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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.

 */

/** @addtogroup genericipc

 * @{

 */

/** @file

 */

/* Lock ordering

 *

 * First the answerbox, then the phone.

 */

#include <synch/spinlock.h>

#include <synch/waitq.h>

#include <synch/synch.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>

#include <arch/interrupt.h>

#include <ipc/irq.h>

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

answerbox_t *ipc_phone_0 = NULL;

static slab_cache_t *ipc_call_slab;

/** Initialize a call structure.

 *

 * @param call		Call structure to be initialized.

 */

static void _ipc_call_init(call_t *call)

{

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

	call->callerbox = &TASK->answerbox;

	call->sender = TASK;

}

/** Allocate and initialize a call structure.

 * 

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

 * TASK->answerbox.

 *

 * @param flags		Parameters for slab_alloc (e.g FRAME_ATOMIC).

 *

 * @return		If flags permit it, return NULL, or initialized kernel

 *			call structure.

 */

call_t *ipc_call_alloc(int flags)

{

	call_t *call;

	call = slab_alloc(ipc_call_slab, flags);

	_ipc_call_init(call);

	return call;

}

/** Initialize a statically allocated call structure.

 *

 * @param call		Statically allocated kernel call structure to be

 *			initialized.

 */

void ipc_call_static_init(call_t *call)

{

	_ipc_call_init(call);

	call->flags |= IPC_CALL_STATIC_ALLOC;

}

/** Deallocate a call structure.

 *

 * @param call		Call structure to be freed.

 */

void ipc_call_free(call_t *call)

{

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

	slab_free(ipc_call_slab, call);

}

/** Initialize an answerbox structure.

 *

 * @param box		Answerbox structure to be initialized.

 */

void ipc_answerbox_init(answerbox_t *box)

{

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

	spinlock_initialize(&box->irq_lock, "ipc_box_irqlock");

	waitq_initialize(&box->wq);

	list_initialize(&box->connected_phones);

	list_initialize(&box->calls);

	list_initialize(&box->dispatched_calls);

	list_initialize(&box->answers);

	list_initialize(&box->irq_notifs);

	list_initialize(&box->irq_head);

	box->task = TASK;

}

/** Connect a phone to an answerbox.

 *

 * @param phone		Initialized phone structure.

 * @param box		Initialized answerbox structure.

 */

void ipc_phone_connect(phone_t *phone, answerbox_t *box)

{

	spinlock_lock(&phone->lock);

	phone->state = IPC_PHONE_CONNECTED;

	phone->callee = box;

	spinlock_lock(&box->lock);

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

	spinlock_unlock(&box->lock);

	spinlock_unlock(&phone->lock);

}

/** Initialize a phone structure.

 *

 * @param phone		Phone structure to be initialized.

 */

void ipc_phone_init(phone_t *phone)

{

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

	phone->callee = NULL;

	phone->state = IPC_PHONE_FREE;

	atomic_set(&phone->active_calls, 0);

}

/** Helper function to facilitate synchronous calls.

 *

 * @param phone		Destination kernel phone structure.

 * @param request	Call structure with request.

 */

void ipc_call_sync(phone_t *phone, call_t *request)

{

	answerbox_t sync_box; 

	ipc_answerbox_init(&sync_box);

	/* We will receive data in a special box. */

	request->callerbox = &sync_box;

	ipc_call(phone, request);

	ipc_wait_for_call(&sync_box, SYNCH_NO_TIMEOUT, SYNCH_FLAGS_NONE);

}

/** Answer a message which was not dispatched and is not listed in any queue.

 *

 * @param call		Call structure to be answered.

 */

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->link, &callerbox->answers);

	spinlock_unlock(&callerbox->lock);

	waitq_wakeup(&callerbox->wq, WAKEUP_FIRST);

}

/** Answer a message which is in a 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->link);

	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.

 *

 * @param phone		Phone structure the call should appear to come from.

 * @param call		Call structure to be answered.

 * @param err		Return value to be used for the answer.

 */

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

{

	call->data.phone = phone;

	atomic_inc(&phone->active_calls);

	IPC_SET_RETVAL(call->data, err);

	_ipc_answer_free_call(call);

}

/** Unsafe unchecking version of ipc_call.

 *

 * @param phone		Phone structure the call comes from.

 * @param box		Destination answerbox structure.

 */

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->link, &box->calls);

	spinlock_unlock(&box->lock);

	waitq_wakeup(&box->wq, WAKEUP_FIRST);

}

/** Send an asynchronous request using a phone to an answerbox.

 *

 * @param phone		Phone structure the call comes from and which is

 *			connected to the destination answerbox.

 * @param call		Call structure with request.

 *

 * @return		Return 0 on success, ENOENT on error.

 */

int ipc_call(phone_t *phone, call_t *call)

{

	answerbox_t *box;

	spinlock_lock(&phone->lock);

	if (phone->state != IPC_PHONE_CONNECTED) {

		spinlock_unlock(&phone->lock);

		if (call->flags & IPC_CALL_FORWARDED) {

			IPC_SET_RETVAL(call->data, EFORWARD);

			_ipc_answer_free_call(call);

		} else {

			if (phone->state == IPC_PHONE_HUNGUP)

				ipc_backsend_err(phone, call, EHANGUP);

			else

				ipc_backsend_err(phone, call, ENOENT);

		}

		return ENOENT;

	}

	box = phone->callee;

	_ipc_call(phone, box, call);

	spinlock_unlock(&phone->lock);

	return 0;

}

/** Disconnect phone from answerbox.

 *

 * This call leaves the phone in the HUNGUP state. The change to 'free' is done

 * lazily later.

 *

 * @param phone		Phone structure to be hung up.

 *              

 * @return		Return 0 if the phone is disconnected.

 *			Return -1 if the phone was already disconnected.

 */

int ipc_phone_hangup(phone_t *phone)

{

	answerbox_t *box;

	call_t *call;

	spinlock_lock(&phone->lock);

	if (phone->state == IPC_PHONE_FREE || phone->state == IPC_PHONE_HUNGUP ||

	    phone->state == IPC_PHONE_CONNECTING) {

		spinlock_unlock(&phone->lock);

		return -1;

	}

	box = phone->callee;

	if (phone->state != IPC_PHONE_SLAMMED) {

		/* Remove myself from answerbox */

		spinlock_lock(&box->lock);

		list_remove(&phone->link);

		spinlock_unlock(&box->lock);

		if (phone->state != IPC_PHONE_SLAMMED) {

			call = ipc_call_alloc(0);

			IPC_SET_METHOD(call->data, IPC_M_PHONE_HUNGUP);

			call->flags |= IPC_CALL_DISCARD_ANSWER;

			_ipc_call(phone, box, call);

		}

	}

	phone->state = IPC_PHONE_HUNGUP;

	spinlock_unlock(&phone->lock);

	return 0;

}

/** Forwards call from one answerbox to another one.

 *

 * @param call		Call structure to be redirected.

 * @param newphone	Phone structure to target answerbox.

 * @param oldbox	Old answerbox structure.

 *

 * @return		Return 0 if forwarding succeeded or an 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->link);

	spinlock_unlock(&oldbox->lock);

	return ipc_call(newphone, call);

}

/** Wait for a phone call.

 *

 * @param box		Answerbox expecting the call.

 * @param usec		Timeout in microseconds. See documentation for

 *			waitq_sleep_timeout() for decription of its special

 *			meaning.

 * @param flags		Select mode of sleep operation. See documentation for

 *			waitq_sleep_timeout() for description of its special

 *			meaning.

 * @return 		Recived call structure or NULL.

 * 

 * To distinguish between a call and an answer, have a look at call->flags.

 */

call_t *ipc_wait_for_call(answerbox_t *box, uint32_t usec, int flags)

{

	call_t *request;

	ipl_t ipl;

	int rc;

restart:

	rc = waitq_sleep_timeout(&box->wq, usec, flags);

	if (SYNCH_FAILED(rc))

		return NULL;

	spinlock_lock(&box->lock);

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

		ipl = interrupts_disable();

		spinlock_lock(&box->irq_lock);

		request = list_get_instance(box->irq_notifs.next, call_t, link);

		list_remove(&request->link);

		spinlock_unlock(&box->irq_lock);

		interrupts_restore(ipl);

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

		/* Handle asynchronous answers */

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

		list_remove(&request->link);

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

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

		/* Handle requests */

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

		list_remove(&request->link);

		/* Append request to dispatch queue */

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

	} else {

		/* This can happen regularly after ipc_cleanup */

		spinlock_unlock(&box->lock);

		goto restart;

	}

	spinlock_unlock(&box->lock);

	return request;

}

/** Answer all calls from list with EHANGUP answer.

 *

 * @param lst		Head of the list to be cleaned up.

 */

static void ipc_cleanup_call_list(link_t *lst)

{

	call_t *call;

	while (!list_empty(lst)) {

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

		list_remove(&call->link);

		IPC_SET_RETVAL(call->data, EHANGUP);

		_ipc_answer_free_call(call);

	}

}

/** Cleans up all IPC communication of the current task.

 *

 * Note: ipc_hangup sets returning answerbox to TASK->answerbox, you

 * have to change it as well if you want to cleanup other tasks than TASK.

 */

void ipc_cleanup(void)

{

	int i;

	call_t *call;

	phone_t *phone;

	DEADLOCK_PROBE_INIT(p_phonelck);

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

	for (i = 0; i < IPC_MAX_PHONES; i++)

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

	/* Disconnect all connected irqs */

	ipc_irq_cleanup(&TASK->answerbox);

	/* 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, link);

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

			spinlock_unlock(&TASK->answerbox.lock);

			DEADLOCK_PROBE(p_phonelck, DEADLOCK_THRESHOLD);

			goto restart_phones;

		}

		/* Disconnect phone */

		ASSERT(phone->state == IPC_PHONE_CONNECTED);

		phone->state = IPC_PHONE_SLAMMED;

		list_remove(&phone->link);

		spinlock_unlock(&phone->lock);

	}

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

	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 (1) {

		/* Go through all phones, until all are FREE... */

		/* Locking not needed, no one else should modify

		 * it, when we are in cleanup */

		for (i = 0; i < IPC_MAX_PHONES; i++) {

			if (TASK->phones[i].state == IPC_PHONE_HUNGUP &&

			    atomic_get(&TASK->phones[i].active_calls) == 0)

				TASK->phones[i].state = IPC_PHONE_FREE;

			/* Just for sure, we might have had some 

			 * IPC_PHONE_CONNECTING phones */

			if (TASK->phones[i].state == IPC_PHONE_CONNECTED)

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

			/* If the hangup succeeded, it has sent a HANGUP 

			 * message, the IPC is now in HUNGUP state, we

			 * wait for the reply to come */

			if (TASK->phones[i].state != IPC_PHONE_FREE)

				break;

		}

		/* Voila, got into cleanup */

		if (i == IPC_MAX_PHONES)

			break;

		call = ipc_wait_for_call(&TASK->answerbox, SYNCH_NO_TIMEOUT,

		    SYNCH_FLAGS_NONE);

		ASSERT((call->flags & IPC_CALL_ANSWERED) ||

		    (call->flags & IPC_CALL_NOTIF));

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

		atomic_dec(&TASK->active_calls);

		ipc_call_free(call);

	}

}

/** Initilize IPC subsystem */

void ipc_init(void)

{

	ipc_call_slab = slab_cache_create("ipc_call", sizeof(call_t), 0, NULL,

	    NULL, 0);

}

/** List answerbox contents.

 *

 * @param taskid	Task ID.

 */

void ipc_print_task(task_id_t taskid)

{

	task_t *task;

	int i;

	call_t *call;

	link_t *tmp;

	spinlock_lock(&tasks_lock);

	task = task_find_by_id(taskid);

	if (task) 

		spinlock_lock(&task->lock);

	spinlock_unlock(&tasks_lock);

	if (!task)

		return;

	/* Print opened phones & details */

	printf("PHONE:\n");

	for (i = 0; i < IPC_MAX_PHONES; i++) {

		spinlock_lock(&task->phones[i].lock);

		if (task->phones[i].state != IPC_PHONE_FREE) {

			printf("%d: ", i);

			switch (task->phones[i].state) {

			case IPC_PHONE_CONNECTING:

				printf("connecting ");

				break;

			case IPC_PHONE_CONNECTED:

				printf("connected to: %p ", 

				       task->phones[i].callee);

				break;

			case IPC_PHONE_SLAMMED:

				printf("slammed by: %p ", 

				       task->phones[i].callee);

				break;

			case IPC_PHONE_HUNGUP:

				printf("hung up - was: %p ", 

				       task->phones[i].callee);

				break;

			default:

				break;

			}

			printf("active: %d\n",

			    atomic_get(&task->phones[i].active_calls));

		}

		spinlock_unlock(&task->phones[i].lock);

	}

	/* Print answerbox - calls */

	spinlock_lock(&task->answerbox.lock);

	printf("ABOX - CALLS:\n");

	for (tmp = task->answerbox.calls.next; tmp != &task->answerbox.calls;

	    tmp = tmp->next) {

		call = list_get_instance(tmp, call_t, link);

		printf("Callid: %p Srctask:%llu M:%d A1:%d A2:%d A3:%d "

		    "Flags:%x\n", call, call->sender->taskid,

		    IPC_GET_METHOD(call->data), IPC_GET_ARG1(call->data),

		    IPC_GET_ARG2(call->data), IPC_GET_ARG3(call->data),

		    call->flags);

	}

	/* Print answerbox - calls */

	printf("ABOX - DISPATCHED CALLS:\n");

	for (tmp=task->answerbox.dispatched_calls.next; 

	     tmp != &task->answerbox.dispatched_calls; 

	     tmp = tmp->next) {

		call = list_get_instance(tmp, call_t, link);

		printf("Callid: %p Srctask:%llu M:%d A1:%d A2:%d A3:%d "

		    "Flags:%x\n", call, call->sender->taskid,

		    IPC_GET_METHOD(call->data), IPC_GET_ARG1(call->data),

		    IPC_GET_ARG2(call->data), IPC_GET_ARG3(call->data),

		    call->flags);

	}

	/* Print answerbox - calls */

	printf("ABOX - ANSWERS:\n");

	for (tmp = task->answerbox.answers.next; tmp != &task->answerbox.answers;

	    tmp = tmp->next) {

		call = list_get_instance(tmp, call_t, link);

		printf("Callid:%p M:%d A1:%d A2:%d A3:%d Flags:%x\n", call,

		    IPC_GET_METHOD(call->data), IPC_GET_ARG1(call->data),

		    IPC_GET_ARG2(call->data), IPC_GET_ARG3(call->data),

		    call->flags);

	}

	spinlock_unlock(&task->answerbox.lock);

	spinlock_unlock(&task->lock);

}

/** @}

 */