sound/core/seq/seq_ports.c

   1 /*
   2  *   ALSA sequencer Ports
   3  *   Copyright (c) 1998 by Frank van de Pol <fvdpol@coil.demon.nl>
   4  *                         Jaroslav Kysela <perex@perex.cz>
   5  *
   6  *
   7  *   This program is free software; you can redistribute it and/or modify
   8  *   it under the terms of the GNU General Public License as published by
   9  *   the Free Software Foundation; either version 2 of the License, or
  10  *   (at your option) any later version.
  11  *
  12  *   This program is distributed in the hope that it will be useful,
  13  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  *   GNU General Public License for more details.
  16  *
  17  *   You should have received a copy of the GNU General Public License
  18  *   along with this program; if not, write to the Free Software
  19  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  20  *
  21  */
  22
  23 #include <sound/core.h>
  24 #include <linux/slab.h>
  25 #include <linux/module.h>
  26 #include "seq_system.h"
  27 #include "seq_ports.h"
  28 #include "seq_clientmgr.h"
  29
  30 /*
  31
  32    registration of client ports
  33
  34  */
  35
  36
  37 /*
  38
  39 NOTE: the current implementation of the port structure as a linked list is
  40 not optimal for clients that have many ports. For sending messages to all
  41 subscribers of a port we first need to find the address of the port
  42 structure, which means we have to traverse the list. A direct access table
  43 (array) would be better, but big preallocated arrays waste memory.
  44
  45 Possible actions:
  46
  47 1) leave it this way, a client does normaly does not have more than a few
  48 ports
  49
  50 2) replace the linked list of ports by a array of pointers which is
  51 dynamicly kmalloced. When a port is added or deleted we can simply allocate
  52 a new array, copy the corresponding pointers, and delete the old one. We
  53 then only need a pointer to this array, and an integer that tells us how
  54 much elements are in array.
  55
  56 */
  57
  58 /* return pointer to port structure - port is locked if found */
  59 struct snd_seq_client_port *snd_seq_port_use_ptr(struct snd_seq_client *client,
  60                                                  int num)
  61 {
  62         struct snd_seq_client_port *port;
  63
  64         if (client == NULL)
  65                 return NULL;
  66         read_lock(&client->ports_lock);
  67         list_for_each_entry(port, &client->ports_list_head, list) {
  68                 if (port->addr.port == num) {
  69                         if (port->closing)
  70                                 break; /* deleting now */
  71                         snd_use_lock_use(&port->use_lock);
  72                         read_unlock(&client->ports_lock);
  73                         return port;
  74                 }
  75         }
  76         read_unlock(&client->ports_lock);
  77         return NULL;            /* not found */
  78 }
  79
  80
  81 /* search for the next port - port is locked if found */
  82 struct snd_seq_client_port *snd_seq_port_query_nearest(struct snd_seq_client *client,
  83                                                        struct snd_seq_port_info *pinfo)
  84 {
  85         int num;
  86         struct snd_seq_client_port *port, *found;
  87
  88         num = pinfo->addr.port;
  89         found = NULL;
  90         read_lock(&client->ports_lock);
  91         list_for_each_entry(port, &client->ports_list_head, list) {
  92                 if (port->addr.port < num)
  93                         continue;
  94                 if (port->addr.port == num) {
  95                         found = port;
  96                         break;
  97                 }
  98                 if (found == NULL || port->addr.port < found->addr.port)
  99                         found = port;
 100         }
 101         if (found) {
 102                 if (found->closing)
 103                         found = NULL;
 104                 else
 105                         snd_use_lock_use(&found->use_lock);
 106         }
 107         read_unlock(&client->ports_lock);
 108         return found;
 109 }
 110
 111
 112 /* initialize snd_seq_port_subs_info */
 113 static void port_subs_info_init(struct snd_seq_port_subs_info *grp)
 114 {
 115         INIT_LIST_HEAD(&grp->list_head);
 116         grp->count = 0;
 117         grp->exclusive = 0;
 118         rwlock_init(&grp->list_lock);
 119         init_rwsem(&grp->list_mutex);
 120         grp->open = NULL;
 121         grp->close = NULL;
 122 }
 123
 124
 125 /* create a port, port number is returned (-1 on failure) */
 126 struct snd_seq_client_port *snd_seq_create_port(struct snd_seq_client *client,
 127                                                 int port)
 128 {
 129         unsigned long flags;
 130         struct snd_seq_client_port *new_port, *p;
 131         int num = -1;
 132
 133         /* sanity check */
 134         if (snd_BUG_ON(!client))
 135                 return NULL;
 136
 137         if (client->num_ports >= SNDRV_SEQ_MAX_PORTS - 1) {
 138                 snd_printk(KERN_WARNING "too many ports for client %d\n", client->number);
 139                 return NULL;
 140         }
 141
 142         /* create a new port */
 143         new_port = kzalloc(sizeof(*new_port), GFP_KERNEL);
 144         if (! new_port) {
 145                 snd_printd("malloc failed for registering client port\n");
 146                 return NULL;    /* failure, out of memory */
 147         }
 148         /* init port data */
 149         new_port->addr.client = client->number;
 150         new_port->addr.port = -1;
 151         new_port->owner = THIS_MODULE;
 152         sprintf(new_port->name, "port-%d", num);
 153         snd_use_lock_init(&new_port->use_lock);
 154         port_subs_info_init(&new_port->c_src);
 155         port_subs_info_init(&new_port->c_dest);
 156
 157         num = port >= 0 ? port : 0;
 158         mutex_lock(&client->ports_mutex);
 159         write_lock_irqsave(&client->ports_lock, flags);
 160         list_for_each_entry(p, &client->ports_list_head, list) {
 161                 if (p->addr.port > num)
 162                         break;
 163                 if (port < 0) /* auto-probe mode */
 164                         num = p->addr.port + 1;
 165         }
 166         /* insert the new port */
 167         list_add_tail(&new_port->list, &p->list);
 168         client->num_ports++;
 169         new_port->addr.port = num;      /* store the port number in the port */
 170         write_unlock_irqrestore(&client->ports_lock, flags);
 171         mutex_unlock(&client->ports_mutex);
 172         sprintf(new_port->name, "port-%d", num);
 173
 174         return new_port;
 175 }
 176
 177 /* */
 178 static int subscribe_port(struct snd_seq_client *client,
 179                           struct snd_seq_client_port *port,
 180                           struct snd_seq_port_subs_info *grp,
 181                           struct snd_seq_port_subscribe *info, int send_ack);
 182 static int unsubscribe_port(struct snd_seq_client *client,
 183                             struct snd_seq_client_port *port,
 184                             struct snd_seq_port_subs_info *grp,
 185                             struct snd_seq_port_subscribe *info, int send_ack);
 186
 187
 188 static struct snd_seq_client_port *get_client_port(struct snd_seq_addr *addr,
 189                                                    struct snd_seq_client **cp)
 190 {
 191         struct snd_seq_client_port *p;
 192         *cp = snd_seq_client_use_ptr(addr->client);
 193         if (*cp) {
 194                 p = snd_seq_port_use_ptr(*cp, addr->port);
 195                 if (! p) {
 196                         snd_seq_client_unlock(*cp);
 197                         *cp = NULL;
 198                 }
 199                 return p;
 200         }
 201         return NULL;
 202 }
 203
 204 static void delete_and_unsubscribe_port(struct snd_seq_client *client,
 205                                         struct snd_seq_client_port *port,
 206                                         struct snd_seq_subscribers *subs,
 207                                         bool is_src, bool ack);
 208
 209 static inline struct snd_seq_subscribers *
 210 get_subscriber(struct list_head *p, bool is_src)
 211 {
 212         if (is_src)
 213                 return list_entry(p, struct snd_seq_subscribers, src_list);
 214         else
 215                 return list_entry(p, struct snd_seq_subscribers, dest_list);
 216 }
 217
 218 /*
 219  * remove all subscribers on the list
 220  * this is called from port_delete, for each src and dest list.
 221  */
 222 static void clear_subscriber_list(struct snd_seq_client *client,
 223                                   struct snd_seq_client_port *port,
 224                                   struct snd_seq_port_subs_info *grp,
 225                                   int is_src)
 226 {
 227         struct list_head *p, *n;
 228
 229         list_for_each_safe(p, n, &grp->list_head) {
 230                 struct snd_seq_subscribers *subs;
 231                 struct snd_seq_client *c;
 232                 struct snd_seq_client_port *aport;
 233
 234                 subs = get_subscriber(p, is_src);
 235                 if (is_src)
 236                         aport = get_client_port(&subs->info.dest, &c);
 237                 else
 238                         aport = get_client_port(&subs->info.sender, &c);
 239                 delete_and_unsubscribe_port(client, port, subs, is_src, false);
 240
 241                 if (!aport) {
 242                         /* looks like the connected port is being deleted.
 243                          * we decrease the counter, and when both ports are deleted
 244                          * remove the subscriber info
 245                          */
 246                         if (atomic_dec_and_test(&subs->ref_count))
 247                                 kfree(subs);
 248                         continue;
 249                 }
 250
 251                 /* ok we got the connected port */
 252                 delete_and_unsubscribe_port(c, aport, subs, !is_src, true);
 253                 kfree(subs);
 254                 snd_seq_port_unlock(aport);
 255                 snd_seq_client_unlock(c);
 256         }
 257 }
 258
 259 /* delete port data */
 260 static int port_delete(struct snd_seq_client *client,
 261                        struct snd_seq_client_port *port)
 262 {
 263         /* set closing flag and wait for all port access are gone */
 264         port->closing = 1;
 265         snd_use_lock_sync(&port->use_lock);
 266
 267         /* clear subscribers info */
 268         clear_subscriber_list(client, port, &port->c_src, true);
 269         clear_subscriber_list(client, port, &port->c_dest, false);
 270
 271         if (port->private_free)
 272                 port->private_free(port->private_data);
 273
 274         snd_BUG_ON(port->c_src.count != 0);
 275         snd_BUG_ON(port->c_dest.count != 0);
 276
 277         kfree(port);
 278         return 0;
 279 }
 280
 281
 282 /* delete a port with the given port id */
 283 int snd_seq_delete_port(struct snd_seq_client *client, int port)
 284 {
 285         unsigned long flags;
 286         struct snd_seq_client_port *found = NULL, *p;
 287
 288         mutex_lock(&client->ports_mutex);
 289         write_lock_irqsave(&client->ports_lock, flags);
 290         list_for_each_entry(p, &client->ports_list_head, list) {
 291                 if (p->addr.port == port) {
 292                         /* ok found.  delete from the list at first */
 293                         list_del(&p->list);
 294                         client->num_ports--;
 295                         found = p;
 296                         break;
 297                 }
 298         }
 299         write_unlock_irqrestore(&client->ports_lock, flags);
 300         mutex_unlock(&client->ports_mutex);
 301         if (found)
 302                 return port_delete(client, found);
 303         else
 304                 return -ENOENT;
 305 }
 306
 307 /* delete the all ports belonging to the given client */
 308 int snd_seq_delete_all_ports(struct snd_seq_client *client)
 309 {
 310         unsigned long flags;
 311         struct list_head deleted_list;
 312         struct snd_seq_client_port *port, *tmp;
 313
 314         /* move the port list to deleted_list, and
 315          * clear the port list in the client data.
 316          */
 317         mutex_lock(&client->ports_mutex);
 318         write_lock_irqsave(&client->ports_lock, flags);
 319         if (! list_empty(&client->ports_list_head)) {
 320                 list_add(&deleted_list, &client->ports_list_head);
 321                 list_del_init(&client->ports_list_head);
 322         } else {
 323                 INIT_LIST_HEAD(&deleted_list);
 324         }
 325         client->num_ports = 0;
 326         write_unlock_irqrestore(&client->ports_lock, flags);
 327
 328         /* remove each port in deleted_list */
 329         list_for_each_entry_safe(port, tmp, &deleted_list, list) {
 330                 list_del(&port->list);
 331                 snd_seq_system_client_ev_port_exit(port->addr.client, port->addr.port);
 332                 port_delete(client, port);
 333         }
 334         mutex_unlock(&client->ports_mutex);
 335         return 0;
 336 }
 337
 338 /* set port info fields */
 339 int snd_seq_set_port_info(struct snd_seq_client_port * port,
 340                           struct snd_seq_port_info * info)
 341 {
 342         if (snd_BUG_ON(!port || !info))
 343                 return -EINVAL;
 344
 345         /* set port name */
 346         if (info->name[0])
 347                 strlcpy(port->name, info->name, sizeof(port->name));
 348
 349         /* set capabilities */
 350         port->capability = info->capability;
 351
 352         /* get port type */
 353         port->type = info->type;
 354
 355         /* information about supported channels/voices */
 356         port->midi_channels = info->midi_channels;
 357         port->midi_voices = info->midi_voices;
 358         port->synth_voices = info->synth_voices;
 359
 360         /* timestamping */
 361         port->timestamping = (info->flags & SNDRV_SEQ_PORT_FLG_TIMESTAMP) ? 1 : 0;
 362         port->time_real = (info->flags & SNDRV_SEQ_PORT_FLG_TIME_REAL) ? 1 : 0;
 363         port->time_queue = info->time_queue;
 364
 365         return 0;
 366 }
 367
 368 /* get port info fields */
 369 int snd_seq_get_port_info(struct snd_seq_client_port * port,
 370                           struct snd_seq_port_info * info)
 371 {
 372         if (snd_BUG_ON(!port || !info))
 373                 return -EINVAL;
 374
 375         /* get port name */
 376         strlcpy(info->name, port->name, sizeof(info->name));
 377
 378         /* get capabilities */
 379         info->capability = port->capability;
 380
 381         /* get port type */
 382         info->type = port->type;
 383
 384         /* information about supported channels/voices */
 385         info->midi_channels = port->midi_channels;
 386         info->midi_voices = port->midi_voices;
 387         info->synth_voices = port->synth_voices;
 388
 389         /* get subscriber counts */
 390         info->read_use = port->c_src.count;
 391         info->write_use = port->c_dest.count;
 392
 393         /* timestamping */
 394         info->flags = 0;
 395         if (port->timestamping) {
 396                 info->flags |= SNDRV_SEQ_PORT_FLG_TIMESTAMP;
 397                 if (port->time_real)
 398                         info->flags |= SNDRV_SEQ_PORT_FLG_TIME_REAL;
 399                 info->time_queue = port->time_queue;
 400         }
 401
 402         return 0;
 403 }
 404
 405
 406
 407 /*
 408  * call callback functions (if any):
 409  * the callbacks are invoked only when the first (for connection) or
 410  * the last subscription (for disconnection) is done.  Second or later
 411  * subscription results in increment of counter, but no callback is
 412  * invoked.
 413  * This feature is useful if these callbacks are associated with
 414  * initialization or termination of devices (see seq_midi.c).
 415  *
 416  * If callback_all option is set, the callback function is invoked
 417  * at each connection/disconnection.
 418  */
 419
 420 static int subscribe_port(struct snd_seq_client *client,
 421                           struct snd_seq_client_port *port,
 422                           struct snd_seq_port_subs_info *grp,
 423                           struct snd_seq_port_subscribe *info,
 424                           int send_ack)
 425 {
 426         int err = 0;
 427
 428         if (!try_module_get(port->owner))
 429                 return -EFAULT;
 430         grp->count++;
 431         if (grp->open && (port->callback_all || grp->count == 1)) {
 432                 err = grp->open(port->private_data, info);
 433                 if (err < 0) {
 434                         module_put(port->owner);
 435                         grp->count--;
 436                 }
 437         }
 438         if (err >= 0 && send_ack && client->type == USER_CLIENT)
 439                 snd_seq_client_notify_subscription(port->addr.client, port->addr.port,
 440                                                    info, SNDRV_SEQ_EVENT_PORT_SUBSCRIBED);
 441
 442         return err;
 443 }
 444
 445 static int unsubscribe_port(struct snd_seq_client *client,
 446                             struct snd_seq_client_port *port,
 447                             struct snd_seq_port_subs_info *grp,
 448                             struct snd_seq_port_subscribe *info,
 449                             int send_ack)
 450 {
 451         int err = 0;
 452
 453         if (! grp->count)
 454                 return -EINVAL;
 455         grp->count--;
 456         if (grp->close && (port->callback_all || grp->count == 0))
 457                 err = grp->close(port->private_data, info);
 458         if (send_ack && client->type == USER_CLIENT)
 459                 snd_seq_client_notify_subscription(port->addr.client, port->addr.port,
 460                                                    info, SNDRV_SEQ_EVENT_PORT_UNSUBSCRIBED);
 461         module_put(port->owner);
 462         return err;
 463 }
 464
 465
 466
 467 /* check if both addresses are identical */
 468 static inline int addr_match(struct snd_seq_addr *r, struct snd_seq_addr *s)
 469 {
 470         return (r->client == s->client) && (r->port == s->port);
 471 }
 472
 473 /* check the two subscribe info match */
 474 /* if flags is zero, checks only sender and destination addresses */
 475 static int match_subs_info(struct snd_seq_port_subscribe *r,
 476                            struct snd_seq_port_subscribe *s)
 477 {
 478         if (addr_match(&r->sender, &s->sender) &&
 479             addr_match(&r->dest, &s->dest)) {
 480                 if (r->flags && r->flags == s->flags)
 481                         return r->queue == s->queue;
 482                 else if (! r->flags)
 483                         return 1;
 484         }
 485         return 0;
 486 }
 487
 488 static int check_and_subscribe_port(struct snd_seq_client *client,
 489                                     struct snd_seq_client_port *port,
 490                                     struct snd_seq_subscribers *subs,
 491                                     bool is_src, bool exclusive, bool ack)
 492 {
 493         struct snd_seq_port_subs_info *grp;
 494         struct list_head *p;
 495         struct snd_seq_subscribers *s;
 496         int err;
 497
 498         grp = is_src ? &port->c_src : &port->c_dest;
 499         err = -EBUSY;
 500         down_write(&grp->list_mutex);
 501         if (exclusive) {
 502                 if (!list_empty(&grp->list_head))
 503                         goto __error;
 504         } else {
 505                 if (grp->exclusive)
 506                         goto __error;
 507                 /* check whether already exists */
 508                 list_for_each(p, &grp->list_head) {
 509                         s = get_subscriber(p, is_src);
 510                         if (match_subs_info(&subs->info, &s->info))
 511                                 goto __error;
 512                 }
 513         }
 514
 515         err = subscribe_port(client, port, grp, &subs->info, ack);
 516         if (err < 0) {
 517                 grp->exclusive = 0;
 518                 goto __error;
 519         }
 520
 521         /* add to list */
 522         write_lock_irq(&grp->list_lock);
 523         if (is_src)
 524                 list_add_tail(&subs->src_list, &grp->list_head);
 525         else
 526                 list_add_tail(&subs->dest_list, &grp->list_head);
 527         grp->exclusive = exclusive;
 528         atomic_inc(&subs->ref_count);
 529         write_unlock_irq(&grp->list_lock);
 530         err = 0;
 531
 532  __error:
 533         up_write(&grp->list_mutex);
 534         return err;
 535 }
 536
 537 static void delete_and_unsubscribe_port(struct snd_seq_client *client,
 538                                         struct snd_seq_client_port *port,
 539                                         struct snd_seq_subscribers *subs,
 540                                         bool is_src, bool ack)
 541 {
 542         struct snd_seq_port_subs_info *grp;
 543
 544         grp = is_src ? &port->c_src : &port->c_dest;
 545         down_write(&grp->list_mutex);
 546         write_lock_irq(&grp->list_lock);
 547         if (is_src)
 548                 list_del(&subs->src_list);
 549         else
 550                 list_del(&subs->dest_list);
 551         grp->exclusive = 0;
 552         write_unlock_irq(&grp->list_lock);
 553         up_write(&grp->list_mutex);
 554
 555         unsubscribe_port(client, port, grp, &subs->info, ack);
 556 }
 557
 558 /* connect two ports */
 559 int snd_seq_port_connect(struct snd_seq_client *connector,
 560                          struct snd_seq_client *src_client,
 561                          struct snd_seq_client_port *src_port,
 562                          struct snd_seq_client *dest_client,
 563                          struct snd_seq_client_port *dest_port,
 564                          struct snd_seq_port_subscribe *info)
 565 {
 566         struct snd_seq_subscribers *subs;
 567         bool exclusive;
 568         int err;
 569
 570         subs = kzalloc(sizeof(*subs), GFP_KERNEL);
 571         if (!subs)
 572                 return -ENOMEM;
 573
 574         subs->info = *info;
 575         atomic_set(&subs->ref_count, 0);
 576         INIT_LIST_HEAD(&subs->src_list);
 577         INIT_LIST_HEAD(&subs->dest_list);
 578
 579         exclusive = !!(info->flags & SNDRV_SEQ_PORT_SUBS_EXCLUSIVE);
 580
 581         err = check_and_subscribe_port(src_client, src_port, subs, true,
 582                                        exclusive,
 583                                        connector->number != src_client->number);
 584         if (err < 0)
 585                 goto error;
 586         err = check_and_subscribe_port(dest_client, dest_port, subs, false,
 587                                        exclusive,
 588                                        connector->number != dest_client->number);
 589         if (err < 0)
 590                 goto error_dest;
 591
 592         return 0;
 593
 594  error_dest:
 595         delete_and_unsubscribe_port(src_client, src_port, subs, true,
 596                                     connector->number != src_client->number);
 597  error:
 598         kfree(subs);
 599         return err;
 600 }
 601
 602 /* remove the connection */
 603 int snd_seq_port_disconnect(struct snd_seq_client *connector,
 604                             struct snd_seq_client *src_client,
 605                             struct snd_seq_client_port *src_port,
 606                             struct snd_seq_client *dest_client,
 607                             struct snd_seq_client_port *dest_port,
 608                             struct snd_seq_port_subscribe *info)
 609 {
 610         struct snd_seq_port_subs_info *src = &src_port->c_src;
 611         struct snd_seq_subscribers *subs;
 612         int err = -ENOENT;
 613
 614         down_write(&src->list_mutex);
 615         /* look for the connection */
 616         list_for_each_entry(subs, &src->list_head, src_list) {
 617                 if (match_subs_info(info, &subs->info)) {
 618                         atomic_dec(&subs->ref_count); /* mark as not ready */
 619                         err = 0;
 620                         break;
 621                 }
 622         }
 623         up_write(&src->list_mutex);
 624         if (err < 0)
 625                 return err;
 626
 627         delete_and_unsubscribe_port(src_client, src_port, subs, true,
 628                                     connector->number != src_client->number);
 629         delete_and_unsubscribe_port(dest_client, dest_port, subs, false,
 630                                     connector->number != dest_client->number);
 631         kfree(subs);
 632         return 0;
 633 }
 634
 635
 636 /* get matched subscriber */
 637 struct snd_seq_subscribers *snd_seq_port_get_subscription(struct snd_seq_port_subs_info *src_grp,
 638                                                           struct snd_seq_addr *dest_addr)
 639 {
 640         struct snd_seq_subscribers *s, *found = NULL;
 641
 642         down_read(&src_grp->list_mutex);
 643         list_for_each_entry(s, &src_grp->list_head, src_list) {
 644                 if (addr_match(dest_addr, &s->info.dest)) {
 645                         found = s;
 646                         break;
 647                 }
 648         }
 649         up_read(&src_grp->list_mutex);
 650         return found;
 651 }
 652
 653 /*
 654  * Attach a device driver that wants to receive events from the
 655  * sequencer.  Returns the new port number on success.
 656  * A driver that wants to receive the events converted to midi, will
 657  * use snd_seq_midisynth_register_port().
 658  */
 659 /* exported */
 660 int snd_seq_event_port_attach(int client,
 661                               struct snd_seq_port_callback *pcbp,
 662                               int cap, int type, int midi_channels,
 663                               int midi_voices, char *portname)
 664 {
 665         struct snd_seq_port_info portinfo;
 666         int  ret;
 667
 668         /* Set up the port */
 669         memset(&portinfo, 0, sizeof(portinfo));
 670         portinfo.addr.client = client;
 671         strlcpy(portinfo.name, portname ? portname : "Unamed port",
 672                 sizeof(portinfo.name));
 673
 674         portinfo.capability = cap;
 675         portinfo.type = type;
 676         portinfo.kernel = pcbp;
 677         portinfo.midi_channels = midi_channels;
 678         portinfo.midi_voices = midi_voices;
 679
 680         /* Create it */
 681         ret = snd_seq_kernel_client_ctl(client,
 682                                         SNDRV_SEQ_IOCTL_CREATE_PORT,
 683                                         &portinfo);
 684
 685         if (ret >= 0)
 686                 ret = portinfo.addr.port;
 687
 688         return ret;
 689 }
 690
 691 EXPORT_SYMBOL(snd_seq_event_port_attach);
 692
 693 /*
 694  * Detach the driver from a port.
 695  */
 696 /* exported */
 697 int snd_seq_event_port_detach(int client, int port)
 698 {
 699         struct snd_seq_port_info portinfo;
 700         int  err;
 701
 702         memset(&portinfo, 0, sizeof(portinfo));
 703         portinfo.addr.client = client;
 704         portinfo.addr.port   = port;
 705         err = snd_seq_kernel_client_ctl(client,
 706                                         SNDRV_SEQ_IOCTL_DELETE_PORT,
 707                                         &portinfo);
 708
 709         return err;
 710 }
 711
 712 EXPORT_SYMBOL(snd_seq_event_port_detach);