/*	$OpenBSD: clock.c,v 1.29 2014/03/29 18:09:29 guenther Exp $	*/

/*
 * Copyright (c) 1998-2003 Michael Shalayeff
 * All rights reserved.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR OR HIS RELATIVES 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 MIND, 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.
 */

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

#include <dev/clock_subr.h>

#include <machine/pdc.h>
#include <machine/iomod.h>
#include <machine/psl.h>
#include <machine/intr.h>
#include <machine/reg.h>
#include <machine/cpufunc.h>
#include <machine/autoconf.h>

u_long	cpu_hzticks;
int	timeset;

int	cpu_hardclock(void *);
u_int	itmr_get_timecount(struct timecounter *);

struct timecounter itmr_timecounter = {
	itmr_get_timecount, NULL, 0xffffffff, 0, "itmr", 0, NULL
};

void
cpu_initclocks(void)
{
	struct cpu_info *ci = curcpu();
	u_long __itmr;

	cpu_hzticks = (PAGE0->mem_10msec * 100) / hz;

	itmr_timecounter.tc_frequency = PAGE0->mem_10msec * 100;
	tc_init(&itmr_timecounter);

	mfctl(CR_ITMR, __itmr);
	ci->ci_itmr = __itmr;
	__itmr += cpu_hzticks;
	mtctl(__itmr, CR_ITMR);
}

int
cpu_hardclock(void *v)
{
	struct cpu_info *ci = curcpu();
	u_long __itmr, delta, eta;
	int wrap;
	register_t eiem;

	/*
	 * Invoke hardclock as many times as there has been cpu_hzticks
	 * ticks since the last interrupt.
	 */
	for (;;) {
		mfctl(CR_ITMR, __itmr);
		delta = __itmr - ci->ci_itmr;
		if (delta >= cpu_hzticks) {
			hardclock(v);
			ci->ci_itmr += cpu_hzticks;
		} else
			break;
	}

	/*
	 * Program the next clock interrupt, making sure it will
	 * indeed happen in the future. This is done with interrupts
	 * disabled to avoid a possible race.
	 */
	eta = ci->ci_itmr + cpu_hzticks;
	wrap = eta < ci->ci_itmr;	/* watch out for a wraparound */
	__asm volatile("mfctl	%%cr15, %0": "=r" (eiem));
	__asm volatile("mtctl	%r0, %cr15");
	mtctl(eta, CR_ITMR);
	mfctl(CR_ITMR, __itmr);
	/*
	 * If we were close enough to the next tick interrupt
	 * value, by the time we have programmed itmr, it might
	 * have passed the value, which would cause a complete
	 * cycle until the next interrupt occurs. On slow
	 * models, this would be a disaster (a complete cycle
	 * taking over two minutes on a 715/33).
	 *
	 * We expect that it will only be necessary to postpone
	 * the interrupt once. Thus, there are two cases:
	 * - We are expecting a wraparound: eta < cpu_itmr.
	 *   itmr is in tracks if either >= cpu_itmr or < eta.
	 * - We are not wrapping: eta > cpu_itmr.
	 *   itmr is in tracks if >= cpu_itmr and < eta (we need
	 *   to keep the >= cpu_itmr test because itmr might wrap
	 *   before eta does).
	 */
	if ((wrap && !(eta > __itmr || __itmr >= ci->ci_itmr)) ||
	    (!wrap && !(eta > __itmr && __itmr >= ci->ci_itmr))) {
		eta += cpu_hzticks;
		mtctl(eta, CR_ITMR);
	}
	__asm volatile("mtctl	%0, %%cr15":: "r" (eiem));

	return (1);
}

/*
 * initialize the system time from the time of day clock
 */
void
inittodr(time_t t)
{
	struct pdc_tod tod PDC_ALIGNMENT;
	int 	error, tbad = 0;
	struct timespec ts;

	if (t < 12*SECYR) {
		printf ("WARNING: preposterous time in file system");
		t = 6*SECYR + 186*SECDAY + SECDAY/2;
		tbad = 1;
	}

	if ((error = pdc_call((iodcio_t)pdc,
	    1, PDC_TOD, PDC_TOD_READ, &tod, 0, 0, 0, 0, 0)))
		printf("clock: failed to fetch (%d)\n", error);

	ts.tv_sec = tod.sec;
	ts.tv_nsec = tod.usec * 1000;
	tc_setclock(&ts);
	timeset = 1;

	if (!tbad) {
		u_long	dt;

		dt = (tod.sec < t)?  t - tod.sec : tod.sec - t;

		if (dt < 2 * SECDAY)
			return;
		printf("WARNING: clock %s %ld days",
		    tod.sec < t? "lost" : "gained", dt / SECDAY);
	}

	printf (" -- CHECK AND RESET THE DATE!\n");
}

/*
 * reset the time of day clock to the value in time
 */
void
resettodr()
{
	struct timeval tv;
	int error;

	/*
	 * We might have been called by boot() due to a crash early
	 * on.  Don't reset the clock chip in this case.
	 */
	if (!timeset)
		return;

	microtime(&tv);

	if ((error = pdc_call((iodcio_t)pdc, 1, PDC_TOD, PDC_TOD_WRITE,
	    tv.tv_sec, tv.tv_usec)))
		printf("clock: failed to save (%d)\n", error);
}

void
setstatclockrate(int newhz)
{
	/* nothing we can do */
}

u_int
itmr_get_timecount(struct timecounter *tc)
{
	u_long __itmr;

	mfctl(CR_ITMR, __itmr);
	return (__itmr);
}