/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma ident   "%Z%%M% %I%     %E% SMI"

#include <sys/types.h>
#include <sys/hsvc.h>
#include <sys/wdt.h>
#include <sys/cmn_err.h>
#include <sys/cyclic.h>
#include <sys/kmem.h>
#include <sys/systm.h>
#include <sys/sysmacros.h>
#include <sys/hypervisor_api.h>
#include <sys/mach_descrip.h>
#include <sys/mdesc.h>

#define WDT_ON                  1
#define WDT_OFF                 0

/*
 * MILLISEC defines the number of milliseconds in a second.
 */
#define WDT_DEFAULT_RESOLUTION  (1 * MILLISEC)  /* Default resolution = 1s */
#define WDT_MIN_TIMEOUT         (1 * MILLISEC)  /* Minimum timeout = 1s */
#define WDT_REGULAR_TIMEOUT     (10 * MILLISEC) /* Default timeout = 10s */
#define WDT_LONG_TIMEOUT        (60 * MILLISEC) /* Long timeout = 60s */

#define WDT_MIN_COREAPI_MAJOR   1
#define WDT_MIN_COREAPI_MINOR   1

static void config_watchdog(uint64_t, int);
static void watchdog_cyclic_init(hrtime_t);

/*
 * Flag used to pat/suspend/resume the watchdog timer.
 */
int watchdog_activated = WDT_OFF;

/*
 * Tuneable to control watchdog functionality. Watchdog can be
 * disabled via /etc/system.
 */
int watchdog_enabled = 1;
static int watchdog_initialized = 0;

/*
 * The following tuneable can be set via /etc/system to control
 * watchdog pat frequency, which is set to approximately 44% of
 * the timeout value.
 */
static uint64_t watchdog_timeout = WDT_REGULAR_TIMEOUT;

static uint64_t watchdog_long_timeout = WDT_LONG_TIMEOUT;
static uint64_t watchdog_resolution = WDT_DEFAULT_RESOLUTION;

void
watchdog_init(void)
{
        int num_nodes;
        int nplat;
        md_t *mdp;
        mde_cookie_t *listp = NULL;
        int listsz;
        uint64_t major;
        uint64_t minor;
        uint64_t watchdog_max_timeout;
        hrtime_t cyclic_interval;

        if (!watchdog_enabled) {
                return;
        }

        if (hsvc_version(HSVC_GROUP_CORE, &major, &minor) != 0 ||
            major != WDT_MIN_COREAPI_MAJOR ||
            minor < WDT_MIN_COREAPI_MINOR) {
                cmn_err(CE_NOTE, "Disabling watchdog as watchdog services are "
                    "not available\n");
                watchdog_enabled = 0;
                return;
        }

        /*
         * Get the watchdog-max-timeout and watchdog-resolution MD properties.
         */
        if ((mdp = md_get_handle()) == NULL) {
                cmn_err(CE_WARN, "Unable to initialize machine description, "
                    "watchdog is disabled.");
                watchdog_enabled = 0;
                return;
        }

        num_nodes = md_node_count(mdp);
        ASSERT(num_nodes > 0);

        listsz = num_nodes * sizeof (mde_cookie_t);
        listp = kmem_zalloc(listsz, KM_SLEEP);

        nplat = md_scan_dag(mdp, md_root_node(mdp),
            md_find_name(mdp, "platform"), md_find_name(mdp, "fwd"), listp);

        ASSERT(nplat == 1);

        if (md_get_prop_val(mdp, listp[0], "watchdog-max-timeout",
            &watchdog_max_timeout) || watchdog_max_timeout < WDT_MIN_TIMEOUT) {
                cmn_err(CE_WARN, "Invalid watchdog-max-timeout, watchdog "
                    "is disabled.");
                watchdog_enabled = 0;
                kmem_free(listp, listsz);
                (void) md_fini_handle(mdp);
                return;
        }

        /*
         * Make sure that watchdog timeout value is within limits.
         */
        if (watchdog_timeout < WDT_MIN_TIMEOUT)
                watchdog_timeout = WDT_MIN_TIMEOUT;
        else if (watchdog_timeout > WDT_LONG_TIMEOUT)
                watchdog_timeout = WDT_LONG_TIMEOUT;

        if (watchdog_timeout > watchdog_max_timeout)
                watchdog_timeout = watchdog_max_timeout;

        if (watchdog_long_timeout > watchdog_max_timeout)
                watchdog_long_timeout = watchdog_max_timeout;

        if (md_get_prop_val(mdp, listp[0], "watchdog-resolution",
            &watchdog_resolution)) {
                cmn_err(CE_WARN, "Cannot read watchdog-resolution, watchdog "
                    "is disabled.");
                watchdog_enabled = 0;
                kmem_free(listp, listsz);
                (void) md_fini_handle(mdp);
                return;
        }

        if (watchdog_resolution == 0 ||
            watchdog_resolution > WDT_DEFAULT_RESOLUTION)
                watchdog_resolution = WDT_DEFAULT_RESOLUTION;

        kmem_free(listp, listsz);
        (void) md_fini_handle(mdp);

        /*
         * round the timeout to the nearest smaller value.
         */
        watchdog_long_timeout -=
            watchdog_long_timeout % watchdog_resolution;
        watchdog_timeout -=
            watchdog_timeout % watchdog_resolution;

        /*
         * Cyclic need to be fired twice the frequency of regular
         * watchdog timeout. Pedantic here and setting cyclic
         * frequency to approximately 44% of watchdog_timeout.
         */
        cyclic_interval = (watchdog_timeout >> 1) - (watchdog_timeout >> 4);
        /*
         * Note that regular timeout interval is in millisecond,
         * therefore to get cyclic interval in nanosecond need to
         * multiply by MICROSEC.
         */
        cyclic_interval *= MICROSEC;

        watchdog_cyclic_init(cyclic_interval);
        watchdog_initialized = 1;
        config_watchdog(watchdog_timeout, WDT_ON);
}

/*
 * Pat the watchdog timer periodically using the hypervisor API.
 * Regular pat occurs when the system runs normally.
 * Long pat is when system panics.
 */
void
watchdog_pat()
{
        if (watchdog_enabled && watchdog_activated) {
                if (panicstr)
                        config_watchdog(watchdog_long_timeout, WDT_ON);
                else
                        config_watchdog(watchdog_timeout, WDT_ON);
        }
}

/*
 * We don't save/restore the remaining watchdog timeout time at present.
 */
void
watchdog_suspend()
{
        if (watchdog_enabled && watchdog_activated) {
                config_watchdog(0, WDT_OFF);
        }
}

/*
 * We don't save/restore the remaining watchdog timeout time at present.
 */
void
watchdog_resume()
{
        if (watchdog_enabled && !watchdog_activated) {
                if (panicstr) {
                        config_watchdog(watchdog_long_timeout, WDT_ON);
                } else {
                        config_watchdog(watchdog_timeout, WDT_ON);
                }
        }
}

void
watchdog_clear()
{
        if (watchdog_enabled && watchdog_activated) {
                config_watchdog(0, WDT_OFF);
        }
}

static void
config_watchdog(uint64_t timeout, int new_state)
{
        uint64_t time_remaining;
        uint64_t ret;

        if (watchdog_initialized) {
                watchdog_activated = new_state;
                ret = hv_mach_set_watchdog(timeout, &time_remaining);
                if (ret != H_EOK) {
                        cmn_err(CE_WARN, "Failed to operate on the watchdog. "
                            "Error = 0x%lx", ret);
                        watchdog_enabled = 0;
                }
        }
}

/*
 * Once the watchdog cyclic is initialized, it won't be removed.
 * The only way to not add the watchdog cyclic is to disable the watchdog
 * by setting the watchdog_enabled to 0 in /etc/system file.
 */
static void
watchdog_cyclic_init(hrtime_t wdt_cyclic_interval)
{
        cyc_handler_t hdlr;
        cyc_time_t when;

        hdlr.cyh_func = (cyc_func_t)watchdog_pat;
        hdlr.cyh_level = CY_HIGH_LEVEL;
        hdlr.cyh_arg = NULL;

        when.cyt_when = 0;
        when.cyt_interval = wdt_cyclic_interval;

        mutex_enter(&cpu_lock);
        (void) cyclic_add(&hdlr, &when);
        mutex_exit(&cpu_lock);
}