arch/i386/kernel/time.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
  60 #include "mach_time.h"
  61
  62 #include <linux/timex.h>
  63 #include <linux/config.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 int pit_latch_buggy;              /* extern */
  74
  75 #include "do_timer.h"
  76
  77 unsigned int cpu_khz;   /* Detected as we calibrate the TSC */
  78 EXPORT_SYMBOL(cpu_khz);
  79
  80 extern unsigned long wall_jiffies;
  81
  82 DEFINE_SPINLOCK(rtc_lock);
  83 EXPORT_SYMBOL(rtc_lock);
  84
  85 /* XXX - necessary to keep things compiling. to be removed later */
  86 u32 pmtmr_ioport;
  87
  88 /*
  89  * This is a special lock that is owned by the CPU and holds the index
  90  * register we are working with.  It is required for NMI access to the
  91  * CMOS/RTC registers.  See include/asm-i386/mc146818rtc.h for details.
  92  */
  93 volatile unsigned long cmos_lock = 0;
  94 EXPORT_SYMBOL(cmos_lock);
  95
  96 /* Routines for accessing the CMOS RAM/RTC. */
  97 unsigned char rtc_cmos_read(unsigned char addr)
  98 {
  99         unsigned char val;
 100         lock_cmos_prefix(addr);
 101         outb_p(addr, RTC_PORT(0));
 102         val = inb_p(RTC_PORT(1));
 103         lock_cmos_suffix(addr);
 104         return val;
 105 }
 106 EXPORT_SYMBOL(rtc_cmos_read);
 107
 108 void rtc_cmos_write(unsigned char val, unsigned char addr)
 109 {
 110         lock_cmos_prefix(addr);
 111         outb_p(addr, RTC_PORT(0));
 112         outb_p(val, RTC_PORT(1));
 113         lock_cmos_suffix(addr);
 114 }
 115 EXPORT_SYMBOL(rtc_cmos_write);
 116
 117 static int set_rtc_mmss(unsigned long nowtime)
 118 {
 119         int retval;
 120         unsigned long flags;
 121
 122         /* gets recalled with irq locally disabled */
 123         /* XXX - does irqsave resolve this? -johnstul */
 124         spin_lock_irqsave(&rtc_lock, flags);
 125         if (efi_enabled)
 126                 retval = efi_set_rtc_mmss(nowtime);
 127         else
 128                 retval = mach_set_rtc_mmss(nowtime);
 129         spin_unlock_irqrestore(&rtc_lock, flags);
 130
 131         return retval;
 132 }
 133
 134
 135 int timer_ack;
 136
 137 #if defined(CONFIG_SMP) && defined(CONFIG_FRAME_POINTER)
 138 unsigned long profile_pc(struct pt_regs *regs)
 139 {
 140         unsigned long pc = instruction_pointer(regs);
 141
 142         if (in_lock_functions(pc))
 143                 return *(unsigned long *)(regs->ebp + 4);
 144
 145         return pc;
 146 }
 147 EXPORT_SYMBOL(profile_pc);
 148 #endif
 149
 150 /*
 151  * This is the same as the above, except we _also_ save the current
 152  * Time Stamp Counter value at the time of the timer interrupt, so that
 153  * we later on can estimate the time of day more exactly.
 154  */
 155 irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
 156 {
 157         /*
 158          * Here we are in the timer irq handler. We just have irqs locally
 159          * disabled but we don't know if the timer_bh is running on the other
 160          * CPU. We need to avoid to SMP race with it. NOTE: we don' t need
 161          * the irq version of write_lock because as just said we have irq
 162          * locally disabled. -arca
 163          */
 164         write_seqlock(&xtime_lock);
 165
 166 #ifdef CONFIG_X86_IO_APIC
 167         if (timer_ack) {
 168                 /*
 169                  * Subtle, when I/O APICs are used we have to ack timer IRQ
 170                  * manually to reset the IRR bit for do_slow_gettimeoffset().
 171                  * This will also deassert NMI lines for the watchdog if run
 172                  * on an 82489DX-based system.
 173                  */
 174                 spin_lock(&i8259A_lock);
 175                 outb(0x0c, PIC_MASTER_OCW3);
 176                 /* Ack the IRQ; AEOI will end it automatically. */
 177                 inb(PIC_MASTER_POLL);
 178                 spin_unlock(&i8259A_lock);
 179         }
 180 #endif
 181
 182         do_timer_interrupt_hook(regs);
 183
 184
 185         if (MCA_bus) {
 186                 /* The PS/2 uses level-triggered interrupts.  You can't
 187                 turn them off, nor would you want to (any attempt to
 188                 enable edge-triggered interrupts usually gets intercepted by a
 189                 special hardware circuit).  Hence we have to acknowledge
 190                 the timer interrupt.  Through some incredibly stupid
 191                 design idea, the reset for IRQ 0 is done by setting the
 192                 high bit of the PPI port B (0x61).  Note that some PS/2s,
 193                 notably the 55SX, work fine if this is removed.  */
 194
 195                 irq = inb_p( 0x61 );    /* read the current state */
 196                 outb_p( irq|0x80, 0x61 );       /* reset the IRQ */
 197         }
 198
 199         write_sequnlock(&xtime_lock);
 200
 201 #ifdef CONFIG_X86_LOCAL_APIC
 202         if (using_apic_timer)
 203                 smp_send_timer_broadcast_ipi(regs);
 204 #endif
 205
 206         return IRQ_HANDLED;
 207 }
 208
 209 /* not static: needed by APM */
 210 unsigned long get_cmos_time(void)
 211 {
 212         unsigned long retval;
 213
 214         spin_lock(&rtc_lock);
 215
 216         if (efi_enabled)
 217                 retval = efi_get_time();
 218         else
 219                 retval = mach_get_cmos_time();
 220
 221         spin_unlock(&rtc_lock);
 222
 223         return retval;
 224 }
 225 EXPORT_SYMBOL(get_cmos_time);
 226
 227 static void sync_cmos_clock(unsigned long dummy);
 228
 229 static DEFINE_TIMER(sync_cmos_timer, sync_cmos_clock, 0, 0);
 230
 231 static void sync_cmos_clock(unsigned long dummy)
 232 {
 233         struct timeval now, next;
 234         int fail = 1;
 235
 236         /*
 237          * If we have an externally synchronized Linux clock, then update
 238          * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
 239          * called as close as possible to 500 ms before the new second starts.
 240          * This code is run on a timer.  If the clock is set, that timer
 241          * may not expire at the correct time.  Thus, we adjust...
 242          */
 243         if (!ntp_synced())
 244                 /*
 245                  * Not synced, exit, do not restart a timer (if one is
 246                  * running, let it run out).
 247                  */
 248                 return;
 249
 250         do_gettimeofday(&now);
 251         if (now.tv_usec >= USEC_AFTER - ((unsigned) TICK_SIZE) / 2 &&
 252             now.tv_usec <= USEC_BEFORE + ((unsigned) TICK_SIZE) / 2)
 253                 fail = set_rtc_mmss(now.tv_sec);
 254
 255         next.tv_usec = USEC_AFTER - now.tv_usec;
 256         if (next.tv_usec <= 0)
 257                 next.tv_usec += USEC_PER_SEC;
 258
 259         if (!fail)
 260                 next.tv_sec = 659;
 261         else
 262                 next.tv_sec = 0;
 263
 264         if (next.tv_usec >= USEC_PER_SEC) {
 265                 next.tv_sec++;
 266                 next.tv_usec -= USEC_PER_SEC;
 267         }
 268         mod_timer(&sync_cmos_timer, jiffies + timeval_to_jiffies(&next));
 269 }
 270
 271 void notify_arch_cmos_timer(void)
 272 {
 273         mod_timer(&sync_cmos_timer, jiffies + 1);
 274 }
 275
 276 static long clock_cmos_diff, sleep_start;
 277
 278 static int timer_suspend(struct sys_device *dev, pm_message_t state)
 279 {
 280         /*
 281          * Estimate time zone so that set_time can update the clock
 282          */
 283         clock_cmos_diff = -get_cmos_time();
 284         clock_cmos_diff += get_seconds();
 285         sleep_start = get_cmos_time();
 286         return 0;
 287 }
 288
 289 static int timer_resume(struct sys_device *dev)
 290 {
 291         unsigned long flags;
 292         unsigned long sec;
 293         unsigned long sleep_length;
 294
 295 #ifdef CONFIG_HPET_TIMER
 296         if (is_hpet_enabled())
 297                 hpet_reenable();
 298 #endif
 299         setup_pit_timer();
 300         sec = get_cmos_time() + clock_cmos_diff;
 301         sleep_length = (get_cmos_time() - sleep_start) * HZ;
 302         write_seqlock_irqsave(&xtime_lock, flags);
 303         xtime.tv_sec = sec;
 304         xtime.tv_nsec = 0;
 305         jiffies_64 += sleep_length;
 306         wall_jiffies += sleep_length;
 307         write_sequnlock_irqrestore(&xtime_lock, flags);
 308         touch_softlockup_watchdog();
 309         return 0;
 310 }
 311
 312 static struct sysdev_class timer_sysclass = {
 313         .resume = timer_resume,
 314         .suspend = timer_suspend,
 315         set_kset_name("timer"),
 316 };
 317
 318
 319 /* XXX this driverfs stuff should probably go elsewhere later -john */
 320 static struct sys_device device_timer = {
 321         .id     = 0,
 322         .cls    = &timer_sysclass,
 323 };
 324
 325 static int time_init_device(void)
 326 {
 327         int error = sysdev_class_register(&timer_sysclass);
 328         if (!error)
 329                 error = sysdev_register(&device_timer);
 330         return error;
 331 }
 332
 333 device_initcall(time_init_device);
 334
 335 #ifdef CONFIG_HPET_TIMER
 336 extern void (*late_time_init)(void);
 337 /* Duplicate of time_init() below, with hpet_enable part added */
 338 static void __init hpet_time_init(void)
 339 {
 340         xtime.tv_sec = get_cmos_time();
 341         xtime.tv_nsec = (INITIAL_JIFFIES % HZ) * (NSEC_PER_SEC / HZ);
 342         set_normalized_timespec(&wall_to_monotonic,
 343                 -xtime.tv_sec, -xtime.tv_nsec);
 344
 345         if ((hpet_enable() >= 0) && hpet_use_timer) {
 346                 printk("Using HPET for base-timer\n");
 347         }
 348
 349         time_init_hook();
 350 }
 351 #endif
 352
 353 void __init time_init(void)
 354 {
 355 #ifdef CONFIG_HPET_TIMER
 356         if (is_hpet_capable()) {
 357                 /*
 358                  * HPET initialization needs to do memory-mapped io. So, let
 359                  * us do a late initialization after mem_init().
 360                  */
 361                 late_time_init = hpet_time_init;
 362                 return;
 363         }
 364 #endif
 365         xtime.tv_sec = get_cmos_time();
 366         xtime.tv_nsec = (INITIAL_JIFFIES % HZ) * (NSEC_PER_SEC / HZ);
 367         set_normalized_timespec(&wall_to_monotonic,
 368                 -xtime.tv_sec, -xtime.tv_nsec);
 369
 370         time_init_hook();
 371 }