1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 *  Virtual Raw MIDI client on Sequencer
4 *
5 *  Copyright (c) 2000 by Takashi Iwai <tiwai@suse.de>,
6 *                        Jaroslav Kysela <perex@perex.cz>
7 */
8
9/*
10 * Virtual Raw MIDI client
11 *
12 * The virtual rawmidi client is a sequencer client which associate
13 * a rawmidi device file.  The created rawmidi device file can be
14 * accessed as a normal raw midi, but its MIDI source and destination
15 * are arbitrary.  For example, a user-client software synth connected
16 * to this port can be used as a normal midi device as well.
17 *
18 * The virtual rawmidi device accepts also multiple opens.  Each file
19 * has its own input buffer, so that no conflict would occur.  The drain
20 * of input/output buffer acts only to the local buffer.
21 *
22 */
23
24#include <linux/init.h>
25#include <linux/wait.h>
26#include <linux/module.h>
27#include <linux/slab.h>
28#include <sound/core.h>
29#include <sound/rawmidi.h>
30#include <sound/info.h>
31#include <sound/control.h>
32#include <sound/minors.h>
33#include <sound/seq_kernel.h>
34#include <sound/seq_midi_event.h>
35#include <sound/seq_virmidi.h>
36
37MODULE_AUTHOR("Takashi Iwai <tiwai@suse.de>");
38MODULE_DESCRIPTION("Virtual Raw MIDI client on Sequencer");
39MODULE_LICENSE("GPL");
40
41/*
42 * initialize an event record
43 */
44static void snd_virmidi_init_event(struct snd_virmidi *vmidi,
45				   struct snd_seq_event *ev)
46{
47	memset(ev, 0, sizeof(*ev));
48	ev->source.port = vmidi->port;
49	switch (vmidi->seq_mode) {
50	case SNDRV_VIRMIDI_SEQ_DISPATCH:
51		ev->dest.client = SNDRV_SEQ_ADDRESS_SUBSCRIBERS;
52		break;
53	case SNDRV_VIRMIDI_SEQ_ATTACH:
54		/* FIXME: source and destination are same - not good.. */
55		ev->dest.client = vmidi->client;
56		ev->dest.port = vmidi->port;
57		break;
58	}
59	ev->type = SNDRV_SEQ_EVENT_NONE;
60}
61
62/*
63 * decode input event and put to read buffer of each opened file
64 */
65
66/* callback for snd_seq_dump_var_event(), bridging to snd_rawmidi_receive() */
67static int dump_to_rawmidi(void *ptr, void *buf, int count)
68{
69	return snd_rawmidi_receive(ptr, buf, count);
70}
71
72static int snd_virmidi_dev_receive_event(struct snd_virmidi_dev *rdev,
73					 struct snd_seq_event *ev,
74					 bool atomic)
75{
76	struct snd_virmidi *vmidi;
77	unsigned char msg[4];
78	int len;
79
80	if (atomic)
81		read_lock(&rdev->filelist_lock);
82	else
83		down_read(&rdev->filelist_sem);
84	list_for_each_entry(vmidi, &rdev->filelist, list) {
85		if (!READ_ONCE(vmidi->trigger))
86			continue;
87		if (ev->type == SNDRV_SEQ_EVENT_SYSEX) {
88			if ((ev->flags & SNDRV_SEQ_EVENT_LENGTH_MASK) != SNDRV_SEQ_EVENT_LENGTH_VARIABLE)
89				continue;
90			snd_seq_dump_var_event(ev, dump_to_rawmidi, vmidi->substream);
91			snd_midi_event_reset_decode(vmidi->parser);
92		} else {
93			len = snd_midi_event_decode(vmidi->parser, msg, sizeof(msg), ev);
94			if (len > 0)
95				snd_rawmidi_receive(vmidi->substream, msg, len);
96		}
97	}
98	if (atomic)
99		read_unlock(&rdev->filelist_lock);
100	else
101		up_read(&rdev->filelist_sem);
102
103	return 0;
104}
105
106/*
107 * event handler of virmidi port
108 */
109static int snd_virmidi_event_input(struct snd_seq_event *ev, int direct,
110				   void *private_data, int atomic, int hop)
111{
112	struct snd_virmidi_dev *rdev;
113
114	rdev = private_data;
115	if (!(rdev->flags & SNDRV_VIRMIDI_USE))
116		return 0; /* ignored */
117	return snd_virmidi_dev_receive_event(rdev, ev, atomic);
118}
119
120/*
121 * trigger rawmidi stream for input
122 */
123static void snd_virmidi_input_trigger(struct snd_rawmidi_substream *substream, int up)
124{
125	struct snd_virmidi *vmidi = substream->runtime->private_data;
126
127	WRITE_ONCE(vmidi->trigger, !!up);
128}
129
130/* process rawmidi bytes and send events;
131 * we need no lock here for vmidi->event since it's handled only in this work
132 */
133static void snd_vmidi_output_work(struct work_struct *work)
134{
135	struct snd_virmidi *vmidi;
136	struct snd_rawmidi_substream *substream;
137	unsigned char input;
138	int ret;
139
140	vmidi = container_of(work, struct snd_virmidi, output_work);
141	substream = vmidi->substream;
142
143	/* discard the outputs in dispatch mode unless subscribed */
144	if (vmidi->seq_mode == SNDRV_VIRMIDI_SEQ_DISPATCH &&
145	    !(vmidi->rdev->flags & SNDRV_VIRMIDI_SUBSCRIBE)) {
146		snd_rawmidi_proceed(substream);
147		return;
148	}
149
150	while (READ_ONCE(vmidi->trigger)) {
151		if (snd_rawmidi_transmit(substream, &input, 1) != 1)
152			break;
153		if (!snd_midi_event_encode_byte(vmidi->parser, input,
154						&vmidi->event))
155			continue;
156		if (vmidi->event.type != SNDRV_SEQ_EVENT_NONE) {
157			ret = snd_seq_kernel_client_dispatch(vmidi->client,
158							     &vmidi->event,
159							     false, 0);
160			vmidi->event.type = SNDRV_SEQ_EVENT_NONE;
161			if (ret < 0)
162				break;
163		}
164		/* rawmidi input might be huge, allow to have a break */
165		cond_resched();
166	}
167}
168
169/*
170 * trigger rawmidi stream for output
171 */
172static void snd_virmidi_output_trigger(struct snd_rawmidi_substream *substream, int up)
173{
174	struct snd_virmidi *vmidi = substream->runtime->private_data;
175
176	WRITE_ONCE(vmidi->trigger, !!up);
177	if (up)
178		queue_work(system_highpri_wq, &vmidi->output_work);
179}
180
181/*
182 * open rawmidi handle for input
183 */
184static int snd_virmidi_input_open(struct snd_rawmidi_substream *substream)
185{
186	struct snd_virmidi_dev *rdev = substream->rmidi->private_data;
187	struct snd_rawmidi_runtime *runtime = substream->runtime;
188	struct snd_virmidi *vmidi;
189
190	vmidi = kzalloc(sizeof(*vmidi), GFP_KERNEL);
191	if (vmidi == NULL)
192		return -ENOMEM;
193	vmidi->substream = substream;
194	if (snd_midi_event_new(0, &vmidi->parser) < 0) {
195		kfree(vmidi);
196		return -ENOMEM;
197	}
198	vmidi->seq_mode = rdev->seq_mode;
199	vmidi->client = rdev->client;
200	vmidi->port = rdev->port;
201	runtime->private_data = vmidi;
202	scoped_guard(rwsem_write, &rdev->filelist_sem) {
203		guard(write_lock_irq)(&rdev->filelist_lock);
204		list_add_tail(&vmidi->list, &rdev->filelist);
205	}
206	vmidi->rdev = rdev;
207	return 0;
208}
209
210/*
211 * open rawmidi handle for output
212 */
213static int snd_virmidi_output_open(struct snd_rawmidi_substream *substream)
214{
215	struct snd_virmidi_dev *rdev = substream->rmidi->private_data;
216	struct snd_rawmidi_runtime *runtime = substream->runtime;
217	struct snd_virmidi *vmidi;
218
219	vmidi = kzalloc(sizeof(*vmidi), GFP_KERNEL);
220	if (vmidi == NULL)
221		return -ENOMEM;
222	vmidi->substream = substream;
223	if (snd_midi_event_new(MAX_MIDI_EVENT_BUF, &vmidi->parser) < 0) {
224		kfree(vmidi);
225		return -ENOMEM;
226	}
227	vmidi->seq_mode = rdev->seq_mode;
228	vmidi->client = rdev->client;
229	vmidi->port = rdev->port;
230	snd_virmidi_init_event(vmidi, &vmidi->event);
231	vmidi->rdev = rdev;
232	INIT_WORK(&vmidi->output_work, snd_vmidi_output_work);
233	runtime->private_data = vmidi;
234	return 0;
235}
236
237/*
238 * close rawmidi handle for input
239 */
240static int snd_virmidi_input_close(struct snd_rawmidi_substream *substream)
241{
242	struct snd_virmidi_dev *rdev = substream->rmidi->private_data;
243	struct snd_virmidi *vmidi = substream->runtime->private_data;
244
245	scoped_guard(rwsem_write, &rdev->filelist_sem) {
246		guard(write_lock_irq)(&rdev->filelist_lock);
247		list_del(&vmidi->list);
248	}
249	snd_midi_event_free(vmidi->parser);
250	substream->runtime->private_data = NULL;
251	kfree(vmidi);
252	return 0;
253}
254
255/*
256 * close rawmidi handle for output
257 */
258static int snd_virmidi_output_close(struct snd_rawmidi_substream *substream)
259{
260	struct snd_virmidi *vmidi = substream->runtime->private_data;
261
262	WRITE_ONCE(vmidi->trigger, false); /* to be sure */
263	cancel_work_sync(&vmidi->output_work);
264	snd_midi_event_free(vmidi->parser);
265	substream->runtime->private_data = NULL;
266	kfree(vmidi);
267	return 0;
268}
269
270/*
271 * drain output work queue
272 */
273static void snd_virmidi_output_drain(struct snd_rawmidi_substream *substream)
274{
275	struct snd_virmidi *vmidi = substream->runtime->private_data;
276
277	flush_work(&vmidi->output_work);
278}
279
280/*
281 * subscribe callback - allow output to rawmidi device
282 */
283static int snd_virmidi_subscribe(void *private_data,
284				 struct snd_seq_port_subscribe *info)
285{
286	struct snd_virmidi_dev *rdev;
287
288	rdev = private_data;
289	if (!try_module_get(rdev->card->module))
290		return -EFAULT;
291	rdev->flags |= SNDRV_VIRMIDI_SUBSCRIBE;
292	return 0;
293}
294
295/*
296 * unsubscribe callback - disallow output to rawmidi device
297 */
298static int snd_virmidi_unsubscribe(void *private_data,
299				   struct snd_seq_port_subscribe *info)
300{
301	struct snd_virmidi_dev *rdev;
302
303	rdev = private_data;
304	rdev->flags &= ~SNDRV_VIRMIDI_SUBSCRIBE;
305	module_put(rdev->card->module);
306	return 0;
307}
308
309
310/*
311 * use callback - allow input to rawmidi device
312 */
313static int snd_virmidi_use(void *private_data,
314			   struct snd_seq_port_subscribe *info)
315{
316	struct snd_virmidi_dev *rdev;
317
318	rdev = private_data;
319	if (!try_module_get(rdev->card->module))
320		return -EFAULT;
321	rdev->flags |= SNDRV_VIRMIDI_USE;
322	return 0;
323}
324
325/*
326 * unuse callback - disallow input to rawmidi device
327 */
328static int snd_virmidi_unuse(void *private_data,
329			     struct snd_seq_port_subscribe *info)
330{
331	struct snd_virmidi_dev *rdev;
332
333	rdev = private_data;
334	rdev->flags &= ~SNDRV_VIRMIDI_USE;
335	module_put(rdev->card->module);
336	return 0;
337}
338
339
340/*
341 *  Register functions
342 */
343
344static const struct snd_rawmidi_ops snd_virmidi_input_ops = {
345	.open = snd_virmidi_input_open,
346	.close = snd_virmidi_input_close,
347	.trigger = snd_virmidi_input_trigger,
348};
349
350static const struct snd_rawmidi_ops snd_virmidi_output_ops = {
351	.open = snd_virmidi_output_open,
352	.close = snd_virmidi_output_close,
353	.trigger = snd_virmidi_output_trigger,
354	.drain = snd_virmidi_output_drain,
355};
356
357/*
358 * create a sequencer client and a port
359 */
360static int snd_virmidi_dev_attach_seq(struct snd_virmidi_dev *rdev)
361{
362	int client;
363	struct snd_seq_port_callback pcallbacks;
364	struct snd_seq_port_info *pinfo __free(kfree) = NULL;
365	int err;
366
367	if (rdev->client >= 0)
368		return 0;
369
370	pinfo = kzalloc(sizeof(*pinfo), GFP_KERNEL);
371	if (!pinfo)
372		return -ENOMEM;
373
374	client = snd_seq_create_kernel_client(rdev->card, rdev->device,
375					      "%s %d-%d", rdev->rmidi->name,
376					      rdev->card->number,
377					      rdev->device);
378	if (client < 0)
379		return client;
380	rdev->client = client;
381
382	/* create a port */
383	pinfo->addr.client = client;
384	sprintf(pinfo->name, "VirMIDI %d-%d", rdev->card->number, rdev->device);
385	/* set all capabilities */
386	pinfo->capability |= SNDRV_SEQ_PORT_CAP_WRITE | SNDRV_SEQ_PORT_CAP_SYNC_WRITE | SNDRV_SEQ_PORT_CAP_SUBS_WRITE;
387	pinfo->capability |= SNDRV_SEQ_PORT_CAP_READ | SNDRV_SEQ_PORT_CAP_SYNC_READ | SNDRV_SEQ_PORT_CAP_SUBS_READ;
388	pinfo->capability |= SNDRV_SEQ_PORT_CAP_DUPLEX;
389	pinfo->direction = SNDRV_SEQ_PORT_DIR_BIDIRECTION;
390	pinfo->type = SNDRV_SEQ_PORT_TYPE_MIDI_GENERIC
391		| SNDRV_SEQ_PORT_TYPE_SOFTWARE
392		| SNDRV_SEQ_PORT_TYPE_PORT;
393	pinfo->midi_channels = 16;
394	memset(&pcallbacks, 0, sizeof(pcallbacks));
395	pcallbacks.owner = THIS_MODULE;
396	pcallbacks.private_data = rdev;
397	pcallbacks.subscribe = snd_virmidi_subscribe;
398	pcallbacks.unsubscribe = snd_virmidi_unsubscribe;
399	pcallbacks.use = snd_virmidi_use;
400	pcallbacks.unuse = snd_virmidi_unuse;
401	pcallbacks.event_input = snd_virmidi_event_input;
402	pinfo->kernel = &pcallbacks;
403	err = snd_seq_kernel_client_ctl(client, SNDRV_SEQ_IOCTL_CREATE_PORT, pinfo);
404	if (err < 0) {
405		snd_seq_delete_kernel_client(client);
406		rdev->client = -1;
407		return err;
408	}
409
410	rdev->port = pinfo->addr.port;
411	return 0; /* success */
412}
413
414
415/*
416 * release the sequencer client
417 */
418static void snd_virmidi_dev_detach_seq(struct snd_virmidi_dev *rdev)
419{
420	if (rdev->client >= 0) {
421		snd_seq_delete_kernel_client(rdev->client);
422		rdev->client = -1;
423	}
424}
425
426/*
427 * register the device
428 */
429static int snd_virmidi_dev_register(struct snd_rawmidi *rmidi)
430{
431	struct snd_virmidi_dev *rdev = rmidi->private_data;
432	int err;
433
434	switch (rdev->seq_mode) {
435	case SNDRV_VIRMIDI_SEQ_DISPATCH:
436		err = snd_virmidi_dev_attach_seq(rdev);
437		if (err < 0)
438			return err;
439		break;
440	case SNDRV_VIRMIDI_SEQ_ATTACH:
441		if (rdev->client == 0)
442			return -EINVAL;
443		/* should check presence of port more strictly.. */
444		break;
445	default:
446		pr_err("ALSA: seq_virmidi: seq_mode is not set: %d\n", rdev->seq_mode);
447		return -EINVAL;
448	}
449	return 0;
450}
451
452
453/*
454 * unregister the device
455 */
456static int snd_virmidi_dev_unregister(struct snd_rawmidi *rmidi)
457{
458	struct snd_virmidi_dev *rdev = rmidi->private_data;
459
460	if (rdev->seq_mode == SNDRV_VIRMIDI_SEQ_DISPATCH)
461		snd_virmidi_dev_detach_seq(rdev);
462	return 0;
463}
464
465/*
466 *
467 */
468static const struct snd_rawmidi_global_ops snd_virmidi_global_ops = {
469	.dev_register = snd_virmidi_dev_register,
470	.dev_unregister = snd_virmidi_dev_unregister,
471};
472
473/*
474 * free device
475 */
476static void snd_virmidi_free(struct snd_rawmidi *rmidi)
477{
478	struct snd_virmidi_dev *rdev = rmidi->private_data;
479	kfree(rdev);
480}
481
482/*
483 * create a new device
484 *
485 */
486/* exported */
487int snd_virmidi_new(struct snd_card *card, int device, struct snd_rawmidi **rrmidi)
488{
489	struct snd_rawmidi *rmidi;
490	struct snd_virmidi_dev *rdev;
491	int err;
492
493	*rrmidi = NULL;
494	err = snd_rawmidi_new(card, "VirMidi", device,
495			      16,	/* may be configurable */
496			      16,	/* may be configurable */
497			      &rmidi);
498	if (err < 0)
499		return err;
500	strcpy(rmidi->name, rmidi->id);
501	rdev = kzalloc(sizeof(*rdev), GFP_KERNEL);
502	if (rdev == NULL) {
503		snd_device_free(card, rmidi);
504		return -ENOMEM;
505	}
506	rdev->card = card;
507	rdev->rmidi = rmidi;
508	rdev->device = device;
509	rdev->client = -1;
510	init_rwsem(&rdev->filelist_sem);
511	rwlock_init(&rdev->filelist_lock);
512	INIT_LIST_HEAD(&rdev->filelist);
513	rdev->seq_mode = SNDRV_VIRMIDI_SEQ_DISPATCH;
514	rmidi->private_data = rdev;
515	rmidi->private_free = snd_virmidi_free;
516	rmidi->ops = &snd_virmidi_global_ops;
517	snd_rawmidi_set_ops(rmidi, SNDRV_RAWMIDI_STREAM_INPUT, &snd_virmidi_input_ops);
518	snd_rawmidi_set_ops(rmidi, SNDRV_RAWMIDI_STREAM_OUTPUT, &snd_virmidi_output_ops);
519	rmidi->info_flags = SNDRV_RAWMIDI_INFO_INPUT |
520			    SNDRV_RAWMIDI_INFO_OUTPUT |
521			    SNDRV_RAWMIDI_INFO_DUPLEX;
522	*rrmidi = rmidi;
523	return 0;
524}
525EXPORT_SYMBOL(snd_virmidi_new);
526