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) {
 138                 pr_warn("ALSA: seq: 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                 return NULL;    /* failure, out of memory */
 146         /* init port data */
 147         new_port->addr.client = client->number;
 148         new_port->addr.port = -1;
 149         new_port->owner = THIS_MODULE;
 150         sprintf(new_port->name, "port-%d", num);
 151         snd_use_lock_init(&new_port->use_lock);
 152         port_subs_info_init(&new_port->c_src);
 153         port_subs_info_init(&new_port->c_dest);
 154
 155         num = port >= 0 ? port : 0;
 156         mutex_lock(&client->ports_mutex);
 157         write_lock_irqsave(&client->ports_lock, flags);
 158         list_for_each_entry(p, &client->ports_list_head, list) {
 159                 if (p->addr.port > num)
 160                         break;
 161                 if (port < 0) /* auto-probe mode */
 162                         num = p->addr.port + 1;
 163         }
 164         /* insert the new port */
 165         list_add_tail(&new_port->list, &p->list);
 166         client->num_ports++;
 167         new_port->addr.port = num;      /* store the port number in the port */
 168         write_unlock_irqrestore(&client->ports_lock, flags);
 169         mutex_unlock(&client->ports_mutex);
 170         sprintf(new_port->name, "port-%d", num);
 171
 172         return new_port;
 173 }
 174
 175 /* */
 176 static int subscribe_port(struct snd_seq_client *client,
 177                           struct snd_seq_client_port *port,
 178                           struct snd_seq_port_subs_info *grp,
 179                           struct snd_seq_port_subscribe *info, int send_ack);
 180 static int unsubscribe_port(struct snd_seq_client *client,
 181                             struct snd_seq_client_port *port,
 182                             struct snd_seq_port_subs_info *grp,
 183                             struct snd_seq_port_subscribe *info, int send_ack);
 184
 185
 186 static struct snd_seq_client_port *get_client_port(struct snd_seq_addr *addr,
 187                                                    struct snd_seq_client **cp)
 188 {
 189         struct snd_seq_client_port *p;
 190         *cp = snd_seq_client_use_ptr(addr->client);
 191         if (*cp) {
 192                 p = snd_seq_port_use_ptr(*cp, addr->port);
 193                 if (! p) {
 194                         snd_seq_client_unlock(*cp);
 195                         *cp = NULL;
 196                 }
 197                 return p;
 198         }
 199         return NULL;
 200 }
 201
 202 static void delete_and_unsubscribe_port(struct snd_seq_client *client,
 203                                         struct snd_seq_client_port *port,
 204                                         struct snd_seq_subscribers *subs,
 205                                         bool is_src, bool ack);
 206
 207 static inline struct snd_seq_subscribers *
 208 get_subscriber(struct list_head *p, bool is_src)
 209 {
 210         if (is_src)
 211                 return list_entry(p, struct snd_seq_subscribers, src_list);
 212         else
 213                 return list_entry(p, struct snd_seq_subscribers, dest_list);
 214 }
 215
 216 /*
 217  * remove all subscribers on the list
 218  * this is called from port_delete, for each src and dest list.
 219  */
 220 static void clear_subscriber_list(struct snd_seq_client *client,
 221                                   struct snd_seq_client_port *port,
 222                                   struct snd_seq_port_subs_info *grp,
 223                                   int is_src)
 224 {
 225         struct list_head *p, *n;
 226
 227         list_for_each_safe(p, n, &grp->list_head) {
 228                 struct snd_seq_subscribers *subs;
 229                 struct snd_seq_client *c;
 230                 struct snd_seq_client_port *aport;
 231
 232                 subs = get_subscriber(p, is_src);
 233                 if (is_src)
 234                         aport = get_client_port(&subs->info.dest, &c);
 235                 else
 236                         aport = get_client_port(&subs->info.sender, &c);
 237                 delete_and_unsubscribe_port(client, port, subs, is_src, false);
 238
 239                 if (!aport) {
 240                         /* looks like the connected port is being deleted.
 241                          * we decrease the counter, and when both ports are deleted
 242                          * remove the subscriber info
 243                          */
 244                         if (atomic_dec_and_test(&subs->ref_count))
 245                                 kfree(subs);
 246                         continue;
 247                 }
 248
 249                 /* ok we got the connected port */
 250                 delete_and_unsubscribe_port(c, aport, subs, !is_src, true);
 251                 kfree(subs);
 252                 snd_seq_port_unlock(aport);
 253                 snd_seq_client_unlock(c);
 254         }
 255 }
 256
 257 /* delete port data */
 258 static int port_delete(struct snd_seq_client *client,
 259                        struct snd_seq_client_port *port)
 260 {
 261         /* set closing flag and wait for all port access are gone */
 262         port->closing = 1;
 263         snd_use_lock_sync(&port->use_lock);
 264
 265         /* clear subscribers info */
 266         clear_subscriber_list(client, port, &port->c_src, true);
 267         clear_subscriber_list(client, port, &port->c_dest, false);
 268
 269         if (port->private_free)
 270                 port->private_free(port->private_data);
 271
 272         snd_BUG_ON(port->c_src.count != 0);
 273         snd_BUG_ON(port->c_dest.count != 0);
 274
 275         kfree(port);
 276         return 0;
 277 }
 278
 279
 280 /* delete a port with the given port id */
 281 int snd_seq_delete_port(struct snd_seq_client *client, int port)
 282 {
 283         unsigned long flags;
 284         struct snd_seq_client_port *found = NULL, *p;
 285
 286         mutex_lock(&client->ports_mutex);
 287         write_lock_irqsave(&client->ports_lock, flags);
 288         list_for_each_entry(p, &client->ports_list_head, list) {
 289                 if (p->addr.port == port) {
 290                         /* ok found.  delete from the list at first */
 291                         list_del(&p->list);
 292                         client->num_ports--;
 293                         found = p;
 294                         break;
 295                 }
 296         }
 297         write_unlock_irqrestore(&client->ports_lock, flags);
 298         mutex_unlock(&client->ports_mutex);
 299         if (found)
 300                 return port_delete(client, found);
 301         else
 302                 return -ENOENT;
 303 }
 304
 305 /* delete the all ports belonging to the given client */
 306 int snd_seq_delete_all_ports(struct snd_seq_client *client)
 307 {
 308         unsigned long flags;
 309         struct list_head deleted_list;
 310         struct snd_seq_client_port *port, *tmp;
 311
 312         /* move the port list to deleted_list, and
 313          * clear the port list in the client data.
 314          */
 315         mutex_lock(&client->ports_mutex);
 316         write_lock_irqsave(&client->ports_lock, flags);
 317         if (! list_empty(&client->ports_list_head)) {
 318                 list_add(&deleted_list, &client->ports_list_head);
 319                 list_del_init(&client->ports_list_head);
 320         } else {
 321                 INIT_LIST_HEAD(&deleted_list);
 322         }
 323         client->num_ports = 0;
 324         write_unlock_irqrestore(&client->ports_lock, flags);
 325
 326         /* remove each port in deleted_list */
 327         list_for_each_entry_safe(port, tmp, &deleted_list, list) {
 328                 list_del(&port->list);
 329                 snd_seq_system_client_ev_port_exit(port->addr.client, port->addr.port);
 330                 port_delete(client, port);
 331         }
 332         mutex_unlock(&client->ports_mutex);
 333         return 0;
 334 }
 335
 336 /* set port info fields */
 337 int snd_seq_set_port_info(struct snd_seq_client_port * port,
 338                           struct snd_seq_port_info * info)
 339 {
 340         if (snd_BUG_ON(!port || !info))
 341                 return -EINVAL;
 342
 343         /* set port name */
 344         if (info->name[0])
 345                 strlcpy(port->name, info->name, sizeof(port->name));
 346
 347         /* set capabilities */
 348         port->capability = info->capability;
 349
 350         /* get port type */
 351         port->type = info->type;
 352
 353         /* information about supported channels/voices */
 354         port->midi_channels = info->midi_channels;
 355         port->midi_voices = info->midi_voices;
 356         port->synth_voices = info->synth_voices;
 357
 358         /* timestamping */
 359         port->timestamping = (info->flags & SNDRV_SEQ_PORT_FLG_TIMESTAMP) ? 1 : 0;
 360         port->time_real = (info->flags & SNDRV_SEQ_PORT_FLG_TIME_REAL) ? 1 : 0;
 361         port->time_queue = info->time_queue;
 362
 363         return 0;
 364 }
 365
 366 /* get port info fields */
 367 int snd_seq_get_port_info(struct snd_seq_client_port * port,
 368                           struct snd_seq_port_info * info)
 369 {
 370         if (snd_BUG_ON(!port || !info))
 371                 return -EINVAL;
 372
 373         /* get port name */
 374         strlcpy(info->name, port->name, sizeof(info->name));
 375
 376         /* get capabilities */
 377         info->capability = port->capability;
 378
 379         /* get port type */
 380         info->type = port->type;
 381
 382         /* information about supported channels/voices */
 383         info->midi_channels = port->midi_channels;
 384         info->midi_voices = port->midi_voices;
 385         info->synth_voices = port->synth_voices;
 386
 387         /* get subscriber counts */
 388         info->read_use = port->c_src.count;
 389         info->write_use = port->c_dest.count;
 390
 391         /* timestamping */
 392         info->flags = 0;
 393         if (port->timestamping) {
 394                 info->flags |= SNDRV_SEQ_PORT_FLG_TIMESTAMP;
 395                 if (port->time_real)
 396                         info->flags |= SNDRV_SEQ_PORT_FLG_TIME_REAL;
 397                 info->time_queue = port->time_queue;
 398         }
 399
 400         return 0;
 401 }
 402
 403
 404
 405 /*
 406  * call callback functions (if any):
 407  * the callbacks are invoked only when the first (for connection) or
 408  * the last subscription (for disconnection) is done.  Second or later
 409  * subscription results in increment of counter, but no callback is
 410  * invoked.
 411  * This feature is useful if these callbacks are associated with
 412  * initialization or termination of devices (see seq_midi.c).
 413  */
 414
 415 static int subscribe_port(struct snd_seq_client *client,
 416                           struct snd_seq_client_port *port,
 417                           struct snd_seq_port_subs_info *grp,
 418                           struct snd_seq_port_subscribe *info,
 419                           int send_ack)
 420 {
 421         int err = 0;
 422
 423         if (!try_module_get(port->owner))
 424                 return -EFAULT;
 425         grp->count++;
 426         if (grp->open && grp->count == 1) {
 427                 err = grp->open(port->private_data, info);
 428                 if (err < 0) {
 429                         module_put(port->owner);
 430                         grp->count--;
 431                 }
 432         }
 433         if (err >= 0 && send_ack && client->type == USER_CLIENT)
 434                 snd_seq_client_notify_subscription(port->addr.client, port->addr.port,
 435                                                    info, SNDRV_SEQ_EVENT_PORT_SUBSCRIBED);
 436
 437         return err;
 438 }
 439
 440 static int unsubscribe_port(struct snd_seq_client *client,
 441                             struct snd_seq_client_port *port,
 442                             struct snd_seq_port_subs_info *grp,
 443                             struct snd_seq_port_subscribe *info,
 444                             int send_ack)
 445 {
 446         int err = 0;
 447
 448         if (! grp->count)
 449                 return -EINVAL;
 450         grp->count--;
 451         if (grp->close && grp->count == 0)
 452                 err = grp->close(port->private_data, info);
 453         if (send_ack && client->type == USER_CLIENT)
 454                 snd_seq_client_notify_subscription(port->addr.client, port->addr.port,
 455                                                    info, SNDRV_SEQ_EVENT_PORT_UNSUBSCRIBED);
 456         module_put(port->owner);
 457         return err;
 458 }
 459
 460
 461
 462 /* check if both addresses are identical */
 463 static inline int addr_match(struct snd_seq_addr *r, struct snd_seq_addr *s)
 464 {
 465         return (r->client == s->client) && (r->port == s->port);
 466 }
 467
 468 /* check the two subscribe info match */
 469 /* if flags is zero, checks only sender and destination addresses */
 470 static int match_subs_info(struct snd_seq_port_subscribe *r,
 471                            struct snd_seq_port_subscribe *s)
 472 {
 473         if (addr_match(&r->sender, &s->sender) &&
 474             addr_match(&r->dest, &s->dest)) {
 475                 if (r->flags && r->flags == s->flags)
 476                         return r->queue == s->queue;
 477                 else if (! r->flags)
 478                         return 1;
 479         }
 480         return 0;
 481 }
 482
 483 static int check_and_subscribe_port(struct snd_seq_client *client,
 484                                     struct snd_seq_client_port *port,
 485                                     struct snd_seq_subscribers *subs,
 486                                     bool is_src, bool exclusive, bool ack)
 487 {
 488         struct snd_seq_port_subs_info *grp;
 489         struct list_head *p;
 490         struct snd_seq_subscribers *s;
 491         int err;
 492
 493         grp = is_src ? &port->c_src : &port->c_dest;
 494         err = -EBUSY;
 495         down_write(&grp->list_mutex);
 496         if (exclusive) {
 497                 if (!list_empty(&grp->list_head))
 498                         goto __error;
 499         } else {
 500                 if (grp->exclusive)
 501                         goto __error;
 502                 /* check whether already exists */
 503                 list_for_each(p, &grp->list_head) {
 504                         s = get_subscriber(p, is_src);
 505                         if (match_subs_info(&subs->info, &s->info))
 506                                 goto __error;
 507                 }
 508         }
 509
 510         err = subscribe_port(client, port, grp, &subs->info, ack);
 511         if (err < 0) {
 512                 grp->exclusive = 0;
 513                 goto __error;
 514         }
 515
 516         /* add to list */
 517         write_lock_irq(&grp->list_lock);
 518         if (is_src)
 519                 list_add_tail(&subs->src_list, &grp->list_head);
 520         else
 521                 list_add_tail(&subs->dest_list, &grp->list_head);
 522         grp->exclusive = exclusive;
 523         atomic_inc(&subs->ref_count);
 524         write_unlock_irq(&grp->list_lock);
 525         err = 0;
 526
 527  __error:
 528         up_write(&grp->list_mutex);
 529         return err;
 530 }
 531
 532 static void delete_and_unsubscribe_port(struct snd_seq_client *client,
 533                                         struct snd_seq_client_port *port,
 534                                         struct snd_seq_subscribers *subs,
 535                                         bool is_src, bool ack)
 536 {
 537         struct snd_seq_port_subs_info *grp;
 538         struct list_head *list;
 539         bool empty;
 540
 541         grp = is_src ? &port->c_src : &port->c_dest;
 542         list = is_src ? &subs->src_list : &subs->dest_list;
 543         down_write(&grp->list_mutex);
 544         write_lock_irq(&grp->list_lock);
 545         empty = list_empty(list);
 546         if (!empty)
 547                 list_del_init(list);
 548         grp->exclusive = 0;
 549         write_unlock_irq(&grp->list_lock);
 550         up_write(&grp->list_mutex);
 551
 552         if (!empty)
 553                 unsubscribe_port(client, port, grp, &subs->info, ack);
 554 }
 555
 556 /* connect two ports */
 557 int snd_seq_port_connect(struct snd_seq_client *connector,
 558                          struct snd_seq_client *src_client,
 559                          struct snd_seq_client_port *src_port,
 560                          struct snd_seq_client *dest_client,
 561                          struct snd_seq_client_port *dest_port,
 562                          struct snd_seq_port_subscribe *info)
 563 {
 564         struct snd_seq_subscribers *subs;
 565         bool exclusive;
 566         int err;
 567
 568         subs = kzalloc(sizeof(*subs), GFP_KERNEL);
 569         if (!subs)
 570                 return -ENOMEM;
 571
 572         subs->info = *info;
 573         atomic_set(&subs->ref_count, 0);
 574         INIT_LIST_HEAD(&subs->src_list);
 575         INIT_LIST_HEAD(&subs->dest_list);
 576
 577         exclusive = !!(info->flags & SNDRV_SEQ_PORT_SUBS_EXCLUSIVE);
 578
 579         err = check_and_subscribe_port(src_client, src_port, subs, true,
 580                                        exclusive,
 581                                        connector->number != src_client->number);
 582         if (err < 0)
 583                 goto error;
 584         err = check_and_subscribe_port(dest_client, dest_port, subs, false,
 585                                        exclusive,
 586                                        connector->number != dest_client->number);
 587         if (err < 0)
 588                 goto error_dest;
 589
 590         return 0;
 591
 592  error_dest:
 593         delete_and_unsubscribe_port(src_client, src_port, subs, true,
 594                                     connector->number != src_client->number);
 595  error:
 596         kfree(subs);
 597         return err;
 598 }
 599
 600 /* remove the connection */
 601 int snd_seq_port_disconnect(struct snd_seq_client *connector,
 602                             struct snd_seq_client *src_client,
 603                             struct snd_seq_client_port *src_port,
 604                             struct snd_seq_client *dest_client,
 605                             struct snd_seq_client_port *dest_port,
 606                             struct snd_seq_port_subscribe *info)
 607 {
 608         struct snd_seq_port_subs_info *src = &src_port->c_src;
 609         struct snd_seq_subscribers *subs;
 610         int err = -ENOENT;
 611
 612         down_write(&src->list_mutex);
 613         /* look for the connection */
 614         list_for_each_entry(subs, &src->list_head, src_list) {
 615                 if (match_subs_info(info, &subs->info)) {
 616                         atomic_dec(&subs->ref_count); /* mark as not ready */
 617                         err = 0;
 618                         break;
 619                 }
 620         }
 621         up_write(&src->list_mutex);
 622         if (err < 0)
 623                 return err;
 624
 625         delete_and_unsubscribe_port(src_client, src_port, subs, true,
 626                                     connector->number != src_client->number);
 627         delete_and_unsubscribe_port(dest_client, dest_port, subs, false,
 628                                     connector->number != dest_client->number);
 629         kfree(subs);
 630         return 0;
 631 }
 632
 633
 634 /* get matched subscriber */
 635 struct snd_seq_subscribers *snd_seq_port_get_subscription(struct snd_seq_port_subs_info *src_grp,
 636                                                           struct snd_seq_addr *dest_addr)
 637 {
 638         struct snd_seq_subscribers *s, *found = NULL;
 639
 640         down_read(&src_grp->list_mutex);
 641         list_for_each_entry(s, &src_grp->list_head, src_list) {
 642                 if (addr_match(dest_addr, &s->info.dest)) {
 643                         found = s;
 644                         break;
 645                 }
 646         }
 647         up_read(&src_grp->list_mutex);
 648         return found;
 649 }
 650
 651 /*
 652  * Attach a device driver that wants to receive events from the
 653  * sequencer.  Returns the new port number on success.
 654  * A driver that wants to receive the events converted to midi, will
 655  * use snd_seq_midisynth_register_port().
 656  */
 657 /* exported */
 658 int snd_seq_event_port_attach(int client,
 659                               struct snd_seq_port_callback *pcbp,
 660                               int cap, int type, int midi_channels,
 661                               int midi_voices, char *portname)
 662 {
 663         struct snd_seq_port_info portinfo;
 664         int  ret;
 665
 666         /* Set up the port */
 667         memset(&portinfo, 0, sizeof(portinfo));
 668         portinfo.addr.client = client;
 669         strlcpy(portinfo.name, portname ? portname : "Unamed port",
 670                 sizeof(portinfo.name));
 671
 672         portinfo.capability = cap;
 673         portinfo.type = type;
 674         portinfo.kernel = pcbp;
 675         portinfo.midi_channels = midi_channels;
 676         portinfo.midi_voices = midi_voices;
 677
 678         /* Create it */
 679         ret = snd_seq_kernel_client_ctl(client,
 680                                         SNDRV_SEQ_IOCTL_CREATE_PORT,
 681                                         &portinfo);
 682
 683         if (ret >= 0)
 684                 ret = portinfo.addr.port;
 685
 686         return ret;
 687 }
 688 EXPORT_SYMBOL(snd_seq_event_port_attach);
 689
 690 /*
 691  * Detach the driver from a port.
 692  */
 693 /* exported */
 694 int snd_seq_event_port_detach(int client, int port)
 695 {
 696         struct snd_seq_port_info portinfo;
 697         int  err;
 698
 699         memset(&portinfo, 0, sizeof(portinfo));
 700         portinfo.addr.client = client;
 701         portinfo.addr.port   = port;
 702         err = snd_seq_kernel_client_ctl(client,
 703                                         SNDRV_SEQ_IOCTL_DELETE_PORT,
 704                                         &portinfo);
 705
 706         return err;
 707 }
 708 EXPORT_SYMBOL(snd_seq_event_port_detach);