root/sound/core/seq/seq_virmidi.c

DEFINITIONS

1. snd_virmidi_init_event
2. snd_virmidi_dev_receive_event
3. snd_virmidi_event_input
4. snd_virmidi_input_trigger
5. snd_vmidi_output_work
6. snd_virmidi_output_trigger
7. snd_virmidi_input_open
8. snd_virmidi_output_open
9. snd_virmidi_input_close
10. snd_virmidi_output_close
11. snd_virmidi_subscribe
12. snd_virmidi_unsubscribe
13. snd_virmidi_use
14. snd_virmidi_unuse
15. snd_virmidi_dev_attach_seq
16. snd_virmidi_dev_detach_seq
17. snd_virmidi_dev_register
18. snd_virmidi_dev_unregister
19. snd_virmidi_free
20. snd_virmidi_new

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *  Virtual Raw MIDI client on Sequencer
   4  *
   5  *  Copyright (c) 2000 by Takashi Iwai <tiwai@suse.de>,
   6  *                        Jaroslav Kysela <perex@perex.cz>
   7  */
   8 
   9 /*
  10  * Virtual Raw MIDI client
  11  *
  12  * The virtual rawmidi client is a sequencer client which associate
  13  * a rawmidi device file.  The created rawmidi device file can be
  14  * accessed as a normal raw midi, but its MIDI source and destination
  15  * are arbitrary.  For example, a user-client software synth connected
  16  * to this port can be used as a normal midi device as well.
  17  *
  18  * The virtual rawmidi device accepts also multiple opens.  Each file
  19  * has its own input buffer, so that no conflict would occur.  The drain
  20  * of input/output buffer acts only to the local buffer.
  21  *
  22  */
  23 
  24 #include <linux/init.h>
  25 #include <linux/wait.h>
  26 #include <linux/module.h>
  27 #include <linux/slab.h>
  28 #include <sound/core.h>
  29 #include <sound/rawmidi.h>
  30 #include <sound/info.h>
  31 #include <sound/control.h>
  32 #include <sound/minors.h>
  33 #include <sound/seq_kernel.h>
  34 #include <sound/seq_midi_event.h>
  35 #include <sound/seq_virmidi.h>
  36 
  37 MODULE_AUTHOR("Takashi Iwai <tiwai@suse.de>");
  38 MODULE_DESCRIPTION("Virtual Raw MIDI client on Sequencer");
  39 MODULE_LICENSE("GPL");
  40 
  41 /*
  42  * initialize an event record
  43  */
  44 static void snd_virmidi_init_event(struct snd_virmidi *vmidi,
  45                                    struct snd_seq_event *ev)
  46 {
  47         memset(ev, 0, sizeof(*ev));
  48         ev->source.port = vmidi->port;
  49         switch (vmidi->seq_mode) {
  50         case SNDRV_VIRMIDI_SEQ_DISPATCH:
  51                 ev->dest.client = SNDRV_SEQ_ADDRESS_SUBSCRIBERS;
  52                 break;
  53         case SNDRV_VIRMIDI_SEQ_ATTACH:
  54                 /* FIXME: source and destination are same - not good.. */
  55                 ev->dest.client = vmidi->client;
  56                 ev->dest.port = vmidi->port;
  57                 break;
  58         }
  59         ev->type = SNDRV_SEQ_EVENT_NONE;
  60 }
  61 
  62 /*
  63  * decode input event and put to read buffer of each opened file
  64  */
  65 static int snd_virmidi_dev_receive_event(struct snd_virmidi_dev *rdev,
  66                                          struct snd_seq_event *ev,
  67                                          bool atomic)
  68 {
  69         struct snd_virmidi *vmidi;
  70         unsigned char msg[4];
  71         int len;
  72 
  73         if (atomic)
  74                 read_lock(&rdev->filelist_lock);
  75         else
  76                 down_read(&rdev->filelist_sem);
  77         list_for_each_entry(vmidi, &rdev->filelist, list) {
  78                 if (!READ_ONCE(vmidi->trigger))
  79                         continue;
  80                 if (ev->type == SNDRV_SEQ_EVENT_SYSEX) {
  81                         if ((ev->flags & SNDRV_SEQ_EVENT_LENGTH_MASK) != SNDRV_SEQ_EVENT_LENGTH_VARIABLE)
  82                                 continue;
  83                         snd_seq_dump_var_event(ev, (snd_seq_dump_func_t)snd_rawmidi_receive, vmidi->substream);
  84                         snd_midi_event_reset_decode(vmidi->parser);
  85                 } else {
  86                         len = snd_midi_event_decode(vmidi->parser, msg, sizeof(msg), ev);
  87                         if (len > 0)
  88                                 snd_rawmidi_receive(vmidi->substream, msg, len);
  89                 }
  90         }
  91         if (atomic)
  92                 read_unlock(&rdev->filelist_lock);
  93         else
  94                 up_read(&rdev->filelist_sem);
  95 
  96         return 0;
  97 }
  98 
  99 /*
 100  * event handler of virmidi port
 101  */
 102 static int snd_virmidi_event_input(struct snd_seq_event *ev, int direct,
 103                                    void *private_data, int atomic, int hop)
 104 {
 105         struct snd_virmidi_dev *rdev;
 106 
 107         rdev = private_data;
 108         if (!(rdev->flags & SNDRV_VIRMIDI_USE))
 109                 return 0; /* ignored */
 110         return snd_virmidi_dev_receive_event(rdev, ev, atomic);
 111 }
 112 
 113 /*
 114  * trigger rawmidi stream for input
 115  */
 116 static void snd_virmidi_input_trigger(struct snd_rawmidi_substream *substream, int up)
 117 {
 118         struct snd_virmidi *vmidi = substream->runtime->private_data;
 119 
 120         WRITE_ONCE(vmidi->trigger, !!up);
 121 }
 122 
 123 /* process rawmidi bytes and send events;
 124  * we need no lock here for vmidi->event since it's handled only in this work
 125  */
 126 static void snd_vmidi_output_work(struct work_struct *work)
 127 {
 128         struct snd_virmidi *vmidi;
 129         struct snd_rawmidi_substream *substream;
 130         unsigned char input;
 131         int ret;
 132 
 133         vmidi = container_of(work, struct snd_virmidi, output_work);
 134         substream = vmidi->substream;
 135 
 136         /* discard the outputs in dispatch mode unless subscribed */
 137         if (vmidi->seq_mode == SNDRV_VIRMIDI_SEQ_DISPATCH &&
 138             !(vmidi->rdev->flags & SNDRV_VIRMIDI_SUBSCRIBE)) {
 139                 snd_rawmidi_proceed(substream);
 140                 return;
 141         }
 142 
 143         while (READ_ONCE(vmidi->trigger)) {
 144                 if (snd_rawmidi_transmit(substream, &input, 1) != 1)
 145                         break;
 146                 if (!snd_midi_event_encode_byte(vmidi->parser, input,
 147                                                 &vmidi->event))
 148                         continue;
 149                 if (vmidi->event.type != SNDRV_SEQ_EVENT_NONE) {
 150                         ret = snd_seq_kernel_client_dispatch(vmidi->client,
 151                                                              &vmidi->event,
 152                                                              false, 0);
 153                         vmidi->event.type = SNDRV_SEQ_EVENT_NONE;
 154                         if (ret < 0)
 155                                 break;
 156                 }
 157                 /* rawmidi input might be huge, allow to have a break */
 158                 cond_resched();
 159         }
 160 }
 161 
 162 /*
 163  * trigger rawmidi stream for output
 164  */
 165 static void snd_virmidi_output_trigger(struct snd_rawmidi_substream *substream, int up)
 166 {
 167         struct snd_virmidi *vmidi = substream->runtime->private_data;
 168 
 169         WRITE_ONCE(vmidi->trigger, !!up);
 170         if (up)
 171                 queue_work(system_highpri_wq, &vmidi->output_work);
 172 }
 173 
 174 /*
 175  * open rawmidi handle for input
 176  */
 177 static int snd_virmidi_input_open(struct snd_rawmidi_substream *substream)
 178 {
 179         struct snd_virmidi_dev *rdev = substream->rmidi->private_data;
 180         struct snd_rawmidi_runtime *runtime = substream->runtime;
 181         struct snd_virmidi *vmidi;
 182 
 183         vmidi = kzalloc(sizeof(*vmidi), GFP_KERNEL);
 184         if (vmidi == NULL)
 185                 return -ENOMEM;
 186         vmidi->substream = substream;
 187         if (snd_midi_event_new(0, &vmidi->parser) < 0) {
 188                 kfree(vmidi);
 189                 return -ENOMEM;
 190         }
 191         vmidi->seq_mode = rdev->seq_mode;
 192         vmidi->client = rdev->client;
 193         vmidi->port = rdev->port;       
 194         runtime->private_data = vmidi;
 195         down_write(&rdev->filelist_sem);
 196         write_lock_irq(&rdev->filelist_lock);
 197         list_add_tail(&vmidi->list, &rdev->filelist);
 198         write_unlock_irq(&rdev->filelist_lock);
 199         up_write(&rdev->filelist_sem);
 200         vmidi->rdev = rdev;
 201         return 0;
 202 }
 203 
 204 /*
 205  * open rawmidi handle for output
 206  */
 207 static int snd_virmidi_output_open(struct snd_rawmidi_substream *substream)
 208 {
 209         struct snd_virmidi_dev *rdev = substream->rmidi->private_data;
 210         struct snd_rawmidi_runtime *runtime = substream->runtime;
 211         struct snd_virmidi *vmidi;
 212 
 213         vmidi = kzalloc(sizeof(*vmidi), GFP_KERNEL);
 214         if (vmidi == NULL)
 215                 return -ENOMEM;
 216         vmidi->substream = substream;
 217         if (snd_midi_event_new(MAX_MIDI_EVENT_BUF, &vmidi->parser) < 0) {
 218                 kfree(vmidi);
 219                 return -ENOMEM;
 220         }
 221         vmidi->seq_mode = rdev->seq_mode;
 222         vmidi->client = rdev->client;
 223         vmidi->port = rdev->port;
 224         snd_virmidi_init_event(vmidi, &vmidi->event);
 225         vmidi->rdev = rdev;
 226         INIT_WORK(&vmidi->output_work, snd_vmidi_output_work);
 227         runtime->private_data = vmidi;
 228         return 0;
 229 }
 230 
 231 /*
 232  * close rawmidi handle for input
 233  */
 234 static int snd_virmidi_input_close(struct snd_rawmidi_substream *substream)
 235 {
 236         struct snd_virmidi_dev *rdev = substream->rmidi->private_data;
 237         struct snd_virmidi *vmidi = substream->runtime->private_data;
 238 
 239         down_write(&rdev->filelist_sem);
 240         write_lock_irq(&rdev->filelist_lock);
 241         list_del(&vmidi->list);
 242         write_unlock_irq(&rdev->filelist_lock);
 243         up_write(&rdev->filelist_sem);
 244         snd_midi_event_free(vmidi->parser);
 245         substream->runtime->private_data = NULL;
 246         kfree(vmidi);
 247         return 0;
 248 }
 249 
 250 /*
 251  * close rawmidi handle for output
 252  */
 253 static int snd_virmidi_output_close(struct snd_rawmidi_substream *substream)
 254 {
 255         struct snd_virmidi *vmidi = substream->runtime->private_data;
 256 
 257         WRITE_ONCE(vmidi->trigger, false); /* to be sure */
 258         cancel_work_sync(&vmidi->output_work);
 259         snd_midi_event_free(vmidi->parser);
 260         substream->runtime->private_data = NULL;
 261         kfree(vmidi);
 262         return 0;
 263 }
 264 
 265 /*
 266  * subscribe callback - allow output to rawmidi device
 267  */
 268 static int snd_virmidi_subscribe(void *private_data,
 269                                  struct snd_seq_port_subscribe *info)
 270 {
 271         struct snd_virmidi_dev *rdev;
 272 
 273         rdev = private_data;
 274         if (!try_module_get(rdev->card->module))
 275                 return -EFAULT;
 276         rdev->flags |= SNDRV_VIRMIDI_SUBSCRIBE;
 277         return 0;
 278 }
 279 
 280 /*
 281  * unsubscribe callback - disallow output to rawmidi device
 282  */
 283 static int snd_virmidi_unsubscribe(void *private_data,
 284                                    struct snd_seq_port_subscribe *info)
 285 {
 286         struct snd_virmidi_dev *rdev;
 287 
 288         rdev = private_data;
 289         rdev->flags &= ~SNDRV_VIRMIDI_SUBSCRIBE;
 290         module_put(rdev->card->module);
 291         return 0;
 292 }
 293 
 294 
 295 /*
 296  * use callback - allow input to rawmidi device
 297  */
 298 static int snd_virmidi_use(void *private_data,
 299                            struct snd_seq_port_subscribe *info)
 300 {
 301         struct snd_virmidi_dev *rdev;
 302 
 303         rdev = private_data;
 304         if (!try_module_get(rdev->card->module))
 305                 return -EFAULT;
 306         rdev->flags |= SNDRV_VIRMIDI_USE;
 307         return 0;
 308 }
 309 
 310 /*
 311  * unuse callback - disallow input to rawmidi device
 312  */
 313 static int snd_virmidi_unuse(void *private_data,
 314                              struct snd_seq_port_subscribe *info)
 315 {
 316         struct snd_virmidi_dev *rdev;
 317 
 318         rdev = private_data;
 319         rdev->flags &= ~SNDRV_VIRMIDI_USE;
 320         module_put(rdev->card->module);
 321         return 0;
 322 }
 323 
 324 
 325 /*
 326  *  Register functions
 327  */
 328 
 329 static const struct snd_rawmidi_ops snd_virmidi_input_ops = {
 330         .open = snd_virmidi_input_open,
 331         .close = snd_virmidi_input_close,
 332         .trigger = snd_virmidi_input_trigger,
 333 };
 334 
 335 static const struct snd_rawmidi_ops snd_virmidi_output_ops = {
 336         .open = snd_virmidi_output_open,
 337         .close = snd_virmidi_output_close,
 338         .trigger = snd_virmidi_output_trigger,
 339 };
 340 
 341 /*
 342  * create a sequencer client and a port
 343  */
 344 static int snd_virmidi_dev_attach_seq(struct snd_virmidi_dev *rdev)
 345 {
 346         int client;
 347         struct snd_seq_port_callback pcallbacks;
 348         struct snd_seq_port_info *pinfo;
 349         int err;
 350 
 351         if (rdev->client >= 0)
 352                 return 0;
 353 
 354         pinfo = kzalloc(sizeof(*pinfo), GFP_KERNEL);
 355         if (!pinfo) {
 356                 err = -ENOMEM;
 357                 goto __error;
 358         }
 359 
 360         client = snd_seq_create_kernel_client(rdev->card, rdev->device,
 361                                               "%s %d-%d", rdev->rmidi->name,
 362                                               rdev->card->number,
 363                                               rdev->device);
 364         if (client < 0) {
 365                 err = client;
 366                 goto __error;
 367         }
 368         rdev->client = client;
 369 
 370         /* create a port */
 371         pinfo->addr.client = client;
 372         sprintf(pinfo->name, "VirMIDI %d-%d", rdev->card->number, rdev->device);
 373         /* set all capabilities */
 374         pinfo->capability |= SNDRV_SEQ_PORT_CAP_WRITE | SNDRV_SEQ_PORT_CAP_SYNC_WRITE | SNDRV_SEQ_PORT_CAP_SUBS_WRITE;
 375         pinfo->capability |= SNDRV_SEQ_PORT_CAP_READ | SNDRV_SEQ_PORT_CAP_SYNC_READ | SNDRV_SEQ_PORT_CAP_SUBS_READ;
 376         pinfo->capability |= SNDRV_SEQ_PORT_CAP_DUPLEX;
 377         pinfo->type = SNDRV_SEQ_PORT_TYPE_MIDI_GENERIC
 378                 | SNDRV_SEQ_PORT_TYPE_SOFTWARE
 379                 | SNDRV_SEQ_PORT_TYPE_PORT;
 380         pinfo->midi_channels = 16;
 381         memset(&pcallbacks, 0, sizeof(pcallbacks));
 382         pcallbacks.owner = THIS_MODULE;
 383         pcallbacks.private_data = rdev;
 384         pcallbacks.subscribe = snd_virmidi_subscribe;
 385         pcallbacks.unsubscribe = snd_virmidi_unsubscribe;
 386         pcallbacks.use = snd_virmidi_use;
 387         pcallbacks.unuse = snd_virmidi_unuse;
 388         pcallbacks.event_input = snd_virmidi_event_input;
 389         pinfo->kernel = &pcallbacks;
 390         err = snd_seq_kernel_client_ctl(client, SNDRV_SEQ_IOCTL_CREATE_PORT, pinfo);
 391         if (err < 0) {
 392                 snd_seq_delete_kernel_client(client);
 393                 rdev->client = -1;
 394                 goto __error;
 395         }
 396 
 397         rdev->port = pinfo->addr.port;
 398         err = 0; /* success */
 399 
 400  __error:
 401         kfree(pinfo);
 402         return err;
 403 }
 404 
 405 
 406 /*
 407  * release the sequencer client
 408  */
 409 static void snd_virmidi_dev_detach_seq(struct snd_virmidi_dev *rdev)
 410 {
 411         if (rdev->client >= 0) {
 412                 snd_seq_delete_kernel_client(rdev->client);
 413                 rdev->client = -1;
 414         }
 415 }
 416 
 417 /*
 418  * register the device
 419  */
 420 static int snd_virmidi_dev_register(struct snd_rawmidi *rmidi)
 421 {
 422         struct snd_virmidi_dev *rdev = rmidi->private_data;
 423         int err;
 424 
 425         switch (rdev->seq_mode) {
 426         case SNDRV_VIRMIDI_SEQ_DISPATCH:
 427                 err = snd_virmidi_dev_attach_seq(rdev);
 428                 if (err < 0)
 429                         return err;
 430                 break;
 431         case SNDRV_VIRMIDI_SEQ_ATTACH:
 432                 if (rdev->client == 0)
 433                         return -EINVAL;
 434                 /* should check presence of port more strictly.. */
 435                 break;
 436         default:
 437                 pr_err("ALSA: seq_virmidi: seq_mode is not set: %d\n", rdev->seq_mode);
 438                 return -EINVAL;
 439         }
 440         return 0;
 441 }
 442 
 443 
 444 /*
 445  * unregister the device
 446  */
 447 static int snd_virmidi_dev_unregister(struct snd_rawmidi *rmidi)
 448 {
 449         struct snd_virmidi_dev *rdev = rmidi->private_data;
 450 
 451         if (rdev->seq_mode == SNDRV_VIRMIDI_SEQ_DISPATCH)
 452                 snd_virmidi_dev_detach_seq(rdev);
 453         return 0;
 454 }
 455 
 456 /*
 457  *
 458  */
 459 static const struct snd_rawmidi_global_ops snd_virmidi_global_ops = {
 460         .dev_register = snd_virmidi_dev_register,
 461         .dev_unregister = snd_virmidi_dev_unregister,
 462 };
 463 
 464 /*
 465  * free device
 466  */
 467 static void snd_virmidi_free(struct snd_rawmidi *rmidi)
 468 {
 469         struct snd_virmidi_dev *rdev = rmidi->private_data;
 470         kfree(rdev);
 471 }
 472 
 473 /*
 474  * create a new device
 475  *
 476  */
 477 /* exported */
 478 int snd_virmidi_new(struct snd_card *card, int device, struct snd_rawmidi **rrmidi)
 479 {
 480         struct snd_rawmidi *rmidi;
 481         struct snd_virmidi_dev *rdev;
 482         int err;
 483         
 484         *rrmidi = NULL;
 485         if ((err = snd_rawmidi_new(card, "VirMidi", device,
 486                                    16,  /* may be configurable */
 487                                    16,  /* may be configurable */
 488                                    &rmidi)) < 0)
 489                 return err;
 490         strcpy(rmidi->name, rmidi->id);
 491         rdev = kzalloc(sizeof(*rdev), GFP_KERNEL);
 492         if (rdev == NULL) {
 493                 snd_device_free(card, rmidi);
 494                 return -ENOMEM;
 495         }
 496         rdev->card = card;
 497         rdev->rmidi = rmidi;
 498         rdev->device = device;
 499         rdev->client = -1;
 500         init_rwsem(&rdev->filelist_sem);
 501         rwlock_init(&rdev->filelist_lock);
 502         INIT_LIST_HEAD(&rdev->filelist);
 503         rdev->seq_mode = SNDRV_VIRMIDI_SEQ_DISPATCH;
 504         rmidi->private_data = rdev;
 505         rmidi->private_free = snd_virmidi_free;
 506         rmidi->ops = &snd_virmidi_global_ops;
 507         snd_rawmidi_set_ops(rmidi, SNDRV_RAWMIDI_STREAM_INPUT, &snd_virmidi_input_ops);
 508         snd_rawmidi_set_ops(rmidi, SNDRV_RAWMIDI_STREAM_OUTPUT, &snd_virmidi_output_ops);
 509         rmidi->info_flags = SNDRV_RAWMIDI_INFO_INPUT |
 510                             SNDRV_RAWMIDI_INFO_OUTPUT |
 511                             SNDRV_RAWMIDI_INFO_DUPLEX;
 512         *rrmidi = rmidi;
 513         return 0;
 514 }
 515 EXPORT_SYMBOL(snd_virmidi_new);