/*
 * Copyright (c) 2006 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.
 *
 */

#include <sys/types.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/systimer.h>
#include <sys/sysctl.h>
#include <sys/signal.h>
#include <sys/interrupt.h>
#include <sys/bus.h>
#include <sys/time.h>
#include <machine/cpu.h>
#include <machine/clock.h>
#include <machine/globaldata.h>
#include <machine/md_var.h>
#include <machine/cothread.h>

#include <sys/thread2.h>

#include <unistd.h>
#include <signal.h>
#include <time.h>
#include <stdio.h>

int disable_rtc_set;
SYSCTL_INT(_machdep, CPU_DISRTCSET, disable_rtc_set,
           CTLFLAG_RW, &disable_rtc_set, 0, "");
SYSCTL_INT(_hw, OID_AUTO, tsc_present, CTLFLAG_RD,
            &tsc_present, 0, "TSC Available");
SYSCTL_INT(_hw, OID_AUTO, tsc_invariant, CTLFLAG_RD,
            &tsc_invariant, 0, "Invariant TSC");
SYSCTL_INT(_hw, OID_AUTO, tsc_mpsync, CTLFLAG_RD,
            &tsc_mpsync, 0, "TSC is synchronized across CPUs");
SYSCTL_QUAD(_hw, OID_AUTO, tsc_frequency, CTLFLAG_RD,
            &tsc_frequency, 0, "TSC Frequency");

int adjkerntz;
int wall_cmos_clock = 0;
SYSCTL_INT(_machdep, CPU_WALLCLOCK, wall_cmos_clock,
    CTLFLAG_RD, &wall_cmos_clock, 0, "");

static cothread_t vktimer_cotd;
static int vktimer_running;
static sysclock_t vktimer_target;
static struct timespec vktimer_ts;
static sysclock_t vktimer_reload[MAXCPU];

extern int use_precise_timer;

/*
 * SYSTIMER IMPLEMENTATION
 */
static sysclock_t vkernel_timer_get_timecount(void);
static void vkernel_timer_construct(struct cputimer *timer, sysclock_t oclock);
static void vktimer_thread(cothread_t cotd);

static struct cputimer vkernel_cputimer = {
        .next           = SLIST_ENTRY_INITIALIZER,
        .name           = "VKERNEL",
        .pri            = CPUTIMER_PRI_VKERNEL,
        .type           = CPUTIMER_VKERNEL,
        .count          = vkernel_timer_get_timecount,
        .fromhz         = cputimer_default_fromhz,
        .fromus         = cputimer_default_fromus,
        .construct      = vkernel_timer_construct,
        .destruct       = cputimer_default_destruct,
        .freq           = 1000000
};

static void     vktimer_intr_reload(struct cputimer_intr *, sysclock_t);
static void     vktimer_intr_initclock(struct cputimer_intr *, boolean_t);

static struct cputimer_intr vkernel_cputimer_intr = {
        .freq = 1000000,
        .reload = vktimer_intr_reload,
        .enable = cputimer_intr_default_enable,
        .config = cputimer_intr_default_config,
        .restart = cputimer_intr_default_restart,
        .pmfixup = cputimer_intr_default_pmfixup,
        .initclock = vktimer_intr_initclock,
        .pcpuhand = NULL,
        .next = SLIST_ENTRY_INITIALIZER,
        .name = "vkernel",
        .type = CPUTIMER_INTR_VKERNEL,
        .prio = CPUTIMER_INTR_PRIO_VKERNEL,
        .caps = CPUTIMER_INTR_CAP_NONE,
        .priv = NULL
};

/*
 * Initialize the systimer subsystem, called from MI code in early boot.
 */
static void
cpu_initclocks(void *arg __unused)
{
        kprintf("initclocks\n");
        cputimer_intr_register(&vkernel_cputimer_intr);
        cputimer_intr_select(&vkernel_cputimer_intr, 0);

        cputimer_register(&vkernel_cputimer);
        cputimer_select(&vkernel_cputimer, 0);
}
SYSINIT(clocksvk, SI_BOOT2_CLOCKREG, SI_ORDER_FIRST, cpu_initclocks, NULL);

/*
 * Constructor to initialize timer->base and get an initial count.
 */
static void
vkernel_timer_construct(struct cputimer *timer, sysclock_t oclock)
{
        timer->base = 0;
        timer->base = oclock - vkernel_timer_get_timecount();
}

/*
 * Get the current counter, with 2's complement rollover.
 *
 * NOTE! MPSAFE, possibly no critical section
 */
static sysclock_t
vkernel_timer_get_timecount(void)
{
        struct timespec ts;
        sysclock_t count;

        if (use_precise_timer)
                clock_gettime(CLOCK_MONOTONIC_PRECISE, &ts);
        else
                clock_gettime(CLOCK_MONOTONIC_FAST, &ts);
        count = ts.tv_nsec / 1000;
        count += (uint64_t)ts.tv_sec * 1000000;

        return count;
}

/*
 * Initialize the interrupt for our core systimer.
 */
static void
vktimer_intr_initclock(struct cputimer_intr *cti __unused,
                       boolean_t selected __unused)
{
        vktimer_target = sys_cputimer->count();

        vktimer_ts.tv_nsec = 1000000000 / 20;
        vktimer_cotd = cothread_create(vktimer_thread, NULL, NULL, "vktimer");
        while (vktimer_running == 0)
                usleep(1000000 / 10);
#if 0
        KKASSERT(kqueue_timer_info == NULL);
        kqueue_timer_info = kqueue_add_timer(vktimer_intr, NULL);
#endif
}

/*
 *
 */
static void
vktimer_sigint(int signo)
{
        /* do nothing, just interrupt */
}

static sysclock_t
vktimer_gettick_us(void)
{
        struct clockinfo info;
        int mib[] = { CTL_KERN, KERN_CLOCKRATE };
        size_t len = sizeof(info);

        if (sysctl(mib, NELEM(mib), &info, &len, NULL, 0) != 0 ||
            len != sizeof(info)) {
                /* Assume 10 milliseconds (== 100hz) */
                return 1000000 / 100;
        } else if (info.tick < 999999) {
                return info.tick;
        } else {
                /* Assume 10 milliseconds (== 100hz) */
                return 1000000 / 100;
        }
}

static void
vktimer_thread(cothread_t cotd)
{
        struct sigaction sa;
        globaldata_t gscan;
        sysclock_t ticklength_us;

        bzero(&sa, sizeof(sa));
        sa.sa_handler = vktimer_sigint;
        sa.sa_flags |= SA_NODEFER;
        sigemptyset(&sa.sa_mask);
        sigaction(SIGINT, &sa, NULL);

        ticklength_us = vktimer_gettick_us();
        vktimer_running = 1;
        while (vktimer_cotd == NULL)
                usleep(1000000 / 10);

        for (;;) {
                sysclock_t curtime;
                sysclock_t reload;
                ssysclock_t delta;
                sysclock_t freq;
                int n;

                /*
                 * Sleep
                 */
                cothread_sleep(cotd, &vktimer_ts);

rescan:
                freq = sys_cputimer->freq;
                curtime = sys_cputimer->count();
                reload = freq - 1;

                /*
                 * Reset the target
                 */
                for (n = 0; n < ncpus; ++n) {
                        gscan = globaldata_find(n);
                        delta = vktimer_reload[n] - curtime;
                        if (delta <= 0 && TAILQ_FIRST(&gscan->gd_systimerq))
                                pthread_kill(ap_tids[n], SIGURG);
                        if (delta > 0 && reload > delta)
                                reload = delta;
                }
                reload += curtime;
                vktimer_target = reload;

                /*
                 * Check for races
                 */
                reload -= curtime;
                for (n = 0; n < ncpus; ++n) {
                        gscan = globaldata_find(n);
                        delta = vktimer_reload[n] - curtime;
                        if (delta > 0 && reload > delta)
                                goto rescan;
                }
                if (sys_cputimer == &vkernel_cputimer &&
                    !use_precise_timer && reload < ticklength_us / 10) {
                        /*
                         * Avoid pointless short sleeps, when we only measure
                         * the current time at tick precision.
                         */
                        reload = ticklength_us / 10;
                }
                vktimer_ts.tv_nsec = muldivu64(reload, 1000000000, freq);
        }
}

/*
 * Reload the interrupt for our core systimer.  Because the caller's
 * reload calculation can be negatively indexed, we need a minimal
 * check to ensure that a reasonable reload value is selected.
 */
static void
vktimer_intr_reload(struct cputimer_intr *cti __unused, sysclock_t reload)
{
        if ((ssysclock_t)reload < 0)            /* neg value */
                reload = 1;
        if (reload >= sys_cputimer->freq)       /* max one second */
                reload = sys_cputimer->freq;
        reload += sys_cputimer->count();
        vktimer_reload[mycpu->gd_cpuid] = reload;
        if (vktimer_cotd && (ssysclock_t)(reload - vktimer_target) < 0) {
                while ((sysclock_t)(reload - vktimer_target) < 0)
                        reload = atomic_swap_long(&vktimer_target, reload);
                cothread_wakeup(vktimer_cotd, &vktimer_ts);
        }
}

/*
 * pcpu clock interrupt (hard interrupt)
 */
void
vktimer_intr(struct intrframe *frame)
{
        struct globaldata *gd = mycpu;
        sysclock_t sysclock_count;

        sysclock_count = sys_cputimer->count();
        ++gd->gd_cnt.v_timer;
        systimer_intr(&sysclock_count, 0, frame);
}

/*
 * 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 ts;
        struct timeval tv;

        gettimeofday(&tv, NULL);
        ts.tv_sec = tv.tv_sec;
        ts.tv_nsec = tv.tv_usec * 1000;
        set_timeofday(&ts);
}

/*
 * Write system time back to the RTC
 */
void
resettodr(void)
{
}

/*
 * We need to enter a critical section to prevent signals from recursing
 * into pthreads.
 */
void
DELAY(int usec)
{
        crit_enter();
        usleep(usec);
        crit_exit();
}

void
DRIVERSLEEP(int usec)
{
        if (mycpu->gd_intr_nesting_level)
                DELAY(usec);
        else if (1000000 / usec >= hz)
                tsleep(DRIVERSLEEP, 0, "DELAY", 1000000 / usec / hz + 1);
        else
                DELAY(usec);
}