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
  64 #include <asm/hpet.h>
  65
  66 #include <asm/arch_hooks.h>
  67
  68 #include "io_ports.h"
  69
  70 #include <asm/i8259.h>
  71
  72 int pit_latch_buggy;              /* extern */
  73
  74 #include "do_timer.h"
  75
  76 unsigned int cpu_khz;   /* Detected as we calibrate the TSC */
  77 EXPORT_SYMBOL(cpu_khz);
  78
  79 extern unsigned long wall_jiffies;
  80
  81 DEFINE_SPINLOCK(rtc_lock);
  82 EXPORT_SYMBOL(rtc_lock);
  83
  84 /*
  85  * This is a special lock that is owned by the CPU and holds the index
  86  * register we are working with.  It is required for NMI access to the
  87  * CMOS/RTC registers.  See include/asm-i386/mc146818rtc.h for details.
  88  */
  89 volatile unsigned long cmos_lock = 0;
  90 EXPORT_SYMBOL(cmos_lock);
  91
  92 /* Routines for accessing the CMOS RAM/RTC. */
  93 unsigned char rtc_cmos_read(unsigned char addr)
  94 {
  95         unsigned char val;
  96         lock_cmos_prefix(addr);
  97         outb_p(addr, RTC_PORT(0));
  98         val = inb_p(RTC_PORT(1));
  99         lock_cmos_suffix(addr);
 100         return val;
 101 }
 102 EXPORT_SYMBOL(rtc_cmos_read);
 103
 104 void rtc_cmos_write(unsigned char val, unsigned char addr)
 105 {
 106         lock_cmos_prefix(addr);
 107         outb_p(addr, RTC_PORT(0));
 108         outb_p(val, RTC_PORT(1));
 109         lock_cmos_suffix(addr);
 110 }
 111 EXPORT_SYMBOL(rtc_cmos_write);
 112
 113 static int set_rtc_mmss(unsigned long nowtime)
 114 {
 115         int retval;
 116         unsigned long flags;
 117
 118         /* gets recalled with irq locally disabled */
 119         /* XXX - does irqsave resolve this? -johnstul */
 120         spin_lock_irqsave(&rtc_lock, flags);
 121         if (efi_enabled)
 122                 retval = efi_set_rtc_mmss(nowtime);
 123         else
 124                 retval = mach_set_rtc_mmss(nowtime);
 125         spin_unlock_irqrestore(&rtc_lock, flags);
 126
 127         return retval;
 128 }
 129
 130
 131 int timer_ack;
 132
 133 #if defined(CONFIG_SMP) && defined(CONFIG_FRAME_POINTER)
 134 unsigned long profile_pc(struct pt_regs *regs)
 135 {
 136         unsigned long pc = instruction_pointer(regs);
 137
 138         if (!user_mode_vm(regs) && in_lock_functions(pc))
 139                 return *(unsigned long *)(regs->ebp + 4);
 140
 141         return pc;
 142 }
 143 EXPORT_SYMBOL(profile_pc);
 144 #endif
 145
 146 /*
 147  * This is the same as the above, except we _also_ save the current
 148  * Time Stamp Counter value at the time of the timer interrupt, so that
 149  * we later on can estimate the time of day more exactly.
 150  */
 151 irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
 152 {
 153         /*
 154          * Here we are in the timer irq handler. We just have irqs locally
 155          * disabled but we don't know if the timer_bh is running on the other
 156          * CPU. We need to avoid to SMP race with it. NOTE: we don' t need
 157          * the irq version of write_lock because as just said we have irq
 158          * locally disabled. -arca
 159          */
 160         write_seqlock(&xtime_lock);
 161
 162 #ifdef CONFIG_X86_IO_APIC
 163         if (timer_ack) {
 164                 /*
 165                  * Subtle, when I/O APICs are used we have to ack timer IRQ
 166                  * manually to reset the IRR bit for do_slow_gettimeoffset().
 167                  * This will also deassert NMI lines for the watchdog if run
 168                  * on an 82489DX-based system.
 169                  */
 170                 spin_lock(&i8259A_lock);
 171                 outb(0x0c, PIC_MASTER_OCW3);
 172                 /* Ack the IRQ; AEOI will end it automatically. */
 173                 inb(PIC_MASTER_POLL);
 174                 spin_unlock(&i8259A_lock);
 175         }
 176 #endif
 177
 178         do_timer_interrupt_hook(regs);
 179
 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                 irq = inb_p( 0x61 );    /* read the current state */
 192                 outb_p( irq|0x80, 0x61 );       /* reset the IRQ */
 193         }
 194
 195         write_sequnlock(&xtime_lock);
 196
 197 #ifdef CONFIG_X86_LOCAL_APIC
 198         if (using_apic_timer)
 199                 smp_send_timer_broadcast_ipi(regs);
 200 #endif
 201
 202         return IRQ_HANDLED;
 203 }
 204
 205 /* not static: needed by APM */
 206 unsigned long get_cmos_time(void)
 207 {
 208         unsigned long retval;
 209         unsigned long flags;
 210
 211         spin_lock_irqsave(&rtc_lock, flags);
 212
 213         if (efi_enabled)
 214                 retval = efi_get_time();
 215         else
 216                 retval = mach_get_cmos_time();
 217
 218         spin_unlock_irqrestore(&rtc_lock, flags);
 219
 220         return retval;
 221 }
 222 EXPORT_SYMBOL(get_cmos_time);
 223
 224 static void sync_cmos_clock(unsigned long dummy);
 225
 226 static DEFINE_TIMER(sync_cmos_timer, sync_cmos_clock, 0, 0);
 227
 228 static void sync_cmos_clock(unsigned long dummy)
 229 {
 230         struct timeval now, next;
 231         int fail = 1;
 232
 233         /*
 234          * If we have an externally synchronized Linux clock, then update
 235          * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
 236          * called as close as possible to 500 ms before the new second starts.
 237          * This code is run on a timer.  If the clock is set, that timer
 238          * may not expire at the correct time.  Thus, we adjust...
 239          */
 240         if (!ntp_synced())
 241                 /*
 242                  * Not synced, exit, do not restart a timer (if one is
 243                  * running, let it run out).
 244                  */
 245                 return;
 246
 247         do_gettimeofday(&now);
 248         if (now.tv_usec >= USEC_AFTER - ((unsigned) TICK_SIZE) / 2 &&
 249             now.tv_usec <= USEC_BEFORE + ((unsigned) TICK_SIZE) / 2)
 250                 fail = set_rtc_mmss(now.tv_sec);
 251
 252         next.tv_usec = USEC_AFTER - now.tv_usec;
 253         if (next.tv_usec <= 0)
 254                 next.tv_usec += USEC_PER_SEC;
 255
 256         if (!fail)
 257                 next.tv_sec = 659;
 258         else
 259                 next.tv_sec = 0;
 260
 261         if (next.tv_usec >= USEC_PER_SEC) {
 262                 next.tv_sec++;
 263                 next.tv_usec -= USEC_PER_SEC;
 264         }
 265         mod_timer(&sync_cmos_timer, jiffies + timeval_to_jiffies(&next));
 266 }
 267
 268 void notify_arch_cmos_timer(void)
 269 {
 270         mod_timer(&sync_cmos_timer, jiffies + 1);
 271 }
 272
 273 static long clock_cmos_diff, sleep_start;
 274
 275 static int timer_suspend(struct sys_device *dev, pm_message_t state)
 276 {
 277         /*
 278          * Estimate time zone so that set_time can update the clock
 279          */
 280         clock_cmos_diff = -get_cmos_time();
 281         clock_cmos_diff += get_seconds();
 282         sleep_start = get_cmos_time();
 283         return 0;
 284 }
 285
 286 static int timer_resume(struct sys_device *dev)
 287 {
 288         unsigned long flags;
 289         unsigned long sec;
 290         unsigned long sleep_length;
 291
 292 #ifdef CONFIG_HPET_TIMER
 293         if (is_hpet_enabled())
 294                 hpet_reenable();
 295 #endif
 296         setup_pit_timer();
 297         sec = get_cmos_time() + clock_cmos_diff;
 298         sleep_length = (get_cmos_time() - sleep_start) * HZ;
 299         write_seqlock_irqsave(&xtime_lock, flags);
 300         xtime.tv_sec = sec;
 301         xtime.tv_nsec = 0;
 302         jiffies_64 += sleep_length;
 303         wall_jiffies += sleep_length;
 304         write_sequnlock_irqrestore(&xtime_lock, flags);
 305         touch_softlockup_watchdog();
 306         return 0;
 307 }
 308
 309 static struct sysdev_class timer_sysclass = {
 310         .resume = timer_resume,
 311         .suspend = timer_suspend,
 312         set_kset_name("timer"),
 313 };
 314
 315
 316 /* XXX this driverfs stuff should probably go elsewhere later -john */
 317 static struct sys_device device_timer = {
 318         .id     = 0,
 319         .cls    = &timer_sysclass,
 320 };
 321
 322 static int time_init_device(void)
 323 {
 324         int error = sysdev_class_register(&timer_sysclass);
 325         if (!error)
 326                 error = sysdev_register(&device_timer);
 327         return error;
 328 }
 329
 330 device_initcall(time_init_device);
 331
 332 #ifdef CONFIG_HPET_TIMER
 333 extern void (*late_time_init)(void);
 334 /* Duplicate of time_init() below, with hpet_enable part added */
 335 static void __init hpet_time_init(void)
 336 {
 337         xtime.tv_sec = get_cmos_time();
 338         xtime.tv_nsec = (INITIAL_JIFFIES % HZ) * (NSEC_PER_SEC / HZ);
 339         set_normalized_timespec(&wall_to_monotonic,
 340                 -xtime.tv_sec, -xtime.tv_nsec);
 341
 342         if ((hpet_enable() >= 0) && hpet_use_timer) {
 343                 printk("Using HPET for base-timer\n");
 344         }
 345
 346         time_init_hook();
 347 }
 348 #endif
 349
 350 void __init time_init(void)
 351 {
 352 #ifdef CONFIG_HPET_TIMER
 353         if (is_hpet_capable()) {
 354                 /*
 355                  * HPET initialization needs to do memory-mapped io. So, let
 356                  * us do a late initialization after mem_init().
 357                  */
 358                 late_time_init = hpet_time_init;
 359                 return;
 360         }
 361 #endif
 362         xtime.tv_sec = get_cmos_time();
 363         xtime.tv_nsec = (INITIAL_JIFFIES % HZ) * (NSEC_PER_SEC / HZ);
 364         set_normalized_timespec(&wall_to_monotonic,
 365                 -xtime.tv_sec, -xtime.tv_nsec);
 366
 367         time_init_hook();
 368 }