/*-
 * Copyright (c) 2014 Tycho Nightingale <tycho.nightingale@pluribusnetworks.com>
 * Copyright (c) 2011 NetApp, Inc.
 * All rights reserved.
 * Copyright (c) 2018 Joyent, Inc.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY NETAPP, INC ``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 NETAPP, INC 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/cdefs.h>
#include "opt_bhyve_snapshot.h"

#include <sys/param.h>
#include <sys/types.h>
#include <sys/queue.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/systm.h>

#include <machine/vmm.h>
#include <machine/vmm_snapshot.h>

#include <dev/vmm/vmm_ktr.h>

#include "vatpic.h"
#include "vioapic.h"
#include "vatpit.h"

static MALLOC_DEFINE(M_VATPIT, "atpit", "bhyve virtual atpit (8254)");

#define VATPIT_LOCK(vatpit)             mtx_lock_spin(&((vatpit)->mtx))
#define VATPIT_UNLOCK(vatpit)           mtx_unlock_spin(&((vatpit)->mtx))
#define VATPIT_LOCKED(vatpit)           mtx_owned(&((vatpit)->mtx))

#define TIMER_SEL_MASK          0xc0
#define TIMER_RW_MASK           0x30
#define TIMER_MODE_MASK         0x0f
#define TIMER_SEL_READBACK      0xc0

#define TIMER_STS_OUT           0x80
#define TIMER_STS_NULLCNT       0x40

#define TIMER_RB_LCTR           0x20
#define TIMER_RB_LSTATUS        0x10
#define TIMER_RB_CTR_2          0x08
#define TIMER_RB_CTR_1          0x04
#define TIMER_RB_CTR_0          0x02

#define TMR2_OUT_STS            0x20

#define PIT_8254_FREQ           1193182
#define TIMER_DIV(freq, hz)     (((freq) + (hz) / 2) / (hz))

struct vatpit_callout_arg {
        struct vatpit   *vatpit;
        int             channel_num;
};

struct channel {
        int             mode;
        uint16_t        initial;        /* initial counter value */
        struct bintime  now_bt;         /* uptime when counter was loaded */
        uint8_t         cr[2];
        uint8_t         ol[2];
        bool            slatched;       /* status latched */
        uint8_t         status;
        int             crbyte;
        int             olbyte;
        int             frbyte;
        struct callout  callout;
        struct bintime  callout_bt;     /* target time */
        struct vatpit_callout_arg callout_arg;
};

struct vatpit {
        struct vm       *vm;
        struct mtx      mtx;

        struct bintime  freq_bt;

        struct channel  channel[3];
};

static void pit_timer_start_cntr0(struct vatpit *vatpit);

static uint64_t
vatpit_delta_ticks(struct vatpit *vatpit, struct channel *c)
{
        struct bintime delta;
        uint64_t result;

        binuptime(&delta);
        bintime_sub(&delta, &c->now_bt);

        result = delta.sec * PIT_8254_FREQ;
        result += delta.frac / vatpit->freq_bt.frac;

        return (result);
}

static int
vatpit_get_out(struct vatpit *vatpit, int channel)
{
        struct channel *c;
        uint64_t delta_ticks;
        int out;

        c = &vatpit->channel[channel];

        switch (c->mode) {
        case TIMER_INTTC:
                delta_ticks = vatpit_delta_ticks(vatpit, c);
                out = (delta_ticks >= c->initial);
                break;
        default:
                out = 0;
                break;
        }

        return (out);
}

static void
vatpit_callout_handler(void *a)
{
        struct vatpit_callout_arg *arg = a;
        struct vatpit *vatpit;
        struct callout *callout;
        struct channel *c;

        vatpit = arg->vatpit;
        c = &vatpit->channel[arg->channel_num];
        callout = &c->callout;

        VM_CTR1(vatpit->vm, "atpit t%d fired", arg->channel_num);

        VATPIT_LOCK(vatpit);

        if (callout_pending(callout))           /* callout was reset */
                goto done;

        if (!callout_active(callout))           /* callout was stopped */
                goto done;

        callout_deactivate(callout);

        if (c->mode == TIMER_RATEGEN) {
                pit_timer_start_cntr0(vatpit);
        }

        vatpic_pulse_irq(vatpit->vm, 0);
        vioapic_pulse_irq(vatpit->vm, 2);

done:
        VATPIT_UNLOCK(vatpit);
        return;
}

static void
pit_timer_start_cntr0(struct vatpit *vatpit)
{
        struct channel *c;
        struct bintime now, delta;
        sbintime_t precision;

        c = &vatpit->channel[0];
        if (c->initial != 0) {
                delta.sec = 0;
                delta.frac = vatpit->freq_bt.frac * c->initial;
                bintime_add(&c->callout_bt, &delta);
                precision = bttosbt(delta) >> tc_precexp;

                /*
                 * Reset 'callout_bt' if the time that the callout
                 * was supposed to fire is more than 'c->initial'
                 * ticks in the past.
                 */
                binuptime(&now);
                if (bintime_cmp(&c->callout_bt, &now, <)) {
                        c->callout_bt = now;
                        bintime_add(&c->callout_bt, &delta);
                }

                callout_reset_sbt(&c->callout, bttosbt(c->callout_bt),
                    precision, vatpit_callout_handler, &c->callout_arg,
                    C_ABSOLUTE);
        }
}

static uint16_t
pit_update_counter(struct vatpit *vatpit, struct channel *c, bool latch)
{
        uint16_t lval;
        uint64_t delta_ticks;

        /* cannot latch a new value until the old one has been consumed */
        if (latch && c->olbyte != 0)
                return (0);

        if (c->initial == 0) {
                /*
                 * This is possibly an o/s bug - reading the value of
                 * the timer without having set up the initial value.
                 *
                 * The original user-space version of this code set
                 * the timer to 100hz in this condition; do the same
                 * here.
                 */
                c->initial = TIMER_DIV(PIT_8254_FREQ, 100);
                binuptime(&c->now_bt);
                c->status &= ~TIMER_STS_NULLCNT;
        }

        delta_ticks = vatpit_delta_ticks(vatpit, c);
        lval = c->initial - delta_ticks % c->initial;

        if (latch) {
                c->olbyte = 2;
                c->ol[1] = lval;                /* LSB */
                c->ol[0] = lval >> 8;           /* MSB */
        }

        return (lval);
}

static int
pit_readback1(struct vatpit *vatpit, int channel, uint8_t cmd)
{
        struct channel *c;

        c = &vatpit->channel[channel];

        /*
         * Latch the count/status of the timer if not already latched.
         * N.B. that the count/status latch-select bits are active-low.
         */
        if (!(cmd & TIMER_RB_LCTR) && !c->olbyte) {
                (void) pit_update_counter(vatpit, c, true);
        }

        if (!(cmd & TIMER_RB_LSTATUS) && !c->slatched) {
                c->slatched = true;
                /*
                 * For mode 0, see if the elapsed time is greater
                 * than the initial value - this results in the
                 * output pin being set to 1 in the status byte.
                 */
                if (c->mode == TIMER_INTTC && vatpit_get_out(vatpit, channel))
                        c->status |= TIMER_STS_OUT;
                else
                        c->status &= ~TIMER_STS_OUT;
        }

        return (0);
}

static int
pit_readback(struct vatpit *vatpit, uint8_t cmd)
{
        int error;

        /*
         * The readback command can apply to all timers.
         */
        error = 0;
        if (cmd & TIMER_RB_CTR_0)
                error = pit_readback1(vatpit, 0, cmd);
        if (!error && cmd & TIMER_RB_CTR_1)
                error = pit_readback1(vatpit, 1, cmd);
        if (!error && cmd & TIMER_RB_CTR_2)
                error = pit_readback1(vatpit, 2, cmd);

        return (error);
}

static int
vatpit_update_mode(struct vatpit *vatpit, uint8_t val)
{
        struct channel *c;
        int sel, rw, mode;

        sel = val & TIMER_SEL_MASK;
        rw = val & TIMER_RW_MASK;
        mode = val & TIMER_MODE_MASK;

        if (sel == TIMER_SEL_READBACK)
                return (pit_readback(vatpit, val));

        if (rw != TIMER_LATCH && rw != TIMER_16BIT)
                return (-1);

        if (rw != TIMER_LATCH) {
                /*
                 * Counter mode is not affected when issuing a
                 * latch command.
                 */
                if (mode != TIMER_INTTC &&
                    mode != TIMER_RATEGEN &&
                    mode != TIMER_SQWAVE &&
                    mode != TIMER_SWSTROBE)
                        return (-1);
        }

        c = &vatpit->channel[sel >> 6];
        if (rw == TIMER_LATCH)
                pit_update_counter(vatpit, c, true);
        else {
                c->mode = mode;
                c->olbyte = 0;  /* reset latch after reprogramming */
                c->status |= TIMER_STS_NULLCNT;
        }

        return (0);
}

int
vatpit_handler(struct vm *vm, bool in, int port, int bytes, uint32_t *eax)
{
        struct vatpit *vatpit;
        struct channel *c;
        uint8_t val;
        int error;

        vatpit = vm_atpit(vm);

        if (bytes != 1)
                return (-1);

        val = *eax;

        if (port == TIMER_MODE) {
                if (in) {
                        VM_CTR0(vatpit->vm, "vatpit attempt to read mode");
                        return (-1);
                }

                VATPIT_LOCK(vatpit);
                error = vatpit_update_mode(vatpit, val);
                VATPIT_UNLOCK(vatpit);

                return (error);
        }

        /* counter ports */
        KASSERT(port >= TIMER_CNTR0 && port <= TIMER_CNTR2,
            ("invalid port 0x%x", port));
        c = &vatpit->channel[port - TIMER_CNTR0];

        VATPIT_LOCK(vatpit);
        if (in && c->slatched) {
                /*
                 * Return the status byte if latched
                 */
                *eax = c->status;
                c->slatched = false;
                c->status = 0;
        } else if (in) {
                /*
                 * The spec says that once the output latch is completely
                 * read it should revert to "following" the counter. Use
                 * the free running counter for this case (i.e. Linux
                 * TSC calibration). Assuming the access mode is 16-bit,
                 * toggle the MSB/LSB bit on each read.
                 */
                if (c->olbyte == 0) {
                        uint16_t tmp;

                        tmp = pit_update_counter(vatpit, c, false);
                        if (c->frbyte)
                                tmp >>= 8;
                        tmp &= 0xff;
                        *eax = tmp;
                        c->frbyte ^= 1;
                }  else
                        *eax = c->ol[--c->olbyte];
        } else {
                c->cr[c->crbyte++] = *eax;
                if (c->crbyte == 2) {
                        c->status &= ~TIMER_STS_NULLCNT;
                        c->frbyte = 0;
                        c->crbyte = 0;
                        c->initial = c->cr[0] | (uint16_t)c->cr[1] << 8;
                        binuptime(&c->now_bt);
                        /* Start an interval timer for channel 0 */
                        if (port == TIMER_CNTR0) {
                                c->callout_bt = c->now_bt;
                                pit_timer_start_cntr0(vatpit);
                        }
                        if (c->initial == 0)
                                c->initial = 0xffff;
                }
        }
        VATPIT_UNLOCK(vatpit);

        return (0);
}

int
vatpit_nmisc_handler(struct vm *vm, bool in, int port, int bytes,
    uint32_t *eax)
{
        struct vatpit *vatpit;

        vatpit = vm_atpit(vm);

        if (in) {
                        VATPIT_LOCK(vatpit);
                        if (vatpit_get_out(vatpit, 2))
                                *eax = TMR2_OUT_STS;
                        else
                                *eax = 0;

                        VATPIT_UNLOCK(vatpit);
        }

        return (0);
}

struct vatpit *
vatpit_init(struct vm *vm)
{
        struct vatpit *vatpit;
        struct vatpit_callout_arg *arg;
        int i;

        vatpit = malloc(sizeof(struct vatpit), M_VATPIT, M_WAITOK | M_ZERO);
        vatpit->vm = vm;

        mtx_init(&vatpit->mtx, "vatpit lock", NULL, MTX_SPIN);

        FREQ2BT(PIT_8254_FREQ, &vatpit->freq_bt);

        for (i = 0; i < 3; i++) {
                callout_init(&vatpit->channel[i].callout, 1);
                arg = &vatpit->channel[i].callout_arg;
                arg->vatpit = vatpit;
                arg->channel_num = i;
        }

        return (vatpit);
}

void
vatpit_cleanup(struct vatpit *vatpit)
{
        int i;

        for (i = 0; i < 3; i++)
                callout_drain(&vatpit->channel[i].callout);

        mtx_destroy(&vatpit->mtx);
        free(vatpit, M_VATPIT);
}

#ifdef BHYVE_SNAPSHOT
int
vatpit_snapshot(struct vatpit *vatpit, struct vm_snapshot_meta *meta)
{
        int ret;
        int i;
        struct channel *channel;

        SNAPSHOT_VAR_OR_LEAVE(vatpit->freq_bt.sec, meta, ret, done);
        SNAPSHOT_VAR_OR_LEAVE(vatpit->freq_bt.frac, meta, ret, done);

        /* properly restore timers; they will NOT work currently */
        printf("%s: snapshot restore does not reset timers!\r\n", __func__);

        for (i = 0; i < nitems(vatpit->channel); i++) {
                channel = &vatpit->channel[i];

                SNAPSHOT_VAR_OR_LEAVE(channel->mode, meta, ret, done);
                SNAPSHOT_VAR_OR_LEAVE(channel->initial, meta, ret, done);
                SNAPSHOT_VAR_OR_LEAVE(channel->now_bt.sec, meta, ret, done);
                SNAPSHOT_VAR_OR_LEAVE(channel->now_bt.frac, meta, ret, done);
                SNAPSHOT_BUF_OR_LEAVE(channel->cr, sizeof(channel->cr),
                        meta, ret, done);
                SNAPSHOT_BUF_OR_LEAVE(channel->ol, sizeof(channel->ol),
                        meta, ret, done);
                SNAPSHOT_VAR_OR_LEAVE(channel->slatched, meta, ret, done);
                SNAPSHOT_VAR_OR_LEAVE(channel->status, meta, ret, done);
                SNAPSHOT_VAR_OR_LEAVE(channel->crbyte, meta, ret, done);
                SNAPSHOT_VAR_OR_LEAVE(channel->frbyte, meta, ret, done);
                SNAPSHOT_VAR_OR_LEAVE(channel->callout_bt.sec, meta, ret, done);
                SNAPSHOT_VAR_OR_LEAVE(channel->callout_bt.frac, meta, ret,
                        done);
        }

done:
        return (ret);
}
#endif