/*
   * 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_WS2008_MAJOR		1
  #define SD_WS2008_VERSION	(SD_WS2008_MAJOR << 16 | SD_MINOR)
  
  #define TS_MAJOR	3
  #define TS_MINOR	0
  #define TS_VERSION	(TS_MAJOR << 16 | TS_MINOR)
  
  #define TS_WS2008_MAJOR		1
  #define TS_WS2008_VERSION	(TS_WS2008_MAJOR << 16 | TS_MINOR)
  
  #define HB_MAJOR	3
  #define HB_MINOR 0
  #define HB_VERSION	(HB_MAJOR << 16 | HB_MINOR)
  
  #define HB_WS2008_MAJOR	1
  #define HB_WS2008_VERSION	(HB_WS2008_MAJOR << 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 void timesync_onchannelcallback(void *context);
  static struct hv_util_service util_timesynch = {
  	.util_cb = timesync_onchannelcallback,
  };
  
  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 guest time to host UTC time.
   */
  static inline void do_adj_guesttime(u64 hosttime)
  {
  	s64 host_tns;
  	struct timespec host_ts;
  
  	host_tns = (hosttime - WLTIMEDELTA) * 100;
  	host_ts = ns_to_timespec(host_tns);
  
  	do_settimeofday(&host_ts);
  }
  
  /*
   * Set the host time in a process context.
   */
  
  struct adj_time_work {
  	struct work_struct work;
  	u64	host_time;
  };
  
  static void hv_set_host_time(struct work_struct *work)
  {
  	struct adj_time_work	*wrk;
  
  	wrk = container_of(work, struct adj_time_work, work);
  	do_adj_guesttime(wrk->host_time);
  	kfree(wrk);
  }
  
  /*
   * 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. The other
   * thing is, systime is automatically set to emulated hardware clock which may
   * not be UTC time or in the same time zone. So, to override these effects, we
   * use the first 50 time samples for initial system time setting.
   */
  static inline void adj_guesttime(u64 hosttime, u8 flags)
  {
  	struct adj_time_work    *wrk;
  	static s32 scnt = 50;
  
  	wrk = kmalloc(sizeof(struct adj_time_work), GFP_ATOMIC);
  	if (wrk == NULL)
  		return;
  
  	wrk->host_time = hosttime;
  	if ((flags & ICTIMESYNCFLAG_SYNC) != 0) {
  		INIT_WORK(&wrk->work, hv_set_host_time);
  		schedule_work(&wrk->work);
  		return;
  	}
  
  	if ((flags & ICTIMESYNCFLAG_SAMPLE) != 0 && scnt > 0) {
  		scnt--;
  		INIT_WORK(&wrk->work, hv_set_host_time);
  		schedule_work(&wrk->work);
  	} else
  		kfree(wrk);
  }
  
  /*
   * 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;
  	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);
  		} else {
  			timedatap = (struct ictimesync_data *)&time_txf_buf[
  				sizeof(struct vmbuspipe_hdr) +
  				sizeof(struct icmsg_hdr)];
  			adj_guesttime(timedatap->parenttime, 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;
  	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_WS2008_VERSION;
  		ts_srv_version = TS_WS2008_VERSION;
  		hb_srv_version = HB_WS2008_VERSION;
  		break;
  
  	default:
  		util_fw_version = UTIL_FW_VERSION;
  		sd_srv_version = SD_VERSION;
  		ts_srv_version = TS_VERSION;
  		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 __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");