h>
32 #include <linux/interrupt.h>
33 #include <linux/time.h>
34 #include <linux/mca.h>
36 #include <asm/arch_hooks.h>
39 #include <asm/timer.h>
45 unsigned long profile_pc(struct pt_regs
*regs
)
47 unsigned long pc
= instruction_pointer(regs
);
50 if (!user_mode_vm(regs
) && in_lock_functions(pc
)) {
51 #ifdef CONFIG_FRAME_POINTER
52 return *(unsigned long *)(regs
->bp
+ sizeof(long));
54 unsigned long *sp
= (unsigned long *)®s
->sp
;
56 /* Return address is either directly at stack pointer
57 or above a saved flags. Eflags has bits 22-31 zero,
58 kernel addresses don't. */
68 EXPORT_SYMBOL(profile_pc
);
71 * This is the same as the above, except we _also_ save the current
72 * Time Stamp Counter value at the time of the timer interrupt, so that
73 * we later on can estimate the time of day more exactly.
75 irqreturn_t
timer_interrupt(int irq
, void *dev_id
)
77 /* Keep nmi watchdog up to date */
78 per_cpu(irq_stat
, smp_processor_id()).irq0_irqs
++;
80 #ifdef CONFIG_X86_IO_APIC
83 * Subtle, when I/O APICs are used we have to ack timer IRQ
84 * manually to deassert NMI lines for the watchdog if run
85 * on an 82489DX-based system.
87 spin_lock(&i8259A_lock
);
88 outb(0x0c, PIC_MASTER_OCW3
);
89 /* Ack the IRQ; AEOI will end it automatically. */
91 spin_unlock(&i8259A_lock
);
95 do_timer_interrupt_hook();
99 /* The PS/2 uses level-triggered interrupts. You can't
100 turn them off, nor would you want to (any attempt to
101 enable edge-triggered interrupts usually gets intercepted by a
102 special hardware circuit). Hence we have to acknowledge
103 the timer interrupt. Through some incredibly stupid
104 design idea, the reset for IRQ 0 is done by setting the
105 high bit of the PPI port B (0x61). Note that some PS/2s,
106 notably the 55SX, work fine if this is removed. */
108 u8 irq_v
= inb_p( 0x61 ); /* read the current state */
109 outb_p( irq_v
|0x80, 0x61 ); /* reset the IRQ */
116 /* Duplicate of time_init() below, with hpet_enable part added */
117 void __init
hpet_time_init(void)
125 * This is called directly from init code; we must delay timer setup in the
126 * HPET case as we can't make the decision to turn on HPET this early in the
129 * The chosen time_init function will usually be hpet_time_init, above, but
130 * in the case of virtual hardware, an alternative function may be substituted.
132 void __init
time_init(void)
134 pre_time_init_hook();
136 late_time_init
= choose_time_init();