arch/x86/kernel/time_32.c

   1 /*
   2  *  Copyright (C) 1991, 1992, 1995  Linus Torvalds
   3  *
   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).
  29  */
  30
  31 #include <linux/errno.h>
  32 #include <linux/sched.h>
  33 #include <linux/kernel.h>
  34 #include <linux/param.h>
  35 #include <linux/string.h>
  36 #include <linux/mm.h>
  37 #include <linux/interrupt.h>
  38 #include <linux/time.h>
  39 #include <linux/delay.h>
  40 #include <linux/init.h>
  41 #include <linux/smp.h>
  42 #include <linux/module.h>
  43 #include <linux/sysdev.h>
  44 #include <linux/bcd.h>
  45 #include <linux/efi.h>
  46 #include <linux/mca.h>
  47
  48 #include <asm/io.h>
  49 #include <asm/smp.h>
  50 #include <asm/irq.h>
  51 #include <asm/msr.h>
  52 #include <asm/delay.h>
  53 #include <asm/mpspec.h>
  54 #include <asm/uaccess.h>
  55 #include <asm/processor.h>
  56 #include <asm/timer.h>
  57 #include <asm/time.h>
  58
  59 #include "mach_time.h"
  60
  61 #include <linux/timex.h>
  62
  63 #include <asm/hpet.h>
  64
  65 #include <asm/arch_hooks.h>
  66
  67 #include "io_ports.h"
  68
  69 #include <asm/i8259.h>
  70
  71 #include "do_timer.h"
  72
  73 unsigned int cpu_khz;   /* Detected as we calibrate the TSC */
  74 EXPORT_SYMBOL(cpu_khz);
  75
  76 DEFINE_SPINLOCK(rtc_lock);
  77 EXPORT_SYMBOL(rtc_lock);
  78
  79 /*
  80  * This is a special lock that is owned by the CPU and holds the index
  81  * register we are working with.  It is required for NMI access to the
  82  * CMOS/RTC registers.  See include/asm-i386/mc146818rtc.h for details.
  83  */
  84 volatile unsigned long cmos_lock = 0;
  85 EXPORT_SYMBOL(cmos_lock);
  86
  87 /* Routines for accessing the CMOS RAM/RTC. */
  88 unsigned char rtc_cmos_read(unsigned char addr)
  89 {
  90         unsigned char val;
  91         lock_cmos_prefix(addr);
  92         outb_p(addr, RTC_PORT(0));
  93         val = inb_p(RTC_PORT(1));
  94         lock_cmos_suffix(addr);
  95         return val;
  96 }
  97 EXPORT_SYMBOL(rtc_cmos_read);
  98
  99 void rtc_cmos_write(unsigned char val, unsigned char addr)
 100 {
 101         lock_cmos_prefix(addr);
 102         outb_p(addr, RTC_PORT(0));
 103         outb_p(val, RTC_PORT(1));
 104         lock_cmos_suffix(addr);
 105 }
 106 EXPORT_SYMBOL(rtc_cmos_write);
 107
 108 static int set_rtc_mmss(unsigned long nowtime)
 109 {
 110         int retval;
 111         unsigned long flags;
 112
 113         /* gets recalled with irq locally disabled */
 114         /* XXX - does irqsave resolve this? -johnstul */
 115         spin_lock_irqsave(&rtc_lock, flags);
 116         retval = set_wallclock(nowtime);
 117         spin_unlock_irqrestore(&rtc_lock, flags);
 118
 119         return retval;
 120 }
 121
 122
 123 int timer_ack;
 124
 125 unsigned long profile_pc(struct pt_regs *regs)
 126 {
 127         unsigned long pc = instruction_pointer(regs);
 128
 129 #ifdef CONFIG_SMP
 130         if (!v8086_mode(regs) && SEGMENT_IS_KERNEL_CODE(regs->xcs) &&
 131             in_lock_functions(pc)) {
 132 #ifdef CONFIG_FRAME_POINTER
 133                 return *(unsigned long *)(regs->ebp + 4);
 134 #else
 135                 unsigned long *sp = (unsigned long *)&regs->esp;
 136
 137                 /* Return address is either directly at stack pointer
 138                    or above a saved eflags. Eflags has bits 22-31 zero,
 139                    kernel addresses don't. */
 140                 if (sp[0] >> 22)
 141                         return sp[0];
 142                 if (sp[1] >> 22)
 143                         return sp[1];
 144 #endif
 145         }
 146 #endif
 147         return pc;
 148 }
 149 EXPORT_SYMBOL(profile_pc);
 150
 151 /*
 152  * This is the same as the above, except we _also_ save the current
 153  * Time Stamp Counter value at the time of the timer interrupt, so that
 154  * we later on can estimate the time of day more exactly.
 155  */
 156 irqreturn_t timer_interrupt(int irq, void *dev_id)
 157 {
 158         /* Keep nmi watchdog up to date */
 159         per_cpu(irq_stat, smp_processor_id()).irq0_irqs++;
 160
 161 #ifdef CONFIG_X86_IO_APIC
 162         if (timer_ack) {
 163                 /*
 164                  * Subtle, when I/O APICs are used we have to ack timer IRQ
 165                  * manually to reset the IRR bit for do_slow_gettimeoffset().
 166                  * This will also deassert NMI lines for the watchdog if run
 167                  * on an 82489DX-based system.
 168                  */
 169                 spin_lock(&i8259A_lock);
 170                 outb(0x0c, PIC_MASTER_OCW3);
 171                 /* Ack the IRQ; AEOI will end it automatically. */
 172                 inb(PIC_MASTER_POLL);
 173                 spin_unlock(&i8259A_lock);
 174         }
 175 #endif
 176
 177         do_timer_interrupt_hook();
 178
 179         if (MCA_bus) {
 180                 /* The PS/2 uses level-triggered interrupts.  You can't
 181                 turn them off, nor would you want to (any attempt to
 182                 enable edge-triggered interrupts usually gets intercepted by a
 183                 special hardware circuit).  Hence we have to acknowledge
 184                 the timer interrupt.  Through some incredibly stupid
 185                 design idea, the reset for IRQ 0 is done by setting the
 186                 high bit of the PPI port B (0x61).  Note that some PS/2s,
 187                 notably the 55SX, work fine if this is removed.  */
 188
 189                 u8 irq_v = inb_p( 0x61 );       /* read the current state */
 190                 outb_p( irq_v|0x80, 0x61 );     /* reset the IRQ */
 191         }
 192
 193         return IRQ_HANDLED;
 194 }
 195
 196 /* not static: needed by APM */
 197 unsigned long read_persistent_clock(void)
 198 {
 199         unsigned long retval;
 200         unsigned long flags;
 201
 202         spin_lock_irqsave(&rtc_lock, flags);
 203
 204         retval = get_wallclock();
 205
 206         spin_unlock_irqrestore(&rtc_lock, flags);
 207
 208         return retval;
 209 }
 210
 211 int update_persistent_clock(struct timespec now)
 212 {
 213         return set_rtc_mmss(now.tv_sec);
 214 }
 215
 216 extern void (*late_time_init)(void);
 217 /* Duplicate of time_init() below, with hpet_enable part added */
 218 void __init hpet_time_init(void)
 219 {
 220         if (!hpet_enable())
 221                 setup_pit_timer();
 222         time_init_hook();
 223 }
 224
 225 /*
 226  * This is called directly from init code; we must delay timer setup in the
 227  * HPET case as we can't make the decision to turn on HPET this early in the
 228  * boot process.
 229  *
 230  * The chosen time_init function will usually be hpet_time_init, above, but
 231  * in the case of virtual hardware, an alternative function may be substituted.
 232  */
 233 void __init time_init(void)
 234 {
 235         tsc_init();
 236         late_time_init = choose_time_init();
 237 }