/*
 *
 * Copyright (c) 2009, 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>
 *
 */
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/vmalloc.h>
#include "osd.h"
#include "logging.h"
#include "VmbusPrivate.h"


struct VMBUS_CONNECTION gVmbusConnection = {
        .ConnectState           = Disconnected,
        .NextGpadlHandle        = ATOMIC_INIT(0xE1E10),
};

/**
 * VmbusConnect - Sends a connect request on the partition service connection
 */
int VmbusConnect(void)
{
        int ret = 0;
        struct vmbus_channel_msginfo *msgInfo = NULL;
        struct vmbus_channel_initiate_contact *msg;
        unsigned long flags;

        DPRINT_ENTER(VMBUS);

        /* Make sure we are not connecting or connected */
        if (gVmbusConnection.ConnectState != Disconnected)
                return -1;

        /* Initialize the vmbus connection */
        gVmbusConnection.ConnectState = Connecting;
        gVmbusConnection.WorkQueue = create_workqueue("hv_vmbus_con");
        if (!gVmbusConnection.WorkQueue) {
                ret = -1;
                goto Cleanup;
        }

        INIT_LIST_HEAD(&gVmbusConnection.ChannelMsgList);
        spin_lock_init(&gVmbusConnection.channelmsg_lock);

        INIT_LIST_HEAD(&gVmbusConnection.ChannelList);
        spin_lock_init(&gVmbusConnection.channel_lock);

        /*
         * Setup the vmbus event connection for channel interrupt
         * abstraction stuff
         */
        gVmbusConnection.InterruptPage = osd_PageAlloc(1);
        if (gVmbusConnection.InterruptPage == NULL) {
                ret = -1;
                goto Cleanup;
        }

        gVmbusConnection.RecvInterruptPage = gVmbusConnection.InterruptPage;
        gVmbusConnection.SendInterruptPage =
                (void *)((unsigned long)gVmbusConnection.InterruptPage +
                        (PAGE_SIZE >> 1));

        /*
         * Setup the monitor notification facility. The 1st page for
         * parent->child and the 2nd page for child->parent
         */
        gVmbusConnection.MonitorPages = osd_PageAlloc(2);
        if (gVmbusConnection.MonitorPages == NULL) {
                ret = -1;
                goto Cleanup;
        }

        msgInfo = kzalloc(sizeof(*msgInfo) +
                          sizeof(struct vmbus_channel_initiate_contact),
                          GFP_KERNEL);
        if (msgInfo == NULL) {
                ret = -1;
                goto Cleanup;
        }

        msgInfo->WaitEvent = osd_WaitEventCreate();
        msg = (struct vmbus_channel_initiate_contact *)msgInfo->Msg;

        msg->Header.MessageType = ChannelMessageInitiateContact;
        msg->VMBusVersionRequested = VMBUS_REVISION_NUMBER;
        msg->InterruptPage = virt_to_phys(gVmbusConnection.InterruptPage);
        msg->MonitorPage1 = virt_to_phys(gVmbusConnection.MonitorPages);
        msg->MonitorPage2 = virt_to_phys(
                        (void *)((unsigned long)gVmbusConnection.MonitorPages +
                                 PAGE_SIZE));

        /*
         * Add to list before we send the request since we may
         * receive the response before returning from this routine
         */
        spin_lock_irqsave(&gVmbusConnection.channelmsg_lock, flags);
        list_add_tail(&msgInfo->MsgListEntry,
                      &gVmbusConnection.ChannelMsgList);

        spin_unlock_irqrestore(&gVmbusConnection.channelmsg_lock, flags);

        DPRINT_DBG(VMBUS, "Vmbus connection - interrupt pfn %llx, "
                   "monitor1 pfn %llx,, monitor2 pfn %llx",
                   msg->InterruptPage, msg->MonitorPage1, msg->MonitorPage2);

        DPRINT_DBG(VMBUS, "Sending channel initiate msg...");
        ret = VmbusPostMessage(msg,
                               sizeof(struct vmbus_channel_initiate_contact));
        if (ret != 0) {
                list_del(&msgInfo->MsgListEntry);
                goto Cleanup;
        }

        /* Wait for the connection response */
        osd_WaitEventWait(msgInfo->WaitEvent);

        list_del(&msgInfo->MsgListEntry);

        /* Check if successful */
        if (msgInfo->Response.VersionResponse.VersionSupported) {
                DPRINT_INFO(VMBUS, "Vmbus connected!!");
                gVmbusConnection.ConnectState = Connected;

        } else {
                DPRINT_ERR(VMBUS, "Vmbus connection failed!!..."
                           "current version (%d) not supported",
                           VMBUS_REVISION_NUMBER);
                ret = -1;
                goto Cleanup;
        }

        kfree(msgInfo->WaitEvent);
        kfree(msgInfo);
        DPRINT_EXIT(VMBUS);

        return 0;

Cleanup:
        gVmbusConnection.ConnectState = Disconnected;

        if (gVmbusConnection.WorkQueue)
                destroy_workqueue(gVmbusConnection.WorkQueue);

        if (gVmbusConnection.InterruptPage) {
                osd_PageFree(gVmbusConnection.InterruptPage, 1);
                gVmbusConnection.InterruptPage = NULL;
        }

        if (gVmbusConnection.MonitorPages) {
                osd_PageFree(gVmbusConnection.MonitorPages, 2);
                gVmbusConnection.MonitorPages = NULL;
        }

        if (msgInfo) {
                kfree(msgInfo->WaitEvent);
                kfree(msgInfo);
        }

        DPRINT_EXIT(VMBUS);

        return ret;
}

/**
 * VmbusDisconnect - Sends a disconnect request on the partition service connection
 */
int VmbusDisconnect(void)
{
        int ret = 0;
        struct vmbus_channel_message_header *msg;

        DPRINT_ENTER(VMBUS);

        /* Make sure we are connected */
        if (gVmbusConnection.ConnectState != Connected)
                return -1;

        msg = kzalloc(sizeof(struct vmbus_channel_message_header), GFP_KERNEL);

        msg->MessageType = ChannelMessageUnload;

        ret = VmbusPostMessage(msg,
                               sizeof(struct vmbus_channel_message_header));
        if (ret != 0)
                goto Cleanup;

        osd_PageFree(gVmbusConnection.InterruptPage, 1);

        /* TODO: iterate thru the msg list and free up */
        destroy_workqueue(gVmbusConnection.WorkQueue);

        gVmbusConnection.ConnectState = Disconnected;

        DPRINT_INFO(VMBUS, "Vmbus disconnected!!");

Cleanup:
        kfree(msg);
        DPRINT_EXIT(VMBUS);
        return ret;
}

/**
 * GetChannelFromRelId - Get the channel object given its child relative id (ie channel id)
 */
struct vmbus_channel *GetChannelFromRelId(u32 relId)
{
        struct vmbus_channel *channel;
        struct vmbus_channel *foundChannel  = NULL;
        unsigned long flags;

        spin_lock_irqsave(&gVmbusConnection.channel_lock, flags);
        list_for_each_entry(channel, &gVmbusConnection.ChannelList, ListEntry) {
                if (channel->OfferMsg.ChildRelId == relId) {
                        foundChannel = channel;
                        break;
                }
        }
        spin_unlock_irqrestore(&gVmbusConnection.channel_lock, flags);

        return foundChannel;
}

/**
 * VmbusProcessChannelEvent - Process a channel event notification
 */
static void VmbusProcessChannelEvent(void *context)
{
        struct vmbus_channel *channel;
        u32 relId = (u32)(unsigned long)context;

        ASSERT(relId > 0);

        /*
         * Find the channel based on this relid and invokes the
         * channel callback to process the event
         */
        channel = GetChannelFromRelId(relId);

        if (channel) {
                VmbusChannelOnChannelEvent(channel);
                /*
                 * WorkQueueQueueWorkItem(channel->dataWorkQueue,
                 *                        VmbusChannelOnChannelEvent,
                 *                        (void*)channel);
                 */
        } else {
                DPRINT_ERR(VMBUS, "channel not found for relid - %d.", relId);
        }
}

/**
 * VmbusOnEvents - Handler for events
 */
void VmbusOnEvents(void)
{
        int dword;
        int maxdword = MAX_NUM_CHANNELS_SUPPORTED >> 5;
        int bit;
        int relid;
        u32 *recvInterruptPage = gVmbusConnection.RecvInterruptPage;

        DPRINT_ENTER(VMBUS);

        /* Check events */
        if (recvInterruptPage) {
                for (dword = 0; dword < maxdword; dword++) {
                        if (recvInterruptPage[dword]) {
                                for (bit = 0; bit < 32; bit++) {
                                        if (test_and_clear_bit(bit, (unsigned long *)&recvInterruptPage[dword])) {
                                                relid = (dword << 5) + bit;
                                                DPRINT_DBG(VMBUS, "event detected for relid - %d", relid);

                                                if (relid == 0) {
                                                        /* special case - vmbus channel protocol msg */
                                                        DPRINT_DBG(VMBUS, "invalid relid - %d", relid);
                                                        continue;
                                                } else {
                                                        /* QueueWorkItem(VmbusProcessEvent, (void*)relid); */
                                                        /* ret = WorkQueueQueueWorkItem(gVmbusConnection.workQueue, VmbusProcessChannelEvent, (void*)relid); */
                                                        VmbusProcessChannelEvent((void *)(unsigned long)relid);
                                                }
                                        }
                                }
                        }
                 }
        }
        DPRINT_EXIT(VMBUS);

        return;
}

/**
 * VmbusPostMessage - Send a msg on the vmbus's message connection
 */
int VmbusPostMessage(void *buffer, size_t bufferLen)
{
        union hv_connection_id connId;

        connId.Asu32 = 0;
        connId.u.Id = VMBUS_MESSAGE_CONNECTION_ID;
        return HvPostMessage(connId, 1, buffer, bufferLen);
}

/**
 * VmbusSetEvent - Send an event notification to the parent
 */
int VmbusSetEvent(u32 childRelId)
{
        int ret = 0;

        DPRINT_ENTER(VMBUS);

        /* Each u32 represents 32 channels */
        set_bit(childRelId & 31,
                (unsigned long *)gVmbusConnection.SendInterruptPage +
                (childRelId >> 5));

        ret = HvSignalEvent();

        DPRINT_EXIT(VMBUS);

        return ret;
}