git.oblomov.eu Git - linux-2.6/blob - 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         down(&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         up(&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         down_write(&grp->list_mutex);
 225         list_for_each_safe(p, n, &grp->list_head) {
 226                 struct snd_seq_subscribers *subs;
 227                 struct snd_seq_client *c;
 228                 struct snd_seq_client_port *aport;
 229
 230                 if (grptype == SRC_LIST) {
 231                         subs = list_entry(p, struct snd_seq_subscribers, src_list);
 232                         aport = get_client_port(&subs->info.dest, &c);
 233                 } else {
 234                         subs = list_entry(p, struct snd_seq_subscribers, dest_list);
 235                         aport = get_client_port(&subs->info.sender, &c);
 236                 }
 237                 list_del(p);
 238                 unsubscribe_port(client, port, grp, &subs->info, 0);
 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                 } else {
 247                         /* ok we got the connected port */
 248                         struct snd_seq_port_subs_info *agrp;
 249                         agrp = (grptype == SRC_LIST) ? &aport->c_dest : &aport->c_src;
 250                         down_write(&agrp->list_mutex);
 251                         if (grptype == SRC_LIST)
 252                                 list_del(&subs->dest_list);
 253                         else
 254                                 list_del(&subs->src_list);
 255                         unsubscribe_port(c, aport, agrp, &subs->info, 1);
 256                         kfree(subs);
 257                         up_write(&agrp->list_mutex);
 258                         snd_seq_port_unlock(aport);
 259                         snd_seq_client_unlock(c);
 260                 }
 261         }
 262         up_write(&grp->list_mutex);
 263 }
 264
 265 /* delete port data */
 266 static int port_delete(struct snd_seq_client *client,
 267                        struct snd_seq_client_port *port)
 268 {
 269         /* set closing flag and wait for all port access are gone */
 270         port->closing = 1;
 271         snd_use_lock_sync(&port->use_lock);
 272
 273         /* clear subscribers info */
 274         clear_subscriber_list(client, port, &port->c_src, SRC_LIST);
 275         clear_subscriber_list(client, port, &port->c_dest, DEST_LIST);
 276
 277         if (port->private_free)
 278                 port->private_free(port->private_data);
 279
 280         snd_assert(port->c_src.count == 0,);
 281         snd_assert(port->c_dest.count == 0,);
 282
 283         kfree(port);
 284         return 0;
 285 }
 286
 287
 288 /* delete a port with the given port id */
 289 int snd_seq_delete_port(struct snd_seq_client *client, int port)
 290 {
 291         unsigned long flags;
 292         struct list_head *l;
 293         struct snd_seq_client_port *found = NULL;
 294
 295         down(&client->ports_mutex);
 296         write_lock_irqsave(&client->ports_lock, flags);
 297         list_for_each(l, &client->ports_list_head) {
 298                 struct snd_seq_client_port *p = list_entry(l, struct snd_seq_client_port, list);
 299                 if (p->addr.port == port) {
 300                         /* ok found.  delete from the list at first */
 301                         list_del(l);
 302                         client->num_ports--;
 303                         found = p;
 304                         break;
 305                 }
 306         }
 307         write_unlock_irqrestore(&client->ports_lock, flags);
 308         up(&client->ports_mutex);
 309         if (found)
 310                 return port_delete(client, found);
 311         else
 312                 return -ENOENT;
 313 }
 314
 315 /* delete the all ports belonging to the given client */
 316 int snd_seq_delete_all_ports(struct snd_seq_client *client)
 317 {
 318         unsigned long flags;
 319         struct list_head deleted_list, *p, *n;
 320
 321         /* move the port list to deleted_list, and
 322          * clear the port list in the client data.
 323          */
 324         down(&client->ports_mutex);
 325         write_lock_irqsave(&client->ports_lock, flags);
 326         if (! list_empty(&client->ports_list_head)) {
 327                 __list_add(&deleted_list,
 328                            client->ports_list_head.prev,
 329                            client->ports_list_head.next);
 330                 INIT_LIST_HEAD(&client->ports_list_head);
 331         } else {
 332                 INIT_LIST_HEAD(&deleted_list);
 333         }
 334         client->num_ports = 0;
 335         write_unlock_irqrestore(&client->ports_lock, flags);
 336
 337         /* remove each port in deleted_list */
 338         list_for_each_safe(p, n, &deleted_list) {
 339                 struct snd_seq_client_port *port = list_entry(p, struct snd_seq_client_port, list);
 340                 list_del(p);
 341                 snd_seq_system_client_ev_port_exit(port->addr.client, port->addr.port);
 342                 port_delete(client, port);
 343         }
 344         up(&client->ports_mutex);
 345         return 0;
 346 }
 347
 348 /* set port info fields */
 349 int snd_seq_set_port_info(struct snd_seq_client_port * port,
 350                           struct snd_seq_port_info * info)
 351 {
 352         snd_assert(port && info, return -EINVAL);
 353
 354         /* set port name */
 355         if (info->name[0])
 356                 strlcpy(port->name, info->name, sizeof(port->name));
 357
 358         /* set capabilities */
 359         port->capability = info->capability;
 360
 361         /* get port type */
 362         port->type = info->type;
 363
 364         /* information about supported channels/voices */
 365         port->midi_channels = info->midi_channels;
 366         port->midi_voices = info->midi_voices;
 367         port->synth_voices = info->synth_voices;
 368
 369         /* timestamping */
 370         port->timestamping = (info->flags & SNDRV_SEQ_PORT_FLG_TIMESTAMP) ? 1 : 0;
 371         port->time_real = (info->flags & SNDRV_SEQ_PORT_FLG_TIME_REAL) ? 1 : 0;
 372         port->time_queue = info->time_queue;
 373
 374         return 0;
 375 }
 376
 377 /* get port info fields */
 378 int snd_seq_get_port_info(struct snd_seq_client_port * port,
 379                           struct snd_seq_port_info * info)
 380 {
 381         snd_assert(port && info, return -EINVAL);
 382
 383         /* get port name */
 384         strlcpy(info->name, port->name, sizeof(info->name));
 385
 386         /* get capabilities */
 387         info->capability = port->capability;
 388
 389         /* get port type */
 390         info->type = port->type;
 391
 392         /* information about supported channels/voices */
 393         info->midi_channels = port->midi_channels;
 394         info->midi_voices = port->midi_voices;
 395         info->synth_voices = port->synth_voices;
 396
 397         /* get subscriber counts */
 398         info->read_use = port->c_src.count;
 399         info->write_use = port->c_dest.count;
 400
 401         /* timestamping */
 402         info->flags = 0;
 403         if (port->timestamping) {
 404                 info->flags |= SNDRV_SEQ_PORT_FLG_TIMESTAMP;
 405                 if (port->time_real)
 406                         info->flags |= SNDRV_SEQ_PORT_FLG_TIME_REAL;
 407                 info->time_queue = port->time_queue;
 408         }
 409
 410         return 0;
 411 }
 412
 413
 414
 415 /*
 416  * call callback functions (if any):
 417  * the callbacks are invoked only when the first (for connection) or
 418  * the last subscription (for disconnection) is done.  Second or later
 419  * subscription results in increment of counter, but no callback is
 420  * invoked.
 421  * This feature is useful if these callbacks are associated with
 422  * initialization or termination of devices (see seq_midi.c).
 423  *
 424  * If callback_all option is set, the callback function is invoked
 425  * at each connnection/disconnection.
 426  */
 427
 428 static int subscribe_port(struct snd_seq_client *client,
 429                           struct snd_seq_client_port *port,
 430                           struct snd_seq_port_subs_info *grp,
 431                           struct snd_seq_port_subscribe *info,
 432                           int send_ack)
 433 {
 434         int err = 0;
 435
 436         if (!try_module_get(port->owner))
 437                 return -EFAULT;
 438         grp->count++;
 439         if (grp->open && (port->callback_all || grp->count == 1)) {
 440                 err = grp->open(port->private_data, info);
 441                 if (err < 0) {
 442                         module_put(port->owner);
 443                         grp->count--;
 444                 }
 445         }
 446         if (err >= 0 && send_ack && client->type == USER_CLIENT)
 447                 snd_seq_client_notify_subscription(port->addr.client, port->addr.port,
 448                                                    info, SNDRV_SEQ_EVENT_PORT_SUBSCRIBED);
 449
 450         return err;
 451 }
 452
 453 static int unsubscribe_port(struct snd_seq_client *client,
 454                             struct snd_seq_client_port *port,
 455                             struct snd_seq_port_subs_info *grp,
 456                             struct snd_seq_port_subscribe *info,
 457                             int send_ack)
 458 {
 459         int err = 0;
 460
 461         if (! grp->count)
 462                 return -EINVAL;
 463         grp->count--;
 464         if (grp->close && (port->callback_all || grp->count == 0))
 465                 err = grp->close(port->private_data, info);
 466         if (send_ack && client->type == USER_CLIENT)
 467                 snd_seq_client_notify_subscription(port->addr.client, port->addr.port,
 468                                                    info, SNDRV_SEQ_EVENT_PORT_UNSUBSCRIBED);
 469         module_put(port->owner);
 470         return err;
 471 }
 472
 473
 474
 475 /* check if both addresses are identical */
 476 static inline int addr_match(struct snd_seq_addr *r, struct snd_seq_addr *s)
 477 {
 478         return (r->client == s->client) && (r->port == s->port);
 479 }
 480
 481 /* check the two subscribe info match */
 482 /* if flags is zero, checks only sender and destination addresses */
 483 static int match_subs_info(struct snd_seq_port_subscribe *r,
 484                            struct snd_seq_port_subscribe *s)
 485 {
 486         if (addr_match(&r->sender, &s->sender) &&
 487             addr_match(&r->dest, &s->dest)) {
 488                 if (r->flags && r->flags == s->flags)
 489                         return r->queue == s->queue;
 490                 else if (! r->flags)
 491                         return 1;
 492         }
 493         return 0;
 494 }
 495
 496
 497 /* connect two ports */
 498 int snd_seq_port_connect(struct snd_seq_client *connector,
 499                          struct snd_seq_client *src_client,
 500                          struct snd_seq_client_port *src_port,
 501                          struct snd_seq_client *dest_client,
 502                          struct snd_seq_client_port *dest_port,
 503                          struct snd_seq_port_subscribe *info)
 504 {
 505         struct snd_seq_port_subs_info *src = &src_port->c_src;
 506         struct snd_seq_port_subs_info *dest = &dest_port->c_dest;
 507         struct snd_seq_subscribers *subs;
 508         struct list_head *p;
 509         int err, src_called = 0;
 510         unsigned long flags;
 511         int exclusive;
 512
 513         subs = kzalloc(sizeof(*subs), GFP_KERNEL);
 514         if (! subs)
 515                 return -ENOMEM;
 516
 517         subs->info = *info;
 518         atomic_set(&subs->ref_count, 2);
 519
 520         down_write(&src->list_mutex);
 521         down_write(&dest->list_mutex);
 522
 523         exclusive = info->flags & SNDRV_SEQ_PORT_SUBS_EXCLUSIVE ? 1 : 0;
 524         err = -EBUSY;
 525         if (exclusive) {
 526                 if (! list_empty(&src->list_head) || ! list_empty(&dest->list_head))
 527                         goto __error;
 528         } else {
 529                 if (src->exclusive || dest->exclusive)
 530                         goto __error;
 531                 /* check whether already exists */
 532                 list_for_each(p, &src->list_head) {
 533                         struct snd_seq_subscribers *s = list_entry(p, struct snd_seq_subscribers, src_list);
 534                         if (match_subs_info(info, &s->info))
 535                                 goto __error;
 536                 }
 537                 list_for_each(p, &dest->list_head) {
 538                         struct snd_seq_subscribers *s = list_entry(p, struct snd_seq_subscribers, dest_list);
 539                         if (match_subs_info(info, &s->info))
 540                                 goto __error;
 541                 }
 542         }
 543
 544         if ((err = subscribe_port(src_client, src_port, src, info,
 545                                   connector->number != src_client->number)) < 0)
 546                 goto __error;
 547         src_called = 1;
 548
 549         if ((err = subscribe_port(dest_client, dest_port, dest, info,
 550                                   connector->number != dest_client->number)) < 0)
 551                 goto __error;
 552
 553         /* add to list */
 554         write_lock_irqsave(&src->list_lock, flags);
 555         // write_lock(&dest->list_lock); // no other lock yet
 556         list_add_tail(&subs->src_list, &src->list_head);
 557         list_add_tail(&subs->dest_list, &dest->list_head);
 558         // write_unlock(&dest->list_lock); // no other lock yet
 559         write_unlock_irqrestore(&src->list_lock, flags);
 560
 561         src->exclusive = dest->exclusive = exclusive;
 562
 563         up_write(&dest->list_mutex);
 564         up_write(&src->list_mutex);
 565         return 0;
 566
 567  __error:
 568         if (src_called)
 569                 unsubscribe_port(src_client, src_port, src, info,
 570                                  connector->number != src_client->number);
 571         kfree(subs);
 572         up_write(&dest->list_mutex);
 573         up_write(&src->list_mutex);
 574         return err;
 575 }
 576
 577
 578 /* remove the connection */
 579 int snd_seq_port_disconnect(struct snd_seq_client *connector,
 580                             struct snd_seq_client *src_client,
 581                             struct snd_seq_client_port *src_port,
 582                             struct snd_seq_client *dest_client,
 583                             struct snd_seq_client_port *dest_port,
 584                             struct snd_seq_port_subscribe *info)
 585 {
 586         struct snd_seq_port_subs_info *src = &src_port->c_src;
 587         struct snd_seq_port_subs_info *dest = &dest_port->c_dest;
 588         struct snd_seq_subscribers *subs;
 589         struct list_head *p;
 590         int err = -ENOENT;
 591         unsigned long flags;
 592
 593         down_write(&src->list_mutex);
 594         down_write(&dest->list_mutex);
 595
 596         /* look for the connection */
 597         list_for_each(p, &src->list_head) {
 598                 subs = list_entry(p, struct snd_seq_subscribers, src_list);
 599                 if (match_subs_info(info, &subs->info)) {
 600                         write_lock_irqsave(&src->list_lock, flags);
 601                         // write_lock(&dest->list_lock);  // no lock yet
 602                         list_del(&subs->src_list);
 603                         list_del(&subs->dest_list);
 604                         // write_unlock(&dest->list_lock);
 605                         write_unlock_irqrestore(&src->list_lock, flags);
 606                         src->exclusive = dest->exclusive = 0;
 607                         unsubscribe_port(src_client, src_port, src, info,
 608                                          connector->number != src_client->number);
 609                         unsubscribe_port(dest_client, dest_port, dest, info,
 610                                          connector->number != dest_client->number);
 611                         kfree(subs);
 612                         err = 0;
 613                         break;
 614                 }
 615         }
 616
 617         up_write(&dest->list_mutex);
 618         up_write(&src->list_mutex);
 619         return err;
 620 }
 621
 622
 623 /* get matched subscriber */
 624 struct snd_seq_subscribers *snd_seq_port_get_subscription(struct snd_seq_port_subs_info *src_grp,
 625                                                           struct snd_seq_addr *dest_addr)
 626 {
 627         struct list_head *p;
 628         struct snd_seq_subscribers *s, *found = NULL;
 629
 630         down_read(&src_grp->list_mutex);
 631         list_for_each(p, &src_grp->list_head) {
 632                 s = list_entry(p, struct snd_seq_subscribers, src_list);
 633                 if (addr_match(dest_addr, &s->info.dest)) {
 634                         found = s;
 635                         break;
 636                 }
 637         }
 638         up_read(&src_grp->list_mutex);
 639         return found;
 640 }
 641
 642 /*
 643  * Attach a device driver that wants to receive events from the
 644  * sequencer.  Returns the new port number on success.
 645  * A driver that wants to receive the events converted to midi, will
 646  * use snd_seq_midisynth_register_port().
 647  */
 648 /* exported */
 649 int snd_seq_event_port_attach(int client,
 650                               struct snd_seq_port_callback *pcbp,
 651                               int cap, int type, int midi_channels,
 652                               int midi_voices, char *portname)
 653 {
 654         struct snd_seq_port_info portinfo;
 655         int  ret;
 656
 657         /* Set up the port */
 658         memset(&portinfo, 0, sizeof(portinfo));
 659         portinfo.addr.client = client;
 660         strlcpy(portinfo.name, portname ? portname : "Unamed port",
 661                 sizeof(portinfo.name));
 662
 663         portinfo.capability = cap;
 664         portinfo.type = type;
 665         portinfo.kernel = pcbp;
 666         portinfo.midi_channels = midi_channels;
 667         portinfo.midi_voices = midi_voices;
 668
 669         /* Create it */
 670         ret = snd_seq_kernel_client_ctl(client,
 671                                         SNDRV_SEQ_IOCTL_CREATE_PORT,
 672                                         &portinfo);
 673
 674         if (ret >= 0)
 675                 ret = portinfo.addr.port;
 676
 677         return ret;
 678 }
 679
 680
 681 /*
 682  * Detach the driver from a port.
 683  */
 684 /* exported */
 685 int snd_seq_event_port_detach(int client, int port)
 686 {
 687         struct snd_seq_port_info portinfo;
 688         int  err;
 689
 690         memset(&portinfo, 0, sizeof(portinfo));
 691         portinfo.addr.client = client;
 692         portinfo.addr.port   = port;
 693         err = snd_seq_kernel_client_ctl(client,
 694                                         SNDRV_SEQ_IOCTL_DELETE_PORT,
 695                                         &portinfo);
 696
 697         return err;
 698 }