/*
   * 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 "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;
  static int util_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;
  	struct icmsg_negotiate *negop = NULL;

  	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) {

  			vmbus_prep_negotiate_resp(icmsghdrp, negop,

  					shut_txf_buf, util_fw_version,
  					sd_srv_version);

  		} 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
  ");

  				break;
  			default:
  				icmsghdrp->status = HV_E_FAIL;
  				execute_shutdown = false;

  				pr_info("Shutdown request received -"
  					    " Invalid request
  ");

  				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.
   */
  
  struct adj_time_work {
  	struct work_struct work;
  	u64	host_time;

  	u64	ref_time;
  	u8	flags;

  };
  
  static void hv_set_host_time(struct work_struct *work)
  {
  	struct adj_time_work	*wrk;

  	s64 host_tns;
  	u64 newtime;
  	struct timespec host_ts;

  
  	wrk = container_of(work, struct adj_time_work, work);

  
  	newtime = wrk->host_time;
  	if (ts_srv_version > TS_VERSION_3) {
  		/*
  		 * Some latency has been introduced since Hyper-V generated
  		 * its time sample. Take that latency into account before
  		 * using TSC reference time sample from Hyper-V.
  		 *
  		 * This sample is given by TimeSync v4 and above hosts.
  		 */
  		u64 current_tick;
  
  		rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
  		newtime += (current_tick - wrk->ref_time);
  	}
  	host_tns = (newtime - WLTIMEDELTA) * 100;
  	host_ts = ns_to_timespec(host_tns);
  
  	do_settimeofday(&host_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 struct adj_time_work  wrk;

  static inline void adj_guesttime(u64 hosttime, u64 reftime, u8 flags)

  {

  	/*
  	 * This check is safe since we are executing in the
  	 * interrupt context and time synch messages arre always
  	 * delivered on the same CPU.
  	 */
  	if (work_pending(&wrk.work))

  		return;

  	wrk.host_time = hosttime;
  	wrk.ref_time = reftime;
  	wrk.flags = flags;

  	if ((flags & (ICTIMESYNCFLAG_SYNC | ICTIMESYNCFLAG_SAMPLE)) != 0) {

  		schedule_work(&wrk.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;

  	struct icmsg_negotiate *negop = NULL;

  	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) {

  			vmbus_prep_negotiate_resp(icmsghdrp, negop,
  						time_txf_buf,
  						util_fw_version,
  						ts_srv_version);

  			pr_info("Using TimeSync version %d.%d
  ",
  				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,
  						0,
  						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;

  	struct icmsg_negotiate *negop = NULL;

  	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) {

  			vmbus_prep_negotiate_resp(icmsghdrp, negop,
  				hbeat_txf_buf, util_fw_version,
  				hb_srv_version);

  		} 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_state(dev->channel, false);

  	hv_set_drvdata(dev, srv);

  	/*
  	 * Based on the host; initialize the framework and
  	 * service version numbers we will negotiate.
  	 */
  	switch (vmbus_proto_version) {
  	case (VERSION_WS2008):
  		util_fw_version = UTIL_WS2K8_FW_VERSION;

  		sd_srv_version = SD_VERSION_1;
  		ts_srv_version = TS_VERSION_1;
  		hb_srv_version = HB_VERSION_1;

  		break;

  	case(VERSION_WIN10):

  		util_fw_version = UTIL_FW_VERSION;
  		sd_srv_version = SD_VERSION;
  		ts_srv_version = TS_VERSION;
  		hb_srv_version = HB_VERSION;

  		break;
  	default:
  		util_fw_version = UTIL_FW_VERSION;
  		sd_srv_version = SD_VERSION;
  		ts_srv_version = TS_VERSION_3;
  		hb_srv_version = HB_VERSION;

  	}

  	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_timesync_init(struct hv_util_service *srv)
  {
  	INIT_WORK(&wrk.work, hv_set_host_time);
  	return 0;
  }
  
  static void hv_timesync_deinit(void)
  {
  	cancel_work_sync(&wrk.work);
  }

  static int __init init_hyperv_utils(void)
  {

  	pr_info("Registering HyperV Utility Driver
  ");

  	return vmbus_driver_register(&util_drv);

  }
  
  static void exit_hyperv_utils(void)
  {

  	pr_info("De-Registered HyperV Utility Driver
  ");

  	vmbus_driver_unregister(&util_drv);

  }
  
  module_init(init_hyperv_utils);
  module_exit(exit_hyperv_utils);
  
  MODULE_DESCRIPTION("Hyper-V Utilities");

  MODULE_LICENSE("GPL");