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/*

 * Copyright (C) 2006 Ondrej Palkovsky

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 * - Redistributions of source code must retain the above copyright

 *   notice, this list of conditions and the following disclaimer.

 * - Redistributions in binary form must reproduce the above copyright

 *   notice, this list of conditions and the following disclaimer in the

 *   documentation and/or other materials provided with the distribution.

 * - The name of the author may not be used to endorse or promote products

 *   derived from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR

 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES

 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.

 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,

 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT

 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF

 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

/* Lock ordering

 *

 * First the answerbox, then the phone

 */

#include <synch/spinlock.h>

#include <synch/waitq.h>

#include <ipc/ipc.h>

#include <errno.h>

#include <mm/slab.h>

#include <arch.h>

#include <proc/task.h>

#include <memstr.h>

#include <debug.h>

#include <print.h>

#include <proc/thread.h>

/* Open channel that is assigned automatically to new tasks */

answerbox_t *ipc_phone_0 = NULL;

static slab_cache_t *ipc_call_slab;

/* Initialize new call */

static void _ipc_call_init(call_t *call)

{

    memsetb((__address)call, sizeof(*call), 0);

    call->callerbox = &TASK->answerbox;

    call->sender = TASK;

}

/** Allocate & initialize call structure

 *

 * The call is initialized, so that the reply will be directed

 * to TASK->answerbox

 */

call_t * ipc_call_alloc(void)

{

    call_t *call;

    call = slab_alloc(ipc_call_slab, 0);

    _ipc_call_init(call);

    return call;

}

/** Initialize allocated call */

void ipc_call_static_init(call_t *call)

{

    _ipc_call_init(call);

    call->flags |= IPC_CALL_STATIC_ALLOC;

}

/** Deallocate call stracuture */

void ipc_call_free(call_t *call)

{

    slab_free(ipc_call_slab, call);

}

/** Initialize answerbox structure

 */

void ipc_answerbox_init(answerbox_t *box)

{

    spinlock_initialize(&box->lock, "ipc_box_lock");

    waitq_initialize(&box->wq);

    list_initialize(&box->connected_phones);

    list_initialize(&box->calls);

    list_initialize(&box->dispatched_calls);

    list_initialize(&box->answers);

    box->task = TASK;

}

/** Connect phone to answerbox */

void ipc_phone_connect(phone_t *phone, answerbox_t *box)

{

    spinlock_lock(&phone->lock);

    ASSERT(!phone->callee);

    phone->busy = IPC_BUSY_CONNECTED;

    phone->callee = box;

    spinlock_lock(&box->lock);

    list_append(&phone->list, &box->connected_phones);

    spinlock_unlock(&box->lock);

    spinlock_unlock(&phone->lock);

}

/** Initialize phone structure and connect phone to naswerbox

 */

void ipc_phone_init(phone_t *phone)

{

    spinlock_initialize(&phone->lock, "phone_lock");

    phone->callee = NULL;

    phone->busy = IPC_BUSY_FREE;

    atomic_set(&phone->active_calls, 0);

}

/** Helper function to facilitate synchronous calls */

void ipc_call_sync(phone_t *phone, call_t *request)

{

    answerbox_t sync_box;

    ipc_answerbox_init(&sync_box);

    /* We will receive data on special box */

    request->callerbox = &sync_box;

    ipc_call(phone, request);

    ipc_wait_for_call(&sync_box, 0);

}

/** Answer message that was not dispatched and is not entered in

 * any queue

 */

static void _ipc_answer_free_call(call_t *call)

{

    answerbox_t *callerbox = call->callerbox;

    call->flags |= IPC_CALL_ANSWERED;

    spinlock_lock(&callerbox->lock);

    list_append(&call->list, &callerbox->answers);

    spinlock_unlock(&callerbox->lock);

    waitq_wakeup(&callerbox->wq, 0);

}

/** Answer message, that is in callee queue

 *

 * @param box Answerbox that is answering the message

 * @param call Modified request that is being sent back

 */

void ipc_answer(answerbox_t *box, call_t *call)

{

    /* Remove from active box */

    spinlock_lock(&box->lock);

    list_remove(&call->list);

    spinlock_unlock(&box->lock);

    /* Send back answer */

    _ipc_answer_free_call(call);

}

/** Simulate sending back a message

 *

 * Most errors are better handled by forming a normal backward

 * message and sending it as a normal answer.

 */

void ipc_backsend_err(phone_t *phone, call_t *call, __native err)

{

    call->data.phone = phone;

    atomic_inc(&phone->active_calls);

    if (phone->busy == IPC_BUSY_CONNECTED)

        IPC_SET_RETVAL(call->data, EHANGUP);

    else

        IPC_SET_RETVAL(call->data, ENOENT);

    _ipc_answer_free_call(call);

}

/* Unsafe unchecking ipc_call */

static void _ipc_call(phone_t *phone, answerbox_t *box, call_t *call)

{

    if (! (call->flags & IPC_CALL_FORWARDED)) {

        atomic_inc(&phone->active_calls);

        call->data.phone = phone;

    }

    spinlock_lock(&box->lock);

    list_append(&call->list, &box->calls);

    spinlock_unlock(&box->lock);

    waitq_wakeup(&box->wq, 0);

}

/** Send a asynchronous request using phone to answerbox

 *

 * @param phone Phone connected to answerbox

 * @param request Request to be sent

 */

int ipc_call(phone_t *phone, call_t *call)

{

    answerbox_t *box;

    spinlock_lock(&phone->lock);

    box = phone->callee;

    if (!box) {

        /* Trying to send over disconnected phone */

        spinlock_unlock(&phone->lock);

        if (call->flags & IPC_CALL_FORWARDED) {

            IPC_SET_RETVAL(call->data, EFORWARD);

            _ipc_answer_free_call(call);

        } else { /* Simulate sending back a message */

            if (phone->busy == IPC_BUSY_CONNECTED)

                ipc_backsend_err(phone, call, EHANGUP);

            else

                ipc_backsend_err(phone, call, ENOENT);

        }

        return ENOENT;

    }

    _ipc_call(phone, box, call);

    spinlock_unlock(&phone->lock);

    return 0;

}

/** Disconnect phone from answerbox

 *

 * It is allowed to call disconnect on already disconnected phone

 *

 * @return 0 - phone disconnected, -1 - the phone was already disconnected

 */

int ipc_phone_hangup(phone_t *phone)

{

    answerbox_t *box;

    call_t *call;

    spinlock_lock(&phone->lock);

    box = phone->callee;

    if (!box) {

        if (phone->busy == IPC_BUSY_CONNECTING) {

            spinlock_unlock(&phone->lock);

            return -1;

        }

        /* Already disconnected phone */

        phone->busy = IPC_BUSY_FREE;

        spinlock_unlock(&phone->lock);

        return 0;

    }

    spinlock_lock(&box->lock);

    list_remove(&phone->list);

    phone->callee = NULL;

    spinlock_unlock(&box->lock);

    call = ipc_call_alloc();

    IPC_SET_METHOD(call->data, IPC_M_PHONE_HUNGUP);

    call->flags |= IPC_CALL_DISCARD_ANSWER;

    _ipc_call(phone, box, call);

    phone->busy = IPC_BUSY_FREE;

    spinlock_unlock(&phone->lock);

    return 0;

}

/** Forwards call from one answerbox to a new one

 *

 * @param request Request to be forwarded

 * @param newbox Target answerbox

 * @param oldbox Old answerbox

 * @return 0 on forward ok, error code, if there was error

 *

 * - the return value serves only as an information for the forwarder,

 *   the original caller is notified automatically with EFORWARD

 */

int ipc_forward(call_t *call, phone_t *newphone, answerbox_t *oldbox)

{

    spinlock_lock(&oldbox->lock);

    list_remove(&call->list);

    spinlock_unlock(&oldbox->lock);

    return ipc_call(newphone, call);

}

/** Wait for phone call

 *

 * @return Recived message address

 * - to distinguish between call and answer, look at call->flags

 */

call_t * ipc_wait_for_call(answerbox_t *box, int flags)

{

    call_t *request;

restart:      

    if (flags & IPC_WAIT_NONBLOCKING) {

        if (waitq_sleep_timeout(&box->wq,0,1) == ESYNCH_WOULD_BLOCK)

            return NULL;

    } else

        waitq_sleep(&box->wq);

    spinlock_lock(&box->lock);

    if (!list_empty(&box->answers)) {

        /* Handle asynchronous answers */

        request = list_get_instance(box->answers.next, call_t, list);

        list_remove(&request->list);

        atomic_dec(&request->data.phone->active_calls);

    } else if (!list_empty(&box->calls)) {

        /* Handle requests */

        request = list_get_instance(box->calls.next, call_t, list);

        list_remove(&request->list);

        /* Append request to dispatch queue */

        list_append(&request->list, &box->dispatched_calls);

    } else {

        /* This can happen regularly after ipc_cleanup, remove

         * the warning in the future when the IPC is

         * more debugged */

        printf("WARNING: Spurious IPC wakeup.\n");

        spinlock_unlock(&box->lock);

        goto restart;

    }

    spinlock_unlock(&box->lock);

    return request;

}

/** Initilize ipc subsystem */

void ipc_init(void)

{

    ipc_call_slab = slab_cache_create("ipc_call",

                      sizeof(call_t),

                      0,

                      NULL, NULL, 0);

}

/** Answer all calls from list with EHANGUP msg */

static void ipc_cleanup_call_list(link_t *lst)

{

    call_t *call;

    while (!list_empty(lst)) {

        call = list_get_instance(lst->next, call_t, list);

        list_remove(&call->list);

        IPC_SET_RETVAL(call->data, EHANGUP);

        _ipc_answer_free_call(call);

    }

}

/** Cleans up all IPC communication of the given task

 *

 *

 */

void ipc_cleanup(task_t *task)

{

    int i;

    call_t *call;

    phone_t *phone;

    /* Disconnect all our phones ('ipc_phone_hangup') */

    for (i=0;i < IPC_MAX_PHONES; i++)

        ipc_phone_hangup(&task->phones[i]);

    /* Disconnect all phones connected to our answerbox */

restart_phones:

    spinlock_lock(&task->answerbox.lock);

    while (!list_empty(&task->answerbox.connected_phones)) {

        phone = list_get_instance(task->answerbox.connected_phones.next,

                      phone_t,

                      list);

        if (! spinlock_trylock(&phone->lock)) {

            spinlock_unlock(&task->answerbox.lock);

            goto restart_phones;

        }

        /* Disconnect phone */

        phone->callee = NULL;

        list_remove(&phone->list);

        spinlock_unlock(&phone->lock);

    }

    /* Answer all messages in 'calls' and 'dispatched_calls' queues */

    spinlock_lock(&task->answerbox.lock);

    ipc_cleanup_call_list(&task->answerbox.dispatched_calls);

    ipc_cleanup_call_list(&task->answerbox.calls);

    spinlock_unlock(&task->answerbox.lock);

    /* Wait for all async answers to arrive */

    while (atomic_get(&task->active_calls)) {

        call = ipc_wait_for_call(&task->answerbox, 0);

        ASSERT(call->flags & IPC_CALL_ANSWERED);

        ASSERT(! (call->flags & IPC_CALL_STATIC_ALLOC));

        atomic_dec(&task->active_calls);

        ipc_call_free(call);

    }

}