/*-
 * Copyright (c) 2014,2016-2017 Microsoft Corp.
 * 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 unmodified, 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 THE AUTHOR ``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 <sys/param.h>
#include <sys/bus.h>
#include <sys/kernel.h>
#include <sys/module.h>
#include <sys/syscallsubr.h>
#include <sys/sysctl.h>
#include <sys/systm.h>

#include <dev/hyperv/include/hyperv.h>
#include <dev/hyperv/include/vmbus.h>
#include <dev/hyperv/utilities/vmbus_icreg.h>
#include <dev/hyperv/utilities/vmbus_icvar.h>

#define VMBUS_TIMESYNC_FWVER_MAJOR      3
#define VMBUS_TIMESYNC_FWVER            \
        VMBUS_IC_VERSION(VMBUS_TIMESYNC_FWVER_MAJOR, 0)

#define VMBUS_TIMESYNC_MSGVER_MAJOR     4
#define VMBUS_TIMESYNC_MSGVER           \
        VMBUS_IC_VERSION(VMBUS_TIMESYNC_MSGVER_MAJOR, 0)

#define VMBUS_TIMESYNC_MSGVER4(sc)      \
        VMBUS_ICVER_LE(VMBUS_IC_VERSION(4, 0), (sc)->ic_msgver)

#define VMBUS_TIMESYNC_DORTT(sc)        \
        (VMBUS_TIMESYNC_MSGVER4((sc)) && hyperv_tc64 != NULL)

static int                      vmbus_timesync_probe(device_t);
static int                      vmbus_timesync_attach(device_t);

static const struct vmbus_ic_desc vmbus_timesync_descs[] = {
        {
                .ic_guid = { .hv_guid = {
                    0x30, 0xe6, 0x27, 0x95, 0xae, 0xd0, 0x7b, 0x49,
                    0xad, 0xce, 0xe8, 0x0a, 0xb0, 0x17, 0x5c, 0xaf } },
                .ic_desc = "Hyper-V Timesync"
        },
        VMBUS_IC_DESC_END
};

static device_method_t vmbus_timesync_methods[] = {
        /* Device interface */
        DEVMETHOD(device_probe,         vmbus_timesync_probe),
        DEVMETHOD(device_attach,        vmbus_timesync_attach),
        DEVMETHOD(device_detach,        vmbus_ic_detach),
        DEVMETHOD_END
};

static driver_t vmbus_timesync_driver = {
        "hvtimesync",
        vmbus_timesync_methods,
        sizeof(struct vmbus_ic_softc)
};

DRIVER_MODULE(hv_timesync, vmbus, vmbus_timesync_driver, NULL, NULL);
MODULE_VERSION(hv_timesync, 1);
MODULE_DEPEND(hv_timesync, vmbus, 1, 1, 1);

SYSCTL_NODE(_hw, OID_AUTO, hvtimesync, CTLFLAG_RW | CTLFLAG_MPSAFE, NULL,
    "Hyper-V timesync interface");

static int vmbus_ts_ignore_sync = 0;
SYSCTL_INT(_hw_hvtimesync, OID_AUTO, ignore_sync, CTLFLAG_RWTUN,
    &vmbus_ts_ignore_sync, 0, "Ignore the sync request.");

/*
 * Trigger sample sync when drift exceeds threshold (ms).
 * Ignore the sample request when set to 0.
 */
static int vmbus_ts_sample_thresh = 100;
SYSCTL_INT(_hw_hvtimesync, OID_AUTO, sample_thresh, CTLFLAG_RWTUN,
    &vmbus_ts_sample_thresh, 0,
    "Threshold that makes sample request trigger the sync (unit: ms).");

static int vmbus_ts_sample_verbose = 0;
SYSCTL_INT(_hw_hvtimesync, OID_AUTO, sample_verbose, CTLFLAG_RWTUN,
    &vmbus_ts_sample_verbose, 0, "Increase sample request verbosity.");

static void
vmbus_timesync(struct vmbus_ic_softc *sc, uint64_t hvtime, uint64_t sent_tc,
    uint8_t tsflags)
{
        struct timespec vm_ts;
        uint64_t hv_ns, vm_ns, rtt = 0;

        if (VMBUS_TIMESYNC_DORTT(sc))
                rtt = hyperv_tc64() - sent_tc;

        hv_ns = (hvtime - VMBUS_ICMSG_TS_BASE + rtt) * HYPERV_TIMER_NS_FACTOR;
        nanotime(&vm_ts);
        vm_ns = (vm_ts.tv_sec * NANOSEC) + vm_ts.tv_nsec;

        if ((tsflags & VMBUS_ICMSG_TS_FLAG_SYNC) && !vmbus_ts_ignore_sync) {
                struct timespec hv_ts;

                if (bootverbose) {
                        device_printf(sc->ic_dev, "apply sync request, "
                            "hv: %ju, vm: %ju\n",
                            (uintmax_t)hv_ns, (uintmax_t)vm_ns);
                }
                hv_ts.tv_sec = hv_ns / NANOSEC;
                hv_ts.tv_nsec = hv_ns % NANOSEC;
                kern_clock_settime(curthread, CLOCK_REALTIME, &hv_ts);
                /* Done! */
                return;
        }

        if ((tsflags & VMBUS_ICMSG_TS_FLAG_SAMPLE) &&
            vmbus_ts_sample_thresh >= 0) {
                int64_t diff;

                if (vmbus_ts_sample_verbose) {
                        device_printf(sc->ic_dev, "sample request, "
                            "hv: %ju, vm: %ju\n",
                            (uintmax_t)hv_ns, (uintmax_t)vm_ns);
                }

                if (hv_ns > vm_ns)
                        diff = hv_ns - vm_ns;
                else
                        diff = vm_ns - hv_ns;
                /* nanosec -> millisec */
                diff /= 1000000;

                if (diff > vmbus_ts_sample_thresh) {
                        struct timespec hv_ts;

                        if (bootverbose) {
                                device_printf(sc->ic_dev,
                                    "apply sample request, hv: %ju, vm: %ju\n",
                                    (uintmax_t)hv_ns, (uintmax_t)vm_ns);
                        }
                        hv_ts.tv_sec = hv_ns / NANOSEC;
                        hv_ts.tv_nsec = hv_ns % NANOSEC;
                        kern_clock_settime(curthread, CLOCK_REALTIME, &hv_ts);
                }
                /* Done */
                return;
        }
}

static void
vmbus_timesync_cb(struct vmbus_channel *chan, void *xsc)
{
        struct vmbus_ic_softc *sc = xsc;
        struct vmbus_icmsg_hdr *hdr;
        int dlen, error;
        uint64_t xactid;
        void *data;

        /*
         * Receive request.
         */
        data = sc->ic_buf;
        dlen = sc->ic_buflen;
        error = vmbus_chan_recv(chan, data, &dlen, &xactid);
        KASSERT(error != ENOBUFS, ("icbuf is not large enough"));
        if (error)
                return;

        if (dlen < sizeof(*hdr)) {
                device_printf(sc->ic_dev, "invalid data len %d\n", dlen);
                return;
        }
        hdr = data;

        /*
         * Update request, which will be echoed back as response.
         */
        switch (hdr->ic_type) {
        case VMBUS_ICMSG_TYPE_NEGOTIATE:
                error = vmbus_ic_negomsg(sc, data, &dlen,
                    VMBUS_TIMESYNC_FWVER, VMBUS_TIMESYNC_MSGVER);
                if (error)
                        return;
                if (VMBUS_TIMESYNC_DORTT(sc))
                        device_printf(sc->ic_dev, "RTT\n");
                break;

        case VMBUS_ICMSG_TYPE_TIMESYNC:
                if (VMBUS_TIMESYNC_MSGVER4(sc)) {
                        const struct vmbus_icmsg_timesync4 *msg4;

                        if (dlen < sizeof(*msg4)) {
                                device_printf(sc->ic_dev, "invalid timesync4 "
                                    "len %d\n", dlen);
                                return;
                        }
                        msg4 = data;
                        vmbus_timesync(sc, msg4->ic_hvtime, msg4->ic_sent_tc,
                            msg4->ic_tsflags);
                } else {
                        const struct vmbus_icmsg_timesync *msg;

                        if (dlen < sizeof(*msg)) {
                                device_printf(sc->ic_dev, "invalid timesync "
                                    "len %d\n", dlen);
                                return;
                        }
                        msg = data;
                        vmbus_timesync(sc, msg->ic_hvtime, 0, msg->ic_tsflags);
                }
                break;

        default:
                device_printf(sc->ic_dev, "got 0x%08x icmsg\n", hdr->ic_type);
                break;
        }

        /*
         * Send response by echoing the request back.
         */
        vmbus_ic_sendresp(sc, chan, data, dlen, xactid);
}

static int
vmbus_timesync_probe(device_t dev)
{

        return (vmbus_ic_probe(dev, vmbus_timesync_descs));
}

static int
vmbus_timesync_attach(device_t dev)
{

        return (vmbus_ic_attach(dev, vmbus_timesync_cb));
}