/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2004 Poul-Henning Kamp
 * Copyright (c) 2013 iXsystems.com,
 *               author: Alfred Perlstein <alfred@freebsd.org>
 *
 * 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
 *    in this position and unchanged.
 * 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 AUTHORS ``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 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.
 *
 */

#include "opt_ddb.h"

#include <sys/param.h>
#include <sys/bus.h>
#include <sys/conf.h>
#include <sys/eventhandler.h>
#include <sys/kdb.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/module.h>
#include <sys/mutex.h>
#include <sys/sysctl.h>
#include <sys/syslog.h>
#include <sys/systm.h>
#include <sys/uio.h>
#include <sys/watchdog.h>
#include <machine/bus.h>

#include <sys/syscallsubr.h> /* kern_clock_gettime() */

#ifdef	COMPAT_FREEBSD14
#define WDIOCPATPAT_14	_IOW('W', 42, u_int)	/* pat the watchdog */
#define WDIOC_SETTIMEOUT_14   _IOW('W', 43, int)	/* set/reset the timer */
#define WDIOC_GETTIMEOUT_14    _IOR('W', 44, int)	/* get total timeout */
#define WDIOC_GETTIMELEFT_14   _IOR('W', 45, int)	/* get time left */
#define WDIOC_GETPRETIMEOUT_14 _IOR('W', 46, int)	/* get the pre-timeout */
#define WDIOC_SETPRETIMEOUT_14 _IOW('W', 47, int)	/* set the pre-timeout */
#endif

static int wd_set_pretimeout(sbintime_t newtimeout, int disableiftoolong);
static void wd_timeout_cb(void *arg);

static struct callout wd_pretimeo_handle;
static sbintime_t wd_pretimeout;
static int wd_pretimeout_act = WD_SOFT_LOG;

static struct callout wd_softtimeo_handle;
static int wd_softtimer;	/* true = use softtimer instead of hardware
				   watchdog */
static int wd_softtimeout_act = WD_SOFT_LOG;	/* action for the software timeout */

static struct cdev *wd_dev;
static volatile sbintime_t wd_last_sbt;	/* last timeout value (sbt) */
static sbintime_t wd_last_sbt_sysctl;	/* last timeout value (sbt) */
static volatile u_int wd_last_u;    /* last timeout value set by kern_do_pat */
static u_int wd_last_u_sysctl;    /* last timeout value set by kern_do_pat */
static u_int wd_last_u_sysctl_secs;    /* wd_last_u in seconds */

SYSCTL_NODE(_hw, OID_AUTO, watchdog, CTLFLAG_RD | CTLFLAG_MPSAFE, 0,
    "Main watchdog device");
SYSCTL_UINT(_hw_watchdog, OID_AUTO, wd_last_u, CTLFLAG_RD,
    &wd_last_u_sysctl, 0, "Watchdog last update time");
SYSCTL_UINT(_hw_watchdog, OID_AUTO, wd_last_u_secs, CTLFLAG_RD,
    &wd_last_u_sysctl_secs, 0, "Watchdog last update time");
SYSCTL_SBINTIME_MSEC(_hw_watchdog, OID_AUTO, wd_last_msecs, CTLFLAG_RD,
    &wd_last_sbt_sysctl, "Watchdog last update time (milliseconds)");

static int wd_lastpat_valid = 0;
static time_t wd_lastpat = 0;	/* when the watchdog was last patted */

/* Hook for external software watchdog to register for use if needed */
void (*wdog_software_attach)(void);

/* Legacy interface to watchdog. */
int
wdog_kern_pat(u_int utim)
{
	sbintime_t sbt;

	if ((utim & WD_LASTVAL) != 0 && (utim & WD_INTERVAL) > 0)
		return (EINVAL);

	if ((utim & WD_LASTVAL) != 0) {
		return (wdog_control(WD_CTRL_RESET));
	}

	utim &= WD_INTERVAL;
	if (utim == WD_TO_NEVER)
		sbt = 0;
	else
		sbt = nstosbt(1ULL << utim);

	return (wdog_kern_pat_sbt(sbt));
}

int
wdog_control(int ctrl)
{
	/* Disable takes precedence */
	if (ctrl == WD_CTRL_DISABLE) {
		wdog_kern_pat(0);
	}

	if ((ctrl & WD_CTRL_RESET) != 0) {
		wdog_kern_pat_sbt(wd_last_sbt);
	} else if ((ctrl & WD_CTRL_ENABLE) != 0) {
		wdog_kern_pat_sbt(wd_last_sbt);
	}

	return (0);
}

int
wdog_kern_pat_sbt(sbintime_t sbt)
{
	sbintime_t error_sbt = 0;
	int pow2ns = 0;
	int error = 0;
	static bool first = true;

	/* legacy uses power-of-2-nanoseconds time. */
	if (sbt != 0) {
		pow2ns = flsll(sbttons(sbt));
	}
	if (wd_last_sbt != sbt) {
		wd_last_u = pow2ns;
		wd_last_u_sysctl = wd_last_u;
		wd_last_u_sysctl_secs = sbt / SBT_1S;

		wd_last_sbt = sbt;
	}

	if (sbt != 0)
		error = EOPNOTSUPP;

	if (wd_softtimer) {
		if (sbt == 0) {
			callout_stop(&wd_softtimeo_handle);
		} else {
			(void) callout_reset_sbt(&wd_softtimeo_handle,
			    sbt, 0, wd_timeout_cb, "soft", 0);
		}
		error = 0;
	} else {
		EVENTHANDLER_INVOKE(watchdog_sbt_list, sbt, &error_sbt, &error);
		EVENTHANDLER_INVOKE(watchdog_list, pow2ns, &error);
	}
	/*
	 * If no hardware watchdog responded, we have not tried to
	 * attach an external software watchdog, and one is available,
	 * attach it now and retry.
	 */
	if (error == EOPNOTSUPP && first && wdog_software_attach != NULL) {
		(*wdog_software_attach)();
		EVENTHANDLER_INVOKE(watchdog_sbt_list, sbt, &error_sbt, &error);
		EVENTHANDLER_INVOKE(watchdog_list, pow2ns, &error);
	}
	first = false;

	/* TODO: Print a (rate limited?) warning if error_sbt is too far away */
	wd_set_pretimeout(wd_pretimeout, true);
	if (!error) {
		struct timespec ts;

		error = kern_clock_gettime(curthread /* XXX */,
		    CLOCK_MONOTONIC_FAST, &ts);
		if (!error) {
			wd_lastpat = ts.tv_sec;
			wd_lastpat_valid = 1;
		}
	}

	return (error);
}

static int
wd_valid_act(int act)
{

	if ((act & ~(WD_SOFT_MASK)) != 0)
		return false;
	return true;
}

#ifdef	COMPAT_FREEBSD14
static int
wd_ioctl_patpat(caddr_t data)
{
	u_int u;

	u = *(u_int *)data;
	if (u & ~(WD_ACTIVE | WD_PASSIVE | WD_LASTVAL | WD_INTERVAL))
		return (EINVAL);
	if ((u & (WD_ACTIVE | WD_PASSIVE)) == (WD_ACTIVE | WD_PASSIVE))
		return (EINVAL);
	if ((u & (WD_ACTIVE | WD_PASSIVE)) == 0 && ((u & WD_INTERVAL) > 0 ||
	    (u & WD_LASTVAL) != 0))
		return (EINVAL);
	if (u & WD_PASSIVE)
		return (ENOSYS);	/* XXX Not implemented yet */
	u &= ~(WD_ACTIVE | WD_PASSIVE);

	return (wdog_kern_pat(u));
}
#endif

static int
wd_get_time_left(struct thread *td, time_t *remainp)
{
	struct timespec ts;
	int error;

	error = kern_clock_gettime(td, CLOCK_MONOTONIC_FAST, &ts);
	if (error)
		return (error);
	if (!wd_lastpat_valid)
		return (ENOENT);
	*remainp = ts.tv_sec - wd_lastpat;
	return (0);
}

static void
wd_timeout_cb(void *arg)
{
	const char *type = arg;

#ifdef DDB
	if ((wd_pretimeout_act & WD_SOFT_DDB)) {
		char kdb_why[80];
		snprintf(kdb_why, sizeof(kdb_why), "watchdog %s-timeout", type);
		kdb_backtrace();
		kdb_enter(KDB_WHY_WATCHDOG, kdb_why);
	}
#endif
	if ((wd_pretimeout_act & WD_SOFT_LOG))
		log(LOG_EMERG, "watchdog %s-timeout, WD_SOFT_LOG\n", type);
	if ((wd_pretimeout_act & WD_SOFT_PRINTF))
		printf("watchdog %s-timeout, WD_SOFT_PRINTF\n", type);
	if ((wd_pretimeout_act & WD_SOFT_PANIC))
		panic("watchdog %s-timeout, WD_SOFT_PANIC set", type);
}

/*
 * Called to manage timeouts.
 * newtimeout needs to be in the range of 0 to actual watchdog timeout.
 * if 0, we disable the pre-timeout.
 * otherwise we set the pre-timeout provided it's not greater than the
 * current actual watchdog timeout.
 */
static int
wd_set_pretimeout(sbintime_t newtimeout, int disableiftoolong)
{
	sbintime_t utime;
	sbintime_t timeout_left;

	utime = wdog_kern_last_timeout_sbt();
	/* do not permit a pre-timeout >= than the timeout. */
	if (newtimeout >= utime) {
		/*
		 * If 'disableiftoolong' then just fall through
		 * so as to disable the pre-watchdog
		 */
		if (disableiftoolong)
			newtimeout = 0;
		else
			return EINVAL;
	}

	/* disable the pre-timeout */
	if (newtimeout == 0) {
		wd_pretimeout = 0;
		callout_stop(&wd_pretimeo_handle);
		return 0;
	}

	timeout_left = utime - newtimeout;
#if 0
	printf("wd_set_pretimeout: "
	    "newtimeout: %d, "
	    "utime: %d -> utime_ticks: %d, "
	    "hz*newtimeout: %d, "
	    "timeout_ticks: %d -> sec: %d\n",
	    newtimeout,
	    utime, pow2ns_to_ticks(utime),
	    hz*newtimeout,
	    timeout_ticks, timeout_ticks / hz);
#endif

	/* We determined the value is sane, so reset the callout */
	(void) callout_reset_sbt(&wd_pretimeo_handle,
	    timeout_left, 0, wd_timeout_cb, "pre", 0);
	wd_pretimeout = newtimeout;
	return 0;
}

static int
wd_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t data,
    int flags __unused, struct thread *td)
{
	sbintime_t sb;
	u_int u;
	time_t timeleft;
	int error;

	error = 0;

	switch (cmd) {
	case WDIOC_SETSOFT:
		u = *(int *)data;
		/* do nothing? */
		if (u == wd_softtimer)
			break;
		/* If there is a pending timeout disallow this ioctl */
		if (wd_last_u != 0) {
			error = EINVAL;
			break;
		}
		wd_softtimer = u;
		break;
	case WDIOC_SETSOFTTIMEOUTACT:
		u = *(int *)data;
		if (wd_valid_act(u)) {
			wd_softtimeout_act = u;
		} else {
			error = EINVAL;
		}
		break;
	case WDIOC_SETPRETIMEOUTACT:
		u = *(int *)data;
		if (wd_valid_act(u)) {
			wd_pretimeout_act = u;
		} else {
			error = EINVAL;
		}
		break;
#ifdef	COMPAT_FREEBSD14
	case WDIOC_GETPRETIMEOUT_14:
		*(int *)data = (int)(wd_pretimeout / SBT_1S);
		break;
	case WDIOC_SETPRETIMEOUT_14:
		error = wd_set_pretimeout(*(int *)data * SBT_1S, false);
		break;
	case WDIOC_GETTIMELEFT_14:
		error = wd_get_time_left(td, &timeleft);
		if (error)
			break;
		*(int *)data = (int)timeleft;
		break;
	case WDIOC_SETTIMEOUT_14:
		u = *(u_int *)data;
		error = wdog_kern_pat_sbt(mstosbt(u * 1000ULL));
		break;
	case WDIOC_GETTIMEOUT_14:
		u = wdog_kern_last_timeout();
		*(u_int *)data = u;
		break;
	case WDIOCPATPAT_14:
		error = wd_ioctl_patpat(data);
		break;
#endif

	/* New API */
	case WDIOC_CONTROL:
		wdog_control(*(int *)data);
		break;
	case WDIOC_SETTIMEOUT:
		sb = *(sbintime_t *)data;
		error = wdog_kern_pat_sbt(sb);
		break;
	case WDIOC_GETTIMEOUT:
		*(sbintime_t *)data = wdog_kern_last_timeout_sbt();
		break;
	case WDIOC_GETTIMELEFT:
		error = wd_get_time_left(td, &timeleft);
		if (error)
			break;
		*(sbintime_t *)data = (sbintime_t)timeleft * SBT_1S;
		break;
	case WDIOC_GETPRETIMEOUT:
		*(sbintime_t *)data = wd_pretimeout;
		break;
	case WDIOC_SETPRETIMEOUT:
		error = wd_set_pretimeout(*(sbintime_t *)data, false);
		break;
	default:
		error = ENOIOCTL;
		break;
	}
	return (error);
}

/*
 * Return the last timeout set, this is NOT the seconds from NOW until timeout,
 * rather it is the amount of seconds passed to WDIOCPATPAT/WDIOC_SETTIMEOUT.
 */
u_int
wdog_kern_last_timeout(void)
{

	return (wd_last_u);
}

sbintime_t
wdog_kern_last_timeout_sbt(void)
{
	return (wd_last_sbt);
}

static struct cdevsw wd_cdevsw = {
	.d_version =	D_VERSION,
	.d_ioctl =	wd_ioctl,
	.d_name =	"watchdog",
};

static int
watchdog_modevent(module_t mod __unused, int type, void *data __unused)
{
	switch(type) {
	case MOD_LOAD:
		callout_init(&wd_pretimeo_handle, 1);
		callout_init(&wd_softtimeo_handle, 1);
		wd_dev = make_dev(&wd_cdevsw, 0,
		    UID_ROOT, GID_WHEEL, 0600, _PATH_WATCHDOG);
		return 0;
	case MOD_UNLOAD:
		callout_stop(&wd_pretimeo_handle);
		callout_stop(&wd_softtimeo_handle);
		callout_drain(&wd_pretimeo_handle);
		callout_drain(&wd_softtimeo_handle);
		destroy_dev(wd_dev);
		return 0;
	case MOD_SHUTDOWN:
		return 0;
	default:
		return EOPNOTSUPP;
	}
}

DEV_MODULE(watchdog, watchdog_modevent, NULL);