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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 answerbox

 */

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);

	}

}