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-/* -*- Mode:C; c-basic-offset:4; tab-width:4 -*-
- ****************************************************************************
- * (C) 2002 - Rolf Neugebauer - Intel Research Cambridge
- ****************************************************************************
- *
- * File: arch.xeno/time.c
- * Author: Rolf Neugebauer
- * Changes:
- *
- * Date: Nov 2002
- *
- * Environment: XenoLinux
- * Description: Interface with Hypervisor to get correct notion of time
- * Currently supports Systemtime and WallClock time.
- *
- * (This has hardly any resemblence with the Linux code but left the
- * copyright notice anyway. Ignore the comments in the copyright notice.)
- ****************************************************************************
- * $Id: c-insert.c,v 1.7 2002/11/08 16:04:34 rn Exp $
- ****************************************************************************
- */
-
-/*
- * linux/arch/i386/kernel/time.c
- *
- * Copyright (C) 1991, 1992, 1995 Linus Torvalds
- *
- * This file contains the PC-specific time handling details:
- * reading the RTC at bootup, etc..
- * 1994-07-02 Alan Modra
- * fixed set_rtc_mmss, fixed time.year for >= 2000, new mktime
- * 1995-03-26 Markus Kuhn
- * fixed 500 ms bug at call to set_rtc_mmss, fixed DS12887
- * precision CMOS clock update
- * 1996-05-03 Ingo Molnar
- * fixed time warps in do_[slow|fast]_gettimeoffset()
- * 1997-09-10 Updated NTP code according to technical memorandum Jan '96
- * "A Kernel Model for Precision Timekeeping" by Dave Mills
- * 1998-09-05 (Various)
- * More robust do_fast_gettimeoffset() algorithm implemented
- * (works with APM, Cyrix 6x86MX and Centaur C6),
- * monotonic gettimeofday() with fast_get_timeoffset(),
- * drift-proof precision TSC calibration on boot
- * (C. Scott Ananian <cananian@alumni.princeton.edu>, Andrew D.
- * Balsa <andrebalsa@altern.org>, Philip Gladstone <philip@raptor.com>;
- * ported from 2.0.35 Jumbo-9 by Michael Krause <m.krause@tu-harburg.de>).
- * 1998-12-16 Andrea Arcangeli
- * Fixed Jumbo-9 code in 2.1.131: do_gettimeofday was missing 1 jiffy
- * because was not accounting lost_ticks.
- * 1998-12-24 Copyright (C) 1998 Andrea Arcangeli
- * Fixed a xtime SMP race (we need the xtime_lock rw spinlock to
- * serialize accesses to xtime/lost_ticks).
- */
-
-#include <asm/smp.h>
-#include <asm/irq.h>
-#include <asm/msr.h>
-#include <asm/delay.h>
-#include <asm/mpspec.h>
-#include <asm/uaccess.h>
-#include <asm/processor.h>
-
-#include <asm/div64.h>
-#include <asm/hypervisor.h>
-
-#include <linux/kernel.h>
-#include <linux/interrupt.h>
-#include <linux/time.h>
-#include <linux/init.h>
-#include <linux/smp.h>
-#include <linux/irq.h>
-
-#undef XENO_TIME_DEBUG /* adds sanity checks and periodic printouts */
-
-spinlock_t rtc_lock = SPIN_LOCK_UNLOCKED;
-extern rwlock_t xtime_lock;
-
-unsigned long cpu_khz; /* get this from Xen, used elsewhere */
-static spinlock_t hyp_stime_lock = SPIN_LOCK_UNLOCKED;
-static spinlock_t hyp_wctime_lock = SPIN_LOCK_UNLOCKED;
-
-static u32 st_scale_f;
-static u32 st_scale_i;
-static u32 shadow_st_pcc;
-static s64 shadow_st;
-
-/*
- * System time.
- * Although the rest of the Linux kernel doesn't know about this, we
- * we use it to extrapolate passage of wallclock time.
- * We need to read the values from the shared info page "atomically"
- * and use the cycle counter value as the "version" number. Clashes
- * should be very rare.
- */
-static inline long long get_s_time(void)
-{
- unsigned long flags;
- u32 delta_tsc, low, pcc;
- u64 delta;
- s64 now;
-
- spin_lock_irqsave(&hyp_stime_lock, flags);
-
- while ((pcc = HYPERVISOR_shared_info->st_timestamp) != shadow_st_pcc)
- {
- barrier();
- shadow_st_pcc = pcc;
- shadow_st = HYPERVISOR_shared_info->system_time;
- barrier();
- }
-
- now = shadow_st;
- /* only use bottom 32bits of TSC. This should be sufficient */
- rdtscl(low);
- delta_tsc = low - pcc;
- delta = ((u64)delta_tsc * st_scale_f);
- delta >>= 32;
- delta += ((u64)delta_tsc * st_scale_i);
-
- spin_unlock_irqrestore(&hyp_time_lock, flags);
-
- return now + delta;
-
-}
-#define NOW() ((long long)get_s_time())
-
-/*
- * Wallclock time.
- * Based on what the hypervisor tells us, extrapolated using system time.
- * Again need to read a number of values from the shared page "atomically".
- * this time using a version number.
- */
-static u32 shadow_wc_version=0;
-static long shadow_tv_sec;
-static long shadow_tv_usec;
-static long long shadow_wc_timestamp;
-void do_gettimeofday(struct timeval *tv)
-{
- unsigned long flags;
- long usec, sec;
- u32 version;
- u64 now;
-
- spin_lock_irqsave(&hyp_wctime_lock, flags);
-
- while ((version = HYPERVISOR_shared_info->wc_version)!= shadow_wc_version)
- {
- barrier();
- shadow_wc_version = version;
- shadow_tv_sec = HYPERVISOR_shared_info->tv_sec;
- shadow_tv_usec = HYPERVISOR_shared_info->tv_usec;
- shadow_wc_timestamp = HYPERVISOR_shared_info->wc_timestamp;
- barrier();
- }
-
- now = NOW();
- usec = ((unsigned long)(now-shadow_wc_timestamp))/1000;
- sec = shadow_tv_sec;
- usec += shadow_tv_usec;
-
- while ( usec >= 1000000 )
- {
- usec -= 1000000;
- sec++;
- }
-
- tv->tv_sec = sec;
- tv->tv_usec = usec;
-
- spin_unlock_irqrestore(&hyp_time_lock, flags);
-
-#ifdef XENO_TIME_DEBUG
- {
- static long long old_now=0;
- static long long wct=0, old_wct=0;
-
- /* This debug code checks if time increase over two subsequent calls */
- wct=(((long long)sec) * 1000000) + usec;
- /* wall clock time going backwards */
- if ((wct < old_wct) ) {
- printk("Urgh1: wc diff=%6ld, usec = %ld (0x%lX)\n",
- (long)(wct-old_wct), usec, usec);
- printk(" st diff=%lld cur st=0x%016llX old st=0x%016llX\n",
- now-old_now, now, old_now);
- }
-
- /* system time going backwards */
- if (now<=old_now) {
- printk("Urgh2: st diff=%lld cur st=0x%016llX old st=0x%016llX\n",
- now-old_now, now, old_now);
- }
- old_wct = wct;
- old_now = now;
- }
-#endif
-
-}
-
-void do_settimeofday(struct timeval *tv)
-{
-/* XXX RN: should do something special here for dom0 */
-#if 0
- write_lock_irq(&xtime_lock);
- /*
- * This is revolting. We need to set "xtime" correctly. However, the
- * value in this location is the value at the most recent update of
- * wall time. Discover what correction gettimeofday() would have
- * made, and then undo it!
- */
- tv->tv_usec -= do_gettimeoffset();
- tv->tv_usec -= (jiffies - wall_jiffies) * (1000000 / HZ);
-
- while ( tv->tv_usec < 0 )
- {
- tv->tv_usec += 1000000;
- tv->tv_sec--;
- }
-
- xtime = *tv;
- time_adjust = 0; /* stop active adjtime() */
- time_status |= STA_UNSYNC;
- time_maxerror = NTP_PHASE_LIMIT;
- time_esterror = NTP_PHASE_LIMIT;
- write_unlock_irq(&xtime_lock);
-#endif
-}
-
-
-/*
- * Timer ISR.
- * Unlike normal Linux these don't come in at a fixed rate of HZ.
- * In here we wrok out how often it should have been called and then call
- * the architecture independent part (do_timer()) the appropriate number of
- * times. A bit of a nasty hack, to keep the "other" notion of wallclock time
- * happy.
- */
-static long long us_per_tick=1000000/HZ;
-static long long last_irq;
-static inline void do_timer_interrupt(int irq, void *dev_id,
- struct pt_regs *regs)
-{
- struct timeval tv;
- long long time, delta;
-
-#ifdef XENO_TIME_DEBUG
- static u32 foo_count = 0;
- foo_count++;
- if (foo_count>= 1000) {
- s64 n = NOW();
- struct timeval tv;
- do_gettimeofday(&tv);
- printk("0x%08X%08X %ld:%ld\n",
- (u32)(n>>32), (u32)n, tv.tv_sec, tv.tv_usec);
- foo_count = 0;
- }
-#endif
- /*
- * The next bit really sucks:
- * Linux not only uses do_gettimeofday() to keep a notion of
- * wallclock time, but also maintains the xtime struct and jiffies.
- * (Even worse some userland code accesses this via the sys_time()
- * system call)
- * Unfortunately, xtime is maintain in the architecture independent
- * part of the timer ISR (./kernel/timer.c sic!). So, although we have
- * perfectly valid notion of wallclock time from the hypervisor we here
- * fake missed timer interrupts so that the arch independent part of
- * the Timer ISR updates jiffies for us *and* once the bh gets run
- * updates xtime accordingly. Yuck!
- */
-
- /* work out the number of jiffies past and update them */
- do_gettimeofday(&tv);
- time = (((long long)tv.tv_sec) * 1000000) + tv.tv_usec;
- delta = time - last_irq;
- if (delta <= 0) {
- printk ("Timer ISR: Time went backwards: %lld\n", delta);
- return;
- }
- while (delta >= us_per_tick) {
- do_timer(regs);
- delta -= us_per_tick;
- last_irq += us_per_tick;
- }
-
-#if 0
- if (!user_mode(regs))
- x86_do_profile(regs->eip);
-#endif
-}
-
-static void timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
-{
- write_lock(&xtime_lock);
- do_timer_interrupt(irq, NULL, regs);
- write_unlock(&xtime_lock);
-}
-
-static struct irqaction irq_timer = {
- timer_interrupt,
- SA_INTERRUPT,
- 0,
- "timer",
- NULL,
- NULL
-};
-
-void __init time_init(void)
-{
- unsigned long long alarm;
- u64 cpu_freq = HYPERVISOR_shared_info->cpu_freq;
- u64 scale;
-
- do_get_fast_time = do_gettimeofday;
-
- cpu_khz = (u32)cpu_freq/1000;
- printk("Xen reported: %lu.%03lu MHz processor.\n",
- cpu_khz / 1000, cpu_khz % 1000);
-
- /*
- * calculate systemtime scaling factor
- * XXX RN: have to cast cpu_freq to u32 limits it to 4.29 GHz.
- * Get a better do_div!
- */
- scale = 1000000000LL << 32;
- do_div(scale,(u32)cpu_freq);
- st_scale_f = scale & 0xffffffff;
- st_scale_i = scale >> 32;
- printk("System Time scale: %X %X\n",st_scale_i, st_scale_f);
-
- do_gettimeofday(&xtime);
- last_irq = (((long long)xtime.tv_sec) * 1000000) + xtime.tv_usec;
-
- setup_irq(TIMER_IRQ, &irq_timer);
-
- /*
- * Start ticker. Note that timing runs of wall clock, not virtual
- * 'domain' time. This means that clock sshould run at the correct
- * rate. For things like scheduling, it's not clear whether it
- * matters which sort of time we use.
- * XXX RN: unimplemented.
- */
-
- rdtscll(alarm);
-#if 0
- alarm += (1000/HZ)*HYPERVISOR_shared_info->ticks_per_ms;
- HYPERVISOR_shared_info->wall_timeout = alarm;
- HYPERVISOR_shared_info->domain_timeout = ~0ULL;
-#endif
- clear_bit(_EVENT_TIMER, &HYPERVISOR_shared_info->events);
-}
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