/*      $NetBSD: clock.c,v 1.27 2012/10/27 17:18:04 chs Exp $	*/

/*
 * Copyright (c) 1992, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This software was developed by the Computer Systems Engineering group
 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
 * contributed to Berkeley.
 *
 * 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, Lawrence Berkeley Laboratory.
 *
 * 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.
 *
 *      @(#)clock.c     8.1 (Berkeley) 6/11/93
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: clock.c,v 1.27 2012/10/27 17:18:04 chs Exp $");

#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/systm.h>
#include <sys/device.h>

#include <machine/psl.h>
#include <machine/bus.h>

#include <dev/mvme/clockvar.h>

static	struct clock_attach_args *clock_args;

struct	evcnt clock_profcnt;
struct	evcnt clock_statcnt;

/*
 * Statistics clock interval and 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).
 */
/* XXX fix comment to match value */
int	clock_statvar = 8192;
int	clock_statmin;		/* statclock interval - (1/2 * variance) */


/*
 * Common parts of clock autoconfiguration.
 */
void
clock_config(device_t dev, struct clock_attach_args *ca, struct evcnt *ev)
{
	extern int delay_divisor;	/* from machdep.c */

	/* Hook up that which we need. */
	clock_args = ca;

	evcnt_attach_dynamic(&clock_profcnt, EVCNT_TYPE_INTR, ev,
	    device_xname(dev), "profint");
	evcnt_attach_dynamic(&clock_statcnt, EVCNT_TYPE_INTR, ev,
	    device_xname(dev), "statint");

	/* Print info about the clock. */
	printf(": delay_divisor %d\n", delay_divisor);
}

/*
 * Set up the real-time and statistics clocks.  Leave stathz 0 only
 * if no alternative timer is available.
 *
 * The frequencies of these clocks must be an even number of microseconds.
 */
void
cpu_initclocks(void)
{
	int statint, minint;

	if (clock_args == NULL)
		panic("clock not configured");

	if (1000000 % hz) {
		printf("cannot get %d Hz clock; using 100 Hz\n", hz);
		hz = 100;
		tick = 1000000 / hz;
	}
	if (stathz == 0)
		stathz = hz;
	if (1000000 % stathz) {
		printf("cannot get %d Hz statclock; using 100 Hz\n", stathz);
		stathz = 100;
	}
	profhz = stathz;	/* always */ 

	statint = 1000000 / stathz;
	minint = statint / 2 + 100;
	while (clock_statvar > minint)
		clock_statvar >>= 1;

	clock_statmin = statint - (clock_statvar >> 1);

	/* Call the machine-specific initclocks hook. */
	(*clock_args->ca_initfunc)(clock_args->ca_arg, tick, statint);
}

void
setstatclockrate(int newhz)
{

	/* XXX should we do something here? XXX */
}