/*
 * Copyright (c) 2010, Microsoft Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
 * Place - Suite 330, Boston, MA 02111-1307 USA.
 *
 * 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_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 2
static const int sd_versions[] = {
        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
};

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

static int hv_timesync_init(struct hv_util_service *srv);
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_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_deinit = hv_kvp_deinit,
};

static struct hv_util_service util_vss = {
        .util_cb = hv_vss_onchannelcallback,
        .util_init = hv_vss_init,
        .util_deinit = hv_vss_deinit,
};

static struct hv_util_service util_fcopy = {
        .util_cb = hv_fcopy_onchannelcallback,
        .util_init = hv_fcopy_init,
        .util_deinit = hv_fcopy_deinit,
};

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

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

static void shutdown_onchannelcallback(void *context)
{
        struct vmbus_channel *channel = context;
        u32 recvlen;
        u64 requestid;
        bool execute_shutdown = false;
        u8  *shut_txf_buf = util_shutdown.recv_buffer;

        struct shutdown_msg_data *shutdown_msg;

        struct icmsg_hdr *icmsghdrp;

        vmbus_recvpacket(channel, shut_txf_buf,
                         PAGE_SIZE, &recvlen, &requestid);

        if (recvlen > 0) {
                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,
                                        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 {
                        shutdown_msg =
                                (struct shutdown_msg_data *)&shut_txf_buf[
                                        sizeof(struct vmbuspipe_hdr) +
                                        sizeof(struct icmsg_hdr)];

                        switch (shutdown_msg->flags) {
                        case 0:
                        case 1:
                                icmsghdrp->status = HV_S_OK;
                                execute_shutdown = true;

                                pr_info("Shutdown request received -"
                                            " graceful shutdown initiated\n");
                                break;
                        default:
                                icmsghdrp->status = HV_E_FAIL;
                                execute_shutdown = false;

                                pr_info("Shutdown request received -"
                                            " Invalid request\n");
                                break;
                        }
                }

                icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
                        | ICMSGHDRFLAG_RESPONSE;

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

        if (execute_shutdown == true)
                schedule_work(&shutdown_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 struct timespec64 hv_get_adj_host_time(void)
{
        struct timespec64 ts;
        u64 newtime, reftime;
        unsigned long flags;

        spin_lock_irqsave(&host_ts.lock, flags);
        reftime = hyperv_cs->read(hyperv_cs);
        newtime = host_ts.host_time + (reftime - host_ts.ref_time);
        ts = ns_to_timespec64((newtime - WLTIMEDELTA) * 100);
        spin_unlock_irqrestore(&host_ts.lock, flags);

        return ts;
}

static void hv_set_host_time(struct work_struct *work)
{
        struct timespec64 ts = hv_get_adj_host_time();

        do_settimeofday64(&ts);
}

/*
 * 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 = hyperv_cs->read(hyperv_cs);
        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)
                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;

        vmbus_recvpacket(channel, time_txf_buf,
                         PAGE_SIZE, &recvlen, &requestid);

        if (recvlen > 0) {
                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,
                                                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 (ts_srv_version > TS_VERSION_3) {
                                refdata = (struct ictimesync_ref_data *)
                                        &time_txf_buf[
                                        sizeof(struct vmbuspipe_hdr) +
                                        sizeof(struct icmsg_hdr)];

                                adj_guesttime(refdata->parenttime,
                                                refdata->vmreferencetime,
                                                refdata->flags);
                        } else {
                                timedatap = (struct ictimesync_data *)
                                        &time_txf_buf[
                                        sizeof(struct vmbuspipe_hdr) +
                                        sizeof(struct icmsg_hdr)];
                                adj_guesttime(timedatap->parenttime,
                                              hyperv_cs->read(hyperv_cs),
                                              timedatap->flags);
                        }
                }

                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) {

                vmbus_recvpacket(channel, hbeat_txf_buf,
                                 PAGE_SIZE, &recvlen, &requestid);

                if (!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,
                                        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 {
                        heartbeat_msg =
                                (struct heartbeat_msg_data *)&hbeat_txf_buf[
                                        sizeof(struct vmbuspipe_hdr) +
                                        sizeof(struct icmsg_hdr)];

                        heartbeat_msg->seq_num += 1;
                }

                icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
                        | ICMSGHDRFLAG_RESPONSE;

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

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(PAGE_SIZE * 4, GFP_KERNEL);
        if (!srv->recv_buffer)
                return -ENOMEM;
        srv->channel = dev->channel;
        if (srv->util_init) {
                ret = srv->util_init(srv);
                if (ret) {
                        ret = -ENODEV;
                        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, 4 * PAGE_SIZE, 4 * PAGE_SIZE, NULL, 0,
                        srv->util_cb, dev->channel);
        if (ret)
                goto error;

        return 0;

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

static int 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);

        return 0;
}

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
        },
        /* File copy GUID */
        { HV_FCOPY_GUID,
          .driver_data = (unsigned long)&util_fcopy
        },
        { },
};

MODULE_DEVICE_TABLE(vmbus, id_table);

/* The one and only one */
static  struct hv_driver util_drv = {
        .name = "hv_util",
        .id_table = id_table,
        .probe =  util_probe,
        .remove =  util_remove,
};

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_adjfreq(struct ptp_clock_info *ptp, s32 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)
{
        *ts = hv_get_adj_host_time();

        return 0;
}

static struct ptp_clock_info ptp_hyperv_info = {
        .name           = "hyperv",
        .enable         = hv_ptp_enable,
        .adjtime        = hv_ptp_adjtime,
        .adjfreq        = hv_ptp_adjfreq,
        .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)
{
        /* TimeSync requires Hyper-V clocksource. */
        if (!hyperv_cs)
                return -ENODEV;

        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: %ld\n",
                       PTR_ERR(hv_ptp_clock));
                hv_ptp_clock = NULL;
        }

        return 0;
}

static void hv_timesync_deinit(void)
{
        if (hv_ptp_clock)
                ptp_clock_unregister(hv_ptp_clock);
        cancel_work_sync(&adj_time_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");