seq_queue.c

linux-2.6.15.6

/*
 *   ALSA sequencer Timing queue handling
 *   Copyright (c) 1998-1999 by Frank van de Pol <[e-mail]>
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that 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
 *
 * MAJOR CHANGES
 *   Nov. 13, 1999	Takashi Iwai <[e-mail]>
 *     - Queues are allocated dynamically via ioctl.
 *     - When owner client is deleted, all owned queues are deleted, too.
 *     - Owner of unlocked queue is kept unmodified even if it is
 *	 manipulated by other clients.
 *     - Owner field in SET_QUEUE_OWNER ioctl must be identical with the
 *       caller client.  i.e. Changing owner to a third client is not
 *       allowed.
 *
 *  Aug. 30, 2000	Takashi Iwai
 *     - Queues are managed in static array again, but with better way.
 *       The API itself is identical.
 *     - The queue is locked when queue_t pinter is returned via
 *       queueptr().  This pointer *MUST* be released afterward by
 *       queuefree(ptr).
 *     - Addition of experimental sync support.
 */

#include <sound/driver.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <sound/core.h>

#include "seq_memory.h"
#include "seq_queue.h"
#include "seq_clientmgr.h"
#include "seq_fifo.h"
#include "seq_timer.h"
#include "seq_info.h"

/* list of allocated queues */
static queue_t *queue_list[SNDRV_SEQ_MAX_QUEUES];
static DEFINE_SPINLOCK(queue_list_lock);
/* number of queues allocated */
static int num_queues;

int snd_seq_queue_get_cur_queues(void)
{
	return num_queues;
}

/*----------------------------------------------------------------*/

/* assign queue id and insert to list */
static int queue_list_add(queue_t *q)
{
	int i;
	unsigned long flags;

	spin_lock_irqsave(&queue_list_lock, flags);
	for (i = 0; i < SNDRV_SEQ_MAX_QUEUES; i++) {
		if (! queue_list[i]) {
			queue_list[i] = q;
			q->queue = i;
			num_queues++;
			spin_unlock_irqrestore(&queue_list_lock, flags);
			return i;
		}
	}
	spin_unlock_irqrestore(&queue_list_lock, flags);
	return -1;
}

static queue_t *queue_list_remove(int id, int client)
{
	queue_t *q;
	unsigned long flags;

	spin_lock_irqsave(&queue_list_lock, flags);
	q = queue_list[id];
	if (q) {
		spin_lock(&q->owner_lock);
		if (q->owner == client) {
			/* found */
			q->klocked = 1;
			spin_unlock(&q->owner_lock);
			queue_list[id] = NULL;
			num_queues--;
			spin_unlock_irqrestore(&queue_list_lock, flags);
			return q;
		}
		spin_unlock(&q->owner_lock);
	}
	spin_unlock_irqrestore(&queue_list_lock, flags);
	return NULL;
}

/*----------------------------------------------------------------*/

/* create new queue (constructor) */
static queue_t *queue_new(int owner, int locked)
{
	queue_t *q;

	q = kzalloc(sizeof(*q), GFP_KERNEL);
	if (q == NULL) {
		snd_printd("malloc failed for snd_seq_queue_new()\n");
		return NULL;
	}

	spin_lock_init(&q->owner_lock);
	spin_lock_init(&q->check_lock);
	init_MUTEX(&q->timer_mutex);
	snd_use_lock_init(&q->use_lock);
	q->queue = -1;

	q->tickq = snd_seq_prioq_new();
	q->timeq = snd_seq_prioq_new();
	q->timer = snd_seq_timer_new();
	if (q->tickq == NULL || q->timeq == NULL || q->timer == NULL) {
		snd_seq_prioq_delete(&q->tickq);
		snd_seq_prioq_delete(&q->timeq);
		snd_seq_timer_delete(&q->timer);
		kfree(q);
		return NULL;
	}

	q->owner = owner;
	q->locked = locked;
	q->klocked = 0;

	return q;
}

/* delete queue (destructor) */
static void queue_delete(queue_t *q)
{
	/* stop and release the timer */
	snd_seq_timer_stop(q->timer);
	snd_seq_timer_close(q);
	/* wait until access free */
	snd_use_lock_sync(&q->use_lock);
	/* release resources... */
	snd_seq_prioq_delete(&q->tickq);
	snd_seq_prioq_delete(&q->timeq);
	snd_seq_timer_delete(&q->timer);

	kfree(q);
}


/*----------------------------------------------------------------*/

/* setup queues */
int __init snd_seq_queues_init(void)
{
	/*
	memset(queue_list, 0, sizeof(queue_list));
	num_queues = 0;
	*/
	return 0;
}

/* delete all existing queues */
void __exit snd_seq_queues_delete(void)
{
	int i;

	/* clear list */
	for (i = 0; i < SNDRV_SEQ_MAX_QUEUES; i++) {
		if (queue_list[i])
			queue_delete(queue_list[i]);
	}
}

/* allocate a new queue -
 * return queue index value or negative value for error
 */
int snd_seq_queue_alloc(int client, int locked, unsigned int info_flags)
{
	queue_t *q;

	q = queue_new(client, locked);
	if (q == NULL)
		return -ENOMEM;
	q->info_flags = info_flags;
	if (queue_list_add(q) < 0) {
		queue_delete(q);
		return -ENOMEM;
	}
	snd_seq_queue_use(q->queue, client, 1); /* use this queue */
	return q->queue;
}

/* delete a queue - queue must be owned by the client */
int snd_seq_queue_delete(int client, int queueid)
{
	queue_t *q;

	if (queueid < 0 || queueid >= SNDRV_SEQ_MAX_QUEUES)
		return -EINVAL;
	q = queue_list_remove(queueid, client);
	if (q == NULL)
		return -EINVAL;
	queue_delete(q);

	return 0;
}


/* return pointer to queue structure for specified id */
queue_t *queueptr(int queueid)
{
	queue_t *q;
	unsigned long flags;

	if (queueid < 0 || queueid >= SNDRV_SEQ_MAX_QUEUES)
		return NULL;
	spin_lock_irqsave(&queue_list_lock, flags);
	q = queue_list[queueid];
	if (q)
		snd_use_lock_use(&q->use_lock);
	spin_unlock_irqrestore(&queue_list_lock, flags);
	return q;
}

/* return the (first) queue matching with the specified name */
queue_t *snd_seq_queue_find_name(char *name)
{
	int i;
	queue_t *q;

	for (i = 0; i < SNDRV_SEQ_MAX_QUEUES; i++) {
		if ((q = queueptr(i)) != NULL) {
			if (strncmp(q->name, name, sizeof(q->name)) == 0)
				return q;
			queuefree(q);
		}
	}
	return NULL;
}


/* -------------------------------------------------------- */

void snd_seq_check_queue(queue_t *q, int atomic, int hop)
{
	unsigned long flags;
	snd_seq_event_cell_t *cell;

	if (q == NULL)
		return;

	/* make this function non-reentrant */
	spin_lock_irqsave(&q->check_lock, flags);
	if (q->check_blocked) {
		q->check_again = 1;
		spin_unlock_irqrestore(&q->check_lock, flags);
		return;		/* other thread is already checking queues */
	}
	q->check_blocked = 1;
	spin_unlock_irqrestore(&q->check_lock, flags);

      __again:
	/* Process tick queue... */
	while ((cell = snd_seq_prioq_cell_peek(q->tickq)) != NULL) {
		if (snd_seq_compare_tick_time(&q->timer->tick.cur_tick, &cell->event.time.tick)) {
			cell = snd_seq_prioq_cell_out(q->tickq);
			if (cell)
				snd_seq_dispatch_event(cell, atomic, hop);
		} else {
			/* event remains in the queue */
			break;
		}
	}


	/* Process time queue... */
	while ((cell = snd_seq_prioq_cell_peek(q->timeq)) != NULL) {
		if (snd_seq_compare_real_time(&q->timer->cur_time, &cell->event.time.time)) {
			cell = snd_seq_prioq_cell_out(q->timeq);
			if (cell)
				snd_seq_dispatch_event(cell, atomic, hop);
		} else {
			/* event remains in the queue */
			break;
		}
	}

	/* free lock */
	spin_lock_irqsave(&q->check_lock, flags);
	if (q->check_again) {
		q->check_again = 0;
		spin_unlock_irqrestore(&q->check_lock, flags);
		goto __again;
	}
	q->check_blocked = 0;
	spin_unlock_irqrestore(&q->check_lock, flags);
}


/* enqueue a event to singe queue */
int snd_seq_enqueue_event(snd_seq_event_cell_t *cell, int atomic, int hop)
{
	int dest, err;
	queue_t *q;

	snd_assert(cell != NULL, return -EINVAL);
	dest = cell->event.queue;	/* destination queue */
	q = queueptr(dest);
	if (q == NULL)
		return -EINVAL;
	/* handle relative time stamps, convert them into absolute */
	if ((cell->event.flags & SNDRV_SEQ_TIME_MODE_MASK) == SNDRV_SEQ_TIME_MODE_REL) {
		switch (cell->event.flags & SNDRV_SEQ_TIME_STAMP_MASK) {
		case SNDRV_SEQ_TIME_STAMP_TICK:
			cell->event.time.tick += q->timer->tick.cur_tick;
			break;

		case SNDRV_SEQ_TIME_STAMP_REAL:
			snd_seq_inc_real_time(&cell->event.time.time, &q->timer->cur_time);
			break;
		}
		cell->event.flags &= ~SNDRV_SEQ_TIME_MODE_MASK;
		cell->event.flags |= SNDRV_SEQ_TIME_MODE_ABS;
	}
	/* enqueue event in the real-time or midi queue */
	switch (cell->event.flags & SNDRV_SEQ_TIME_STAMP_MASK) {
	case SNDRV_SEQ_TIME_STAMP_TICK:
		err = snd_seq_prioq_cell_in(q->tickq, cell);
		break;

	case SNDRV_SEQ_TIME_STAMP_REAL:
	default:
		err = snd_seq_prioq_cell_in(q->timeq, cell);
		break;
	}

	if (err < 0) {
		queuefree(q); /* unlock */
		return err;
	}

	/* trigger dispatching */
	snd_seq_check_queue(q, atomic, hop);

	queuefree(q); /* unlock */

	return 0;
}


/*----------------------------------------------------------------*/

static inline int check_access(queue_t *q, int client)
{
	return (q->owner == client) || (!q->locked && !q->klocked);
}

/* check if the client has permission to modify queue parameters.
 * if it does, lock the queue
 */
static int queue_access_lock(queue_t *q, int client)
{
	unsigned long flags;
	int access_ok;
	
	spin_lock_irqsave(&q->owner_lock, flags);
	access_ok = check_access(q, client);
	if (access_ok)
		q->klocked = 1;
	spin_unlock_irqrestore(&q->owner_lock, flags);
	return access_ok;
}

/* unlock the queue */
static inline void queue_access_unlock(queue_t *q)
{
	unsigned long flags;

	spin_lock_irqsave(&q->owner_lock, flags);
	q->klocked = 0;
	spin_unlock_irqrestore(&q->owner_lock, flags);
}