NetBSD-5.0.2/sys/arch/arc/arc/timer.c
/* $NetBSD: timer.c,v 1.9 2006/09/24 02:20:48 tsutsui Exp $ */
/* NetBSD: clock.c,v 1.31 2001/05/27 13:53:24 sommerfeld Exp */
/*
* Copyright (c) 1992, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* the Systems Programming Group of the University of Utah Computer
* Science Department and Ralph Campbell.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* from: Utah Hdr: clock.c 1.18 91/01/21
*
* @(#)clock.c 8.1 (Berkeley) 6/10/93
*/
/*
* Copyright (c) 1988 University of Utah.
*
* This code is derived from software contributed to Berkeley by
* the Systems Programming Group of the University of Utah Computer
* Science Department and Ralph Campbell.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* from: Utah Hdr: clock.c 1.18 91/01/21
*
* @(#)clock.c 8.1 (Berkeley) 6/10/93
*/
#include <sys/cdefs.h> /* RCS ID & Copyright macro defns */
__KERNEL_RCSID(0, "$NetBSD: timer.c,v 1.9 2006/09/24 02:20:48 tsutsui Exp $");
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/systm.h>
#include <mips/locore.h>
#include <mips/mips3_clock.h>
#include <arc/arc/timervar.h>
struct device *timerdev;
const struct timerfns *timerfns;
int timerinitted;
uint32_t last_cp0_count;
#ifdef ENABLE_INT5_STATCLOCK
/*
* Statistics clock variance, in usec. Variance must be a
* power of two. Since this gives us an even number, not an odd number,
* we discard one case and compensate. That is, a variance of 1024 would
* give us offsets in [0..1023]. Instead, we take offsets in [1..1023].
* This is symmetric about the point 512, or statvar/2, and thus averages
* to that value (assuming uniform random numbers).
*/
static const uint32_t statvar = 1024;
static uint32_t statint; /* number of clock ticks for stathz */
static uint32_t statmin; /* minimum stat clock count in ticks */
static uint32_t statprev;/* last value of we set statclock to */
static u_int statcountperusec; /* number of ticks per usec at current stathz */
#endif
void
timerattach(struct device *dev, const struct timerfns *fns)
{
/*
* Just bookkeeping.
*/
if (timerfns != NULL)
panic("timerattach: multiple timers");
timerdev = dev;
timerfns = fns;
}
/*
* Machine-dependent clock routines.
*/
/*
* Start the real-time and statistics clocks. Leave stathz 0 since there
* are no other timers available.
*/
void
cpu_initclocks(void)
{
#ifdef ENABLE_INT5_STATCLOCK
if (stathz == 0)
stathz = hz;
if (profhz == 0)
profhz = hz * 5;
setstatclockrate(stathz);
#endif
if (timerfns == NULL)
panic("cpu_initclocks: no timer attached");
/*
* Get the clock started.
*/
(*timerfns->tf_init)(timerdev);
/* init timecounter */
mips3_init_tc();
#ifdef ENABLE_INT5_STATCLOCK
/* enable interrupts including CPU INT 5 */
_splnone();
#endif
}
/*
* We assume newhz is either stathz or profhz, and that neither will
* change after being set up above. Could recalculate intervals here
* but that would be a drag.
*/
void
setstatclockrate(int newhz)
{
#ifdef ENABLE_INT5_STATCLOCK
uint32_t countpersecond, statvarticks;
statprev = mips3_cp0_count_read();
statint = ((curcpu()->ci_cpu_freq + newhz / 2) / newhz) / 2;
/* Get the total ticks a second */
countpersecond = statint * newhz;
/* now work out how many ticks per usec */
statcountperusec = countpersecond / 1000000;
/* calculate a variance range of statvar */
statvarticks = statcountperusec * statvar;
/* minimum is statint - 50% of variant */
statmin = statint - (statvarticks / 2);
mips3_cp0_compare_write(statprev + statint);
#endif
}
#ifdef ENABLE_INT5_STATCLOCK
void
statclockintr(struct clockframe *cfp)
{
uint32_t curcount, statnext, delta, r;
int lost;
lost = 0;
do {
r = (uint32_t)random() & (statvar - 1);
} while (r == 0);
statnext = statprev + statmin + (r * statcountperusec);
mips3_cp0_compare_write(statnext);
curcount = mips3_cp0_count_read();
delta = statnext - curcount;
while (__predict_false((int32_t)delta < 0)) {
lost++;
delta += statint;
}
if (__predict_false(lost > 0)) {
statnext = curcount + delta;
mips3_cp0_compare_write(statnext);
for (; lost > 0; lost--)
statclock(cfp);
}
statclock(cfp);
statprev = statnext;
}
#endif