// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2010, Microsoft Corporation.
 *
 * Authors:
 *   Haiyang Zhang <haiyangz@microsoft.com>
 *   Hank Janssen  <hjanssen@microsoft.com>
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/sysctl.h>
#include <linux/reboot.h>
#include <linux/hyperv.h>
#include <linux/clockchips.h>
#include <linux/ptp_clock_kernel.h>
#include <asm/mshyperv.h>

#include "hyperv_vmbus.h"

#define SD_MAJOR        3
#define SD_MINOR        0
#define SD_MINOR_1      1
#define SD_MINOR_2      2
#define SD_VERSION_3_1  (SD_MAJOR << 16 | SD_MINOR_1)
#define SD_VERSION_3_2  (SD_MAJOR << 16 | SD_MINOR_2)
#define SD_VERSION      (SD_MAJOR << 16 | SD_MINOR)

#define SD_MAJOR_1      1
#define SD_VERSION_1    (SD_MAJOR_1 << 16 | SD_MINOR)

#define TS_MAJOR        4
#define TS_MINOR        0
#define TS_VERSION      (TS_MAJOR << 16 | TS_MINOR)

#define TS_MAJOR_1      1
#define TS_VERSION_1    (TS_MAJOR_1 << 16 | TS_MINOR)

#define TS_MAJOR_3      3
#define TS_VERSION_3    (TS_MAJOR_3 << 16 | TS_MINOR)

#define HB_MAJOR        3
#define HB_MINOR        0
#define HB_VERSION      (HB_MAJOR << 16 | HB_MINOR)

#define HB_MAJOR_1      1
#define HB_VERSION_1    (HB_MAJOR_1 << 16 | HB_MINOR)

static int sd_srv_version;
static int ts_srv_version;
static int hb_srv_version;

#define SD_VER_COUNT 4
static const int sd_versions[] = {
        SD_VERSION_3_2,
        SD_VERSION_3_1,
        SD_VERSION,
        SD_VERSION_1
};

#define TS_VER_COUNT 3
static const int ts_versions[] = {
        TS_VERSION,
        TS_VERSION_3,
        TS_VERSION_1
};

#define HB_VER_COUNT 2
static const int hb_versions[] = {
        HB_VERSION,
        HB_VERSION_1
};

#define FW_VER_COUNT 2
static const int fw_versions[] = {
        UTIL_FW_VERSION,
        UTIL_WS2K8_FW_VERSION
};

/*
 * Send the "hibernate" udev event in a thread context.
 */
struct hibernate_work_context {
        struct work_struct work;
        struct hv_device *dev;
};

static struct hibernate_work_context hibernate_context;
static bool hibernation_supported;

static void send_hibernate_uevent(struct work_struct *work)
{
        char *uevent_env[2] = { "EVENT=hibernate", NULL };
        struct hibernate_work_context *ctx;

        ctx = container_of(work, struct hibernate_work_context, work);

        kobject_uevent_env(&ctx->dev->device.kobj, KOBJ_CHANGE, uevent_env);

        pr_info("Sent hibernation uevent\n");
}

static int hv_shutdown_init(struct hv_util_service *srv)
{
        struct vmbus_channel *channel = srv->channel;

        INIT_WORK(&hibernate_context.work, send_hibernate_uevent);
        hibernate_context.dev = channel->device_obj;

        hibernation_supported = hv_is_hibernation_supported();

        return 0;
}

static void shutdown_onchannelcallback(void *context);
static struct hv_util_service util_shutdown = {
        .util_cb = shutdown_onchannelcallback,
        .util_init = hv_shutdown_init,
};

static int hv_timesync_init(struct hv_util_service *srv);
static int hv_timesync_pre_suspend(void);
static void hv_timesync_deinit(void);

static void timesync_onchannelcallback(void *context);
static struct hv_util_service util_timesynch = {
        .util_cb = timesync_onchannelcallback,
        .util_init = hv_timesync_init,
        .util_pre_suspend = hv_timesync_pre_suspend,
        .util_deinit = hv_timesync_deinit,
};

static void heartbeat_onchannelcallback(void *context);
static struct hv_util_service util_heartbeat = {
        .util_cb = heartbeat_onchannelcallback,
};

static struct hv_util_service util_kvp = {
        .util_cb = hv_kvp_onchannelcallback,
        .util_init = hv_kvp_init,
        .util_init_transport = hv_kvp_init_transport,
        .util_pre_suspend = hv_kvp_pre_suspend,
        .util_pre_resume = hv_kvp_pre_resume,
        .util_deinit = hv_kvp_deinit,
};

static struct hv_util_service util_vss = {
        .util_cb = hv_vss_onchannelcallback,
        .util_init = hv_vss_init,
        .util_init_transport = hv_vss_init_transport,
        .util_pre_suspend = hv_vss_pre_suspend,
        .util_pre_resume = hv_vss_pre_resume,
        .util_deinit = hv_vss_deinit,
};

static void perform_shutdown(struct work_struct *dummy)
{
        orderly_poweroff(true);
}

static void perform_restart(struct work_struct *dummy)
{
        orderly_reboot();
}

/*
 * Perform the shutdown operation in a thread context.
 */
static DECLARE_WORK(shutdown_work, perform_shutdown);

/*
 * Perform the restart operation in a thread context.
 */
static DECLARE_WORK(restart_work, perform_restart);

static void shutdown_onchannelcallback(void *context)
{
        struct vmbus_channel *channel = context;
        struct work_struct *work = NULL;
        u32 recvlen;
        u64 requestid;
        u8  *shut_txf_buf = util_shutdown.recv_buffer;

        struct shutdown_msg_data *shutdown_msg;

        struct icmsg_hdr *icmsghdrp;

        if (vmbus_recvpacket(channel, shut_txf_buf, HV_HYP_PAGE_SIZE, &recvlen, &requestid)) {
                pr_err_ratelimited("Shutdown request received. Could not read into shut txf buf\n");
                return;
        }

        if (!recvlen)
                return;

        /* Ensure recvlen is big enough to read header data */
        if (recvlen < ICMSG_HDR) {
                pr_err_ratelimited("Shutdown request received. Packet length too small: %d\n",
                                   recvlen);
                return;
        }

        icmsghdrp = (struct icmsg_hdr *)&shut_txf_buf[sizeof(struct vmbuspipe_hdr)];

        if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
                if (vmbus_prep_negotiate_resp(icmsghdrp,
                                shut_txf_buf, recvlen,
                                fw_versions, FW_VER_COUNT,
                                sd_versions, SD_VER_COUNT,
                                NULL, &sd_srv_version)) {
                        pr_info("Shutdown IC version %d.%d\n",
                                sd_srv_version >> 16,
                                sd_srv_version & 0xFFFF);
                }
        } else if (icmsghdrp->icmsgtype == ICMSGTYPE_SHUTDOWN) {
                /* Ensure recvlen is big enough to contain shutdown_msg_data struct */
                if (recvlen < ICMSG_HDR + sizeof(struct shutdown_msg_data)) {
                        pr_err_ratelimited("Invalid shutdown msg data. Packet length too small: %u\n",
                                           recvlen);
                        return;
                }

                shutdown_msg = (struct shutdown_msg_data *)&shut_txf_buf[ICMSG_HDR];

                /*
                 * shutdown_msg->flags can be 0(shut down), 2(reboot),
                 * or 4(hibernate). It may bitwise-OR 1, which means
                 * performing the request by force. Linux always tries
                 * to perform the request by force.
                 */
                switch (shutdown_msg->flags) {
                case 0:
                case 1:
                        icmsghdrp->status = HV_S_OK;
                        work = &shutdown_work;
                        pr_info("Shutdown request received - graceful shutdown initiated\n");
                        break;
                case 2:
                case 3:
                        icmsghdrp->status = HV_S_OK;
                        work = &restart_work;
                        pr_info("Restart request received - graceful restart initiated\n");
                        break;
                case 4:
                case 5:
                        pr_info("Hibernation request received\n");
                        icmsghdrp->status = hibernation_supported ?
                                HV_S_OK : HV_E_FAIL;
                        if (hibernation_supported)
                                work = &hibernate_context.work;
                        break;
                default:
                        icmsghdrp->status = HV_E_FAIL;
                        pr_info("Shutdown request received - Invalid request\n");
                        break;
                }
        } else {
                icmsghdrp->status = HV_E_FAIL;
                pr_err_ratelimited("Shutdown request received. Invalid msg type: %d\n",
                                   icmsghdrp->icmsgtype);
        }

        icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
                | ICMSGHDRFLAG_RESPONSE;

        vmbus_sendpacket(channel, shut_txf_buf,
                         recvlen, requestid,
                         VM_PKT_DATA_INBAND, 0);

        if (work)
                schedule_work(work);
}

/*
 * Set the host time in a process context.
 */
static struct work_struct adj_time_work;

/*
 * The last time sample, received from the host. PTP device responds to
 * requests by using this data and the current partition-wide time reference
 * count.
 */
static struct {
        u64                             host_time;
        u64                             ref_time;
        spinlock_t                      lock;
} host_ts;

static bool timesync_implicit;

module_param(timesync_implicit, bool, 0644);
MODULE_PARM_DESC(timesync_implicit, "If set treat SAMPLE as SYNC when clock is behind");

static inline u64 reftime_to_ns(u64 reftime)
{
        return (reftime - WLTIMEDELTA) * 100;
}

/*
 * Hard coded threshold for host timesync delay: 600 seconds
 */
static const u64 HOST_TIMESYNC_DELAY_THRESH = 600 * (u64)NSEC_PER_SEC;

static int hv_get_adj_host_time(struct timespec64 *ts)
{
        u64 newtime, reftime, timediff_adj;
        unsigned long flags;
        int ret = 0;

        spin_lock_irqsave(&host_ts.lock, flags);
        reftime = hv_read_reference_counter();

        /*
         * We need to let the caller know that last update from host
         * is older than the max allowable threshold. clock_gettime()
         * and PTP ioctl do not have a documented error that we could
         * return for this specific case. Use ESTALE to report this.
         */
        timediff_adj = reftime - host_ts.ref_time;
        if (timediff_adj * 100 > HOST_TIMESYNC_DELAY_THRESH) {
                pr_warn_once("TIMESYNC IC: Stale time stamp, %llu nsecs old\n",
                             (timediff_adj * 100));
                ret = -ESTALE;
        }

        newtime = host_ts.host_time + timediff_adj;
        *ts = ns_to_timespec64(reftime_to_ns(newtime));
        spin_unlock_irqrestore(&host_ts.lock, flags);

        return ret;
}

static void hv_set_host_time(struct work_struct *work)
{

        struct timespec64 ts;

        if (!hv_get_adj_host_time(&ts))
                do_settimeofday64(&ts);
}

/*
 * Due to a bug on Hyper-V hosts, the sync flag may not always be sent on resume.
 * Force a sync if the guest is behind.
 */
static inline bool hv_implicit_sync(u64 host_time)
{
        struct timespec64 new_ts;
        struct timespec64 threshold_ts;

        new_ts = ns_to_timespec64(reftime_to_ns(host_time));
        ktime_get_real_ts64(&threshold_ts);

        threshold_ts.tv_sec += 5;

        /*
         * If guest behind the host by 5 or more seconds.
         */
        if (timespec64_compare(&new_ts, &threshold_ts) >= 0)
                return true;

        return false;
}

/*
 * Synchronize time with host after reboot, restore, etc.
 *
 * ICTIMESYNCFLAG_SYNC flag bit indicates reboot, restore events of the VM.
 * After reboot the flag ICTIMESYNCFLAG_SYNC is included in the first time
 * message after the timesync channel is opened. Since the hv_utils module is
 * loaded after hv_vmbus, the first message is usually missed. This bit is
 * considered a hard request to discipline the clock.
 *
 * ICTIMESYNCFLAG_SAMPLE bit indicates a time sample from host. This is
 * typically used as a hint to the guest. The guest is under no obligation
 * to discipline the clock.
 */
static inline void adj_guesttime(u64 hosttime, u64 reftime, u8 adj_flags)
{
        unsigned long flags;
        u64 cur_reftime;

        /*
         * Save the adjusted time sample from the host and the snapshot
         * of the current system time.
         */
        spin_lock_irqsave(&host_ts.lock, flags);

        cur_reftime = hv_read_reference_counter();
        host_ts.host_time = hosttime;
        host_ts.ref_time = cur_reftime;

        /*
         * TimeSync v4 messages contain reference time (guest's Hyper-V
         * clocksource read when the time sample was generated), we can
         * improve the precision by adding the delta between now and the
         * time of generation. For older protocols we set
         * reftime == cur_reftime on call.
         */
        host_ts.host_time += (cur_reftime - reftime);

        spin_unlock_irqrestore(&host_ts.lock, flags);

        /* Schedule work to do do_settimeofday64() */
        if ((adj_flags & ICTIMESYNCFLAG_SYNC) ||
            (timesync_implicit && hv_implicit_sync(host_ts.host_time)))
                schedule_work(&adj_time_work);
}

/*
 * Time Sync Channel message handler.
 */
static void timesync_onchannelcallback(void *context)
{
        struct vmbus_channel *channel = context;
        u32 recvlen;
        u64 requestid;
        struct icmsg_hdr *icmsghdrp;
        struct ictimesync_data *timedatap;
        struct ictimesync_ref_data *refdata;
        u8 *time_txf_buf = util_timesynch.recv_buffer;

        /*
         * Drain the ring buffer and use the last packet to update
         * host_ts
         */
        while (1) {
                int ret = vmbus_recvpacket(channel, time_txf_buf,
                                           HV_HYP_PAGE_SIZE, &recvlen,
                                           &requestid);
                if (ret) {
                        pr_err_ratelimited("TimeSync IC pkt recv failed (Err: %d)\n",
                                           ret);
                        break;
                }

                if (!recvlen)
                        break;

                /* Ensure recvlen is big enough to read header data */
                if (recvlen < ICMSG_HDR) {
                        pr_err_ratelimited("Timesync request received. Packet length too small: %d\n",
                                           recvlen);
                        break;
                }

                icmsghdrp = (struct icmsg_hdr *)&time_txf_buf[
                                sizeof(struct vmbuspipe_hdr)];

                if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
                        if (vmbus_prep_negotiate_resp(icmsghdrp,
                                                time_txf_buf, recvlen,
                                                fw_versions, FW_VER_COUNT,
                                                ts_versions, TS_VER_COUNT,
                                                NULL, &ts_srv_version)) {
                                pr_info("TimeSync IC version %d.%d\n",
                                        ts_srv_version >> 16,
                                        ts_srv_version & 0xFFFF);
                        }
                } else if (icmsghdrp->icmsgtype == ICMSGTYPE_TIMESYNC) {
                        if (ts_srv_version > TS_VERSION_3) {
                                /* Ensure recvlen is big enough to read ictimesync_ref_data */
                                if (recvlen < ICMSG_HDR + sizeof(struct ictimesync_ref_data)) {
                                        pr_err_ratelimited("Invalid ictimesync ref data. Length too small: %u\n",
                                                           recvlen);
                                        break;
                                }
                                refdata = (struct ictimesync_ref_data *)&time_txf_buf[ICMSG_HDR];

                                adj_guesttime(refdata->parenttime,
                                                refdata->vmreferencetime,
                                                refdata->flags);
                        } else {
                                /* Ensure recvlen is big enough to read ictimesync_data */
                                if (recvlen < ICMSG_HDR + sizeof(struct ictimesync_data)) {
                                        pr_err_ratelimited("Invalid ictimesync data. Length too small: %u\n",
                                                           recvlen);
                                        break;
                                }
                                timedatap = (struct ictimesync_data *)&time_txf_buf[ICMSG_HDR];

                                adj_guesttime(timedatap->parenttime,
                                              hv_read_reference_counter(),
                                              timedatap->flags);
                        }
                } else {
                        icmsghdrp->status = HV_E_FAIL;
                        pr_err_ratelimited("Timesync request received. Invalid msg type: %d\n",
                                           icmsghdrp->icmsgtype);
                }

                icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
                        | ICMSGHDRFLAG_RESPONSE;

                vmbus_sendpacket(channel, time_txf_buf,
                                 recvlen, requestid,
                                 VM_PKT_DATA_INBAND, 0);
        }
}

/*
 * Heartbeat functionality.
 * Every two seconds, Hyper-V send us a heartbeat request message.
 * we respond to this message, and Hyper-V knows we are alive.
 */
static void heartbeat_onchannelcallback(void *context)
{
        struct vmbus_channel *channel = context;
        u32 recvlen;
        u64 requestid;
        struct icmsg_hdr *icmsghdrp;
        struct heartbeat_msg_data *heartbeat_msg;
        u8 *hbeat_txf_buf = util_heartbeat.recv_buffer;

        while (1) {

                if (vmbus_recvpacket(channel, hbeat_txf_buf, HV_HYP_PAGE_SIZE,
                                     &recvlen, &requestid)) {
                        pr_err_ratelimited("Heartbeat request received. Could not read into hbeat txf buf\n");
                        return;
                }

                if (!recvlen)
                        break;

                /* Ensure recvlen is big enough to read header data */
                if (recvlen < ICMSG_HDR) {
                        pr_err_ratelimited("Heartbeat request received. Packet length too small: %d\n",
                                           recvlen);
                        break;
                }

                icmsghdrp = (struct icmsg_hdr *)&hbeat_txf_buf[
                                sizeof(struct vmbuspipe_hdr)];

                if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
                        if (vmbus_prep_negotiate_resp(icmsghdrp,
                                        hbeat_txf_buf, recvlen,
                                        fw_versions, FW_VER_COUNT,
                                        hb_versions, HB_VER_COUNT,
                                        NULL, &hb_srv_version)) {

                                pr_info("Heartbeat IC version %d.%d\n",
                                        hb_srv_version >> 16,
                                        hb_srv_version & 0xFFFF);
                        }
                } else if (icmsghdrp->icmsgtype == ICMSGTYPE_HEARTBEAT) {
                        /*
                         * Ensure recvlen is big enough to read seq_num. Reserved area is not
                         * included in the check as the host may not fill it up entirely
                         */
                        if (recvlen < ICMSG_HDR + sizeof(u64)) {
                                pr_err_ratelimited("Invalid heartbeat msg data. Length too small: %u\n",
                                                   recvlen);
                                break;
                        }
                        heartbeat_msg = (struct heartbeat_msg_data *)&hbeat_txf_buf[ICMSG_HDR];

                        heartbeat_msg->seq_num += 1;
                } else {
                        icmsghdrp->status = HV_E_FAIL;
                        pr_err_ratelimited("Heartbeat request received. Invalid msg type: %d\n",
                                           icmsghdrp->icmsgtype);
                }

                icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
                        | ICMSGHDRFLAG_RESPONSE;

                vmbus_sendpacket(channel, hbeat_txf_buf,
                                 recvlen, requestid,
                                 VM_PKT_DATA_INBAND, 0);
        }
}

#define HV_UTIL_RING_SEND_SIZE VMBUS_RING_SIZE(3 * HV_HYP_PAGE_SIZE)
#define HV_UTIL_RING_RECV_SIZE VMBUS_RING_SIZE(3 * HV_HYP_PAGE_SIZE)

static int util_probe(struct hv_device *dev,
                        const struct hv_vmbus_device_id *dev_id)
{
        struct hv_util_service *srv =
                (struct hv_util_service *)dev_id->driver_data;
        int ret;

        srv->recv_buffer = kmalloc_array(4, HV_HYP_PAGE_SIZE, GFP_KERNEL);
        if (!srv->recv_buffer)
                return -ENOMEM;
        srv->channel = dev->channel;
        if (srv->util_init) {
                ret = srv->util_init(srv);
                if (ret)
                        goto error1;
        }

        /*
         * The set of services managed by the util driver are not performance
         * critical and do not need batched reading. Furthermore, some services
         * such as KVP can only handle one message from the host at a time.
         * Turn off batched reading for all util drivers before we open the
         * channel.
         */
        set_channel_read_mode(dev->channel, HV_CALL_DIRECT);

        hv_set_drvdata(dev, srv);

        ret = vmbus_open(dev->channel, HV_UTIL_RING_SEND_SIZE,
                         HV_UTIL_RING_RECV_SIZE, NULL, 0, srv->util_cb,
                         dev->channel);
        if (ret)
                goto error;

        if (srv->util_init_transport) {
                ret = srv->util_init_transport();
                if (ret) {
                        vmbus_close(dev->channel);
                        goto error;
                }
        }
        return 0;

error:
        if (srv->util_deinit)
                srv->util_deinit();
error1:
        kfree(srv->recv_buffer);
        return ret;
}

static void util_remove(struct hv_device *dev)
{
        struct hv_util_service *srv = hv_get_drvdata(dev);

        if (srv->util_deinit)
                srv->util_deinit();
        vmbus_close(dev->channel);
        kfree(srv->recv_buffer);
}

/*
 * When we're in util_suspend(), all the userspace processes have been frozen
 * (refer to hibernate() -> freeze_processes()). The userspace is thawed only
 * after the whole resume procedure, including util_resume(), finishes.
 */
static int util_suspend(struct hv_device *dev)
{
        struct hv_util_service *srv = hv_get_drvdata(dev);
        int ret = 0;

        if (srv->util_pre_suspend) {
                ret = srv->util_pre_suspend();
                if (ret)
                        return ret;
        }

        vmbus_close(dev->channel);

        return 0;
}

static int util_resume(struct hv_device *dev)
{
        struct hv_util_service *srv = hv_get_drvdata(dev);
        int ret = 0;

        if (srv->util_pre_resume) {
                ret = srv->util_pre_resume();
                if (ret)
                        return ret;
        }

        ret = vmbus_open(dev->channel, HV_UTIL_RING_SEND_SIZE,
                         HV_UTIL_RING_RECV_SIZE, NULL, 0, srv->util_cb,
                         dev->channel);
        return ret;
}

static const struct hv_vmbus_device_id id_table[] = {
        /* Shutdown guid */
        { HV_SHUTDOWN_GUID,
          .driver_data = (unsigned long)&util_shutdown
        },
        /* Time synch guid */
        { HV_TS_GUID,
          .driver_data = (unsigned long)&util_timesynch
        },
        /* Heartbeat guid */
        { HV_HEART_BEAT_GUID,
          .driver_data = (unsigned long)&util_heartbeat
        },
        /* KVP guid */
        { HV_KVP_GUID,
          .driver_data = (unsigned long)&util_kvp
        },
        /* VSS GUID */
        { HV_VSS_GUID,
          .driver_data = (unsigned long)&util_vss
        },
        { },
};

MODULE_DEVICE_TABLE(vmbus, id_table);

/* The one and only one */
static  struct hv_driver util_drv = {
        .name = "hv_utils",
        .id_table = id_table,
        .probe =  util_probe,
        .remove =  util_remove,
        .suspend = util_suspend,
        .resume =  util_resume,
        .driver = {
                .probe_type = PROBE_PREFER_ASYNCHRONOUS,
        },
};

static int hv_ptp_enable(struct ptp_clock_info *info,
                         struct ptp_clock_request *request, int on)
{
        return -EOPNOTSUPP;
}

static int hv_ptp_settime(struct ptp_clock_info *p, const struct timespec64 *ts)
{
        return -EOPNOTSUPP;
}

static int hv_ptp_adjfine(struct ptp_clock_info *ptp, long delta)
{
        return -EOPNOTSUPP;
}
static int hv_ptp_adjtime(struct ptp_clock_info *ptp, s64 delta)
{
        return -EOPNOTSUPP;
}

static int hv_ptp_gettime(struct ptp_clock_info *info, struct timespec64 *ts)
{
        return hv_get_adj_host_time(ts);
}

static struct ptp_clock_info ptp_hyperv_info = {
        .name           = "hyperv",
        .enable         = hv_ptp_enable,
        .adjtime        = hv_ptp_adjtime,
        .adjfine        = hv_ptp_adjfine,
        .gettime64      = hv_ptp_gettime,
        .settime64      = hv_ptp_settime,
        .owner          = THIS_MODULE,
};

static struct ptp_clock *hv_ptp_clock;

static int hv_timesync_init(struct hv_util_service *srv)
{
        spin_lock_init(&host_ts.lock);

        INIT_WORK(&adj_time_work, hv_set_host_time);

        /*
         * ptp_clock_register() returns NULL when CONFIG_PTP_1588_CLOCK is
         * disabled but the driver is still useful without the PTP device
         * as it still handles the ICTIMESYNCFLAG_SYNC case.
         */
        hv_ptp_clock = ptp_clock_register(&ptp_hyperv_info, NULL);
        if (IS_ERR_OR_NULL(hv_ptp_clock)) {
                pr_err("cannot register PTP clock: %d\n",
                       PTR_ERR_OR_ZERO(hv_ptp_clock));
                hv_ptp_clock = NULL;
        }

        return 0;
}

static void hv_timesync_cancel_work(void)
{
        cancel_work_sync(&adj_time_work);
}

static int hv_timesync_pre_suspend(void)
{
        hv_timesync_cancel_work();
        return 0;
}

static void hv_timesync_deinit(void)
{
        if (hv_ptp_clock)
                ptp_clock_unregister(hv_ptp_clock);

        hv_timesync_cancel_work();
}

static int __init init_hyperv_utils(void)
{
        pr_info("Registering HyperV Utility Driver\n");

        return vmbus_driver_register(&util_drv);
}

static void exit_hyperv_utils(void)
{
        pr_info("De-Registered HyperV Utility Driver\n");

        vmbus_driver_unregister(&util_drv);
}

module_init(init_hyperv_utils);
module_exit(exit_hyperv_utils);

MODULE_DESCRIPTION("Hyper-V Utilities");
MODULE_LICENSE("GPL");