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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;

/** 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);

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

    call->callerbox = &TASK->answerbox;

    call->sender = TASK;

    return call;

}

/** Initialize allocated call */

void ipc_call_init(call_t *call)

{

    call->callerbox = &TASK->answerbox;

    call->flags = IPC_CALL_STATIC_ALLOC;

    call->sender = TASK;

}

/** 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)

{

    ASSERT(!phone->callee);

    phone->busy = 1;

    phone->callee = box;

    spinlock_lock(&box->lock);

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

    spinlock_unlock(&box->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 = 0;

}

/** Disconnect phone from answerbox */

void ipc_phone_destroy(phone_t *phone)

{

    answerbox_t *box = phone->callee;

    ASSERT(box);

    spinlock_lock(&box->lock);

    list_remove(&phone->list);

    spinlock_unlock(&box->lock);

}

/** 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);

}

/** Send a asynchronous request using phone to answerbox

 *

 * @param phone Phone connected to answerbox

 * @param request Request to be sent

 */

void ipc_call(phone_t *phone, call_t *call)

{

    answerbox_t *box = phone->callee;

    ASSERT(box);

    spinlock_lock(&box->lock);

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

    spinlock_unlock(&box->lock);

    waitq_wakeup(&box->wq, 0);

}

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

 *

 * @param request Request to be forwarded

 * @param newbox Target answerbox

 * @param oldbox Old answerbox

 */

void ipc_forward(call_t *call, answerbox_t *newbox, answerbox_t *oldbox)

{

    spinlock_lock(&oldbox->lock);

    list_remove(&call->list);

    spinlock_unlock(&oldbox->lock);

    spinlock_lock(&newbox->lock);

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

    spinlock_lock(&newbox->lock);

    waitq_wakeup(&newbox->wq, 0);

}

/** Answer message back to phone

 *

 * @param box Answerbox that is answering the message

 * @param request Modified request that is being sent back

 */

void ipc_answer(answerbox_t *box, call_t *request)

{

    answerbox_t *callerbox = request->callerbox;

    request->flags &= ~IPC_CALL_DISPATCHED;

    request->flags |= IPC_CALL_ANSWERED;

    spinlock_lock(&box->lock);

    list_remove(&request->list);

    spinlock_unlock(&box->lock);

    spinlock_lock(&callerbox->lock);

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

    spinlock_unlock(&callerbox->lock);

    waitq_wakeup(&callerbox->wq, 0);

}

/** 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;

    spinlock_lock(&box->lock);

    while (1) {

        if (!list_empty(&box->answers)) {

            /* Handle asynchronous answers */

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

            list_remove(&request->list);

        } 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);

            request->flags |= IPC_CALL_DISPATCHED;

        } else {

            if (!(flags & IPC_WAIT_NONBLOCKING)) {

                /* Wait for event to appear */

                spinlock_unlock(&box->lock);

                waitq_sleep(&box->wq);

                spinlock_lock(&box->lock);

                continue;

            }

            request = NULL;

        }

        break;

    }

    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);

}