1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * ALSA sequencer Ports
4 * Copyright (c) 1998 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 <linux/module.h>
11 #include "seq_system.h"
12 #include "seq_ports.h"
13 #include "seq_clientmgr.h"
14
15 /*
16
17 registration of client ports
18
19 */
20
21
22 /*
23
24 NOTE: the current implementation of the port structure as a linked list is
25 not optimal for clients that have many ports. For sending messages to all
26 subscribers of a port we first need to find the address of the port
27 structure, which means we have to traverse the list. A direct access table
28 (array) would be better, but big preallocated arrays waste memory.
29
30 Possible actions:
31
32 1) leave it this way, a client does normaly does not have more than a few
33 ports
34
35 2) replace the linked list of ports by a array of pointers which is
36 dynamicly kmalloced. When a port is added or deleted we can simply allocate
37 a new array, copy the corresponding pointers, and delete the old one. We
38 then only need a pointer to this array, and an integer that tells us how
39 much elements are in array.
40
41 */
42
43 /* return pointer to port structure - port is locked if found */
snd_seq_port_use_ptr(struct snd_seq_client * client,int num)44 struct snd_seq_client_port *snd_seq_port_use_ptr(struct snd_seq_client *client,
45 int num)
46 {
47 struct snd_seq_client_port *port;
48
49 if (client == NULL)
50 return NULL;
51 guard(read_lock)(&client->ports_lock);
52 list_for_each_entry(port, &client->ports_list_head, list) {
53 if (port->addr.port == num) {
54 if (port->closing)
55 break; /* deleting now */
56 snd_use_lock_use(&port->use_lock);
57 return port;
58 }
59 }
60 return NULL; /* not found */
61 }
62
63
64 /* search for the next port - port is locked if found */
snd_seq_port_query_nearest(struct snd_seq_client * client,struct snd_seq_port_info * pinfo)65 struct snd_seq_client_port *snd_seq_port_query_nearest(struct snd_seq_client *client,
66 struct snd_seq_port_info *pinfo)
67 {
68 int num;
69 struct snd_seq_client_port *port, *found;
70 bool check_inactive = (pinfo->capability & SNDRV_SEQ_PORT_CAP_INACTIVE);
71
72 num = pinfo->addr.port;
73 found = NULL;
74 guard(read_lock)(&client->ports_lock);
75 list_for_each_entry(port, &client->ports_list_head, list) {
76 if ((port->capability & SNDRV_SEQ_PORT_CAP_INACTIVE) &&
77 !check_inactive)
78 continue; /* skip inactive ports */
79 if (port->addr.port < num)
80 continue;
81 if (port->addr.port == num) {
82 found = port;
83 break;
84 }
85 if (found == NULL || port->addr.port < found->addr.port)
86 found = port;
87 }
88 if (found) {
89 if (found->closing)
90 found = NULL;
91 else
92 snd_use_lock_use(&found->use_lock);
93 }
94 return found;
95 }
96
97
98 /* initialize snd_seq_port_subs_info */
port_subs_info_init(struct snd_seq_port_subs_info * grp)99 static void port_subs_info_init(struct snd_seq_port_subs_info *grp)
100 {
101 INIT_LIST_HEAD(&grp->list_head);
102 grp->count = 0;
103 grp->exclusive = 0;
104 rwlock_init(&grp->list_lock);
105 init_rwsem(&grp->list_mutex);
106 grp->open = NULL;
107 grp->close = NULL;
108 }
109
110
111 /* create a port, port number or a negative error code is returned
112 * the caller needs to unref the port via snd_seq_port_unlock() appropriately
113 */
snd_seq_create_port(struct snd_seq_client * client,int port,struct snd_seq_client_port ** port_ret)114 int snd_seq_create_port(struct snd_seq_client *client, int port,
115 struct snd_seq_client_port **port_ret)
116 {
117 struct snd_seq_client_port *new_port, *p;
118 int num;
119
120 *port_ret = NULL;
121
122 /* sanity check */
123 if (snd_BUG_ON(!client))
124 return -EINVAL;
125
126 if (client->num_ports >= SNDRV_SEQ_MAX_PORTS) {
127 pr_warn("ALSA: seq: too many ports for client %d\n", client->number);
128 return -EINVAL;
129 }
130
131 /* create a new port */
132 new_port = kzalloc(sizeof(*new_port), GFP_KERNEL);
133 if (!new_port)
134 return -ENOMEM; /* failure, out of memory */
135 /* init port data */
136 new_port->addr.client = client->number;
137 new_port->addr.port = -1;
138 new_port->owner = THIS_MODULE;
139 snd_use_lock_init(&new_port->use_lock);
140 port_subs_info_init(&new_port->c_src);
141 port_subs_info_init(&new_port->c_dest);
142 snd_use_lock_use(&new_port->use_lock);
143
144 num = max(port, 0);
145 guard(mutex)(&client->ports_mutex);
146 guard(write_lock_irq)(&client->ports_lock);
147 list_for_each_entry(p, &client->ports_list_head, list) {
148 if (p->addr.port == port) {
149 kfree(new_port);
150 return -EBUSY;
151 }
152 if (p->addr.port > num)
153 break;
154 if (port < 0) /* auto-probe mode */
155 num = p->addr.port + 1;
156 }
157 /* insert the new port */
158 list_add_tail(&new_port->list, &p->list);
159 client->num_ports++;
160 new_port->addr.port = num; /* store the port number in the port */
161 sprintf(new_port->name, "port-%d", num);
162 *port_ret = new_port;
163
164 return num;
165 }
166
167 /* */
168 static int subscribe_port(struct snd_seq_client *client,
169 struct snd_seq_client_port *port,
170 struct snd_seq_port_subs_info *grp,
171 struct snd_seq_port_subscribe *info, int send_ack);
172 static int unsubscribe_port(struct snd_seq_client *client,
173 struct snd_seq_client_port *port,
174 struct snd_seq_port_subs_info *grp,
175 struct snd_seq_port_subscribe *info, int send_ack);
176
177
get_client_port(struct snd_seq_addr * addr,struct snd_seq_client ** cp)178 static struct snd_seq_client_port *get_client_port(struct snd_seq_addr *addr,
179 struct snd_seq_client **cp)
180 {
181 struct snd_seq_client_port *p;
182 *cp = snd_seq_client_use_ptr(addr->client);
183 if (*cp) {
184 p = snd_seq_port_use_ptr(*cp, addr->port);
185 if (! p) {
186 snd_seq_client_unlock(*cp);
187 *cp = NULL;
188 }
189 return p;
190 }
191 return NULL;
192 }
193
194 static void delete_and_unsubscribe_port(struct snd_seq_client *client,
195 struct snd_seq_client_port *port,
196 struct snd_seq_subscribers *subs,
197 bool is_src, bool ack);
198
199 static inline struct snd_seq_subscribers *
get_subscriber(struct list_head * p,bool is_src)200 get_subscriber(struct list_head *p, bool is_src)
201 {
202 if (is_src)
203 return list_entry(p, struct snd_seq_subscribers, src_list);
204 else
205 return list_entry(p, struct snd_seq_subscribers, dest_list);
206 }
207
208 /*
209 * remove all subscribers on the list
210 * this is called from port_delete, for each src and dest list.
211 */
clear_subscriber_list(struct snd_seq_client * client,struct snd_seq_client_port * port,struct snd_seq_port_subs_info * grp,int is_src)212 static void clear_subscriber_list(struct snd_seq_client *client,
213 struct snd_seq_client_port *port,
214 struct snd_seq_port_subs_info *grp,
215 int is_src)
216 {
217 struct list_head *p, *n;
218
219 list_for_each_safe(p, n, &grp->list_head) {
220 struct snd_seq_subscribers *subs;
221 struct snd_seq_client *c;
222 struct snd_seq_client_port *aport;
223
224 subs = get_subscriber(p, is_src);
225 if (is_src)
226 aport = get_client_port(&subs->info.dest, &c);
227 else
228 aport = get_client_port(&subs->info.sender, &c);
229 delete_and_unsubscribe_port(client, port, subs, is_src, false);
230
231 if (!aport) {
232 /* looks like the connected port is being deleted.
233 * we decrease the counter, and when both ports are deleted
234 * remove the subscriber info
235 */
236 if (atomic_dec_and_test(&subs->ref_count))
237 kfree(subs);
238 continue;
239 }
240
241 /* ok we got the connected port */
242 delete_and_unsubscribe_port(c, aport, subs, !is_src, true);
243 kfree(subs);
244 snd_seq_port_unlock(aport);
245 snd_seq_client_unlock(c);
246 }
247 }
248
249 /* delete port data */
port_delete(struct snd_seq_client * client,struct snd_seq_client_port * port)250 static int port_delete(struct snd_seq_client *client,
251 struct snd_seq_client_port *port)
252 {
253 /* set closing flag and wait for all port access are gone */
254 port->closing = 1;
255 snd_use_lock_sync(&port->use_lock);
256
257 /* clear subscribers info */
258 clear_subscriber_list(client, port, &port->c_src, true);
259 clear_subscriber_list(client, port, &port->c_dest, false);
260
261 if (port->private_free)
262 port->private_free(port->private_data);
263
264 snd_BUG_ON(port->c_src.count != 0);
265 snd_BUG_ON(port->c_dest.count != 0);
266
267 kfree(port);
268 return 0;
269 }
270
271
272 /* delete a port with the given port id */
snd_seq_delete_port(struct snd_seq_client * client,int port)273 int snd_seq_delete_port(struct snd_seq_client *client, int port)
274 {
275 struct snd_seq_client_port *found = NULL, *p;
276
277 scoped_guard(mutex, &client->ports_mutex) {
278 guard(write_lock_irq)(&client->ports_lock);
279 list_for_each_entry(p, &client->ports_list_head, list) {
280 if (p->addr.port == port) {
281 /* ok found. delete from the list at first */
282 list_del(&p->list);
283 client->num_ports--;
284 found = p;
285 break;
286 }
287 }
288 }
289 if (found)
290 return port_delete(client, found);
291 else
292 return -ENOENT;
293 }
294
295 /* delete the all ports belonging to the given client */
snd_seq_delete_all_ports(struct snd_seq_client * client)296 int snd_seq_delete_all_ports(struct snd_seq_client *client)
297 {
298 struct list_head deleted_list;
299 struct snd_seq_client_port *port, *tmp;
300
301 /* move the port list to deleted_list, and
302 * clear the port list in the client data.
303 */
304 guard(mutex)(&client->ports_mutex);
305 scoped_guard(write_lock_irq, &client->ports_lock) {
306 if (!list_empty(&client->ports_list_head)) {
307 list_add(&deleted_list, &client->ports_list_head);
308 list_del_init(&client->ports_list_head);
309 } else {
310 INIT_LIST_HEAD(&deleted_list);
311 }
312 client->num_ports = 0;
313 }
314
315 /* remove each port in deleted_list */
316 list_for_each_entry_safe(port, tmp, &deleted_list, list) {
317 list_del(&port->list);
318 snd_seq_system_client_ev_port_exit(port->addr.client, port->addr.port);
319 port_delete(client, port);
320 }
321 return 0;
322 }
323
324 /* set port info fields */
snd_seq_set_port_info(struct snd_seq_client_port * port,struct snd_seq_port_info * info)325 int snd_seq_set_port_info(struct snd_seq_client_port * port,
326 struct snd_seq_port_info * info)
327 {
328 if (snd_BUG_ON(!port || !info))
329 return -EINVAL;
330
331 /* set port name */
332 if (info->name[0])
333 strscpy(port->name, info->name, sizeof(port->name));
334
335 /* set capabilities */
336 port->capability = info->capability;
337
338 /* get port type */
339 port->type = info->type;
340
341 /* information about supported channels/voices */
342 port->midi_channels = info->midi_channels;
343 port->midi_voices = info->midi_voices;
344 port->synth_voices = info->synth_voices;
345
346 /* timestamping */
347 port->timestamping = (info->flags & SNDRV_SEQ_PORT_FLG_TIMESTAMP) ? 1 : 0;
348 port->time_real = (info->flags & SNDRV_SEQ_PORT_FLG_TIME_REAL) ? 1 : 0;
349 port->time_queue = info->time_queue;
350
351 /* UMP direction and group */
352 port->direction = info->direction;
353 port->ump_group = info->ump_group;
354 if (port->ump_group > SNDRV_UMP_MAX_GROUPS)
355 port->ump_group = 0;
356
357 /* fill default port direction */
358 if (!port->direction) {
359 if (info->capability & SNDRV_SEQ_PORT_CAP_READ)
360 port->direction |= SNDRV_SEQ_PORT_DIR_INPUT;
361 if (info->capability & SNDRV_SEQ_PORT_CAP_WRITE)
362 port->direction |= SNDRV_SEQ_PORT_DIR_OUTPUT;
363 }
364
365 port->is_midi1 = !!(info->flags & SNDRV_SEQ_PORT_FLG_IS_MIDI1);
366
367 return 0;
368 }
369
370 /* get port info fields */
snd_seq_get_port_info(struct snd_seq_client_port * port,struct snd_seq_port_info * info)371 int snd_seq_get_port_info(struct snd_seq_client_port * port,
372 struct snd_seq_port_info * info)
373 {
374 if (snd_BUG_ON(!port || !info))
375 return -EINVAL;
376
377 /* get port name */
378 strscpy(info->name, port->name, sizeof(info->name));
379
380 /* get capabilities */
381 info->capability = port->capability;
382
383 /* get port type */
384 info->type = port->type;
385
386 /* information about supported channels/voices */
387 info->midi_channels = port->midi_channels;
388 info->midi_voices = port->midi_voices;
389 info->synth_voices = port->synth_voices;
390
391 /* get subscriber counts */
392 info->read_use = port->c_src.count;
393 info->write_use = port->c_dest.count;
394
395 /* timestamping */
396 info->flags = 0;
397 if (port->timestamping) {
398 info->flags |= SNDRV_SEQ_PORT_FLG_TIMESTAMP;
399 if (port->time_real)
400 info->flags |= SNDRV_SEQ_PORT_FLG_TIME_REAL;
401 info->time_queue = port->time_queue;
402 }
403
404 if (port->is_midi1)
405 info->flags |= SNDRV_SEQ_PORT_FLG_IS_MIDI1;
406
407 /* UMP direction and group */
408 info->direction = port->direction;
409 info->ump_group = port->ump_group;
410
411 return 0;
412 }
413
414
415
416 /*
417 * call callback functions (if any):
418 * the callbacks are invoked only when the first (for connection) or
419 * the last subscription (for disconnection) is done. Second or later
420 * subscription results in increment of counter, but no callback is
421 * invoked.
422 * This feature is useful if these callbacks are associated with
423 * initialization or termination of devices (see seq_midi.c).
424 */
425
subscribe_port(struct snd_seq_client * client,struct snd_seq_client_port * port,struct snd_seq_port_subs_info * grp,struct snd_seq_port_subscribe * info,int send_ack)426 static int subscribe_port(struct snd_seq_client *client,
427 struct snd_seq_client_port *port,
428 struct snd_seq_port_subs_info *grp,
429 struct snd_seq_port_subscribe *info,
430 int send_ack)
431 {
432 int err = 0;
433
434 if (!try_module_get(port->owner))
435 return -EFAULT;
436 grp->count++;
437 if (grp->open && grp->count == 1) {
438 err = grp->open(port->private_data, info);
439 if (err < 0) {
440 module_put(port->owner);
441 grp->count--;
442 }
443 }
444 if (err >= 0 && send_ack && client->type == USER_CLIENT)
445 snd_seq_client_notify_subscription(port->addr.client, port->addr.port,
446 info, SNDRV_SEQ_EVENT_PORT_SUBSCRIBED);
447
448 return err;
449 }
450
unsubscribe_port(struct snd_seq_client * client,struct snd_seq_client_port * port,struct snd_seq_port_subs_info * grp,struct snd_seq_port_subscribe * info,int send_ack)451 static int unsubscribe_port(struct snd_seq_client *client,
452 struct snd_seq_client_port *port,
453 struct snd_seq_port_subs_info *grp,
454 struct snd_seq_port_subscribe *info,
455 int send_ack)
456 {
457 int err = 0;
458
459 if (! grp->count)
460 return -EINVAL;
461 grp->count--;
462 if (grp->close && grp->count == 0)
463 err = grp->close(port->private_data, info);
464 if (send_ack && client->type == USER_CLIENT)
465 snd_seq_client_notify_subscription(port->addr.client, port->addr.port,
466 info, SNDRV_SEQ_EVENT_PORT_UNSUBSCRIBED);
467 module_put(port->owner);
468 return err;
469 }
470
471
472
473 /* check if both addresses are identical */
addr_match(struct snd_seq_addr * r,struct snd_seq_addr * s)474 static inline int addr_match(struct snd_seq_addr *r, struct snd_seq_addr *s)
475 {
476 return (r->client == s->client) && (r->port == s->port);
477 }
478
479 /* check the two subscribe info match */
480 /* if flags is zero, checks only sender and destination addresses */
match_subs_info(struct snd_seq_port_subscribe * r,struct snd_seq_port_subscribe * s)481 static int match_subs_info(struct snd_seq_port_subscribe *r,
482 struct snd_seq_port_subscribe *s)
483 {
484 if (addr_match(&r->sender, &s->sender) &&
485 addr_match(&r->dest, &s->dest)) {
486 if (r->flags && r->flags == s->flags)
487 return r->queue == s->queue;
488 else if (! r->flags)
489 return 1;
490 }
491 return 0;
492 }
493
check_and_subscribe_port(struct snd_seq_client * client,struct snd_seq_client_port * port,struct snd_seq_subscribers * subs,bool is_src,bool exclusive,bool ack)494 static int check_and_subscribe_port(struct snd_seq_client *client,
495 struct snd_seq_client_port *port,
496 struct snd_seq_subscribers *subs,
497 bool is_src, bool exclusive, bool ack)
498 {
499 struct snd_seq_port_subs_info *grp;
500 struct list_head *p;
501 struct snd_seq_subscribers *s;
502 int err;
503
504 grp = is_src ? &port->c_src : &port->c_dest;
505 guard(rwsem_write)(&grp->list_mutex);
506 if (exclusive) {
507 if (!list_empty(&grp->list_head))
508 return -EBUSY;
509 } else {
510 if (grp->exclusive)
511 return -EBUSY;
512 /* check whether already exists */
513 list_for_each(p, &grp->list_head) {
514 s = get_subscriber(p, is_src);
515 if (match_subs_info(&subs->info, &s->info))
516 return -EBUSY;
517 }
518 }
519
520 err = subscribe_port(client, port, grp, &subs->info, ack);
521 if (err < 0) {
522 grp->exclusive = 0;
523 return err;
524 }
525
526 /* add to list */
527 guard(write_lock_irq)(&grp->list_lock);
528 if (is_src)
529 list_add_tail(&subs->src_list, &grp->list_head);
530 else
531 list_add_tail(&subs->dest_list, &grp->list_head);
532 grp->exclusive = exclusive;
533 atomic_inc(&subs->ref_count);
534
535 return 0;
536 }
537
538 /* called with grp->list_mutex held */
__delete_and_unsubscribe_port(struct snd_seq_client * client,struct snd_seq_client_port * port,struct snd_seq_subscribers * subs,bool is_src,bool ack)539 static void __delete_and_unsubscribe_port(struct snd_seq_client *client,
540 struct snd_seq_client_port *port,
541 struct snd_seq_subscribers *subs,
542 bool is_src, bool ack)
543 {
544 struct snd_seq_port_subs_info *grp;
545 struct list_head *list;
546 bool empty;
547
548 grp = is_src ? &port->c_src : &port->c_dest;
549 list = is_src ? &subs->src_list : &subs->dest_list;
550 scoped_guard(write_lock_irq, &grp->list_lock) {
551 empty = list_empty(list);
552 if (!empty)
553 list_del_init(list);
554 grp->exclusive = 0;
555 }
556
557 if (!empty)
558 unsubscribe_port(client, port, grp, &subs->info, ack);
559 }
560
delete_and_unsubscribe_port(struct snd_seq_client * client,struct snd_seq_client_port * port,struct snd_seq_subscribers * subs,bool is_src,bool ack)561 static void delete_and_unsubscribe_port(struct snd_seq_client *client,
562 struct snd_seq_client_port *port,
563 struct snd_seq_subscribers *subs,
564 bool is_src, bool ack)
565 {
566 struct snd_seq_port_subs_info *grp;
567
568 grp = is_src ? &port->c_src : &port->c_dest;
569 guard(rwsem_write)(&grp->list_mutex);
570 __delete_and_unsubscribe_port(client, port, subs, is_src, ack);
571 }
572
573 /* connect two ports */
snd_seq_port_connect(struct snd_seq_client * connector,struct snd_seq_client * src_client,struct snd_seq_client_port * src_port,struct snd_seq_client * dest_client,struct snd_seq_client_port * dest_port,struct snd_seq_port_subscribe * info)574 int snd_seq_port_connect(struct snd_seq_client *connector,
575 struct snd_seq_client *src_client,
576 struct snd_seq_client_port *src_port,
577 struct snd_seq_client *dest_client,
578 struct snd_seq_client_port *dest_port,
579 struct snd_seq_port_subscribe *info)
580 {
581 struct snd_seq_subscribers *subs;
582 bool exclusive;
583 int err;
584
585 subs = kzalloc(sizeof(*subs), GFP_KERNEL);
586 if (!subs)
587 return -ENOMEM;
588
589 subs->info = *info;
590 atomic_set(&subs->ref_count, 0);
591 INIT_LIST_HEAD(&subs->src_list);
592 INIT_LIST_HEAD(&subs->dest_list);
593
594 exclusive = !!(info->flags & SNDRV_SEQ_PORT_SUBS_EXCLUSIVE);
595
596 err = check_and_subscribe_port(src_client, src_port, subs, true,
597 exclusive,
598 connector->number != src_client->number);
599 if (err < 0)
600 goto error;
601 err = check_and_subscribe_port(dest_client, dest_port, subs, false,
602 exclusive,
603 connector->number != dest_client->number);
604 if (err < 0)
605 goto error_dest;
606
607 return 0;
608
609 error_dest:
610 delete_and_unsubscribe_port(src_client, src_port, subs, true,
611 connector->number != src_client->number);
612 error:
613 kfree(subs);
614 return err;
615 }
616
617 /* remove the connection */
snd_seq_port_disconnect(struct snd_seq_client * connector,struct snd_seq_client * src_client,struct snd_seq_client_port * src_port,struct snd_seq_client * dest_client,struct snd_seq_client_port * dest_port,struct snd_seq_port_subscribe * info)618 int snd_seq_port_disconnect(struct snd_seq_client *connector,
619 struct snd_seq_client *src_client,
620 struct snd_seq_client_port *src_port,
621 struct snd_seq_client *dest_client,
622 struct snd_seq_client_port *dest_port,
623 struct snd_seq_port_subscribe *info)
624 {
625 struct snd_seq_port_subs_info *dest = &dest_port->c_dest;
626 struct snd_seq_subscribers *subs;
627 int err = -ENOENT;
628
629 /* always start from deleting the dest port for avoiding concurrent
630 * deletions
631 */
632 scoped_guard(rwsem_write, &dest->list_mutex) {
633 /* look for the connection */
634 list_for_each_entry(subs, &dest->list_head, dest_list) {
635 if (match_subs_info(info, &subs->info)) {
636 __delete_and_unsubscribe_port(dest_client, dest_port,
637 subs, false,
638 connector->number != dest_client->number);
639 err = 0;
640 break;
641 }
642 }
643 }
644 if (err < 0)
645 return err;
646
647 delete_and_unsubscribe_port(src_client, src_port, subs, true,
648 connector->number != src_client->number);
649 kfree(subs);
650 return 0;
651 }
652
653
654 /* get matched subscriber */
snd_seq_port_get_subscription(struct snd_seq_port_subs_info * src_grp,struct snd_seq_addr * dest_addr,struct snd_seq_port_subscribe * subs)655 int snd_seq_port_get_subscription(struct snd_seq_port_subs_info *src_grp,
656 struct snd_seq_addr *dest_addr,
657 struct snd_seq_port_subscribe *subs)
658 {
659 struct snd_seq_subscribers *s;
660 int err = -ENOENT;
661
662 guard(rwsem_read)(&src_grp->list_mutex);
663 list_for_each_entry(s, &src_grp->list_head, src_list) {
664 if (addr_match(dest_addr, &s->info.dest)) {
665 *subs = s->info;
666 err = 0;
667 break;
668 }
669 }
670 return err;
671 }
672
673 /*
674 * Attach a device driver that wants to receive events from the
675 * sequencer. Returns the new port number on success.
676 * A driver that wants to receive the events converted to midi, will
677 * use snd_seq_midisynth_register_port().
678 */
679 /* exported */
snd_seq_event_port_attach(int client,struct snd_seq_port_callback * pcbp,int cap,int type,int midi_channels,int midi_voices,char * portname)680 int snd_seq_event_port_attach(int client,
681 struct snd_seq_port_callback *pcbp,
682 int cap, int type, int midi_channels,
683 int midi_voices, char *portname)
684 {
685 struct snd_seq_port_info portinfo;
686 int ret;
687
688 /* Set up the port */
689 memset(&portinfo, 0, sizeof(portinfo));
690 portinfo.addr.client = client;
691 strscpy(portinfo.name, portname ? portname : "Unnamed port",
692 sizeof(portinfo.name));
693
694 portinfo.capability = cap;
695 portinfo.type = type;
696 portinfo.kernel = pcbp;
697 portinfo.midi_channels = midi_channels;
698 portinfo.midi_voices = midi_voices;
699
700 /* Create it */
701 ret = snd_seq_kernel_client_ctl(client,
702 SNDRV_SEQ_IOCTL_CREATE_PORT,
703 &portinfo);
704
705 if (ret >= 0)
706 ret = portinfo.addr.port;
707
708 return ret;
709 }
710 EXPORT_SYMBOL(snd_seq_event_port_attach);
711
712 /*
713 * Detach the driver from a port.
714 */
715 /* exported */
snd_seq_event_port_detach(int client,int port)716 int snd_seq_event_port_detach(int client, int port)
717 {
718 struct snd_seq_port_info portinfo;
719 int err;
720
721 memset(&portinfo, 0, sizeof(portinfo));
722 portinfo.addr.client = client;
723 portinfo.addr.port = port;
724 err = snd_seq_kernel_client_ctl(client,
725 SNDRV_SEQ_IOCTL_DELETE_PORT,
726 &portinfo);
727
728 return err;
729 }
730 EXPORT_SYMBOL(snd_seq_event_port_detach);
731