sound/core/seq/seq_timer.c - arm/linux-arm64-legacy - Git at Google

 /*
  *   ALSA sequencer Timer
  *   Copyright (c) 1998-1999 by Frank van de Pol <fvdpol@coil.demon.nl>
  *                              Jaroslav Kysela <perex@suse.cz>
  *
  *
  *   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
  *
  */

 #include <sound/driver.h>
 #include <sound/core.h>
 #include <linux/slab.h>
 #include "seq_timer.h"
 #include "seq_queue.h"
 #include "seq_info.h"

 extern int seq_default_timer_class;
 extern int seq_default_timer_sclass;
 extern int seq_default_timer_card;
 extern int seq_default_timer_device;
 extern int seq_default_timer_subdevice;
 extern int seq_default_timer_resolution;

 #define SKEW_BASE	0x10000	/* 16bit shift */

 static void snd_seq_timer_set_tick_resolution(seq_timer_tick_t *tick,
 					      int tempo, int ppq, int nticks)
 {
 	if (tempo < 1000000)
 		tick->resolution = (tempo * 1000) / ppq;
 	else {
 		/* might overflow.. */
 		unsigned int s;
 		s = tempo % ppq;
 		s = (s * 1000) / ppq;
 		tick->resolution = (tempo / ppq) * 1000;
 		tick->resolution += s;
 	}
 	if (tick->resolution <= 0)
 		tick->resolution = 1;
 	tick->resolution *= nticks;
 	snd_seq_timer_update_tick(tick, 0);
 }

 /* create new timer (constructor) */
 seq_timer_t *snd_seq_timer_new(void)
 {
 	seq_timer_t *tmr;

 	tmr = kcalloc(1, sizeof(*tmr), GFP_KERNEL);
 	if (tmr == NULL) {
 		snd_printd("malloc failed for snd_seq_timer_new() \n");
 		return NULL;
 	}
 	spin_lock_init(&tmr->lock);

 	/* reset setup to defaults */
 	snd_seq_timer_defaults(tmr);

 	/* reset time */
 	snd_seq_timer_reset(tmr);

 	return tmr;
 }

 /* delete timer (destructor) */
 void snd_seq_timer_delete(seq_timer_t **tmr)
 {
 	seq_timer_t *t = *tmr;
 	*tmr = NULL;

 	if (t == NULL) {
 		snd_printd("oops: snd_seq_timer_delete() called with NULL timer\n");
 		return;
 	}
 	t->running = 0;

 	/* reset time */
 	snd_seq_timer_stop(t);
 	snd_seq_timer_reset(t);

 	kfree(t);
 }

 void snd_seq_timer_defaults(seq_timer_t * tmr)
 {
 	/* setup defaults */
 	tmr->ppq = 96;		/* 96 PPQ */
 	tmr->tempo = 500000;	/* 120 BPM */
 	snd_seq_timer_set_tick_resolution(&tmr->tick, tmr->tempo, tmr->ppq, 1);
 	tmr->running = 0;

 	tmr->type = SNDRV_SEQ_TIMER_ALSA;
 	tmr->alsa_id.dev_class = seq_default_timer_class;
 	tmr->alsa_id.dev_sclass = seq_default_timer_sclass;
 	tmr->alsa_id.card = seq_default_timer_card;
 	tmr->alsa_id.device = seq_default_timer_device;
 	tmr->alsa_id.subdevice = seq_default_timer_subdevice;
 	tmr->preferred_resolution = seq_default_timer_resolution;

 	tmr->skew = tmr->skew_base = SKEW_BASE;
 }

 void snd_seq_timer_reset(seq_timer_t * tmr)
 {
 	unsigned long flags;

 	spin_lock_irqsave(&tmr->lock, flags);

 	/* reset time & songposition */
 	tmr->cur_time.tv_sec = 0;
 	tmr->cur_time.tv_nsec = 0;

 	tmr->tick.cur_tick = 0;
 	tmr->tick.fraction = 0;

 	spin_unlock_irqrestore(&tmr->lock, flags);
 }


 /* called by timer interrupt routine. the period time since previous invocation is passed */
 static void snd_seq_timer_interrupt(snd_timer_instance_t *timeri,
 				    unsigned long resolution,
 				    unsigned long ticks)
 {
 	unsigned long flags;
 	queue_t *q = (queue_t *)timeri->callback_data;
 	seq_timer_t *tmr;

 	if (q == NULL)
 		return;
 	tmr = q->timer;
 	if (tmr == NULL)
 		return;
 	if (!tmr->running)
 		return;

 	resolution *= ticks;
 	if (tmr->skew != tmr->skew_base) {
 		/* FIXME: assuming skew_base = 0x10000 */
 		resolution = (resolution >> 16) * tmr->skew +
 			(((resolution & 0xffff) * tmr->skew) >> 16);
 	}

 	spin_lock_irqsave(&tmr->lock, flags);

 	/* update timer */
 	snd_seq_inc_time_nsec(&tmr->cur_time, resolution);

 	/* calculate current tick */
 	snd_seq_timer_update_tick(&tmr->tick, resolution);

 	/* register actual time of this timer update */
 	do_gettimeofday(&tmr->last_update);

 	spin_unlock_irqrestore(&tmr->lock, flags);

 	/* check queues and dispatch events */
 	snd_seq_check_queue(q, 1, 0);
 }

 /* set current tempo */
 int snd_seq_timer_set_tempo(seq_timer_t * tmr, int tempo)
 {
 	unsigned long flags;

 	snd_assert(tmr, return -EINVAL);
 	if (tempo <= 0)
 		return -EINVAL;
 	spin_lock_irqsave(&tmr->lock, flags);
 	if ((unsigned int)tempo != tmr->tempo) {
 		tmr->tempo = tempo;
 		snd_seq_timer_set_tick_resolution(&tmr->tick, tmr->tempo, tmr->ppq, 1);
 	}
 	spin_unlock_irqrestore(&tmr->lock, flags);
 	return 0;
 }

 /* set current ppq */
 int snd_seq_timer_set_ppq(seq_timer_t * tmr, int ppq)
 {
 	unsigned long flags;

 	snd_assert(tmr, return -EINVAL);
 	if (ppq <= 0)
 		return -EINVAL;
 	spin_lock_irqsave(&tmr->lock, flags);
 	if (tmr->running && (ppq != tmr->ppq)) {
 		/* refuse to change ppq on running timers */
 		/* because it will upset the song position (ticks) */
 		spin_unlock_irqrestore(&tmr->lock, flags);
 		snd_printd("seq: cannot change ppq of a running timer\n");
 		return -EBUSY;
 	}

 	tmr->ppq = ppq;
 	snd_seq_timer_set_tick_resolution(&tmr->tick, tmr->tempo, tmr->ppq, 1);
 	spin_unlock_irqrestore(&tmr->lock, flags);
 	return 0;
 }

 /* set current tick position */
 int snd_seq_timer_set_position_tick(seq_timer_t *tmr, snd_seq_tick_time_t position)
 {
 	unsigned long flags;

 	snd_assert(tmr, return -EINVAL);

 	spin_lock_irqsave(&tmr->lock, flags);
 	tmr->tick.cur_tick = position;
 	tmr->tick.fraction = 0;
 	spin_unlock_irqrestore(&tmr->lock, flags);
 	return 0;
 }

 /* set current real-time position */
 int snd_seq_timer_set_position_time(seq_timer_t *tmr, snd_seq_real_time_t position)
 {
 	unsigned long flags;

 	snd_assert(tmr, return -EINVAL);

 	snd_seq_sanity_real_time(&position);
 	spin_lock_irqsave(&tmr->lock, flags);
 	tmr->cur_time = position;
 	spin_unlock_irqrestore(&tmr->lock, flags);
 	return 0;
 }

 /* set timer skew */
 int snd_seq_timer_set_skew(seq_timer_t *tmr, unsigned int skew, unsigned int base)
 {
 	unsigned long flags;

 	snd_assert(tmr, return -EINVAL);

 	/* FIXME */
 	if (base != SKEW_BASE) {
 		snd_printd("invalid skew base 0x%x\n", base);
 		return -EINVAL;
 	}
 	spin_lock_irqsave(&tmr->lock, flags);
 	tmr->skew = skew;
 	spin_unlock_irqrestore(&tmr->lock, flags);
 	return 0;
 }

 int snd_seq_timer_open(queue_t *q)
 {
 	snd_timer_instance_t *t;
 	seq_timer_t *tmr;
 	char str[32];
 	int err;

 	tmr = q->timer;
 	snd_assert(tmr != NULL, return -EINVAL);
 	if (tmr->timeri)
 		return -EBUSY;
 	sprintf(str, "sequencer queue %i", q->queue);
 	if (tmr->type != SNDRV_SEQ_TIMER_ALSA)	/* standard ALSA timer */
 		return -EINVAL;
 	if (tmr->alsa_id.dev_class != SNDRV_TIMER_CLASS_SLAVE)
 		tmr->alsa_id.dev_sclass = SNDRV_TIMER_SCLASS_SEQUENCER;
 	err = snd_timer_open(&t, str, &tmr->alsa_id, q->queue);
 	if (err < 0 && tmr->alsa_id.dev_class != SNDRV_TIMER_CLASS_SLAVE) {
 		if (tmr->alsa_id.dev_class != SNDRV_TIMER_CLASS_GLOBAL ||
 		    tmr->alsa_id.device != SNDRV_TIMER_GLOBAL_SYSTEM) {
 			snd_timer_id_t tid;
 			memset(&tid, 0, sizeof(tid));
 			tid.dev_class = SNDRV_TIMER_CLASS_GLOBAL;
 			tid.dev_sclass = SNDRV_TIMER_SCLASS_SEQUENCER;
 			tid.card = -1;
 			tid.device = SNDRV_TIMER_GLOBAL_SYSTEM;
 			err = snd_timer_open(&t, str, &tid, q->queue);
 		}
 		if (err < 0) {
 			snd_printk(KERN_ERR "seq fatal error: cannot create timer (%i)\n", err);
 			return err;
 		}
 	}
 	t->callback = snd_seq_timer_interrupt;
 	t->callback_data = q;
 	t->flags |= SNDRV_TIMER_IFLG_AUTO;
 	tmr->timeri = t;
 	return 0;
 }

 int snd_seq_timer_close(queue_t *q)
 {
 	seq_timer_t *tmr;

 	tmr = q->timer;
 	snd_assert(tmr != NULL, return -EINVAL);
 	if (tmr->timeri) {
 		snd_timer_stop(tmr->timeri);
 		snd_timer_close(tmr->timeri);
 		tmr->timeri = NULL;
 	}
 	return 0;
 }

 int snd_seq_timer_stop(seq_timer_t * tmr)
 {
 	if (! tmr->timeri)
 		return -EINVAL;
 	if (!tmr->running)
 		return 0;
 	tmr->running = 0;
 	snd_timer_pause(tmr->timeri);
 	return 0;
 }

 static int initialize_timer(seq_timer_t *tmr)
 {
 	snd_timer_t *t;
 	t = tmr->timeri->timer;
 	snd_assert(t, return -EINVAL);

 	tmr->ticks = 1;
 	if (tmr->preferred_resolution &&
 	    ! (t->hw.flags & SNDRV_TIMER_HW_SLAVE)) {
 		unsigned long r = t->hw.resolution;
 		if (! r && t->hw.c_resolution)
 			r = t->hw.c_resolution(t);
 		if (r) {
 			tmr->ticks = (unsigned int)(1000000000uL / (r * tmr->preferred_resolution));
 			if (! tmr->ticks)
 				tmr->ticks = 1;
 		}
 	}
 	tmr->initialized = 1;
 	return 0;
 }

 int snd_seq_timer_start(seq_timer_t * tmr)
 {
 	if (! tmr->timeri)
 		return -EINVAL;
 	if (tmr->running)
 		snd_seq_timer_stop(tmr);
 	snd_seq_timer_reset(tmr);
 	if (initialize_timer(tmr) < 0)
 		return -EINVAL;
 	snd_timer_start(tmr->timeri, tmr->ticks);
 	tmr->running = 1;
 	do_gettimeofday(&tmr->last_update);
 	return 0;
 }

 int snd_seq_timer_continue(seq_timer_t * tmr)
 {
 	if (! tmr->timeri)
 		return -EINVAL;
 	if (tmr->running)
 		return -EBUSY;
 	if (! tmr->initialized) {
 		snd_seq_timer_reset(tmr);
 		if (initialize_timer(tmr) < 0)
 			return -EINVAL;
 	}
 	snd_timer_start(tmr->timeri, tmr->ticks);
 	tmr->running = 1;
 	do_gettimeofday(&tmr->last_update);
 	return 0;
 }

 /* return current 'real' time. use timeofday() to get better granularity. */
 snd_seq_real_time_t snd_seq_timer_get_cur_time(seq_timer_t *tmr)
 {
 	snd_seq_real_time_t cur_time;

 	cur_time = tmr->cur_time;
 	if (tmr->running) {
 		struct timeval tm;
 		int usec;
 		do_gettimeofday(&tm);
 		usec = (int)(tm.tv_usec - tmr->last_update.tv_usec);
 		if (usec < 0) {
 			cur_time.tv_nsec += (1000000 + usec) * 1000;
 			cur_time.tv_sec += tm.tv_sec - tmr->last_update.tv_sec - 1;
 		} else {
 			cur_time.tv_nsec += usec * 1000;
 			cur_time.tv_sec += tm.tv_sec - tmr->last_update.tv_sec;
 		}
 		snd_seq_sanity_real_time(&cur_time);
 	}

 	return cur_time;
 }

 /* TODO: use interpolation on tick queue (will only be useful for very
  high PPQ values) */
 snd_seq_tick_time_t snd_seq_timer_get_cur_tick(seq_timer_t *tmr)
 {
 	return tmr->tick.cur_tick;
 }


 /* exported to seq_info.c */
 void snd_seq_info_timer_read(snd_info_entry_t *entry, snd_info_buffer_t * buffer)
 {
 	int idx;
 	queue_t *q;
 	seq_timer_t *tmr;
 	snd_timer_instance_t *ti;
 	unsigned long resolution;

 	for (idx = 0; idx < SNDRV_SEQ_MAX_QUEUES; idx++) {
 		q = queueptr(idx);
 		if (q == NULL)
 			continue;
 		if ((tmr = q->timer) == NULL ||
 		    (ti = tmr->timeri) == NULL) {
 			queuefree(q);
 			continue;
 		}
 		snd_iprintf(buffer, "Timer for queue %i : %s\n", q->queue, ti->timer->name);
 		resolution = snd_timer_resolution(ti) * tmr->ticks;
 		snd_iprintf(buffer, "  Period time : %lu.%09lu\n", resolution / 1000000000, resolution % 1000000000);
 		snd_iprintf(buffer, "  Skew : %u / %u\n", tmr->skew, tmr->skew_base);
 		queuefree(q);
  	}
 }
	/*
	* ALSA sequencer Timer
	* Copyright (c) 1998-1999 by Frank van de Pol <fvdpol@coil.demon.nl>
	* Jaroslav Kysela <perex@suse.cz>
	*
	*
	* 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
	*
	*/

	#include <sound/driver.h>
	#include <sound/core.h>
	#include <linux/slab.h>
	#include "seq_timer.h"
	#include "seq_queue.h"
	#include "seq_info.h"

	extern int seq_default_timer_class;
	extern int seq_default_timer_sclass;
	extern int seq_default_timer_card;
	extern int seq_default_timer_device;
	extern int seq_default_timer_subdevice;
	extern int seq_default_timer_resolution;

	#define SKEW_BASE 0x10000 /* 16bit shift */

	static void snd_seq_timer_set_tick_resolution(seq_timer_tick_t *tick,
	int tempo, int ppq, int nticks)
	{
	if (tempo < 1000000)
	tick->resolution = (tempo * 1000) / ppq;
	else {
	/* might overflow.. */
	unsigned int s;
	s = tempo % ppq;
	s = (s * 1000) / ppq;
	tick->resolution = (tempo / ppq) * 1000;
	tick->resolution += s;
	}
	if (tick->resolution <= 0)
	tick->resolution = 1;
	tick->resolution *= nticks;
	snd_seq_timer_update_tick(tick, 0);
	}

	/* create new timer (constructor) */
	seq_timer_t *snd_seq_timer_new(void)
	{
	seq_timer_t *tmr;

	tmr = kcalloc(1, sizeof(*tmr), GFP_KERNEL);
	if (tmr == NULL) {
	snd_printd("malloc failed for snd_seq_timer_new() \n");
	return NULL;
	}
	spin_lock_init(&tmr->lock);

	/* reset setup to defaults */
	snd_seq_timer_defaults(tmr);

	/* reset time */
	snd_seq_timer_reset(tmr);

	return tmr;
	}

	/* delete timer (destructor) */
	void snd_seq_timer_delete(seq_timer_t **tmr)
	{
	seq_timer_t t = tmr;
	*tmr = NULL;

	if (t == NULL) {
	snd_printd("oops: snd_seq_timer_delete() called with NULL timer\n");
	return;
	}
	t->running = 0;

	/* reset time */
	snd_seq_timer_stop(t);
	snd_seq_timer_reset(t);

	kfree(t);
	}

	void snd_seq_timer_defaults(seq_timer_t * tmr)
	{
	/* setup defaults */
	tmr->ppq = 96; /* 96 PPQ */
	tmr->tempo = 500000; /* 120 BPM */
	snd_seq_timer_set_tick_resolution(&tmr->tick, tmr->tempo, tmr->ppq, 1);
	tmr->running = 0;

	tmr->type = SNDRV_SEQ_TIMER_ALSA;
	tmr->alsa_id.dev_class = seq_default_timer_class;
	tmr->alsa_id.dev_sclass = seq_default_timer_sclass;
	tmr->alsa_id.card = seq_default_timer_card;
	tmr->alsa_id.device = seq_default_timer_device;
	tmr->alsa_id.subdevice = seq_default_timer_subdevice;
	tmr->preferred_resolution = seq_default_timer_resolution;

	tmr->skew = tmr->skew_base = SKEW_BASE;
	}

	void snd_seq_timer_reset(seq_timer_t * tmr)
	{
	unsigned long flags;

	spin_lock_irqsave(&tmr->lock, flags);

	/* reset time & songposition */
	tmr->cur_time.tv_sec = 0;
	tmr->cur_time.tv_nsec = 0;

	tmr->tick.cur_tick = 0;
	tmr->tick.fraction = 0;

	spin_unlock_irqrestore(&tmr->lock, flags);
	}


	/* called by timer interrupt routine. the period time since previous invocation is passed */
	static void snd_seq_timer_interrupt(snd_timer_instance_t *timeri,
	unsigned long resolution,
	unsigned long ticks)
	{
	unsigned long flags;
	queue_t q = (queue_t )timeri->callback_data;
	seq_timer_t *tmr;

	if (q == NULL)
	return;
	tmr = q->timer;
	if (tmr == NULL)
	return;
	if (!tmr->running)
	return;

	resolution *= ticks;
	if (tmr->skew != tmr->skew_base) {
	/* FIXME: assuming skew_base = 0x10000 */
	resolution = (resolution >> 16) * tmr->skew +
	(((resolution & 0xffff) * tmr->skew) >> 16);
	}

	spin_lock_irqsave(&tmr->lock, flags);

	/* update timer */
	snd_seq_inc_time_nsec(&tmr->cur_time, resolution);

	/* calculate current tick */
	snd_seq_timer_update_tick(&tmr->tick, resolution);

	/* register actual time of this timer update */
	do_gettimeofday(&tmr->last_update);

	spin_unlock_irqrestore(&tmr->lock, flags);

	/* check queues and dispatch events */
	snd_seq_check_queue(q, 1, 0);
	}

	/* set current tempo */
	int snd_seq_timer_set_tempo(seq_timer_t * tmr, int tempo)
	{
	unsigned long flags;

	snd_assert(tmr, return -EINVAL);
	if (tempo <= 0)
	return -EINVAL;
	spin_lock_irqsave(&tmr->lock, flags);
	if ((unsigned int)tempo != tmr->tempo) {
	tmr->tempo = tempo;
	snd_seq_timer_set_tick_resolution(&tmr->tick, tmr->tempo, tmr->ppq, 1);
	}
	spin_unlock_irqrestore(&tmr->lock, flags);
	return 0;
	}

	/* set current ppq */
	int snd_seq_timer_set_ppq(seq_timer_t * tmr, int ppq)
	{
	unsigned long flags;

	snd_assert(tmr, return -EINVAL);
	if (ppq <= 0)
	return -EINVAL;
	spin_lock_irqsave(&tmr->lock, flags);
	if (tmr->running && (ppq != tmr->ppq)) {
	/* refuse to change ppq on running timers */
	/* because it will upset the song position (ticks) */
	spin_unlock_irqrestore(&tmr->lock, flags);
	snd_printd("seq: cannot change ppq of a running timer\n");
	return -EBUSY;
	}

	tmr->ppq = ppq;
	snd_seq_timer_set_tick_resolution(&tmr->tick, tmr->tempo, tmr->ppq, 1);
	spin_unlock_irqrestore(&tmr->lock, flags);
	return 0;
	}

	/* set current tick position */
	int snd_seq_timer_set_position_tick(seq_timer_t *tmr, snd_seq_tick_time_t position)
	{
	unsigned long flags;

	snd_assert(tmr, return -EINVAL);

	spin_lock_irqsave(&tmr->lock, flags);
	tmr->tick.cur_tick = position;
	tmr->tick.fraction = 0;
	spin_unlock_irqrestore(&tmr->lock, flags);
	return 0;
	}

	/* set current real-time position */
	int snd_seq_timer_set_position_time(seq_timer_t *tmr, snd_seq_real_time_t position)
	{
	unsigned long flags;

	snd_assert(tmr, return -EINVAL);

	snd_seq_sanity_real_time(&position);
	spin_lock_irqsave(&tmr->lock, flags);
	tmr->cur_time = position;
	spin_unlock_irqrestore(&tmr->lock, flags);
	return 0;
	}

	/* set timer skew */
	int snd_seq_timer_set_skew(seq_timer_t *tmr, unsigned int skew, unsigned int base)
	{
	unsigned long flags;

	snd_assert(tmr, return -EINVAL);

	/* FIXME */
	if (base != SKEW_BASE) {
	snd_printd("invalid skew base 0x%x\n", base);
	return -EINVAL;
	}
	spin_lock_irqsave(&tmr->lock, flags);
	tmr->skew = skew;
	spin_unlock_irqrestore(&tmr->lock, flags);
	return 0;
	}

	int snd_seq_timer_open(queue_t *q)
	{
	snd_timer_instance_t *t;
	seq_timer_t *tmr;
	char str[32];
	int err;

	tmr = q->timer;
	snd_assert(tmr != NULL, return -EINVAL);
	if (tmr->timeri)
	return -EBUSY;
	sprintf(str, "sequencer queue %i", q->queue);
	if (tmr->type != SNDRV_SEQ_TIMER_ALSA) /* standard ALSA timer */
	return -EINVAL;
	if (tmr->alsa_id.dev_class != SNDRV_TIMER_CLASS_SLAVE)
	tmr->alsa_id.dev_sclass = SNDRV_TIMER_SCLASS_SEQUENCER;
	err = snd_timer_open(&t, str, &tmr->alsa_id, q->queue);
	if (err < 0 && tmr->alsa_id.dev_class != SNDRV_TIMER_CLASS_SLAVE) {
	if (tmr->alsa_id.dev_class != SNDRV_TIMER_CLASS_GLOBAL \|\|
	tmr->alsa_id.device != SNDRV_TIMER_GLOBAL_SYSTEM) {
	snd_timer_id_t tid;
	memset(&tid, 0, sizeof(tid));
	tid.dev_class = SNDRV_TIMER_CLASS_GLOBAL;
	tid.dev_sclass = SNDRV_TIMER_SCLASS_SEQUENCER;
	tid.card = -1;
	tid.device = SNDRV_TIMER_GLOBAL_SYSTEM;
	err = snd_timer_open(&t, str, &tid, q->queue);
	}
	if (err < 0) {
	snd_printk(KERN_ERR "seq fatal error: cannot create timer (%i)\n", err);
	return err;
	}
	}
	t->callback = snd_seq_timer_interrupt;
	t->callback_data = q;
	t->flags \|= SNDRV_TIMER_IFLG_AUTO;
	tmr->timeri = t;
	return 0;
	}

	int snd_seq_timer_close(queue_t *q)
	{
	seq_timer_t *tmr;

	tmr = q->timer;
	snd_assert(tmr != NULL, return -EINVAL);
	if (tmr->timeri) {
	snd_timer_stop(tmr->timeri);
	snd_timer_close(tmr->timeri);
	tmr->timeri = NULL;
	}
	return 0;
	}

	int snd_seq_timer_stop(seq_timer_t * tmr)
	{
	if (! tmr->timeri)
	return -EINVAL;
	if (!tmr->running)
	return 0;
	tmr->running = 0;
	snd_timer_pause(tmr->timeri);
	return 0;
	}

	static int initialize_timer(seq_timer_t *tmr)
	{
	snd_timer_t *t;
	t = tmr->timeri->timer;
	snd_assert(t, return -EINVAL);

	tmr->ticks = 1;
	if (tmr->preferred_resolution &&
	! (t->hw.flags & SNDRV_TIMER_HW_SLAVE)) {
	unsigned long r = t->hw.resolution;
	if (! r && t->hw.c_resolution)
	r = t->hw.c_resolution(t);
	if (r) {
	tmr->ticks = (unsigned int)(1000000000uL / (r * tmr->preferred_resolution));
	if (! tmr->ticks)
	tmr->ticks = 1;
	}
	}
	tmr->initialized = 1;
	return 0;
	}

	int snd_seq_timer_start(seq_timer_t * tmr)
	{
	if (! tmr->timeri)
	return -EINVAL;
	if (tmr->running)
	snd_seq_timer_stop(tmr);
	snd_seq_timer_reset(tmr);
	if (initialize_timer(tmr) < 0)
	return -EINVAL;
	snd_timer_start(tmr->timeri, tmr->ticks);
	tmr->running = 1;
	do_gettimeofday(&tmr->last_update);
	return 0;
	}

	int snd_seq_timer_continue(seq_timer_t * tmr)
	{
	if (! tmr->timeri)
	return -EINVAL;
	if (tmr->running)
	return -EBUSY;
	if (! tmr->initialized) {
	snd_seq_timer_reset(tmr);
	if (initialize_timer(tmr) < 0)
	return -EINVAL;
	}
	snd_timer_start(tmr->timeri, tmr->ticks);
	tmr->running = 1;
	do_gettimeofday(&tmr->last_update);
	return 0;
	}

	/* return current 'real' time. use timeofday() to get better granularity. */
	snd_seq_real_time_t snd_seq_timer_get_cur_time(seq_timer_t *tmr)
	{
	snd_seq_real_time_t cur_time;

	cur_time = tmr->cur_time;
	if (tmr->running) {
	struct timeval tm;
	int usec;
	do_gettimeofday(&tm);
	usec = (int)(tm.tv_usec - tmr->last_update.tv_usec);
	if (usec < 0) {
	cur_time.tv_nsec += (1000000 + usec) * 1000;
	cur_time.tv_sec += tm.tv_sec - tmr->last_update.tv_sec - 1;
	} else {
	cur_time.tv_nsec += usec * 1000;
	cur_time.tv_sec += tm.tv_sec - tmr->last_update.tv_sec;
	}
	snd_seq_sanity_real_time(&cur_time);
	}

	return cur_time;
	}

	/* TODO: use interpolation on tick queue (will only be useful for very
	high PPQ values) */
	snd_seq_tick_time_t snd_seq_timer_get_cur_tick(seq_timer_t *tmr)
	{
	return tmr->tick.cur_tick;
	}


	/* exported to seq_info.c */
	void snd_seq_info_timer_read(snd_info_entry_t entry, snd_info_buffer_t buffer)
	{
	int idx;
	queue_t *q;
	seq_timer_t *tmr;
	snd_timer_instance_t *ti;
	unsigned long resolution;

	for (idx = 0; idx < SNDRV_SEQ_MAX_QUEUES; idx++) {
	q = queueptr(idx);
	if (q == NULL)
	continue;
	if ((tmr = q->timer) == NULL \|\|
	(ti = tmr->timeri) == NULL) {
	queuefree(q);
	continue;
	}
	snd_iprintf(buffer, "Timer for queue %i : %s\n", q->queue, ti->timer->name);
	resolution = snd_timer_resolution(ti) * tmr->ticks;
	snd_iprintf(buffer, " Period time : %lu.%09lu\n", resolution / 1000000000, resolution % 1000000000);
	snd_iprintf(buffer, " Skew : %u / %u\n", tmr->skew, tmr->skew_base);
	queuefree(q);
	}
	}