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
37 MODULE_AUTHOR("Takashi Iwai <tiwai@suse.de>");
38 MODULE_DESCRIPTION("Virtual Raw MIDI client on Sequencer");
39 MODULE_LICENSE("GPL");
40
41 /*
42 * initialize an event record
43 */
44 static 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() */
67 static int dump_to_rawmidi(void *ptr, void *buf, int count)
68 {
69 return snd_rawmidi_receive(ptr, buf, count);
70 }
71
72 static 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 */
109 static 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 */
123 static 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 */
133 static 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 */
172 static 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 */
184 static 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 */
213 static 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 */
240 static 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 */
258 static 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 */
273 static 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 */
283 static 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 */
298 static 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 */
313 static 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 */
328 static 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
344 static 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
350 static 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 */
360 static 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 */
418 static 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 */
429 static 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 */
456 static 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 */
468 static 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 */
476 static 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 */
487 int 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 }
525 EXPORT_SYMBOL(snd_virmidi_new);
526
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