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(substream: ptr, buffer: 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(sem: &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(event: ev, func: dump_to_rawmidi, private_data: vmidi->substream);
91 snd_midi_event_reset_decode(dev: vmidi->parser);
92 } else {
93 len = snd_midi_event_decode(dev: vmidi->parser, buf: msg, count: sizeof(msg), ev);
94 if (len > 0)
95 snd_rawmidi_receive(substream: vmidi->substream, buffer: msg, count: len);
96 }
97 }
98 if (atomic)
99 read_unlock(&rdev->filelist_lock);
100 else
101 up_read(sem: &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, buffer: &input, count: 1) != 1)
152 break;
153 if (!snd_midi_event_encode_byte(dev: vmidi->parser, c: input,
154 ev: &vmidi->event))
155 continue;
156 if (vmidi->event.type != SNDRV_SEQ_EVENT_NONE) {
157 ret = snd_seq_kernel_client_dispatch(client: vmidi->client,
158 ev: &vmidi->event,
159 atomic: false, hop: 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(wq: system_highpri_wq, work: &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(bufsize: 0, rdev: &vmidi->parser) < 0) {
195 kfree(objp: 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)(l: &rdev->filelist_lock);
204 list_add_tail(new: &vmidi->list, head: &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, rdev: &vmidi->parser) < 0) {
224 kfree(objp: 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, ev: &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)(l: &rdev->filelist_lock);
247 list_del(entry: &vmidi->list);
248 }
249 snd_midi_event_free(dev: vmidi->parser);
250 substream->runtime->private_data = NULL;
251 kfree(objp: 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(work: &vmidi->output_work);
264 snd_midi_event_free(dev: vmidi->parser);
265 substream->runtime->private_data = NULL;
266 kfree(objp: 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(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(module: 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(module: 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(module: 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(module: 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(card: rdev->card, client_index: rdev->device,
375 name_fmt: "%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(buf: pinfo->name, fmt: "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, arg: 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(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(objp: 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, id: "VirMidi", device,
495 output_count: 16, /* may be configurable */
496 input_count: 16, /* may be configurable */
497 rmidi: &rmidi);
498 if (err < 0)
499 return err;
500 strscpy(rmidi->name, rmidi->id);
501 rdev = kzalloc(sizeof(*rdev), GFP_KERNEL);
502 if (rdev == NULL) {
503 snd_device_free(card, device_data: 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(list: &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, stream: SNDRV_RAWMIDI_STREAM_INPUT, ops: &snd_virmidi_input_ops);
518 snd_rawmidi_set_ops(rmidi, stream: SNDRV_RAWMIDI_STREAM_OUTPUT, ops: &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

source code of linux/sound/core/seq/seq_virmidi.c