2 * linux/arch/i386/kernel/time.c
4 * Copyright (C) 1991, 1992, 1995 Linus Torvalds
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).
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>
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>
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>
60 #include "mach_time.h"
62 #include <linux/timex.h>
63 #include <linux/config.h>
67 #include <asm/arch_hooks.h>
71 extern spinlock_t i8259A_lock;
72 int pit_latch_buggy; /* extern */
76 u64 jiffies_64 = INITIAL_JIFFIES;
78 EXPORT_SYMBOL(jiffies_64);
80 unsigned long cpu_khz; /* Detected as we calibrate the TSC */
82 extern unsigned long wall_jiffies;
84 DEFINE_SPINLOCK(rtc_lock);
86 DEFINE_SPINLOCK(i8253_lock);
87 EXPORT_SYMBOL(i8253_lock);
89 struct timer_opts *cur_timer = &timer_none;
92 * This version of gettimeofday has microsecond resolution
93 * and better than microsecond precision on fast x86 machines with TSC.
95 void do_gettimeofday(struct timeval *tv)
98 unsigned long usec, sec;
99 unsigned long max_ntp_tick;
104 seq = read_seqbegin(&xtime_lock);
106 usec = cur_timer->get_offset();
107 lost = jiffies - wall_jiffies;
110 * If time_adjust is negative then NTP is slowing the clock
111 * so make sure not to go into next possible interval.
112 * Better to lose some accuracy than have time go backwards..
114 if (unlikely(time_adjust < 0)) {
115 max_ntp_tick = (USEC_PER_SEC / HZ) - tickadj;
116 usec = min(usec, max_ntp_tick);
119 usec += lost * max_ntp_tick;
121 else if (unlikely(lost))
122 usec += lost * (USEC_PER_SEC / HZ);
125 usec += (xtime.tv_nsec / 1000);
126 } while (read_seqretry(&xtime_lock, seq));
128 while (usec >= 1000000) {
137 EXPORT_SYMBOL(do_gettimeofday);
139 int do_settimeofday(struct timespec *tv)
141 time_t wtm_sec, sec = tv->tv_sec;
142 long wtm_nsec, nsec = tv->tv_nsec;
144 if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
147 write_seqlock_irq(&xtime_lock);
149 * This is revolting. We need to set "xtime" correctly. However, the
150 * value in this location is the value at the most recent update of
151 * wall time. Discover what correction gettimeofday() would have
152 * made, and then undo it!
154 nsec -= cur_timer->get_offset() * NSEC_PER_USEC;
155 nsec -= (jiffies - wall_jiffies) * TICK_NSEC;
157 wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
158 wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
160 set_normalized_timespec(&xtime, sec, nsec);
161 set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
163 time_adjust = 0; /* stop active adjtime() */
164 time_status |= STA_UNSYNC;
165 time_maxerror = NTP_PHASE_LIMIT;
166 time_esterror = NTP_PHASE_LIMIT;
167 write_sequnlock_irq(&xtime_lock);
172 EXPORT_SYMBOL(do_settimeofday);
174 static int set_rtc_mmss(unsigned long nowtime)
178 /* gets recalled with irq locally disabled */
179 spin_lock(&rtc_lock);
181 retval = efi_set_rtc_mmss(nowtime);
183 retval = mach_set_rtc_mmss(nowtime);
184 spin_unlock(&rtc_lock);
189 /* last time the cmos clock got updated */
190 static long last_rtc_update;
194 /* monotonic_clock(): returns # of nanoseconds passed since time_init()
195 * Note: This function is required to return accurate
196 * time even in the absence of multiple timer ticks.
198 unsigned long long monotonic_clock(void)
200 return cur_timer->monotonic_clock();
202 EXPORT_SYMBOL(monotonic_clock);
204 #if defined(CONFIG_SMP) && defined(CONFIG_FRAME_POINTER)
205 unsigned long profile_pc(struct pt_regs *regs)
207 unsigned long pc = instruction_pointer(regs);
209 if (in_lock_functions(pc))
210 return *(unsigned long *)(regs->ebp + 4);
214 EXPORT_SYMBOL(profile_pc);
218 * timer_interrupt() needs to keep up the real-time clock,
219 * as well as call the "do_timer()" routine every clocktick
221 static inline void do_timer_interrupt(int irq, void *dev_id,
222 struct pt_regs *regs)
224 #ifdef CONFIG_X86_IO_APIC
227 * Subtle, when I/O APICs are used we have to ack timer IRQ
228 * manually to reset the IRR bit for do_slow_gettimeoffset().
229 * This will also deassert NMI lines for the watchdog if run
230 * on an 82489DX-based system.
232 spin_lock(&i8259A_lock);
233 outb(0x0c, PIC_MASTER_OCW3);
234 /* Ack the IRQ; AEOI will end it automatically. */
235 inb(PIC_MASTER_POLL);
236 spin_unlock(&i8259A_lock);
240 do_timer_interrupt_hook(regs);
243 * If we have an externally synchronized Linux clock, then update
244 * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
245 * called as close as possible to 500 ms before the new second starts.
247 if ((time_status & STA_UNSYNC) == 0 &&
248 xtime.tv_sec > last_rtc_update + 660 &&
249 (xtime.tv_nsec / 1000)
250 >= USEC_AFTER - ((unsigned) TICK_SIZE) / 2 &&
251 (xtime.tv_nsec / 1000)
252 <= USEC_BEFORE + ((unsigned) TICK_SIZE) / 2) {
253 /* horrible...FIXME */
255 if (efi_set_rtc_mmss(xtime.tv_sec) == 0)
256 last_rtc_update = xtime.tv_sec;
258 last_rtc_update = xtime.tv_sec - 600;
259 } else if (set_rtc_mmss(xtime.tv_sec) == 0)
260 last_rtc_update = xtime.tv_sec;
262 last_rtc_update = xtime.tv_sec - 600; /* do it again in 60 s */
266 /* The PS/2 uses level-triggered interrupts. You can't
267 turn them off, nor would you want to (any attempt to
268 enable edge-triggered interrupts usually gets intercepted by a
269 special hardware circuit). Hence we have to acknowledge
270 the timer interrupt. Through some incredibly stupid
271 design idea, the reset for IRQ 0 is done by setting the
272 high bit of the PPI port B (0x61). Note that some PS/2s,
273 notably the 55SX, work fine if this is removed. */
275 irq = inb_p( 0x61 ); /* read the current state */
276 outb_p( irq|0x80, 0x61 ); /* reset the IRQ */
281 * This is the same as the above, except we _also_ save the current
282 * Time Stamp Counter value at the time of the timer interrupt, so that
283 * we later on can estimate the time of day more exactly.
285 irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
288 * Here we are in the timer irq handler. We just have irqs locally
289 * disabled but we don't know if the timer_bh is running on the other
290 * CPU. We need to avoid to SMP race with it. NOTE: we don' t need
291 * the irq version of write_lock because as just said we have irq
292 * locally disabled. -arca
294 write_seqlock(&xtime_lock);
296 cur_timer->mark_offset();
298 do_timer_interrupt(irq, NULL, regs);
300 write_sequnlock(&xtime_lock);
304 /* not static: needed by APM */
305 unsigned long get_cmos_time(void)
307 unsigned long retval;
309 spin_lock(&rtc_lock);
312 retval = efi_get_time();
314 retval = mach_get_cmos_time();
316 spin_unlock(&rtc_lock);
321 static long clock_cmos_diff, sleep_start;
323 static int timer_suspend(struct sys_device *dev, u32 state)
326 * Estimate time zone so that set_time can update the clock
328 clock_cmos_diff = -get_cmos_time();
329 clock_cmos_diff += get_seconds();
330 sleep_start = get_cmos_time();
334 static int timer_resume(struct sys_device *dev)
338 unsigned long sleep_length;
340 #ifdef CONFIG_HPET_TIMER
341 if (is_hpet_enabled())
344 sec = get_cmos_time() + clock_cmos_diff;
345 sleep_length = (get_cmos_time() - sleep_start) * HZ;
346 write_seqlock_irqsave(&xtime_lock, flags);
349 write_sequnlock_irqrestore(&xtime_lock, flags);
350 jiffies += sleep_length;
351 wall_jiffies += sleep_length;
355 static struct sysdev_class timer_sysclass = {
356 .resume = timer_resume,
357 .suspend = timer_suspend,
358 set_kset_name("timer"),
362 /* XXX this driverfs stuff should probably go elsewhere later -john */
363 static struct sys_device device_timer = {
365 .cls = &timer_sysclass,
368 static int time_init_device(void)
370 int error = sysdev_class_register(&timer_sysclass);
372 error = sysdev_register(&device_timer);
376 device_initcall(time_init_device);
378 #ifdef CONFIG_HPET_TIMER
379 extern void (*late_time_init)(void);
380 /* Duplicate of time_init() below, with hpet_enable part added */
381 void __init hpet_time_init(void)
383 xtime.tv_sec = get_cmos_time();
384 xtime.tv_nsec = (INITIAL_JIFFIES % HZ) * (NSEC_PER_SEC / HZ);
385 set_normalized_timespec(&wall_to_monotonic,
386 -xtime.tv_sec, -xtime.tv_nsec);
388 if (hpet_enable() >= 0) {
389 printk("Using HPET for base-timer\n");
392 cur_timer = select_timer();
393 printk(KERN_INFO "Using %s for high-res timesource\n",cur_timer->name);
399 void __init time_init(void)
401 #ifdef CONFIG_HPET_TIMER
402 if (is_hpet_capable()) {
404 * HPET initialization needs to do memory-mapped io. So, let
405 * us do a late initialization after mem_init().
407 late_time_init = hpet_time_init;
411 xtime.tv_sec = get_cmos_time();
412 xtime.tv_nsec = (INITIAL_JIFFIES % HZ) * (NSEC_PER_SEC / HZ);
413 set_normalized_timespec(&wall_to_monotonic,
414 -xtime.tv_sec, -xtime.tv_nsec);
416 cur_timer = select_timer();
417 printk(KERN_INFO "Using %s for high-res timesource\n",cur_timer->name);