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