arch/x86/kernel/time_32.c

   1 /*
   2  *  linux/arch/i386/kernel/time.c
   3  *
   4  *  Copyright (C) 1991, 1992, 1995  Linus Torvalds
   5  *
   6  * This file contains the PC-specific time handling details:
   7  * reading the RTC at bootup, etc..
   8  * 1994-07-02    Alan Modra
   9  *      fixed set_rtc_mmss, fixed time.year for >= 2000, new mktime
  10  * 1995-03-26    Markus Kuhn
  11  *      fixed 500 ms bug at call to set_rtc_mmss, fixed DS12887
  12  *      precision CMOS clock update
  13  * 1996-05-03    Ingo Molnar
  14  *      fixed time warps in do_[slow|fast]_gettimeoffset()
  15  * 1997-09-10   Updated NTP code according to technical memorandum Jan '96
  16  *              "A Kernel Model for Precision Timekeeping" by Dave Mills
  17  * 1998-09-05    (Various)
  18  *      More robust do_fast_gettimeoffset() algorithm implemented
  19  *      (works with APM, Cyrix 6x86MX and Centaur C6),
  20  *      monotonic gettimeofday() with fast_get_timeoffset(),
  21  *      drift-proof precision TSC calibration on boot
  22  *      (C. Scott Ananian <cananian@alumni.princeton.edu>, Andrew D.
  23  *      Balsa <andrebalsa@altern.org>, Philip Gladstone <philip@raptor.com>;
  24  *      ported from 2.0.35 Jumbo-9 by Michael Krause <m.krause@tu-harburg.de>).
  25  * 1998-12-16    Andrea Arcangeli
  26  *      Fixed Jumbo-9 code in 2.1.131: do_gettimeofday was missing 1 jiffy
  27  *      because was not accounting lost_ticks.
  28  * 1998-12-24 Copyright (C) 1998  Andrea Arcangeli
  29  *      Fixed a xtime SMP race (we need the xtime_lock rw spinlock to
  30  *      serialize accesses to xtime/lost_ticks).
  31  */
  32
  33 #include <linux/errno.h>
  34 #include <linux/sched.h>
  35 #include <linux/kernel.h>
  36 #include <linux/param.h>
  37 #include <linux/string.h>
  38 #include <linux/mm.h>
  39 #include <linux/interrupt.h>
  40 #include <linux/time.h>
  41 #include <linux/delay.h>
  42 #include <linux/init.h>
  43 #include <linux/smp.h>
  44 #include <linux/module.h>
  45 #include <linux/sysdev.h>
  46 #include <linux/bcd.h>
  47 #include <linux/efi.h>
  48 #include <linux/mca.h>
  49
  50 #include <asm/io.h>
  51 #include <asm/smp.h>
  52 #include <asm/irq.h>
  53 #include <asm/msr.h>
  54 #include <asm/delay.h>
  55 #include <asm/mpspec.h>
  56 #include <asm/uaccess.h>
  57 #include <asm/processor.h>
  58 #include <asm/timer.h>
  59 #include <asm/time.h>
  60
  61 #include "mach_time.h"
  62
  63 #include <linux/timex.h>
  64
  65 #include <asm/hpet.h>
  66
  67 #include <asm/arch_hooks.h>
  68
  69 #include "io_ports.h"
  70
  71 #include <asm/i8259.h>
  72
  73 #include "do_timer.h"
  74
  75 unsigned int cpu_khz;   /* Detected as we calibrate the TSC */
  76 EXPORT_SYMBOL(cpu_khz);
  77
  78 DEFINE_SPINLOCK(rtc_lock);
  79 EXPORT_SYMBOL(rtc_lock);
  80
  81 /*
  82  * This is a special lock that is owned by the CPU and holds the index
  83  * register we are working with.  It is required for NMI access to the
  84  * CMOS/RTC registers.  See include/asm-i386/mc146818rtc.h for details.
  85  */
  86 volatile unsigned long cmos_lock = 0;
  87 EXPORT_SYMBOL(cmos_lock);
  88
  89 /* Routines for accessing the CMOS RAM/RTC. */
  90 unsigned char rtc_cmos_read(unsigned char addr)
  91 {
  92         unsigned char val;
  93         lock_cmos_prefix(addr);
  94         outb_p(addr, RTC_PORT(0));
  95         val = inb_p(RTC_PORT(1));
  96         lock_cmos_suffix(addr);
  97         return val;
  98 }
  99 EXPORT_SYMBOL(rtc_cmos_read);
 100
 101 void rtc_cmos_write(unsigned char val, unsigned char addr)
 102 {
 103         lock_cmos_prefix(addr);
 104         outb_p(addr, RTC_PORT(0));
 105         outb_p(val, RTC_PORT(1));
 106         lock_cmos_suffix(addr);
 107 }
 108 EXPORT_SYMBOL(rtc_cmos_write);
 109
 110 static int set_rtc_mmss(unsigned long nowtime)
 111 {
 112         int retval;
 113         unsigned long flags;
 114
 115         /* gets recalled with irq locally disabled */
 116         /* XXX - does irqsave resolve this? -johnstul */
 117         spin_lock_irqsave(&rtc_lock, flags);
 118         retval = set_wallclock(nowtime);
 119         spin_unlock_irqrestore(&rtc_lock, flags);
 120
 121         return retval;
 122 }
 123
 124
 125 int timer_ack;
 126
 127 unsigned long profile_pc(struct pt_regs *regs)
 128 {
 129         unsigned long pc = instruction_pointer(regs);
 130
 131 #ifdef CONFIG_SMP
 132         if (!v8086_mode(regs) && SEGMENT_IS_KERNEL_CODE(regs->xcs) &&
 133             in_lock_functions(pc)) {
 134 #ifdef CONFIG_FRAME_POINTER
 135                 return *(unsigned long *)(regs->ebp + 4);
 136 #else
 137                 unsigned long *sp = (unsigned long *)&regs->esp;
 138
 139                 /* Return address is either directly at stack pointer
 140                    or above a saved eflags. Eflags has bits 22-31 zero,
 141                    kernel addresses don't. */
 142                 if (sp[0] >> 22)
 143                         return sp[0];
 144                 if (sp[1] >> 22)
 145                         return sp[1];
 146 #endif
 147         }
 148 #endif
 149         return pc;
 150 }
 151 EXPORT_SYMBOL(profile_pc);
 152
 153 /*
 154  * This is the same as the above, except we _also_ save the current
 155  * Time Stamp Counter value at the time of the timer interrupt, so that
 156  * we later on can estimate the time of day more exactly.
 157  */
 158 irqreturn_t timer_interrupt(int irq, void *dev_id)
 159 {
 160         /* Keep nmi watchdog up to date */
 161         per_cpu(irq_stat, smp_processor_id()).irq0_irqs++;
 162
 163 #ifdef CONFIG_X86_IO_APIC
 164         if (timer_ack) {
 165                 /*
 166                  * Subtle, when I/O APICs are used we have to ack timer IRQ
 167                  * manually to reset the IRR bit for do_slow_gettimeoffset().
 168                  * This will also deassert NMI lines for the watchdog if run
 169                  * on an 82489DX-based system.
 170                  */
 171                 spin_lock(&i8259A_lock);
 172                 outb(0x0c, PIC_MASTER_OCW3);
 173                 /* Ack the IRQ; AEOI will end it automatically. */
 174                 inb(PIC_MASTER_POLL);
 175                 spin_unlock(&i8259A_lock);
 176         }
 177 #endif
 178
 179         do_timer_interrupt_hook();
 180
 181         if (MCA_bus) {
 182                 /* The PS/2 uses level-triggered interrupts.  You can't
 183                 turn them off, nor would you want to (any attempt to
 184                 enable edge-triggered interrupts usually gets intercepted by a
 185                 special hardware circuit).  Hence we have to acknowledge
 186                 the timer interrupt.  Through some incredibly stupid
 187                 design idea, the reset for IRQ 0 is done by setting the
 188                 high bit of the PPI port B (0x61).  Note that some PS/2s,
 189                 notably the 55SX, work fine if this is removed.  */
 190
 191                 u8 irq_v = inb_p( 0x61 );       /* read the current state */
 192                 outb_p( irq_v|0x80, 0x61 );     /* reset the IRQ */
 193         }
 194
 195         return IRQ_HANDLED;
 196 }
 197
 198 /* not static: needed by APM */
 199 unsigned long read_persistent_clock(void)
 200 {
 201         unsigned long retval;
 202         unsigned long flags;
 203
 204         spin_lock_irqsave(&rtc_lock, flags);
 205
 206         retval = get_wallclock();
 207
 208         spin_unlock_irqrestore(&rtc_lock, flags);
 209
 210         return retval;
 211 }
 212
 213 int update_persistent_clock(struct timespec now)
 214 {
 215         return set_rtc_mmss(now.tv_sec);
 216 }
 217
 218 extern void (*late_time_init)(void);
 219 /* Duplicate of time_init() below, with hpet_enable part added */
 220 void __init hpet_time_init(void)
 221 {
 222         if (!hpet_enable())
 223                 setup_pit_timer();
 224         time_init_hook();
 225 }
 226
 227 /*
 228  * This is called directly from init code; we must delay timer setup in the
 229  * HPET case as we can't make the decision to turn on HPET this early in the
 230  * boot process.
 231  *
 232  * The chosen time_init function will usually be hpet_time_init, above, but
 233  * in the case of virtual hardware, an alternative function may be substituted.
 234  */
 235 void __init time_init(void)
 236 {
 237         tsc_init();
 238         late_time_init = choose_time_init();
 239 }