/*
 * Copyright (c) 2005 The DragonFly Project.  All rights reserved.
 *
 * This code is derived from software contributed to The DragonFly Project
 * by Matthew Dillon <dillon@backplane.com>
 *
 * 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 DragonFly Project 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 COPYRIGHT HOLDERS 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
 * COPYRIGHT HOLDERS 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.
 */
/*
 * Generic cputimer - access to a reliable, free-running counter.
 */

#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/systm.h>
#include <sys/thread.h>
#include <sys/globaldata.h>
#include <sys/serialize.h>
#include <sys/systimer.h>
#include <sys/sysctl.h>

extern void     pcpu_timer_process(void);
extern void     pcpu_timer_process_frame(struct intrframe *);

static uint64_t dummy_cpucounter_count(void);

static sysclock_t dummy_cputimer_count(void);

static struct cputimer dummy_cputimer = {
    .next               = SLIST_ENTRY_INITIALIZER,
    .name               = "dummy",
    .pri                = CPUTIMER_PRI_DUMMY,
    .type               = CPUTIMER_DUMMY,
    .count              = dummy_cputimer_count,
    .fromhz             = cputimer_default_fromhz,
    .fromus             = cputimer_default_fromus,
    .construct          = cputimer_default_construct,
    .destruct           = cputimer_default_destruct,
    .freq               = 1000000,
    .freq64_usec        = (1000000LL << 32) / 1000000,
    .freq64_nsec        = (1000000000LL << 32) / 1000000
};

static struct cpucounter dummy_cpucounter = {
        .freq           = 1000000ULL,
        .count          = dummy_cpucounter_count,
        .flags          = CPUCOUNTER_FLAG_MPSYNC,
        .prio           = CPUCOUNTER_PRIO_DUMMY,
        .type           = CPUCOUNTER_DUMMY
};

struct cputimer *sys_cputimer = &dummy_cputimer;
SLIST_HEAD(, cputimer) cputimerhead = SLIST_HEAD_INITIALIZER(&cputimerhead);

static SLIST_HEAD(, cpucounter) cpucounterhead =
    SLIST_HEAD_INITIALIZER(cpucounterhead);

static int      cputimer_intr_ps_reqs;
static struct lwkt_serialize cputimer_intr_ps_slize =
    LWKT_SERIALIZE_INITIALIZER;

/*
 * Generic cputimer API
 */
void
cputimer_select(struct cputimer *timer, int pri)
{
    sysclock_t oldclock, newclock;
    struct cputimer *oldtimer;

    /*
     * Calculate helper fields
     */
    cputimer_set_frequency(timer, timer->freq);

    /*
     * Install a new cputimer if its priority allows it.
     */
    if (pri == 0)
        pri = timer->pri;
    if (pri >= sys_cputimer->pri) {
        oldtimer = sys_cputimer;
        oldclock = oldtimer->count();
        timer->construct(timer, oldclock);
        newclock = timer->count();
        if (newclock < oldclock) {
                kprintf("Warning: timer %s jumped backward! "
                        "oldclock=%ju, newclock=%ju\n",
                        timer->name, (uintmax_t)oldclock, (uintmax_t)newclock);
        }
        cputimer_intr_config(timer);
        sys_cputimer = timer;
        oldtimer->destruct(oldtimer);
        systimer_changed();
    }
}

/*
 * Register a timer.  If the timer has already been registered, do nothing.
 */
void
cputimer_register(struct cputimer *timer)
{
    struct cputimer *scan;

    /*
     * Initialize dummy_cputimer if the slist is empty, it does not get
     * registered the normal way.
     */
    if (SLIST_EMPTY(&cputimerhead))
        SLIST_FIRST(&cputimerhead) = &dummy_cputimer;
    SLIST_FOREACH(scan, &cputimerhead, next) {
        if (scan == timer)
            return;
    }
    SLIST_INSERT_HEAD(&cputimerhead, timer, next);
}

/*
 * Deregister a timer.  If the timer has already been deregistered, do nothing.
 */
void
cputimer_deregister(struct cputimer *timer)
{
    struct cputimer *scan;
    struct cputimer *best;

    /*
     * Locate and remove the timer.  If the timer is our currently active
     * timer, revert to the dummy timer.
     */
    SLIST_FOREACH(scan, &cputimerhead, next) {
        if (timer == scan) {
            if (timer == sys_cputimer)
                cputimer_select(&dummy_cputimer, 0x7FFFFFFF);
            SLIST_REMOVE(&cputimerhead, timer, cputimer, next);
            break;
        }
    }

    /*
     * If sys_cputimer reverted to the dummy, select the best one
     */
    if (sys_cputimer == &dummy_cputimer) {
        best = NULL;
        SLIST_FOREACH(scan, &cputimerhead, next) {
            if (best == NULL || scan->pri > best->pri)
                best = scan;
        }
        if (best)
            cputimer_select(best, 0x7FFFFFFF);
    }
}

/*
 * Calculate usec / tick and nsec / tick, scaled by (1 << 32).
 *
 * so e.g. a 3 mhz timer would be 3 usec / tick x (1 << 32),
 * or 3000 nsec / tick x (1 << 32)
 */
void
cputimer_set_frequency(struct cputimer *timer, sysclock_t freq)
{
    timer->freq = freq;
    timer->freq64_usec = (1000000LL << 32) / freq;
    timer->freq64_nsec = (1000000000LL << 32) / freq;
    if (timer == sys_cputimer)
        cputimer_intr_config(timer);
}

sysclock_t
cputimer_default_fromhz(int64_t freq)
{
    return(sys_cputimer->freq / freq + 1);
}

sysclock_t
cputimer_default_fromus(int64_t us)
{
    return muldivu64(us, sys_cputimer->freq, 1000000);
}

/*
 * Dummy counter implementation
 */
static
sysclock_t
dummy_cputimer_count(void)
{
    return(++dummy_cputimer.base);
}

void
cputimer_default_construct(struct cputimer *cputimer, sysclock_t oldclock)
{
    cputimer->base = oldclock;
}

void
cputimer_default_destruct(struct cputimer *cputimer)
{
}

/************************************************************************
 *                              SYSCTL SUPPORT                          *
 ************************************************************************
 *
 * Note: the ability to change the systimer is not currently enabled
 * because it will mess up systimer calculations.  You have to live
 * with what is configured at boot.
 */
static int
sysctl_cputimer_reglist(SYSCTL_HANDLER_ARGS)
{
    struct cputimer *scan;
    int error = 0;
    int loop = 0;

    /*
     * Build a list of available timers
     */
    SLIST_FOREACH(scan, &cputimerhead, next) {
        if (error == 0 && loop)
            error = SYSCTL_OUT(req, " ", 1);
        if (error == 0)
            error = SYSCTL_OUT(req, scan->name, strlen(scan->name));
        ++loop;
    }
    return (error);
}

static int
sysctl_cputimer_name(SYSCTL_HANDLER_ARGS)
{
    int error;

    error = SYSCTL_OUT(req, sys_cputimer->name, strlen(sys_cputimer->name));
    return (error);
}

static int
sysctl_cputimer_clock(SYSCTL_HANDLER_ARGS)
{
    sysclock_t clock;
    int error;

    clock = sys_cputimer->count();
    error = SYSCTL_OUT(req, &clock, sizeof(clock));
    return (error);
}

static int
sysctl_cputimer_freq(SYSCTL_HANDLER_ARGS)
{
    int error;

    error = SYSCTL_OUT(req, &sys_cputimer->freq, sizeof(sys_cputimer->freq));
    return (error);
}

SYSCTL_DECL(_kern_cputimer);
SYSCTL_NODE(_kern, OID_AUTO, cputimer, CTLFLAG_RW, NULL, "cputimer");

SYSCTL_PROC(_kern_cputimer, OID_AUTO, select, CTLTYPE_STRING|CTLFLAG_RD,
            NULL, 0, sysctl_cputimer_reglist, "A", "");
SYSCTL_PROC(_kern_cputimer, OID_AUTO, name, CTLTYPE_STRING|CTLFLAG_RD,
            NULL, 0, sysctl_cputimer_name, "A", "");
SYSCTL_PROC(_kern_cputimer, OID_AUTO, clock, CTLTYPE_ULONG|CTLFLAG_RD,
            NULL, 0, sysctl_cputimer_clock, "LU", "");
SYSCTL_PROC(_kern_cputimer, OID_AUTO, freq, CTLTYPE_LONG|CTLFLAG_RD,
            NULL, 0, sysctl_cputimer_freq, "L", "");

static struct cputimer_intr *sys_cputimer_intr;
static uint32_t cputimer_intr_caps;
SLIST_HEAD(, cputimer_intr) cputimer_intr_head =
        SLIST_HEAD_INITIALIZER(&cputimer_intr_head);

void
cputimer_intr_register(struct cputimer_intr *cti)
{
    struct cputimer_intr *scan;

    SLIST_FOREACH(scan, &cputimer_intr_head, next) {
        if (scan == cti)
            return;
    }
    cti->config(cti, sys_cputimer);
    SLIST_INSERT_HEAD(&cputimer_intr_head, cti, next);
}

void
cputimer_intr_deregister(struct cputimer_intr *cti)
{
    KKASSERT(cti != sys_cputimer_intr);
    SLIST_REMOVE(&cputimer_intr_head, cti, cputimer_intr, next);
}

int
cputimer_intr_select(struct cputimer_intr *cti, int prio)
{
    KKASSERT(cti != NULL);

    if (prio == 0)
        prio = cti->prio;

    if (sys_cputimer_intr == NULL) {
        KKASSERT(cputimer_intr_caps == 0);
        sys_cputimer_intr = cti;
        return 0;
    }

    if ((cti->caps & cputimer_intr_caps) == cputimer_intr_caps) {
        if (prio > sys_cputimer_intr->prio) {
            sys_cputimer_intr = cti;
            return 0;
        } else {
            return EBUSY;
        }
    } else {
        return EOPNOTSUPP;
    }
}

void
cputimer_intr_default_enable(struct cputimer_intr *cti __unused)
{
}

void
cputimer_intr_default_restart(struct cputimer_intr *cti)
{
    cti->reload(cti, 0);
}

void
cputimer_intr_default_config(struct cputimer_intr *cti __unused,
                             const struct cputimer *timer __unused)
{
}

void
cputimer_intr_default_pmfixup(struct cputimer_intr *cti __unused)
{
}

void
cputimer_intr_default_initclock(struct cputimer_intr *cti __unused,
                                boolean_t selected __unused)
{
}

void
cputimer_intr_enable(void)
{
    struct cputimer_intr *cti;

    SLIST_FOREACH(cti, &cputimer_intr_head, next)
        cti->enable(cti);
}

void
cputimer_intr_config(const struct cputimer *timer)
{
    struct cputimer_intr *cti;

    SLIST_FOREACH(cti, &cputimer_intr_head, next)
        cti->config(cti, timer);
}

void
cputimer_intr_pmfixup(void)
{
    struct cputimer_intr *cti;

    SLIST_FOREACH(cti, &cputimer_intr_head, next)
        cti->pmfixup(cti);
}

void
cputimer_intr_reload(sysclock_t reload)
{
    struct cputimer_intr *cti = sys_cputimer_intr;

    cti->reload(cti, reload);
}

void
cputimer_intr_restart(void)
{
    struct cputimer_intr *cti = sys_cputimer_intr;

    cti->restart(cti);
}

int
cputimer_intr_select_caps(uint32_t caps)
{
    struct cputimer_intr *cti, *maybe;
    int error;

    maybe = NULL;
    SLIST_FOREACH(cti, &cputimer_intr_head, next) {
        if ((cti->caps & caps) == caps) {
            if (maybe == NULL)
                maybe = cti;
            else if (cti->prio > maybe->prio)
                maybe = cti;
        }
    }
    if (maybe == NULL)
        return ENOENT;

    if (sys_cputimer_intr == maybe)
        return 0;

    cputimer_intr_caps = caps;
    error = cputimer_intr_select(maybe, CPUTIMER_INTR_PRIO_MAX);
    KKASSERT(!error);

    return ERESTART;
}

static void
cputimer_intr_initclocks(void)
{
    struct cputimer_intr *cti, *ncti;

    /*
     * An interrupt cputimer may deregister itself,
     * so use SLIST_FOREACH_MUTABLE here.
     */
    SLIST_FOREACH_MUTABLE(cti, &cputimer_intr_head, next, ncti) {
        boolean_t selected = FALSE;

        if (cti == sys_cputimer_intr)
            selected = TRUE;
        cti->initclock(cti, selected);
    }
}
/* NOTE: Must be SECOND to allow platform initialization to go first */
SYSINIT(cputimer_intr, SI_BOOT2_CLOCKREG, SI_ORDER_SECOND,
        cputimer_intr_initclocks, NULL);

static int
sysctl_cputimer_intr_reglist(SYSCTL_HANDLER_ARGS)
{
    struct cputimer_intr *scan;
    int error = 0;
    int loop = 0;

    /*
     * Build a list of available interrupt cputimers
     */
    SLIST_FOREACH(scan, &cputimer_intr_head, next) {
        if (error == 0 && loop)
            error = SYSCTL_OUT(req, " ", 1);
        if (error == 0)
            error = SYSCTL_OUT(req, scan->name, strlen(scan->name));
        ++loop;
    }
    return (error);
}

static int
sysctl_cputimer_intr_freq(SYSCTL_HANDLER_ARGS)
{
    int error;

    error = SYSCTL_OUT(req, &sys_cputimer_intr->freq,
                       sizeof(sys_cputimer_intr->freq));
    return (error);
}

static int
sysctl_cputimer_intr_select(SYSCTL_HANDLER_ARGS)
{
    struct cputimer_intr *cti;
    char name[32];
    int error;

    ksnprintf(name, sizeof(name), "%s", sys_cputimer_intr->name);
    error = sysctl_handle_string(oidp, name, sizeof(name), req);
    if (error != 0 || req->newptr == NULL)
        return error;

    SLIST_FOREACH(cti, &cputimer_intr_head, next) {
        if (strcmp(cti->name, name) == 0)
            break;
    }
    if (cti == NULL)
        return ENOENT;
    if (cti == sys_cputimer_intr)
        return 0;

    error = cputimer_intr_select(cti, CPUTIMER_INTR_PRIO_MAX);
    if (!error)
        cputimer_intr_restart();
    return error;
}

SYSCTL_NODE(_kern_cputimer, OID_AUTO, intr, CTLFLAG_RW, NULL,
            "interrupt cputimer");

SYSCTL_PROC(_kern_cputimer_intr, OID_AUTO, reglist, CTLTYPE_STRING|CTLFLAG_RD,
            NULL, 0, sysctl_cputimer_intr_reglist, "A", "");
SYSCTL_PROC(_kern_cputimer_intr, OID_AUTO, freq, CTLTYPE_LONG|CTLFLAG_RD,
            NULL, 0, sysctl_cputimer_intr_freq, "L", "");
SYSCTL_PROC(_kern_cputimer_intr, OID_AUTO, select, CTLTYPE_STRING|CTLFLAG_RW,
            NULL, 0, sysctl_cputimer_intr_select, "A", "");

int
cputimer_intr_powersave_addreq(void)
{
    int error = 0;

    lwkt_serialize_enter(&cputimer_intr_ps_slize);

    ++cputimer_intr_ps_reqs;
    if (cputimer_intr_ps_reqs == 1) {
        /*
         * Upon the first power saving request, switch to an one shot
         * timer, which would not stop in the any power saving state.
         */
        error = cputimer_intr_select_caps(CPUTIMER_INTR_CAP_PS);
        if (error == ERESTART) {
            error = 0;
            if (bootverbose)
                kprintf("cputimer: first power save request, restart\n");
            cputimer_intr_restart();
        } else if (error) {
            kprintf("no suitable intr cputimer found\n");
            --cputimer_intr_ps_reqs;
        } else if (bootverbose) {
            kprintf("cputimer: first power save request\n");
        }
    }

    lwkt_serialize_exit(&cputimer_intr_ps_slize);

    return error;
}

void
cputimer_intr_powersave_remreq(void)
{
    lwkt_serialize_enter(&cputimer_intr_ps_slize);

    KASSERT(cputimer_intr_ps_reqs > 0,
        ("invalid # of powersave reqs %d", cputimer_intr_ps_reqs));
    --cputimer_intr_ps_reqs;
    if (cputimer_intr_ps_reqs == 0) {
        int error;

        /* No one needs power saving, use a better one shot timer. */
        error = cputimer_intr_select_caps(CPUTIMER_INTR_CAP_NONE);
        KKASSERT(!error || error == ERESTART);
        if (error == ERESTART) {
            if (bootverbose)
                kprintf("cputimer: no powser save request, restart\n");
            cputimer_intr_restart();
        } else if (bootverbose) {
            kprintf("cputimer: no power save request\n");
        }
    }

    lwkt_serialize_exit(&cputimer_intr_ps_slize);
}

static __inline void
cputimer_intr_pcpuhand(void)
{
    struct cputimer_intr *cti = sys_cputimer_intr;

    if (cti->pcpuhand != NULL)
        cti->pcpuhand(cti);
}

static void
pcpu_timer_process_oncpu(struct globaldata *gd, struct intrframe *frame)
{
        sysclock_t count;

        cputimer_intr_pcpuhand();

        gd->gd_timer_running = 0;

        count = sys_cputimer->count();
        if (TAILQ_FIRST(&gd->gd_systimerq) != NULL)
                systimer_intr(&count, 0, frame);
}

void
pcpu_timer_process(void)
{
        pcpu_timer_process_oncpu(mycpu, NULL);
}

void
pcpu_timer_process_frame(struct intrframe *frame)
{
        pcpu_timer_process_oncpu(mycpu, frame);
}

static uint64_t
dummy_cpucounter_count(void)
{
        struct timeval tv;

        microuptime(&tv);
        return ((tv.tv_sec * 1000000ULL) + tv.tv_usec);
}

const struct cpucounter *
cpucounter_find_pcpu(void)
{
        const struct cpucounter *cc, *ret;

        ret = &dummy_cpucounter;
        SLIST_FOREACH(cc, &cpucounterhead, link) {
                if (cc->prio > ret->prio)
                        ret = cc;
        }
        return (ret);
}

const struct cpucounter *
cpucounter_find(void)
{
        const struct cpucounter *cc, *ret;

        ret = &dummy_cpucounter;
        SLIST_FOREACH(cc, &cpucounterhead, link) {
                if ((cc->flags & CPUCOUNTER_FLAG_MPSYNC) &&
                    cc->prio > ret->prio)
                        ret = cc;
        }
        KASSERT(ret->flags & CPUCOUNTER_FLAG_MPSYNC,
            ("cpucounter %u is not MPsync", ret->type));
        return (ret);
}

void
cpucounter_register(struct cpucounter *cc)
{

        SLIST_INSERT_HEAD(&cpucounterhead, cc, link);
}