drivers/most/core.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * core.c - Implementation of core module of MOST Linux driver stack
   4  *
   5  * Copyright (C) 2013-2020 Microchip Technology Germany II GmbH & Co. KG
   6  */
   7
   8 #include <linux/module.h>
   9 #include <linux/fs.h>
  10 #include <linux/slab.h>
  11 #include <linux/init.h>
  12 #include <linux/device.h>
  13 #include <linux/list.h>
  14 #include <linux/poll.h>
  15 #include <linux/wait.h>
  16 #include <linux/kobject.h>
  17 #include <linux/mutex.h>
  18 #include <linux/completion.h>
  19 #include <linux/sysfs.h>
  20 #include <linux/kthread.h>
  21 #include <linux/dma-mapping.h>
  22 #include <linux/idr.h>
  23 #include <linux/most.h>
  24
  25 #define MAX_CHANNELS    64
  26 #define STRING_SIZE     80
  27
  28 static struct ida mdev_id;
  29 static int dummy_num_buffers;
  30 static struct list_head comp_list;
  31
  32 struct pipe {
  33         struct most_component *comp;
  34         int refs;
  35         int num_buffers;
  36 };
  37
  38 struct most_channel {
  39         struct device dev;
  40         struct completion cleanup;
  41         atomic_t mbo_ref;
  42         atomic_t mbo_nq_level;
  43         u16 channel_id;
  44         char name[STRING_SIZE];
  45         bool is_poisoned;
  46         struct mutex start_mutex; /* channel activation synchronization */
  47         struct mutex nq_mutex; /* nq thread synchronization */
  48         int is_starving;
  49         struct most_interface *iface;
  50         struct most_channel_config cfg;
  51         bool keep_mbo;
  52         bool enqueue_halt;
  53         struct list_head fifo;
  54         spinlock_t fifo_lock; /* fifo access synchronization */
  55         struct list_head halt_fifo;
  56         struct list_head list;
  57         struct pipe pipe0;
  58         struct pipe pipe1;
  59         struct list_head trash_fifo;
  60         struct task_struct *hdm_enqueue_task;
  61         wait_queue_head_t hdm_fifo_wq;
  62
  63 };
  64
  65 #define to_channel(d) container_of(d, struct most_channel, dev)
  66
  67 struct interface_private {
  68         int dev_id;
  69         char name[STRING_SIZE];
  70         struct most_channel *channel[MAX_CHANNELS];
  71         struct list_head channel_list;
  72 };
  73
  74 static const struct {
  75         int most_ch_data_type;
  76         const char *name;
  77 } ch_data_type[] = {
  78         { MOST_CH_CONTROL, "control" },
  79         { MOST_CH_ASYNC, "async" },
  80         { MOST_CH_SYNC, "sync" },
  81         { MOST_CH_ISOC, "isoc"},
  82         { MOST_CH_ISOC, "isoc_avp"},
  83 };
  84
  85 /**
  86  * list_pop_mbo - retrieves the first MBO of the list and removes it
  87  * @ptr: the list head to grab the MBO from.
  88  */
  89 #define list_pop_mbo(ptr)                                               \
  90 ({                                                                      \
  91         struct mbo *_mbo = list_first_entry(ptr, struct mbo, list);     \
  92         list_del(&_mbo->list);                                          \
  93         _mbo;                                                           \
  94 })
  95
  96 /**
  97  * most_free_mbo_coherent - free an MBO and its coherent buffer
  98  * @mbo: most buffer
  99  */
 100 static void most_free_mbo_coherent(struct mbo *mbo)
 101 {
 102         struct most_channel *c = mbo->context;
 103         u16 const coherent_buf_size = c->cfg.buffer_size + c->cfg.extra_len;
 104
 105         if (c->iface->dma_free)
 106                 c->iface->dma_free(mbo, coherent_buf_size);
 107         else
 108                 kfree(mbo->virt_address);
 109         kfree(mbo);
 110         if (atomic_sub_and_test(1, &c->mbo_ref))
 111                 complete(&c->cleanup);
 112 }
 113
 114 /**
 115  * flush_channel_fifos - clear the channel fifos
 116  * @c: pointer to channel object
 117  */
 118 static void flush_channel_fifos(struct most_channel *c)
 119 {
 120         unsigned long flags, hf_flags;
 121         struct mbo *mbo, *tmp;
 122
 123         if (list_empty(&c->fifo) && list_empty(&c->halt_fifo))
 124                 return;
 125
 126         spin_lock_irqsave(&c->fifo_lock, flags);
 127         list_for_each_entry_safe(mbo, tmp, &c->fifo, list) {
 128                 list_del(&mbo->list);
 129                 spin_unlock_irqrestore(&c->fifo_lock, flags);
 130                 most_free_mbo_coherent(mbo);
 131                 spin_lock_irqsave(&c->fifo_lock, flags);
 132         }
 133         spin_unlock_irqrestore(&c->fifo_lock, flags);
 134
 135         spin_lock_irqsave(&c->fifo_lock, hf_flags);
 136         list_for_each_entry_safe(mbo, tmp, &c->halt_fifo, list) {
 137                 list_del(&mbo->list);
 138                 spin_unlock_irqrestore(&c->fifo_lock, hf_flags);
 139                 most_free_mbo_coherent(mbo);
 140                 spin_lock_irqsave(&c->fifo_lock, hf_flags);
 141         }
 142         spin_unlock_irqrestore(&c->fifo_lock, hf_flags);
 143
 144         if (unlikely((!list_empty(&c->fifo) || !list_empty(&c->halt_fifo))))
 145                 dev_warn(&c->dev, "Channel or trash fifo not empty\n");
 146 }
 147
 148 /**
 149  * flush_trash_fifo - clear the trash fifo
 150  * @c: pointer to channel object
 151  */
 152 static int flush_trash_fifo(struct most_channel *c)
 153 {
 154         struct mbo *mbo, *tmp;
 155         unsigned long flags;
 156
 157         spin_lock_irqsave(&c->fifo_lock, flags);
 158         list_for_each_entry_safe(mbo, tmp, &c->trash_fifo, list) {
 159                 list_del(&mbo->list);
 160                 spin_unlock_irqrestore(&c->fifo_lock, flags);
 161                 most_free_mbo_coherent(mbo);
 162                 spin_lock_irqsave(&c->fifo_lock, flags);
 163         }
 164         spin_unlock_irqrestore(&c->fifo_lock, flags);
 165         return 0;
 166 }
 167
 168 static ssize_t available_directions_show(struct device *dev,
 169                                          struct device_attribute *attr,
 170                                          char *buf)
 171 {
 172         struct most_channel *c = to_channel(dev);
 173         unsigned int i = c->channel_id;
 174
 175         strcpy(buf, "");
 176         if (c->iface->channel_vector[i].direction & MOST_CH_RX)
 177                 strcat(buf, "rx ");
 178         if (c->iface->channel_vector[i].direction & MOST_CH_TX)
 179                 strcat(buf, "tx ");
 180         strcat(buf, "\n");
 181         return strlen(buf);
 182 }
 183
 184 static ssize_t available_datatypes_show(struct device *dev,
 185                                         struct device_attribute *attr,
 186                                         char *buf)
 187 {
 188         struct most_channel *c = to_channel(dev);
 189         unsigned int i = c->channel_id;
 190
 191         strcpy(buf, "");
 192         if (c->iface->channel_vector[i].data_type & MOST_CH_CONTROL)
 193                 strcat(buf, "control ");
 194         if (c->iface->channel_vector[i].data_type & MOST_CH_ASYNC)
 195                 strcat(buf, "async ");
 196         if (c->iface->channel_vector[i].data_type & MOST_CH_SYNC)
 197                 strcat(buf, "sync ");
 198         if (c->iface->channel_vector[i].data_type & MOST_CH_ISOC)
 199                 strcat(buf, "isoc ");
 200         strcat(buf, "\n");
 201         return strlen(buf);
 202 }
 203
 204 static ssize_t number_of_packet_buffers_show(struct device *dev,
 205                                              struct device_attribute *attr,
 206                                              char *buf)
 207 {
 208         struct most_channel *c = to_channel(dev);
 209         unsigned int i = c->channel_id;
 210
 211         return snprintf(buf, PAGE_SIZE, "%d\n",
 212                         c->iface->channel_vector[i].num_buffers_packet);
 213 }
 214
 215 static ssize_t number_of_stream_buffers_show(struct device *dev,
 216                                              struct device_attribute *attr,
 217                                              char *buf)
 218 {
 219         struct most_channel *c = to_channel(dev);
 220         unsigned int i = c->channel_id;
 221
 222         return snprintf(buf, PAGE_SIZE, "%d\n",
 223                         c->iface->channel_vector[i].num_buffers_streaming);
 224 }
 225
 226 static ssize_t size_of_packet_buffer_show(struct device *dev,
 227                                           struct device_attribute *attr,
 228                                           char *buf)
 229 {
 230         struct most_channel *c = to_channel(dev);
 231         unsigned int i = c->channel_id;
 232
 233         return snprintf(buf, PAGE_SIZE, "%d\n",
 234                         c->iface->channel_vector[i].buffer_size_packet);
 235 }
 236
 237 static ssize_t size_of_stream_buffer_show(struct device *dev,
 238                                           struct device_attribute *attr,
 239                                           char *buf)
 240 {
 241         struct most_channel *c = to_channel(dev);
 242         unsigned int i = c->channel_id;
 243
 244         return snprintf(buf, PAGE_SIZE, "%d\n",
 245                         c->iface->channel_vector[i].buffer_size_streaming);
 246 }
 247
 248 static ssize_t channel_starving_show(struct device *dev,
 249                                      struct device_attribute *attr,
 250                                      char *buf)
 251 {
 252         struct most_channel *c = to_channel(dev);
 253
 254         return snprintf(buf, PAGE_SIZE, "%d\n", c->is_starving);
 255 }
 256
 257 static ssize_t set_number_of_buffers_show(struct device *dev,
 258                                           struct device_attribute *attr,
 259                                           char *buf)
 260 {
 261         struct most_channel *c = to_channel(dev);
 262
 263         return snprintf(buf, PAGE_SIZE, "%d\n", c->cfg.num_buffers);
 264 }
 265
 266 static ssize_t set_buffer_size_show(struct device *dev,
 267                                     struct device_attribute *attr,
 268                                     char *buf)
 269 {
 270         struct most_channel *c = to_channel(dev);
 271
 272         return snprintf(buf, PAGE_SIZE, "%d\n", c->cfg.buffer_size);
 273 }
 274
 275 static ssize_t set_direction_show(struct device *dev,
 276                                   struct device_attribute *attr,
 277                                   char *buf)
 278 {
 279         struct most_channel *c = to_channel(dev);
 280
 281         if (c->cfg.direction & MOST_CH_TX)
 282                 return snprintf(buf, PAGE_SIZE, "tx\n");
 283         else if (c->cfg.direction & MOST_CH_RX)
 284                 return snprintf(buf, PAGE_SIZE, "rx\n");
 285         return snprintf(buf, PAGE_SIZE, "unconfigured\n");
 286 }
 287
 288 static ssize_t set_datatype_show(struct device *dev,
 289                                  struct device_attribute *attr,
 290                                  char *buf)
 291 {
 292         int i;
 293         struct most_channel *c = to_channel(dev);
 294
 295         for (i = 0; i < ARRAY_SIZE(ch_data_type); i++) {
 296                 if (c->cfg.data_type & ch_data_type[i].most_ch_data_type)
 297                         return snprintf(buf, PAGE_SIZE, "%s",
 298                                         ch_data_type[i].name);
 299         }
 300         return snprintf(buf, PAGE_SIZE, "unconfigured\n");
 301 }
 302
 303 static ssize_t set_subbuffer_size_show(struct device *dev,
 304                                        struct device_attribute *attr,
 305                                        char *buf)
 306 {
 307         struct most_channel *c = to_channel(dev);
 308
 309         return snprintf(buf, PAGE_SIZE, "%d\n", c->cfg.subbuffer_size);
 310 }
 311
 312 static ssize_t set_packets_per_xact_show(struct device *dev,
 313                                          struct device_attribute *attr,
 314                                          char *buf)
 315 {
 316         struct most_channel *c = to_channel(dev);
 317
 318         return snprintf(buf, PAGE_SIZE, "%d\n", c->cfg.packets_per_xact);
 319 }
 320
 321 static ssize_t set_dbr_size_show(struct device *dev,
 322                                  struct device_attribute *attr, char *buf)
 323 {
 324         struct most_channel *c = to_channel(dev);
 325
 326         return snprintf(buf, PAGE_SIZE, "%d\n", c->cfg.dbr_size);
 327 }
 328
 329 #define to_dev_attr(a) container_of(a, struct device_attribute, attr)
 330 static umode_t channel_attr_is_visible(struct kobject *kobj,
 331                                        struct attribute *attr, int index)
 332 {
 333         struct device_attribute *dev_attr = to_dev_attr(attr);
 334         struct device *dev = kobj_to_dev(kobj);
 335         struct most_channel *c = to_channel(dev);
 336
 337         if (!strcmp(dev_attr->attr.name, "set_dbr_size") &&
 338             (c->iface->interface != ITYPE_MEDIALB_DIM2))
 339                 return 0;
 340         if (!strcmp(dev_attr->attr.name, "set_packets_per_xact") &&
 341             (c->iface->interface != ITYPE_USB))
 342                 return 0;
 343
 344         return attr->mode;
 345 }
 346
 347 #define DEV_ATTR(_name)  (&dev_attr_##_name.attr)
 348
 349 static DEVICE_ATTR_RO(available_directions);
 350 static DEVICE_ATTR_RO(available_datatypes);
 351 static DEVICE_ATTR_RO(number_of_packet_buffers);
 352 static DEVICE_ATTR_RO(number_of_stream_buffers);
 353 static DEVICE_ATTR_RO(size_of_stream_buffer);
 354 static DEVICE_ATTR_RO(size_of_packet_buffer);
 355 static DEVICE_ATTR_RO(channel_starving);
 356 static DEVICE_ATTR_RO(set_buffer_size);
 357 static DEVICE_ATTR_RO(set_number_of_buffers);
 358 static DEVICE_ATTR_RO(set_direction);
 359 static DEVICE_ATTR_RO(set_datatype);
 360 static DEVICE_ATTR_RO(set_subbuffer_size);
 361 static DEVICE_ATTR_RO(set_packets_per_xact);
 362 static DEVICE_ATTR_RO(set_dbr_size);
 363
 364 static struct attribute *channel_attrs[] = {
 365         DEV_ATTR(available_directions),
 366         DEV_ATTR(available_datatypes),
 367         DEV_ATTR(number_of_packet_buffers),
 368         DEV_ATTR(number_of_stream_buffers),
 369         DEV_ATTR(size_of_stream_buffer),
 370         DEV_ATTR(size_of_packet_buffer),
 371         DEV_ATTR(channel_starving),
 372         DEV_ATTR(set_buffer_size),
 373         DEV_ATTR(set_number_of_buffers),
 374         DEV_ATTR(set_direction),
 375         DEV_ATTR(set_datatype),
 376         DEV_ATTR(set_subbuffer_size),
 377         DEV_ATTR(set_packets_per_xact),
 378         DEV_ATTR(set_dbr_size),
 379         NULL,
 380 };
 381
 382 static struct attribute_group channel_attr_group = {
 383         .attrs = channel_attrs,
 384         .is_visible = channel_attr_is_visible,
 385 };
 386
 387 static const struct attribute_group *channel_attr_groups[] = {
 388         &channel_attr_group,
 389         NULL,
 390 };
 391
 392 static ssize_t description_show(struct device *dev,
 393                                 struct device_attribute *attr,
 394                                 char *buf)
 395 {
 396         struct most_interface *iface = dev_get_drvdata(dev);
 397
 398         return snprintf(buf, PAGE_SIZE, "%s\n", iface->description);
 399 }
 400
 401 static ssize_t interface_show(struct device *dev,
 402                               struct device_attribute *attr,
 403                               char *buf)
 404 {
 405         struct most_interface *iface = dev_get_drvdata(dev);
 406
 407         switch (iface->interface) {
 408         case ITYPE_LOOPBACK:
 409                 return snprintf(buf, PAGE_SIZE, "loopback\n");
 410         case ITYPE_I2C:
 411                 return snprintf(buf, PAGE_SIZE, "i2c\n");
 412         case ITYPE_I2S:
 413                 return snprintf(buf, PAGE_SIZE, "i2s\n");
 414         case ITYPE_TSI:
 415                 return snprintf(buf, PAGE_SIZE, "tsi\n");
 416         case ITYPE_HBI:
 417                 return snprintf(buf, PAGE_SIZE, "hbi\n");
 418         case ITYPE_MEDIALB_DIM:
 419                 return snprintf(buf, PAGE_SIZE, "mlb_dim\n");
 420         case ITYPE_MEDIALB_DIM2:
 421                 return snprintf(buf, PAGE_SIZE, "mlb_dim2\n");
 422         case ITYPE_USB:
 423                 return snprintf(buf, PAGE_SIZE, "usb\n");
 424         case ITYPE_PCIE:
 425                 return snprintf(buf, PAGE_SIZE, "pcie\n");
 426         }
 427         return snprintf(buf, PAGE_SIZE, "unknown\n");
 428 }
 429
 430 static DEVICE_ATTR_RO(description);
 431 static DEVICE_ATTR_RO(interface);
 432
 433 static struct attribute *interface_attrs[] = {
 434         DEV_ATTR(description),
 435         DEV_ATTR(interface),
 436         NULL,
 437 };
 438
 439 static struct attribute_group interface_attr_group = {
 440         .attrs = interface_attrs,
 441 };
 442
 443 static const struct attribute_group *interface_attr_groups[] = {
 444         &interface_attr_group,
 445         NULL,
 446 };
 447
 448 static struct most_component *match_component(char *name)
 449 {
 450         struct most_component *comp;
 451
 452         list_for_each_entry(comp, &comp_list, list) {
 453                 if (!strcmp(comp->name, name))
 454                         return comp;
 455         }
 456         return NULL;
 457 }
 458
 459 struct show_links_data {
 460         int offs;
 461         char *buf;
 462 };
 463
 464 static int print_links(struct device *dev, void *data)
 465 {
 466         struct show_links_data *d = data;
 467         int offs = d->offs;
 468         char *buf = d->buf;
 469         struct most_channel *c;
 470         struct most_interface *iface = dev_get_drvdata(dev);
 471
 472         list_for_each_entry(c, &iface->p->channel_list, list) {
 473                 if (c->pipe0.comp) {
 474                         offs += scnprintf(buf + offs,
 475                                          PAGE_SIZE - offs,
 476                                          "%s:%s:%s\n",
 477                                          c->pipe0.comp->name,
 478                                          dev_name(iface->dev),
 479                                          dev_name(&c->dev));
 480                 }
 481                 if (c->pipe1.comp) {
 482                         offs += scnprintf(buf + offs,
 483                                          PAGE_SIZE - offs,
 484                                          "%s:%s:%s\n",
 485                                          c->pipe1.comp->name,
 486                                          dev_name(iface->dev),
 487                                          dev_name(&c->dev));
 488                 }
 489         }
 490         d->offs = offs;
 491         return 0;
 492 }
 493
 494 static int most_match(struct device *dev, struct device_driver *drv)
 495 {
 496         if (!strcmp(dev_name(dev), "most"))
 497                 return 0;
 498         else
 499                 return 1;
 500 }
 501
 502 static struct bus_type mostbus = {
 503         .name = "most",
 504         .match = most_match,
 505 };
 506
 507 static ssize_t links_show(struct device_driver *drv, char *buf)
 508 {
 509         struct show_links_data d = { .buf = buf };
 510
 511         bus_for_each_dev(&mostbus, NULL, &d, print_links);
 512         return d.offs;
 513 }
 514
 515 static ssize_t components_show(struct device_driver *drv, char *buf)
 516 {
 517         struct most_component *comp;
 518         int offs = 0;
 519
 520         list_for_each_entry(comp, &comp_list, list) {
 521                 offs += scnprintf(buf + offs, PAGE_SIZE - offs, "%s\n",
 522                                  comp->name);
 523         }
 524         return offs;
 525 }
 526
 527 /**
 528  * get_channel - get pointer to channel
 529  * @mdev: name of the device interface
 530  * @mdev_ch: name of channel
 531  */
 532 static struct most_channel *get_channel(char *mdev, char *mdev_ch)
 533 {
 534         struct device *dev = NULL;
 535         struct most_interface *iface;
 536         struct most_channel *c, *tmp;
 537
 538         dev = bus_find_device_by_name(&mostbus, NULL, mdev);
 539         if (!dev)
 540                 return NULL;
 541         put_device(dev);
 542         iface = dev_get_drvdata(dev);
 543         list_for_each_entry_safe(c, tmp, &iface->p->channel_list, list) {
 544                 if (!strcmp(dev_name(&c->dev), mdev_ch))
 545                         return c;
 546         }
 547         return NULL;
 548 }
 549
 550 static
 551 inline int link_channel_to_component(struct most_channel *c,
 552                                      struct most_component *comp,
 553                                      char *name,
 554                                      char *comp_param)
 555 {
 556         int ret;
 557         struct most_component **comp_ptr;
 558
 559         if (!c->pipe0.comp)
 560                 comp_ptr = &c->pipe0.comp;
 561         else if (!c->pipe1.comp)
 562                 comp_ptr = &c->pipe1.comp;
 563         else
 564                 return -ENOSPC;
 565
 566         *comp_ptr = comp;
 567         ret = comp->probe_channel(c->iface, c->channel_id, &c->cfg, name,
 568                                   comp_param);
 569         if (ret) {
 570                 *comp_ptr = NULL;
 571                 return ret;
 572         }
 573         return 0;
 574 }
 575
 576 int most_set_cfg_buffer_size(char *mdev, char *mdev_ch, u16 val)
 577 {
 578         struct most_channel *c = get_channel(mdev, mdev_ch);
 579
 580         if (!c)
 581                 return -ENODEV;
 582         c->cfg.buffer_size = val;
 583         return 0;
 584 }
 585
 586 int most_set_cfg_subbuffer_size(char *mdev, char *mdev_ch, u16 val)
 587 {
 588         struct most_channel *c = get_channel(mdev, mdev_ch);
 589
 590         if (!c)
 591                 return -ENODEV;
 592         c->cfg.subbuffer_size = val;
 593         return 0;
 594 }
 595
 596 int most_set_cfg_dbr_size(char *mdev, char *mdev_ch, u16 val)
 597 {
 598         struct most_channel *c = get_channel(mdev, mdev_ch);
 599
 600         if (!c)
 601                 return -ENODEV;
 602         c->cfg.dbr_size = val;
 603         return 0;
 604 }
 605
 606 int most_set_cfg_num_buffers(char *mdev, char *mdev_ch, u16 val)
 607 {
 608         struct most_channel *c = get_channel(mdev, mdev_ch);
 609
 610         if (!c)
 611                 return -ENODEV;
 612         c->cfg.num_buffers = val;
 613         return 0;
 614 }
 615
 616 int most_set_cfg_datatype(char *mdev, char *mdev_ch, char *buf)
 617 {
 618         int i;
 619         struct most_channel *c = get_channel(mdev, mdev_ch);
 620
 621         if (!c)
 622                 return -ENODEV;
 623         for (i = 0; i < ARRAY_SIZE(ch_data_type); i++) {
 624                 if (!strcmp(buf, ch_data_type[i].name)) {
 625                         c->cfg.data_type = ch_data_type[i].most_ch_data_type;
 626                         break;
 627                 }
 628         }
 629
 630         if (i == ARRAY_SIZE(ch_data_type))
 631                 dev_warn(&c->dev, "Invalid attribute settings\n");
 632         return 0;
 633 }
 634
 635 int most_set_cfg_direction(char *mdev, char *mdev_ch, char *buf)
 636 {
 637         struct most_channel *c = get_channel(mdev, mdev_ch);
 638
 639         if (!c)
 640                 return -ENODEV;
 641         if (!strcmp(buf, "dir_rx")) {
 642                 c->cfg.direction = MOST_CH_RX;
 643         } else if (!strcmp(buf, "rx")) {
 644                 c->cfg.direction = MOST_CH_RX;
 645         } else if (!strcmp(buf, "dir_tx")) {
 646                 c->cfg.direction = MOST_CH_TX;
 647         } else if (!strcmp(buf, "tx")) {
 648                 c->cfg.direction = MOST_CH_TX;
 649         } else {
 650                 dev_err(&c->dev, "Invalid direction\n");
 651                 return -ENODATA;
 652         }
 653         return 0;
 654 }
 655
 656 int most_set_cfg_packets_xact(char *mdev, char *mdev_ch, u16 val)
 657 {
 658         struct most_channel *c = get_channel(mdev, mdev_ch);
 659
 660         if (!c)
 661                 return -ENODEV;
 662         c->cfg.packets_per_xact = val;
 663         return 0;
 664 }
 665
 666 int most_cfg_complete(char *comp_name)
 667 {
 668         struct most_component *comp;
 669
 670         comp = match_component(comp_name);
 671         if (!comp)
 672                 return -ENODEV;
 673
 674         return comp->cfg_complete();
 675 }
 676
 677 int most_add_link(char *mdev, char *mdev_ch, char *comp_name, char *link_name,
 678                   char *comp_param)
 679 {
 680         struct most_channel *c = get_channel(mdev, mdev_ch);
 681         struct most_component *comp = match_component(comp_name);
 682
 683         if (!c || !comp)
 684                 return -ENODEV;
 685
 686         return link_channel_to_component(c, comp, link_name, comp_param);
 687 }
 688
 689 int most_remove_link(char *mdev, char *mdev_ch, char *comp_name)
 690 {
 691         struct most_channel *c;
 692         struct most_component *comp;
 693
 694         comp = match_component(comp_name);
 695         if (!comp)
 696                 return -ENODEV;
 697         c = get_channel(mdev, mdev_ch);
 698         if (!c)
 699                 return -ENODEV;
 700
 701         if (comp->disconnect_channel(c->iface, c->channel_id))
 702                 return -EIO;
 703         if (c->pipe0.comp == comp)
 704                 c->pipe0.comp = NULL;
 705         if (c->pipe1.comp == comp)
 706                 c->pipe1.comp = NULL;
 707         return 0;
 708 }
 709
 710 #define DRV_ATTR(_name)  (&driver_attr_##_name.attr)
 711
 712 static DRIVER_ATTR_RO(links);
 713 static DRIVER_ATTR_RO(components);
 714
 715 static struct attribute *mc_attrs[] = {
 716         DRV_ATTR(links),
 717         DRV_ATTR(components),
 718         NULL,
 719 };
 720
 721 static struct attribute_group mc_attr_group = {
 722         .attrs = mc_attrs,
 723 };
 724
 725 static const struct attribute_group *mc_attr_groups[] = {
 726         &mc_attr_group,
 727         NULL,
 728 };
 729
 730 static struct device_driver mostbus_driver = {
 731         .name = "most_core",
 732         .bus = &mostbus,
 733         .groups = mc_attr_groups,
 734 };
 735
 736 static inline void trash_mbo(struct mbo *mbo)
 737 {
 738         unsigned long flags;
 739         struct most_channel *c = mbo->context;
 740
 741         spin_lock_irqsave(&c->fifo_lock, flags);
 742         list_add(&mbo->list, &c->trash_fifo);
 743         spin_unlock_irqrestore(&c->fifo_lock, flags);
 744 }
 745
 746 static bool hdm_mbo_ready(struct most_channel *c)
 747 {
 748         bool empty;
 749
 750         if (c->enqueue_halt)
 751                 return false;
 752
 753         spin_lock_irq(&c->fifo_lock);
 754         empty = list_empty(&c->halt_fifo);
 755         spin_unlock_irq(&c->fifo_lock);
 756
 757         return !empty;
 758 }
 759
 760 static void nq_hdm_mbo(struct mbo *mbo)
 761 {
 762         unsigned long flags;
 763         struct most_channel *c = mbo->context;
 764
 765         spin_lock_irqsave(&c->fifo_lock, flags);
 766         list_add_tail(&mbo->list, &c->halt_fifo);
 767         spin_unlock_irqrestore(&c->fifo_lock, flags);
 768         wake_up_interruptible(&c->hdm_fifo_wq);
 769 }
 770
 771 static int hdm_enqueue_thread(void *data)
 772 {
 773         struct most_channel *c = data;
 774         struct mbo *mbo;
 775         int ret;
 776         typeof(c->iface->enqueue) enqueue = c->iface->enqueue;
 777
 778         while (likely(!kthread_should_stop())) {
 779                 wait_event_interruptible(c->hdm_fifo_wq,
 780                                          hdm_mbo_ready(c) ||
 781                                          kthread_should_stop());
 782
 783                 mutex_lock(&c->nq_mutex);
 784                 spin_lock_irq(&c->fifo_lock);
 785                 if (unlikely(c->enqueue_halt || list_empty(&c->halt_fifo))) {
 786                         spin_unlock_irq(&c->fifo_lock);
 787                         mutex_unlock(&c->nq_mutex);
 788                         continue;
 789                 }
 790
 791                 mbo = list_pop_mbo(&c->halt_fifo);
 792                 spin_unlock_irq(&c->fifo_lock);
 793
 794                 if (c->cfg.direction == MOST_CH_RX)
 795                         mbo->buffer_length = c->cfg.buffer_size;
 796
 797                 ret = enqueue(mbo->ifp, mbo->hdm_channel_id, mbo);
 798                 mutex_unlock(&c->nq_mutex);
 799
 800                 if (unlikely(ret)) {
 801                         dev_err(&c->dev, "Buffer enqueue failed\n");
 802                         nq_hdm_mbo(mbo);
 803                         c->hdm_enqueue_task = NULL;
 804                         return 0;
 805                 }
 806         }
 807
 808         return 0;
 809 }
 810
 811 static int run_enqueue_thread(struct most_channel *c, int channel_id)
 812 {
 813         struct task_struct *task =
 814                 kthread_run(hdm_enqueue_thread, c, "hdm_fifo_%d",
 815                             channel_id);
 816
 817         if (IS_ERR(task))
 818                 return PTR_ERR(task);
 819
 820         c->hdm_enqueue_task = task;
 821         return 0;
 822 }
 823
 824 /**
 825  * arm_mbo - recycle MBO for further usage
 826  * @mbo: most buffer
 827  *
 828  * This puts an MBO back to the list to have it ready for up coming
 829  * tx transactions.
 830  *
 831  * In case the MBO belongs to a channel that recently has been
 832  * poisoned, the MBO is scheduled to be trashed.
 833  * Calls the completion handler of an attached component.
 834  */
 835 static void arm_mbo(struct mbo *mbo)
 836 {
 837         unsigned long flags;
 838         struct most_channel *c;
 839
 840         c = mbo->context;
 841
 842         if (c->is_poisoned) {
 843                 trash_mbo(mbo);
 844                 return;
 845         }
 846
 847         spin_lock_irqsave(&c->fifo_lock, flags);
 848         ++*mbo->num_buffers_ptr;
 849         list_add_tail(&mbo->list, &c->fifo);
 850         spin_unlock_irqrestore(&c->fifo_lock, flags);
 851
 852         if (c->pipe0.refs && c->pipe0.comp->tx_completion)
 853                 c->pipe0.comp->tx_completion(c->iface, c->channel_id);
 854
 855         if (c->pipe1.refs && c->pipe1.comp->tx_completion)
 856                 c->pipe1.comp->tx_completion(c->iface, c->channel_id);
 857 }
 858
 859 /**
 860  * arm_mbo_chain - helper function that arms an MBO chain for the HDM
 861  * @c: pointer to interface channel
 862  * @dir: direction of the channel
 863  * @compl: pointer to completion function
 864  *
 865  * This allocates buffer objects including the containing DMA coherent
 866  * buffer and puts them in the fifo.
 867  * Buffers of Rx channels are put in the kthread fifo, hence immediately
 868  * submitted to the HDM.
 869  *
 870  * Returns the number of allocated and enqueued MBOs.
 871  */
 872 static int arm_mbo_chain(struct most_channel *c, int dir,
 873                          void (*compl)(struct mbo *))
 874 {
 875         unsigned int i;
 876         struct mbo *mbo;
 877         unsigned long flags;
 878         u32 coherent_buf_size = c->cfg.buffer_size + c->cfg.extra_len;
 879
 880         atomic_set(&c->mbo_nq_level, 0);
 881
 882         for (i = 0; i < c->cfg.num_buffers; i++) {
 883                 mbo = kzalloc(sizeof(*mbo), GFP_KERNEL);
 884                 if (!mbo)
 885                         goto flush_fifos;
 886
 887                 mbo->context = c;
 888                 mbo->ifp = c->iface;
 889                 mbo->hdm_channel_id = c->channel_id;
 890                 if (c->iface->dma_alloc) {
 891                         mbo->virt_address =
 892                                 c->iface->dma_alloc(mbo, coherent_buf_size);
 893                 } else {
 894                         mbo->virt_address =
 895                                 kzalloc(coherent_buf_size, GFP_KERNEL);
 896                 }
 897                 if (!mbo->virt_address)
 898                         goto release_mbo;
 899
 900                 mbo->complete = compl;
 901                 mbo->num_buffers_ptr = &dummy_num_buffers;
 902                 if (dir == MOST_CH_RX) {
 903                         nq_hdm_mbo(mbo);
 904                         atomic_inc(&c->mbo_nq_level);
 905                 } else {
 906                         spin_lock_irqsave(&c->fifo_lock, flags);
 907                         list_add_tail(&mbo->list, &c->fifo);
 908                         spin_unlock_irqrestore(&c->fifo_lock, flags);
 909                 }
 910         }
 911         return c->cfg.num_buffers;
 912
 913 release_mbo:
 914         kfree(mbo);
 915
 916 flush_fifos:
 917         flush_channel_fifos(c);
 918         return 0;
 919 }
 920
 921 /**
 922  * most_submit_mbo - submits an MBO to fifo
 923  * @mbo: most buffer
 924  */
 925 void most_submit_mbo(struct mbo *mbo)
 926 {
 927         if (WARN_ONCE(!mbo || !mbo->context,
 928                       "Bad buffer or missing channel reference\n"))
 929                 return;
 930
 931         nq_hdm_mbo(mbo);
 932 }
 933 EXPORT_SYMBOL_GPL(most_submit_mbo);
 934
 935 /**
 936  * most_write_completion - write completion handler
 937  * @mbo: most buffer
 938  *
 939  * This recycles the MBO for further usage. In case the channel has been
 940  * poisoned, the MBO is scheduled to be trashed.
 941  */
 942 static void most_write_completion(struct mbo *mbo)
 943 {
 944         struct most_channel *c;
 945
 946         c = mbo->context;
 947         if (unlikely(c->is_poisoned || (mbo->status == MBO_E_CLOSE)))
 948                 trash_mbo(mbo);
 949         else
 950                 arm_mbo(mbo);
 951 }
 952
 953 int channel_has_mbo(struct most_interface *iface, int id,
 954                     struct most_component *comp)
 955 {
 956         struct most_channel *c = iface->p->channel[id];
 957         unsigned long flags;
 958         int empty;
 959
 960         if (unlikely(!c))
 961                 return -EINVAL;
 962
 963         if (c->pipe0.refs && c->pipe1.refs &&
 964             ((comp == c->pipe0.comp && c->pipe0.num_buffers <= 0) ||
 965              (comp == c->pipe1.comp && c->pipe1.num_buffers <= 0)))
 966                 return 0;
 967
 968         spin_lock_irqsave(&c->fifo_lock, flags);
 969         empty = list_empty(&c->fifo);
 970         spin_unlock_irqrestore(&c->fifo_lock, flags);
 971         return !empty;
 972 }
 973 EXPORT_SYMBOL_GPL(channel_has_mbo);
 974
 975 /**
 976  * most_get_mbo - get pointer to an MBO of pool
 977  * @iface: pointer to interface instance
 978  * @id: channel ID
 979  * @comp: driver component
 980  *
 981  * This attempts to get a free buffer out of the channel fifo.
 982  * Returns a pointer to MBO on success or NULL otherwise.
 983  */
 984 struct mbo *most_get_mbo(struct most_interface *iface, int id,
 985                          struct most_component *comp)
 986 {
 987         struct mbo *mbo;
 988         struct most_channel *c;
 989         unsigned long flags;
 990         int *num_buffers_ptr;
 991
 992         c = iface->p->channel[id];
 993         if (unlikely(!c))
 994                 return NULL;
 995
 996         if (c->pipe0.refs && c->pipe1.refs &&
 997             ((comp == c->pipe0.comp && c->pipe0.num_buffers <= 0) ||
 998              (comp == c->pipe1.comp && c->pipe1.num_buffers <= 0)))
 999                 return NULL;
1000
1001         if (comp == c->pipe0.comp)
1002                 num_buffers_ptr = &c->pipe0.num_buffers;
1003         else if (comp == c->pipe1.comp)
1004                 num_buffers_ptr = &c->pipe1.num_buffers;
1005         else
1006                 num_buffers_ptr = &dummy_num_buffers;
1007
1008         spin_lock_irqsave(&c->fifo_lock, flags);
1009         if (list_empty(&c->fifo)) {
1010                 spin_unlock_irqrestore(&c->fifo_lock, flags);
1011                 return NULL;
1012         }
1013         mbo = list_pop_mbo(&c->fifo);
1014         --*num_buffers_ptr;
1015         spin_unlock_irqrestore(&c->fifo_lock, flags);
1016
1017         mbo->num_buffers_ptr = num_buffers_ptr;
1018         mbo->buffer_length = c->cfg.buffer_size;
1019         return mbo;
1020 }
1021 EXPORT_SYMBOL_GPL(most_get_mbo);
1022
1023 /**
1024  * most_put_mbo - return buffer to pool
1025  * @mbo: most buffer
1026  */
1027 void most_put_mbo(struct mbo *mbo)
1028 {
1029         struct most_channel *c = mbo->context;
1030
1031         if (c->cfg.direction == MOST_CH_TX) {
1032                 arm_mbo(mbo);
1033                 return;
1034         }
1035         nq_hdm_mbo(mbo);
1036         atomic_inc(&c->mbo_nq_level);
1037 }
1038 EXPORT_SYMBOL_GPL(most_put_mbo);
1039
1040 /**
1041  * most_read_completion - read completion handler
1042  * @mbo: most buffer
1043  *
1044  * This function is called by the HDM when data has been received from the
1045  * hardware and copied to the buffer of the MBO.
1046  *
1047  * In case the channel has been poisoned it puts the buffer in the trash queue.
1048  * Otherwise, it passes the buffer to an component for further processing.
1049  */
1050 static void most_read_completion(struct mbo *mbo)
1051 {
1052         struct most_channel *c = mbo->context;
1053
1054         if (unlikely(c->is_poisoned || (mbo->status == MBO_E_CLOSE))) {
1055                 trash_mbo(mbo);
1056                 return;
1057         }
1058
1059         if (mbo->status == MBO_E_INVAL) {
1060                 nq_hdm_mbo(mbo);
1061                 atomic_inc(&c->mbo_nq_level);
1062                 return;
1063         }
1064
1065         if (atomic_sub_and_test(1, &c->mbo_nq_level))
1066                 c->is_starving = 1;
1067
1068         if (c->pipe0.refs && c->pipe0.comp->rx_completion &&
1069             c->pipe0.comp->rx_completion(mbo) == 0)
1070                 return;
1071
1072         if (c->pipe1.refs && c->pipe1.comp->rx_completion &&
1073             c->pipe1.comp->rx_completion(mbo) == 0)
1074                 return;
1075
1076         most_put_mbo(mbo);
1077 }
1078
1079 /**
1080  * most_start_channel - prepares a channel for communication
1081  * @iface: pointer to interface instance
1082  * @id: channel ID
1083  * @comp: driver component
1084  *
1085  * This prepares the channel for usage. Cross-checks whether the
1086  * channel's been properly configured.
1087  *
1088  * Returns 0 on success or error code otherwise.
1089  */
1090 int most_start_channel(struct most_interface *iface, int id,
1091                        struct most_component *comp)
1092 {
1093         int num_buffer;
1094         int ret;
1095         struct most_channel *c = iface->p->channel[id];
1096
1097         if (unlikely(!c))
1098                 return -EINVAL;
1099
1100         mutex_lock(&c->start_mutex);
1101         if (c->pipe0.refs + c->pipe1.refs > 0)
1102                 goto out; /* already started by another component */
1103
1104         if (!try_module_get(iface->mod)) {
1105                 dev_err(&c->dev, "Failed to acquire HDM lock\n");
1106                 mutex_unlock(&c->start_mutex);
1107                 return -ENOLCK;
1108         }
1109
1110         c->cfg.extra_len = 0;
1111         if (c->iface->configure(c->iface, c->channel_id, &c->cfg)) {
1112                 dev_err(&c->dev, "Channel configuration failed. Go check settings...\n");
1113                 ret = -EINVAL;
1114                 goto err_put_module;
1115         }
1116
1117         init_waitqueue_head(&c->hdm_fifo_wq);
1118
1119         if (c->cfg.direction == MOST_CH_RX)
1120                 num_buffer = arm_mbo_chain(c, c->cfg.direction,
1121                                            most_read_completion);
1122         else
1123                 num_buffer = arm_mbo_chain(c, c->cfg.direction,
1124                                            most_write_completion);
1125         if (unlikely(!num_buffer)) {
1126                 ret = -ENOMEM;
1127                 goto err_put_module;
1128         }
1129
1130         ret = run_enqueue_thread(c, id);
1131         if (ret)
1132                 goto err_put_module;
1133
1134         c->is_starving = 0;
1135         c->pipe0.num_buffers = c->cfg.num_buffers / 2;
1136         c->pipe1.num_buffers = c->cfg.num_buffers - c->pipe0.num_buffers;
1137         atomic_set(&c->mbo_ref, num_buffer);
1138
1139 out:
1140         if (comp == c->pipe0.comp)
1141                 c->pipe0.refs++;
1142         if (comp == c->pipe1.comp)
1143                 c->pipe1.refs++;
1144         mutex_unlock(&c->start_mutex);
1145         return 0;
1146
1147 err_put_module:
1148         module_put(iface->mod);
1149         mutex_unlock(&c->start_mutex);
1150         return ret;
1151 }
1152 EXPORT_SYMBOL_GPL(most_start_channel);
1153
1154 /**
1155  * most_stop_channel - stops a running channel
1156  * @iface: pointer to interface instance
1157  * @id: channel ID
1158  * @comp: driver component
1159  */
1160 int most_stop_channel(struct most_interface *iface, int id,
1161                       struct most_component *comp)
1162 {
1163         struct most_channel *c;
1164
1165         if (unlikely((!iface) || (id >= iface->num_channels) || (id < 0))) {
1166                 pr_err("Bad interface or index out of range\n");
1167                 return -EINVAL;
1168         }
1169         c = iface->p->channel[id];
1170         if (unlikely(!c))
1171                 return -EINVAL;
1172
1173         mutex_lock(&c->start_mutex);
1174         if (c->pipe0.refs + c->pipe1.refs >= 2)
1175                 goto out;
1176
1177         if (c->hdm_enqueue_task)
1178                 kthread_stop(c->hdm_enqueue_task);
1179         c->hdm_enqueue_task = NULL;
1180
1181         if (iface->mod)
1182                 module_put(iface->mod);
1183
1184         c->is_poisoned = true;
1185         if (c->iface->poison_channel(c->iface, c->channel_id)) {
1186                 dev_err(&c->dev, "Failed to stop channel %d of interface %s\n", c->channel_id,
1187                         c->iface->description);
1188                 mutex_unlock(&c->start_mutex);
1189                 return -EAGAIN;
1190         }
1191         flush_trash_fifo(c);
1192         flush_channel_fifos(c);
1193
1194 #ifdef CMPL_INTERRUPTIBLE
1195         if (wait_for_completion_interruptible(&c->cleanup)) {
1196                 dev_err(&c->dev, "Interrupted while cleaning up channel %d\n", c->channel_id);
1197                 mutex_unlock(&c->start_mutex);
1198                 return -EINTR;
1199         }
1200 #else
1201         wait_for_completion(&c->cleanup);
1202 #endif
1203         c->is_poisoned = false;
1204
1205 out:
1206         if (comp == c->pipe0.comp)
1207                 c->pipe0.refs--;
1208         if (comp == c->pipe1.comp)
1209                 c->pipe1.refs--;
1210         mutex_unlock(&c->start_mutex);
1211         return 0;
1212 }
1213 EXPORT_SYMBOL_GPL(most_stop_channel);
1214
1215 /**
1216  * most_register_component - registers a driver component with the core
1217  * @comp: driver component
1218  */
1219 int most_register_component(struct most_component *comp)
1220 {
1221         if (!comp) {
1222                 pr_err("Bad component\n");
1223                 return -EINVAL;
1224         }
1225         list_add_tail(&comp->list, &comp_list);
1226         return 0;
1227 }
1228 EXPORT_SYMBOL_GPL(most_register_component);
1229
1230 static int disconnect_channels(struct device *dev, void *data)
1231 {
1232         struct most_interface *iface;
1233         struct most_channel *c, *tmp;
1234         struct most_component *comp = data;
1235
1236         iface = dev_get_drvdata(dev);
1237         list_for_each_entry_safe(c, tmp, &iface->p->channel_list, list) {
1238                 if (c->pipe0.comp == comp || c->pipe1.comp == comp)
1239                         comp->disconnect_channel(c->iface, c->channel_id);
1240                 if (c->pipe0.comp == comp)
1241                         c->pipe0.comp = NULL;
1242                 if (c->pipe1.comp == comp)
1243                         c->pipe1.comp = NULL;
1244         }
1245         return 0;
1246 }
1247
1248 /**
1249  * most_deregister_component - deregisters a driver component with the core
1250  * @comp: driver component
1251  */
1252 int most_deregister_component(struct most_component *comp)
1253 {
1254         if (!comp) {
1255                 pr_err("Bad component\n");
1256                 return -EINVAL;
1257         }
1258
1259         bus_for_each_dev(&mostbus, NULL, comp, disconnect_channels);
1260         list_del(&comp->list);
1261         return 0;
1262 }
1263 EXPORT_SYMBOL_GPL(most_deregister_component);
1264
1265 static void release_channel(struct device *dev)
1266 {
1267         struct most_channel *c = to_channel(dev);
1268
1269         kfree(c);
1270 }
1271
1272 /**
1273  * most_register_interface - registers an interface with core
1274  * @iface: device interface
1275  *
1276  * Allocates and initializes a new interface instance and all of its channels.
1277  * Returns a pointer to kobject or an error pointer.
1278  */
1279 int most_register_interface(struct most_interface *iface)
1280 {
1281         unsigned int i;
1282         int id;
1283         struct most_channel *c;
1284
1285         if (!iface || !iface->enqueue || !iface->configure ||
1286             !iface->poison_channel || (iface->num_channels > MAX_CHANNELS))
1287                 return -EINVAL;
1288
1289         id = ida_simple_get(&mdev_id, 0, 0, GFP_KERNEL);
1290         if (id < 0) {
1291                 dev_err(iface->dev, "Failed to allocate device ID\n");
1292                 return id;
1293         }
1294
1295         iface->p = kzalloc(sizeof(*iface->p), GFP_KERNEL);
1296         if (!iface->p) {
1297                 ida_simple_remove(&mdev_id, id);
1298                 return -ENOMEM;
1299         }
1300
1301         INIT_LIST_HEAD(&iface->p->channel_list);
1302         iface->p->dev_id = id;
1303         strscpy(iface->p->name, iface->description, sizeof(iface->p->name));
1304         iface->dev->bus = &mostbus;
1305         iface->dev->groups = interface_attr_groups;
1306         dev_set_drvdata(iface->dev, iface);
1307         if (device_register(iface->dev)) {
1308                 dev_err(iface->dev, "Failed to register interface device\n");
1309                 kfree(iface->p);
1310                 put_device(iface->dev);
1311                 ida_simple_remove(&mdev_id, id);
1312                 return -ENOMEM;
1313         }
1314
1315         for (i = 0; i < iface->num_channels; i++) {
1316                 const char *name_suffix = iface->channel_vector[i].name_suffix;
1317
1318                 c = kzalloc(sizeof(*c), GFP_KERNEL);
1319                 if (!c)
1320                         goto err_free_resources;
1321                 if (!name_suffix)
1322                         snprintf(c->name, STRING_SIZE, "ch%d", i);
1323                 else
1324                         snprintf(c->name, STRING_SIZE, "%s", name_suffix);
1325                 c->dev.init_name = c->name;
1326                 c->dev.parent = iface->dev;
1327                 c->dev.groups = channel_attr_groups;
1328                 c->dev.release = release_channel;
1329                 iface->p->channel[i] = c;
1330                 c->is_starving = 0;
1331                 c->iface = iface;
1332                 c->channel_id = i;
1333                 c->keep_mbo = false;
1334                 c->enqueue_halt = false;
1335                 c->is_poisoned = false;
1336                 c->cfg.direction = 0;
1337                 c->cfg.data_type = 0;
1338                 c->cfg.num_buffers = 0;
1339                 c->cfg.buffer_size = 0;
1340                 c->cfg.subbuffer_size = 0;
1341                 c->cfg.packets_per_xact = 0;
1342                 spin_lock_init(&c->fifo_lock);
1343                 INIT_LIST_HEAD(&c->fifo);
1344                 INIT_LIST_HEAD(&c->trash_fifo);
1345                 INIT_LIST_HEAD(&c->halt_fifo);
1346                 init_completion(&c->cleanup);
1347                 atomic_set(&c->mbo_ref, 0);
1348                 mutex_init(&c->start_mutex);
1349                 mutex_init(&c->nq_mutex);
1350                 list_add_tail(&c->list, &iface->p->channel_list);
1351                 if (device_register(&c->dev)) {
1352                         dev_err(&c->dev, "Failed to register channel device\n");
1353                         goto err_free_most_channel;
1354                 }
1355         }
1356         most_interface_register_notify(iface->description);
1357         return 0;
1358
1359 err_free_most_channel:
1360         put_device(&c->dev);
1361
1362 err_free_resources:
1363         while (i > 0) {
1364                 c = iface->p->channel[--i];
1365                 device_unregister(&c->dev);
1366         }
1367         kfree(iface->p);
1368         device_unregister(iface->dev);
1369         ida_simple_remove(&mdev_id, id);
1370         return -ENOMEM;
1371 }
1372 EXPORT_SYMBOL_GPL(most_register_interface);
1373
1374 /**
1375  * most_deregister_interface - deregisters an interface with core
1376  * @iface: device interface
1377  *
1378  * Before removing an interface instance from the list, all running
1379  * channels are stopped and poisoned.
1380  */
1381 void most_deregister_interface(struct most_interface *iface)
1382 {
1383         int i;
1384         struct most_channel *c;
1385
1386         for (i = 0; i < iface->num_channels; i++) {
1387                 c = iface->p->channel[i];
1388                 if (c->pipe0.comp)
1389                         c->pipe0.comp->disconnect_channel(c->iface,
1390                                                         c->channel_id);
1391                 if (c->pipe1.comp)
1392                         c->pipe1.comp->disconnect_channel(c->iface,
1393                                                         c->channel_id);
1394                 c->pipe0.comp = NULL;
1395                 c->pipe1.comp = NULL;
1396                 list_del(&c->list);
1397                 device_unregister(&c->dev);
1398         }
1399
1400         ida_simple_remove(&mdev_id, iface->p->dev_id);
1401         kfree(iface->p);
1402         device_unregister(iface->dev);
1403 }
1404 EXPORT_SYMBOL_GPL(most_deregister_interface);
1405
1406 /**
1407  * most_stop_enqueue - prevents core from enqueueing MBOs
1408  * @iface: pointer to interface
1409  * @id: channel id
1410  *
1411  * This is called by an HDM that _cannot_ attend to its duties and
1412  * is imminent to get run over by the core. The core is not going to
1413  * enqueue any further packets unless the flagging HDM calls
1414  * most_resume enqueue().
1415  */
1416 void most_stop_enqueue(struct most_interface *iface, int id)
1417 {
1418         struct most_channel *c = iface->p->channel[id];
1419
1420         if (!c)
1421                 return;
1422
1423         mutex_lock(&c->nq_mutex);
1424         c->enqueue_halt = true;
1425         mutex_unlock(&c->nq_mutex);
1426 }
1427 EXPORT_SYMBOL_GPL(most_stop_enqueue);
1428
1429 /**
1430  * most_resume_enqueue - allow core to enqueue MBOs again
1431  * @iface: pointer to interface
1432  * @id: channel id
1433  *
1434  * This clears the enqueue halt flag and enqueues all MBOs currently
1435  * sitting in the wait fifo.
1436  */
1437 void most_resume_enqueue(struct most_interface *iface, int id)
1438 {
1439         struct most_channel *c = iface->p->channel[id];
1440
1441         if (!c)
1442                 return;
1443
1444         mutex_lock(&c->nq_mutex);
1445         c->enqueue_halt = false;
1446         mutex_unlock(&c->nq_mutex);
1447
1448         wake_up_interruptible(&c->hdm_fifo_wq);
1449 }
1450 EXPORT_SYMBOL_GPL(most_resume_enqueue);
1451
1452 static int __init most_init(void)
1453 {
1454         int err;
1455
1456         INIT_LIST_HEAD(&comp_list);
1457         ida_init(&mdev_id);
1458
1459         err = bus_register(&mostbus);
1460         if (err) {
1461                 pr_err("Failed to register most bus\n");
1462                 return err;
1463         }
1464         err = driver_register(&mostbus_driver);
1465         if (err) {
1466                 pr_err("Failed to register core driver\n");
1467                 goto err_unregister_bus;
1468         }
1469         configfs_init();
1470         return 0;
1471
1472 err_unregister_bus:
1473         bus_unregister(&mostbus);
1474         return err;
1475 }
1476
1477 static void __exit most_exit(void)
1478 {
1479         driver_unregister(&mostbus_driver);
1480         bus_unregister(&mostbus);
1481         ida_destroy(&mdev_id);
1482 }
1483
1484 subsys_initcall(most_init);
1485 module_exit(most_exit);
1486 MODULE_LICENSE("GPL");
1487 MODULE_AUTHOR("Christian Gromm <christian.gromm@microchip.com>");
1488 MODULE_DESCRIPTION("Core module of stacked MOST Linux driver");