seq_timer.c

  1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 *   ALSA sequencer Timer
  4 *   Copyright (c) 1998-1999 by Frank van de Pol <fvdpol@coil.demon.nl>
  5 *                              Jaroslav Kysela <perex@perex.cz>
  6 */
  7
  8#include <sound/core.h>
  9#include <linux/slab.h>
 10#include "seq_timer.h"
 11#include "seq_queue.h"
 12#include "seq_info.h"
 13
 14/* allowed sequencer timer frequencies, in Hz */
 15#define MIN_FREQUENCY		10
 16#define MAX_FREQUENCY		6250
 17#define DEFAULT_FREQUENCY	1000
 18
 19#define SKEW_BASE	0x10000	/* 16bit shift */
 20
 21static void snd_seq_timer_set_tick_resolution(struct snd_seq_timer *tmr)
 22{
 23	unsigned int threshold =
 24		tmr->tempo_base == 1000 ? 1000000 : 10000;
 25
 26	if (tmr->tempo < threshold)
 27		tmr->tick.resolution = (tmr->tempo * tmr->tempo_base) / tmr->ppq;
 28	else {
 29		/* might overflow.. */
 30		unsigned int s;
 31		s = tmr->tempo % tmr->ppq;
 32		s = (s * tmr->tempo_base) / tmr->ppq;
 33		tmr->tick.resolution = (tmr->tempo / tmr->ppq) * tmr->tempo_base;
 34		tmr->tick.resolution += s;
 35	}
 36	if (tmr->tick.resolution <= 0)
 37		tmr->tick.resolution = 1;
 38	snd_seq_timer_update_tick(&tmr->tick, 0);
 39}
 40
 41/* create new timer (constructor) */
 42struct snd_seq_timer *snd_seq_timer_new(void)
 43{
 44	struct snd_seq_timer *tmr;
 45	
 46	tmr = kzalloc(sizeof(*tmr), GFP_KERNEL);
 47	if (!tmr)
 48		return NULL;
 49	spin_lock_init(&tmr->lock);
 50
 51	/* reset setup to defaults */
 52	snd_seq_timer_defaults(tmr);
 53	
 54	/* reset time */
 55	snd_seq_timer_reset(tmr);
 56	
 57	return tmr;
 58}
 59
 60/* delete timer (destructor) */
 61void snd_seq_timer_delete(struct snd_seq_timer **tmr)
 62{
 63	struct snd_seq_timer *t = *tmr;
 64	*tmr = NULL;
 65
 66	if (t == NULL) {
 67		pr_debug("ALSA: seq: snd_seq_timer_delete() called with NULL timer\n");
 68		return;
 69	}
 70	t->running = 0;
 71
 72	/* reset time */
 73	snd_seq_timer_stop(t);
 74	snd_seq_timer_reset(t);
 75
 76	kfree(t);
 77}
 78
 79void snd_seq_timer_defaults(struct snd_seq_timer * tmr)
 80{
 81	guard(spinlock_irqsave)(&tmr->lock);
 82	/* setup defaults */
 83	tmr->ppq = 96;		/* 96 PPQ */
 84	tmr->tempo = 500000;	/* 120 BPM */
 85	tmr->tempo_base = 1000;	/* 1us */
 86	snd_seq_timer_set_tick_resolution(tmr);
 87	tmr->running = 0;
 88
 89	tmr->type = SNDRV_SEQ_TIMER_ALSA;
 90	tmr->alsa_id.dev_class = seq_default_timer_class;
 91	tmr->alsa_id.dev_sclass = seq_default_timer_sclass;
 92	tmr->alsa_id.card = seq_default_timer_card;
 93	tmr->alsa_id.device = seq_default_timer_device;
 94	tmr->alsa_id.subdevice = seq_default_timer_subdevice;
 95	tmr->preferred_resolution = seq_default_timer_resolution;
 96
 97	tmr->skew = tmr->skew_base = SKEW_BASE;
 98}
 99
100static void seq_timer_reset(struct snd_seq_timer *tmr)
101{
102	/* reset time & songposition */
103	tmr->cur_time.tv_sec = 0;
104	tmr->cur_time.tv_nsec = 0;
105
106	tmr->tick.cur_tick = 0;
107	tmr->tick.fraction = 0;
108}
109
110void snd_seq_timer_reset(struct snd_seq_timer *tmr)
111{
112	guard(spinlock_irqsave)(&tmr->lock);
113	seq_timer_reset(tmr);
114}
115
116
117/* called by timer interrupt routine. the period time since previous invocation is passed */
118static void snd_seq_timer_interrupt(struct snd_timer_instance *timeri,
119				    unsigned long resolution,
120				    unsigned long ticks)
121{
122	struct snd_seq_queue *q = timeri->callback_data;
123	struct snd_seq_timer *tmr;
124
125	if (q == NULL)
126		return;
127	tmr = q->timer;
128	if (tmr == NULL)
129		return;
130
131	scoped_guard(spinlock_irqsave, &tmr->lock) {
132		if (!tmr->running)
133			return;
134
135		resolution *= ticks;
136		if (tmr->skew != tmr->skew_base) {
137			/* FIXME: assuming skew_base = 0x10000 */
138			resolution = (resolution >> 16) * tmr->skew +
139				(((resolution & 0xffff) * tmr->skew) >> 16);
140		}
141
142		/* update timer */
143		snd_seq_inc_time_nsec(&tmr->cur_time, resolution);
144
145		/* calculate current tick */
146		snd_seq_timer_update_tick(&tmr->tick, resolution);
147
148		/* register actual time of this timer update */
149		ktime_get_ts64(&tmr->last_update);
150	}
151
152	/* check queues and dispatch events */
153	snd_seq_check_queue(q, 1, 0);
154}
155
156/* set current tempo */
157int snd_seq_timer_set_tempo(struct snd_seq_timer * tmr, int tempo)
158{
159	if (snd_BUG_ON(!tmr))
160		return -EINVAL;
161	if (tempo <= 0)
162		return -EINVAL;
163	guard(spinlock_irqsave)(&tmr->lock);
164	if ((unsigned int)tempo != tmr->tempo) {
165		tmr->tempo = tempo;
166		snd_seq_timer_set_tick_resolution(tmr);
167	}
168	return 0;
169}
170
171/* set current tempo, ppq and base in a shot */
172int snd_seq_timer_set_tempo_ppq(struct snd_seq_timer *tmr, int tempo, int ppq,
173				unsigned int tempo_base)
174{
175	int changed;
176
177	if (snd_BUG_ON(!tmr))
178		return -EINVAL;
179	if (tempo <= 0 || ppq <= 0)
180		return -EINVAL;
181	/* allow only 10ns or 1us tempo base for now */
182	if (tempo_base && tempo_base != 10 && tempo_base != 1000)
183		return -EINVAL;
184	guard(spinlock_irqsave)(&tmr->lock);
185	if (tmr->running && (ppq != tmr->ppq)) {
186		/* refuse to change ppq on running timers */
187		/* because it will upset the song position (ticks) */
188		pr_debug("ALSA: seq: cannot change ppq of a running timer\n");
189		return -EBUSY;
190	}
191	changed = (tempo != tmr->tempo) || (ppq != tmr->ppq);
192	tmr->tempo = tempo;
193	tmr->ppq = ppq;
194	tmr->tempo_base = tempo_base ? tempo_base : 1000;
195	if (changed)
196		snd_seq_timer_set_tick_resolution(tmr);
197	return 0;
198}
199
200/* set current tick position */
201int snd_seq_timer_set_position_tick(struct snd_seq_timer *tmr,
202				    snd_seq_tick_time_t position)
203{
204	if (snd_BUG_ON(!tmr))
205		return -EINVAL;
206
207	guard(spinlock_irqsave)(&tmr->lock);
208	tmr->tick.cur_tick = position;
209	tmr->tick.fraction = 0;
210	return 0;
211}
212
213/* set current real-time position */
214int snd_seq_timer_set_position_time(struct snd_seq_timer *tmr,
215				    snd_seq_real_time_t position)
216{
217	if (snd_BUG_ON(!tmr))
218		return -EINVAL;
219
220	snd_seq_sanity_real_time(&position);
221	guard(spinlock_irqsave)(&tmr->lock);
222	tmr->cur_time = position;
223	return 0;
224}
225
226/* set timer skew */
227int snd_seq_timer_set_skew(struct snd_seq_timer *tmr, unsigned int skew,
228			   unsigned int base)
229{
230	if (snd_BUG_ON(!tmr))
231		return -EINVAL;
232
233	/* FIXME */
234	if (base != SKEW_BASE) {
235		pr_debug("ALSA: seq: invalid skew base 0x%x\n", base);
236		return -EINVAL;
237	}
238	guard(spinlock_irqsave)(&tmr->lock);
239	tmr->skew = skew;
240	return 0;
241}
242
243int snd_seq_timer_open(struct snd_seq_queue *q)
244{
245	struct snd_timer_instance *t;
246	struct snd_seq_timer *tmr;
247	char str[32];
248	int err;
249
250	tmr = q->timer;
251	if (snd_BUG_ON(!tmr))
252		return -EINVAL;
253	if (tmr->timeri)
254		return -EBUSY;
255	sprintf(str, "sequencer queue %i", q->queue);
256	if (tmr->type != SNDRV_SEQ_TIMER_ALSA)	/* standard ALSA timer */
257		return -EINVAL;
258	if (tmr->alsa_id.dev_class != SNDRV_TIMER_CLASS_SLAVE)
259		tmr->alsa_id.dev_sclass = SNDRV_TIMER_SCLASS_SEQUENCER;
260	t = snd_timer_instance_new(str);
261	if (!t)
262		return -ENOMEM;
263	t->callback = snd_seq_timer_interrupt;
264	t->callback_data = q;
265	t->flags |= SNDRV_TIMER_IFLG_AUTO;
266	err = snd_timer_open(t, &tmr->alsa_id, q->queue);
267	if (err < 0 && tmr->alsa_id.dev_class != SNDRV_TIMER_CLASS_SLAVE) {
268		if (tmr->alsa_id.dev_class != SNDRV_TIMER_CLASS_GLOBAL ||
269		    tmr->alsa_id.device != SNDRV_TIMER_GLOBAL_SYSTEM) {
270			struct snd_timer_id tid;
271			memset(&tid, 0, sizeof(tid));
272			tid.dev_class = SNDRV_TIMER_CLASS_GLOBAL;
273			tid.dev_sclass = SNDRV_TIMER_SCLASS_SEQUENCER;
274			tid.card = -1;
275			tid.device = SNDRV_TIMER_GLOBAL_SYSTEM;
276			err = snd_timer_open(t, &tid, q->queue);
277		}
278	}
279	if (err < 0) {
280		pr_err("ALSA: seq fatal error: cannot create timer (%i)\n", err);
281		snd_timer_instance_free(t);
282		return err;
283	}
284	scoped_guard(spinlock_irq, &tmr->lock) {
285		if (tmr->timeri)
286			err = -EBUSY;
287		else
288			tmr->timeri = t;
289	}
290	if (err < 0) {
291		snd_timer_close(t);
292		snd_timer_instance_free(t);
293		return err;
294	}
295	return 0;
296}
297
298int snd_seq_timer_close(struct snd_seq_queue *q)
299{
300	struct snd_seq_timer *tmr;
301	struct snd_timer_instance *t;
302	
303	tmr = q->timer;
304	if (snd_BUG_ON(!tmr))
305		return -EINVAL;
306	scoped_guard(spinlock_irq, &tmr->lock) {
307		t = tmr->timeri;
308		tmr->timeri = NULL;
309	}
310	if (t) {
311		snd_timer_close(t);
312		snd_timer_instance_free(t);
313	}
314	return 0;
315}
316
317static int seq_timer_stop(struct snd_seq_timer *tmr)
318{
319	if (! tmr->timeri)
320		return -EINVAL;
321	if (!tmr->running)
322		return 0;
323	tmr->running = 0;
324	snd_timer_pause(tmr->timeri);
325	return 0;
326}
327
328int snd_seq_timer_stop(struct snd_seq_timer *tmr)
329{
330	guard(spinlock_irqsave)(&tmr->lock);
331	return seq_timer_stop(tmr);
332}
333
334static int initialize_timer(struct snd_seq_timer *tmr)
335{
336	struct snd_timer *t;
337	unsigned long freq;
338
339	t = tmr->timeri->timer;
340	if (!t)
341		return -EINVAL;
342
343	freq = tmr->preferred_resolution;
344	if (!freq)
345		freq = DEFAULT_FREQUENCY;
346	else if (freq < MIN_FREQUENCY)
347		freq = MIN_FREQUENCY;
348	else if (freq > MAX_FREQUENCY)
349		freq = MAX_FREQUENCY;
350
351	tmr->ticks = 1;
352	if (!(t->hw.flags & SNDRV_TIMER_HW_SLAVE)) {
353		unsigned long r = snd_timer_resolution(tmr->timeri);
354		if (r) {
355			tmr->ticks = (unsigned int)(1000000000uL / (r * freq));
356			if (! tmr->ticks)
357				tmr->ticks = 1;
358		}
359	}
360	tmr->initialized = 1;
361	return 0;
362}
363
364static int seq_timer_start(struct snd_seq_timer *tmr)
365{
366	if (! tmr->timeri)
367		return -EINVAL;
368	if (tmr->running)
369		seq_timer_stop(tmr);
370	seq_timer_reset(tmr);
371	if (initialize_timer(tmr) < 0)
372		return -EINVAL;
373	snd_timer_start(tmr->timeri, tmr->ticks);
374	tmr->running = 1;
375	ktime_get_ts64(&tmr->last_update);
376	return 0;
377}
378
379int snd_seq_timer_start(struct snd_seq_timer *tmr)
380{
381	guard(spinlock_irqsave)(&tmr->lock);
382	return seq_timer_start(tmr);
383}
384
385static int seq_timer_continue(struct snd_seq_timer *tmr)
386{
387	if (! tmr->timeri)
388		return -EINVAL;
389	if (tmr->running)
390		return -EBUSY;
391	if (! tmr->initialized) {
392		seq_timer_reset(tmr);
393		if (initialize_timer(tmr) < 0)
394			return -EINVAL;
395	}
396	snd_timer_start(tmr->timeri, tmr->ticks);
397	tmr->running = 1;
398	ktime_get_ts64(&tmr->last_update);
399	return 0;
400}
401
402int snd_seq_timer_continue(struct snd_seq_timer *tmr)
403{
404	guard(spinlock_irqsave)(&tmr->lock);
405	return seq_timer_continue(tmr);
406}
407
408/* return current 'real' time. use timeofday() to get better granularity. */
409snd_seq_real_time_t snd_seq_timer_get_cur_time(struct snd_seq_timer *tmr,
410					       bool adjust_ktime)
411{
412	snd_seq_real_time_t cur_time;
413
414	guard(spinlock_irqsave)(&tmr->lock);
415	cur_time = tmr->cur_time;
416	if (adjust_ktime && tmr->running) {
417		struct timespec64 tm;
418
419		ktime_get_ts64(&tm);
420		tm = timespec64_sub(tm, tmr->last_update);
421		cur_time.tv_nsec += tm.tv_nsec;
422		cur_time.tv_sec += tm.tv_sec;
423		snd_seq_sanity_real_time(&cur_time);
424	}
425	return cur_time;	
426}
427
428/* TODO: use interpolation on tick queue (will only be useful for very
429 high PPQ values) */
430snd_seq_tick_time_t snd_seq_timer_get_cur_tick(struct snd_seq_timer *tmr)
431{
432	guard(spinlock_irqsave)(&tmr->lock);
433	return tmr->tick.cur_tick;
434}
435
436
437#ifdef CONFIG_SND_PROC_FS
438/* exported to seq_info.c */
439void snd_seq_info_timer_read(struct snd_info_entry *entry,
440			     struct snd_info_buffer *buffer)
441{
442	int idx;
443	struct snd_seq_timer *tmr;
444	struct snd_timer_instance *ti;
445	unsigned long resolution;
446	
447	for (idx = 0; idx < SNDRV_SEQ_MAX_QUEUES; idx++) {
448		struct snd_seq_queue *q __free(snd_seq_queue) = queueptr(idx);
449
450		if (q == NULL)
451			continue;
452		scoped_guard(mutex, &q->timer_mutex) {
453			tmr = q->timer;
454			if (!tmr)
455				break;
456			ti = tmr->timeri;
457			if (!ti)
458				break;
459			snd_iprintf(buffer, "Timer for queue %i : %s\n", q->queue, ti->timer->name);
460			resolution = snd_timer_resolution(ti) * tmr->ticks;
461			snd_iprintf(buffer, "  Period time : %lu.%09lu\n", resolution / 1000000000, resolution % 1000000000);
462			snd_iprintf(buffer, "  Skew : %u / %u\n", tmr->skew, tmr->skew_base);
463		}
464 	}
465}
466#endif /* CONFIG_SND_PROC_FS */
467