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/* -*- Mode:C; c-basic-offset:4; tab-width:4 -*-
****************************************************************************
* (C) 2003 - Rolf Neugebauer - Intel Research Cambridge
****************************************************************************
*
* File: time.c
* Author: Rolf Neugebauer (neugebar@dcs.gla.ac.uk)
* Changes:
*
* Date: Jul 2003
*
* Environment: Xen Minimal OS
* Description: Simple time and timer functions
*
****************************************************************************
* $Id: c-insert.c,v 1.7 2002/11/08 16:04:34 rn Exp $
****************************************************************************
*/
#include <os.h>
#include <types.h>
#include <hypervisor.h>
#include <events.h>
#include <time.h>
#include <lib.h>
/************************************************************************
* Time functions
*************************************************************************/
static unsigned int rdtsc_bitshift;
static u32 st_scale_f;
static u32 st_scale_i;
static u32 shadow_st_pcc;
static s_time_t shadow_st;
static u32 shadow_wc_version=0;
static long shadow_tv_sec;
static long shadow_tv_usec;
static s_time_t shadow_wc_timestamp;
/*
* System 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.
*/
inline s_time_t get_s_time(void)
{
s32 delta_tsc;
u32 low;
u64 delta, tsc;
u32 version;
u64 cpu_freq, scale;
/* check if our values are still up-to-date */
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;
shadow_st_pcc = HYPERVISOR_shared_info->st_timestamp;
shadow_st = HYPERVISOR_shared_info->system_time;
rdtsc_bitshift = HYPERVISOR_shared_info->rdtsc_bitshift;
cpu_freq = HYPERVISOR_shared_info->cpu_freq;
/* XXX cpu_freq as u32 limits it to 4.29 GHz. Get a better do_div! */
scale = 1000000000LL << (32 + rdtsc_bitshift);
scale /= cpu_freq;
st_scale_f = scale & 0xffffffff;
st_scale_i = scale >> 32;
barrier();
}
rdtscll(tsc);
low = (u32)(tsc >> rdtsc_bitshift);
delta_tsc = (s32)(low - shadow_st_pcc);
if ( unlikely(delta_tsc < 0) ) delta_tsc = 0;
delta = ((u64)delta_tsc * st_scale_f);
delta >>= 32;
delta += ((u64)delta_tsc * st_scale_i);
return shadow_st + delta;
}
/*
* 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.
*/
void gettimeofday(struct timeval *tv)
{
long usec, sec;
u64 now;
now = get_s_time();
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;
}
static void timer_handler(int ev, struct pt_regs *regs)
{
static int i;
s_time_t now;
i++;
if (i >= 1000) {
now = get_s_time();
printf("T(%lld)\n", now);
i = 0;
}
}
void init_time(void)
{
u64 __cpu_khz;
unsigned long cpu_khz;
__cpu_khz = HYPERVISOR_shared_info->cpu_freq;
cpu_khz = (u32) (__cpu_khz/1000);
printk("Xen reported: %lu.%03lu MHz processor.\n",
cpu_khz / 1000, cpu_khz % 1000);
add_ev_action(EV_TIMER, &timer_handler);
enable_ev_action(EV_TIMER);
enable_hypervisor_event(EV_TIMER);
}
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