/*-
 * Copyright (c) 1988 University of Utah.
 * Copyright (c) 1982, 1990, 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.
 *
 * 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.
 * 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 $Hdr: clock.c 1.18 91/01/21$
 *	from: @(#)clock.c	8.2 (Berkeley) 1/12/94
 *	from: NetBSD: clock_subr.c,v 1.6 2001/07/07 17:04:02 thorpej Exp
 *	and
 *	from: src/sys/i386/isa/clock.c,v 1.176 2001/09/04
 */

/*
 * Helpers for time-of-day clocks. This is useful for architectures that need
 * support multiple models of such clocks, and generally serves to make the
 * code more machine-independent.
 * If the clock in question can also be used as a time counter, the driver
 * needs to initiate this.
 * This code is not yet used by all architectures.
 */

/*
 * Generic routines to convert between a POSIX date
 * (seconds since 1/1/1970) and yr/mo/day/hr/min/sec
 * Derived from NetBSD arch/hp300/hp300/clock.c
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD: src/sys/kern/subr_clock.c,v 1.6 2005/01/06 23:35:39 imp Exp $");

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

/* XXX: for the  CPU_* sysctl OID constants. */
#include <machine/cpu.h>

#include "clock_if.h"

static __inline int leapyear(int year);
static int sysctl_machdep_adjkerntz(SYSCTL_HANDLER_ARGS);

#define	FEBRUARY	2
#define	days_in_year(y) 	(leapyear(y) ? 366 : 365)
#define	days_in_month(y, m) \
	(month_days[(m) - 1] + (m == FEBRUARY ? leapyear(y) : 0))
/* Day of week. Days are counted from 1/1/1970, which was a Thursday */
#define	day_of_week(days)	(((days) + 4) % 7)

static const int month_days[12] = {
	31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
};

static device_t clock_dev = NULL;
static long clock_res;

int adjkerntz;		/* local offset from GMT in seconds */
int disable_rtc_set;	/* disable resettodr() if != 0 */
int wall_cmos_clock;	/* wall CMOS clock assumed if != 0 */

/*
 * These have traditionally been in machdep, but should probably be moved to
 * kern.
 */
SYSCTL_PROC(_machdep, CPU_ADJKERNTZ, adjkerntz, CTLTYPE_INT|CTLFLAG_RW,
	&adjkerntz, 0, sysctl_machdep_adjkerntz, "I", "");

SYSCTL_INT(_machdep, CPU_DISRTCSET, disable_rtc_set,
	CTLFLAG_RW, &disable_rtc_set, 0, "");

SYSCTL_INT(_machdep, CPU_WALLCLOCK, wall_cmos_clock,
	CTLFLAG_RW, &wall_cmos_clock, 0, "");

static int
sysctl_machdep_adjkerntz(SYSCTL_HANDLER_ARGS)
{
	int error;
	error = sysctl_handle_int(oidp, oidp->oid_arg1, oidp->oid_arg2,
		req);
	if (!error && req->newptr)
		resettodr();
	return (error);
}

/*
 * This inline avoids some unnecessary modulo operations
 * as compared with the usual macro:
 *   ( ((year % 4) == 0 &&
 *      (year % 100) != 0) ||
 *     ((year % 400) == 0) )
 * It is otherwise equivalent.
 */
static __inline int
leapyear(int year)
{
	int rv = 0;

	if ((year & 3) == 0) {
		rv = 1;
		if ((year % 100) == 0) {
			rv = 0;
			if ((year % 400) == 0)
				rv = 1;
		}
	}
	return (rv);
}

int
clock_ct_to_ts(struct clocktime *ct, struct timespec *ts)
{
	time_t secs;
	int i, year, days;

	year = ct->year;

	/* Sanity checks. */
	if (ct->mon < 1 || ct->mon > 12 || ct->day < 1 ||
	    ct->day > days_in_month(year, ct->mon) ||
	    ct->hour > 23 ||  ct->min > 59 || ct->sec > 59 ||
	    ct->year > 2037)		/* time_t overflow */
		return (EINVAL);

	/*
	 * Compute days since start of time
	 * First from years, then from months.
	 */
	days = 0;
	for (i = POSIX_BASE_YEAR; i < year; i++)
		days += days_in_year(i);

	/* Months */
	for (i = 1; i < ct->mon; i++)
	  	days += days_in_month(year, i);
	days += (ct->day - 1);

	/* Another sanity check. */
	if (ct->dow != -1 && ct->dow != day_of_week(days))
		return (EINVAL);

	/* Add hours, minutes, seconds. */
	secs = ((days * 24 + ct->hour) * 60 + ct->min) * 60 + ct->sec;

	ts->tv_sec = secs;
	ts->tv_nsec = ct->nsec;
	return (0);
}

void
clock_ts_to_ct(struct timespec *ts, struct clocktime *ct)
{
	int i, year, days;
	time_t rsec;	/* remainder seconds */
	time_t secs;

	secs = ts->tv_sec;
	days = secs / SECDAY;
	rsec = secs % SECDAY;

	ct->dow = day_of_week(days);

	/* Subtract out whole years, counting them in i. */
	for (year = POSIX_BASE_YEAR; days >= days_in_year(year); year++)
		days -= days_in_year(year);
	ct->year = year;

	/* Subtract out whole months, counting them in i. */
	for (i = 1; days >= days_in_month(year, i); i++)
		days -= days_in_month(year, i);
	ct->mon = i;

	/* Days are what is left over (+1) from all that. */
	ct->day = days + 1;

	/* Hours, minutes, seconds are easy */
	ct->hour = rsec / 3600;
	rsec = rsec % 3600;
	ct->min  = rsec / 60;
	rsec = rsec % 60;
	ct->sec  = rsec;
	ct->nsec = ts->tv_nsec;
}

void
clock_register(device_t dev, long res)
{

	if (clock_dev != NULL) {
		if (clock_res > res) {
			if (bootverbose) {
				device_printf(dev, "not installed as "
				    "time-of-day clock: clock %s has higher "
				    "resolution\n", device_get_name(clock_dev));
			}
			return;
		} else {
			if (bootverbose) {
				device_printf(clock_dev, "removed as "
				    "time-of-day clock: clock %s has higher "
				    "resolution\n", device_get_name(dev));
			}
		}
	}
	clock_dev = dev;
	clock_res = res;
	if (bootverbose) {
		device_printf(dev, "registered as a time-of-day clock "
		    "(resolution %ldus)\n", res);
	}
}

/*
 * inittodr and settodr derived from the i386 versions written
 * by Christoph Robitschko <chmr@edvz.tu-graz.ac.at>,  reintroduced and
 * updated by Chris Stenton <chris@gnome.co.uk> 8/10/94
 */

/*
 * Initialize the time of day register, based on the time base which is, e.g.
 * from a filesystem.
 */
void
inittodr(time_t base)
{
	struct timespec diff, ref, ts;
	int error;

	if (base) {
		ref.tv_sec = base;
		ref.tv_nsec = 0;
		tc_setclock(&ref);
	}

	if (clock_dev == NULL) {
		printf("warning: no time-of-day clock registered, system time "
		    "will not be set accurately\n");
		return;
	}
	error = CLOCK_GETTIME(clock_dev, &ts);
	if (error != 0 && error != EINVAL) {
		printf("warning: clock_gettime failed (%d), the system time "
		    "will not be set accurately\n", error);
		return;
	}
	if (error == EINVAL || ts.tv_sec < 0) {
		printf("Invalid time in real time clock.\n");
		printf("Check and reset the date immediately!\n");
	}

	ts.tv_sec += tz_minuteswest * 60 +
	    (wall_cmos_clock ? adjkerntz : 0);

	if (timespeccmp(&ref, &ts, >)) {
		diff = ref;
		timespecsub(&ref, &ts);
	} else {
		diff = ts;
		timespecsub(&diff, &ref);
	}
	if (ts.tv_sec >= 2) {
		/* badly off, adjust it */
		tc_setclock(&ts);
	}
}

/*
 * Write system time back to RTC
 */
void
resettodr()
{
	struct timespec ts;
	int error;

	if (disable_rtc_set || clock_dev == NULL)
		return;

	getnanotime(&ts);
	ts.tv_sec -= tz_minuteswest * 60 + (wall_cmos_clock ? adjkerntz : 0);
	if ((error = CLOCK_SETTIME(clock_dev, &ts)) != 0) {
		printf("warning: clock_settime failed (%d), time-of-day clock "
		    "not adjusted to system time\n", error);
		return;
	}
}
