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 err = snd_rawmidi_new(card, "VirMidi", device, 486 16, /* may be configurable */ 487 16, /* may be configurable */ 488 &rmidi); 489 if (err < 0) 490 return err; 491 strcpy(rmidi->name, rmidi->id); 492 rdev = kzalloc(sizeof(*rdev), GFP_KERNEL); 493 if (rdev == NULL) { 494 snd_device_free(card, rmidi); 495 return -ENOMEM; 496 } 497 rdev->card = card; 498 rdev->rmidi = rmidi; 499 rdev->device = device; 500 rdev->client = -1; 501 init_rwsem(&rdev->filelist_sem); 502 rwlock_init(&rdev->filelist_lock); 503 INIT_LIST_HEAD(&rdev->filelist); 504 rdev->seq_mode = SNDRV_VIRMIDI_SEQ_DISPATCH; 505 rmidi->private_data = rdev; 506 rmidi->private_free = snd_virmidi_free; 507 rmidi->ops = &snd_virmidi_global_ops; 508 snd_rawmidi_set_ops(rmidi, SNDRV_RAWMIDI_STREAM_INPUT, &snd_virmidi_input_ops); 509 snd_rawmidi_set_ops(rmidi, SNDRV_RAWMIDI_STREAM_OUTPUT, &snd_virmidi_output_ops); 510 rmidi->info_flags = SNDRV_RAWMIDI_INFO_INPUT | 511 SNDRV_RAWMIDI_INFO_OUTPUT | 512 SNDRV_RAWMIDI_INFO_DUPLEX; 513 *rrmidi = rmidi; 514 return 0; 515 } 516 EXPORT_SYMBOL(snd_virmidi_new); 517