drivers/staging/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
  24 #include "most.h"
  25
  26 #define MAX_CHANNELS    64
  27 #define STRING_SIZE     80
  28
  29 static struct ida mdev_id;
  30 static int dummy_num_buffers;
  31
  32 static struct mostcore {
  33         struct device dev;
  34         struct device_driver drv;
  35         struct bus_type bus;
  36         struct list_head comp_list;
  37 } mc;
  38
  39 #define to_driver(d) container_of(d, struct mostcore, drv)
  40
  41 struct pipe {
  42         struct most_component *comp;
  43         int refs;
  44         int num_buffers;
  45 };
  46
  47 struct most_channel {
  48         struct device dev;
  49         struct completion cleanup;
  50         atomic_t mbo_ref;
  51         atomic_t mbo_nq_level;
  52         u16 channel_id;
  53         char name[STRING_SIZE];
  54         bool is_poisoned;
  55         struct mutex start_mutex; /* channel activation synchronization */
  56         struct mutex nq_mutex; /* nq thread synchronization */
  57         int is_starving;
  58         struct most_interface *iface;
  59         struct most_channel_config cfg;
  60         bool keep_mbo;
  61         bool enqueue_halt;
  62         struct list_head fifo;
  63         spinlock_t fifo_lock; /* fifo access synchronization */
  64         struct list_head halt_fifo;
  65         struct list_head list;
  66         struct pipe pipe0;
  67         struct pipe pipe1;
  68         struct list_head trash_fifo;
  69         struct task_struct *hdm_enqueue_task;
  70         wait_queue_head_t hdm_fifo_wq;
  71
  72 };
  73
  74 #define to_channel(d) container_of(d, struct most_channel, dev)
  75
  76 struct interface_private {
  77         int dev_id;
  78         char name[STRING_SIZE];
  79         struct most_channel *channel[MAX_CHANNELS];
  80         struct list_head channel_list;
  81 };
  82
  83 static const struct {
  84         int most_ch_data_type;
  85         const char *name;
  86 } ch_data_type[] = {
  87         { MOST_CH_CONTROL, "control" },
  88         { MOST_CH_ASYNC, "async" },
  89         { MOST_CH_SYNC, "sync" },
  90         { MOST_CH_ISOC, "isoc"},
  91         { MOST_CH_ISOC, "isoc_avp"},
  92 };
  93
  94 /**
  95  * list_pop_mbo - retrieves the first MBO of the list and removes it
  96  * @ptr: the list head to grab the MBO from.
  97  */
  98 #define list_pop_mbo(ptr)                                               \
  99 ({                                                                      \
 100         struct mbo *_mbo = list_first_entry(ptr, struct mbo, list);     \
 101         list_del(&_mbo->list);                                          \
 102         _mbo;                                                           \
 103 })
 104
 105 /**
 106  * most_free_mbo_coherent - free an MBO and its coherent buffer
 107  * @mbo: most buffer
 108  */
 109 static void most_free_mbo_coherent(struct mbo *mbo)
 110 {
 111         struct most_channel *c = mbo->context;
 112         u16 const coherent_buf_size = c->cfg.buffer_size + c->cfg.extra_len;
 113
 114         if (c->iface->dma_free)
 115                 c->iface->dma_free(mbo, coherent_buf_size);
 116         else
 117                 kfree(mbo->virt_address);
 118         kfree(mbo);
 119         if (atomic_sub_and_test(1, &c->mbo_ref))
 120                 complete(&c->cleanup);
 121 }
 122
 123 /**
 124  * flush_channel_fifos - clear the channel fifos
 125  * @c: pointer to channel object
 126  */
 127 static void flush_channel_fifos(struct most_channel *c)
 128 {
 129         unsigned long flags, hf_flags;
 130         struct mbo *mbo, *tmp;
 131
 132         if (list_empty(&c->fifo) && list_empty(&c->halt_fifo))
 133                 return;
 134
 135         spin_lock_irqsave(&c->fifo_lock, flags);
 136         list_for_each_entry_safe(mbo, tmp, &c->fifo, list) {
 137                 list_del(&mbo->list);
 138                 spin_unlock_irqrestore(&c->fifo_lock, flags);
 139                 most_free_mbo_coherent(mbo);
 140                 spin_lock_irqsave(&c->fifo_lock, flags);
 141         }
 142         spin_unlock_irqrestore(&c->fifo_lock, flags);
 143
 144         spin_lock_irqsave(&c->fifo_lock, hf_flags);
 145         list_for_each_entry_safe(mbo, tmp, &c->halt_fifo, list) {
 146                 list_del(&mbo->list);
 147                 spin_unlock_irqrestore(&c->fifo_lock, hf_flags);
 148                 most_free_mbo_coherent(mbo);
 149                 spin_lock_irqsave(&c->fifo_lock, hf_flags);
 150         }
 151         spin_unlock_irqrestore(&c->fifo_lock, hf_flags);
 152
 153         if (unlikely((!list_empty(&c->fifo) || !list_empty(&c->halt_fifo))))
 154                 dev_warn(&mc.dev, "fifo | trash fifo not empty\n");
 155 }
 156
 157 /**
 158  * flush_trash_fifo - clear the trash fifo
 159  * @c: pointer to channel object
 160  */
 161 static int flush_trash_fifo(struct most_channel *c)
 162 {
 163         struct mbo *mbo, *tmp;
 164         unsigned long flags;
 165
 166         spin_lock_irqsave(&c->fifo_lock, flags);
 167         list_for_each_entry_safe(mbo, tmp, &c->trash_fifo, list) {
 168                 list_del(&mbo->list);
 169                 spin_unlock_irqrestore(&c->fifo_lock, flags);
 170                 most_free_mbo_coherent(mbo);
 171                 spin_lock_irqsave(&c->fifo_lock, flags);
 172         }
 173         spin_unlock_irqrestore(&c->fifo_lock, flags);
 174         return 0;
 175 }
 176
 177 static ssize_t available_directions_show(struct device *dev,
 178                                          struct device_attribute *attr,
 179                                          char *buf)
 180 {
 181         struct most_channel *c = to_channel(dev);
 182         unsigned int i = c->channel_id;
 183
 184         strcpy(buf, "");
 185         if (c->iface->channel_vector[i].direction & MOST_CH_RX)
 186                 strcat(buf, "rx ");
 187         if (c->iface->channel_vector[i].direction & MOST_CH_TX)
 188                 strcat(buf, "tx ");
 189         strcat(buf, "\n");
 190         return strlen(buf);
 191 }
 192
 193 static ssize_t available_datatypes_show(struct device *dev,
 194                                         struct device_attribute *attr,
 195                                         char *buf)
 196 {
 197         struct most_channel *c = to_channel(dev);
 198         unsigned int i = c->channel_id;
 199
 200         strcpy(buf, "");
 201         if (c->iface->channel_vector[i].data_type & MOST_CH_CONTROL)
 202                 strcat(buf, "control ");
 203         if (c->iface->channel_vector[i].data_type & MOST_CH_ASYNC)
 204                 strcat(buf, "async ");
 205         if (c->iface->channel_vector[i].data_type & MOST_CH_SYNC)
 206                 strcat(buf, "sync ");
 207         if (c->iface->channel_vector[i].data_type & MOST_CH_ISOC)
 208                 strcat(buf, "isoc ");
 209         strcat(buf, "\n");
 210         return strlen(buf);
 211 }
 212
 213 static ssize_t number_of_packet_buffers_show(struct device *dev,
 214                                              struct device_attribute *attr,
 215                                              char *buf)
 216 {
 217         struct most_channel *c = to_channel(dev);
 218         unsigned int i = c->channel_id;
 219
 220         return snprintf(buf, PAGE_SIZE, "%d\n",
 221                         c->iface->channel_vector[i].num_buffers_packet);
 222 }
 223
 224 static ssize_t number_of_stream_buffers_show(struct device *dev,
 225                                              struct device_attribute *attr,
 226                                              char *buf)
 227 {
 228         struct most_channel *c = to_channel(dev);
 229         unsigned int i = c->channel_id;
 230
 231         return snprintf(buf, PAGE_SIZE, "%d\n",
 232                         c->iface->channel_vector[i].num_buffers_streaming);
 233 }
 234
 235 static ssize_t size_of_packet_buffer_show(struct device *dev,
 236                                           struct device_attribute *attr,
 237                                           char *buf)
 238 {
 239         struct most_channel *c = to_channel(dev);
 240         unsigned int i = c->channel_id;
 241
 242         return snprintf(buf, PAGE_SIZE, "%d\n",
 243                         c->iface->channel_vector[i].buffer_size_packet);
 244 }
 245
 246 static ssize_t size_of_stream_buffer_show(struct device *dev,
 247                                           struct device_attribute *attr,
 248                                           char *buf)
 249 {
 250         struct most_channel *c = to_channel(dev);
 251         unsigned int i = c->channel_id;
 252
 253         return snprintf(buf, PAGE_SIZE, "%d\n",
 254                         c->iface->channel_vector[i].buffer_size_streaming);
 255 }
 256
 257 static ssize_t channel_starving_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->is_starving);
 264 }
 265
 266 static ssize_t set_number_of_buffers_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.num_buffers);
 273 }
 274
 275 static ssize_t set_buffer_size_show(struct device *dev,
 276                                     struct device_attribute *attr,
 277                                     char *buf)
 278 {
 279         struct most_channel *c = to_channel(dev);
 280
 281         return snprintf(buf, PAGE_SIZE, "%d\n", c->cfg.buffer_size);
 282 }
 283
 284 static ssize_t set_direction_show(struct device *dev,
 285                                   struct device_attribute *attr,
 286                                   char *buf)
 287 {
 288         struct most_channel *c = to_channel(dev);
 289
 290         if (c->cfg.direction & MOST_CH_TX)
 291                 return snprintf(buf, PAGE_SIZE, "tx\n");
 292         else if (c->cfg.direction & MOST_CH_RX)
 293                 return snprintf(buf, PAGE_SIZE, "rx\n");
 294         return snprintf(buf, PAGE_SIZE, "unconfigured\n");
 295 }
 296
 297 static ssize_t set_datatype_show(struct device *dev,
 298                                  struct device_attribute *attr,
 299                                  char *buf)
 300 {
 301         int i;
 302         struct most_channel *c = to_channel(dev);
 303
 304         for (i = 0; i < ARRAY_SIZE(ch_data_type); i++) {
 305                 if (c->cfg.data_type & ch_data_type[i].most_ch_data_type)
 306                         return snprintf(buf, PAGE_SIZE, "%s",
 307                                         ch_data_type[i].name);
 308         }
 309         return snprintf(buf, PAGE_SIZE, "unconfigured\n");
 310 }
 311
 312 static ssize_t set_subbuffer_size_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.subbuffer_size);
 319 }
 320
 321 static ssize_t set_packets_per_xact_show(struct device *dev,
 322                                          struct device_attribute *attr,
 323                                          char *buf)
 324 {
 325         struct most_channel *c = to_channel(dev);
 326
 327         return snprintf(buf, PAGE_SIZE, "%d\n", c->cfg.packets_per_xact);
 328 }
 329
 330 static ssize_t set_dbr_size_show(struct device *dev,
 331                                  struct device_attribute *attr, char *buf)
 332 {
 333         struct most_channel *c = to_channel(dev);
 334
 335         return snprintf(buf, PAGE_SIZE, "%d\n", c->cfg.dbr_size);
 336 }
 337
 338 #define to_dev_attr(a) container_of(a, struct device_attribute, attr)
 339 static umode_t channel_attr_is_visible(struct kobject *kobj,
 340                                        struct attribute *attr, int index)
 341 {
 342         struct device_attribute *dev_attr = to_dev_attr(attr);
 343         struct device *dev = kobj_to_dev(kobj);
 344         struct most_channel *c = to_channel(dev);
 345
 346         if (!strcmp(dev_attr->attr.name, "set_dbr_size") &&
 347             (c->iface->interface != ITYPE_MEDIALB_DIM2))
 348                 return 0;
 349         if (!strcmp(dev_attr->attr.name, "set_packets_per_xact") &&
 350             (c->iface->interface != ITYPE_USB))
 351                 return 0;
 352
 353         return attr->mode;
 354 }
 355
 356 #define DEV_ATTR(_name)  (&dev_attr_##_name.attr)
 357
 358 static DEVICE_ATTR_RO(available_directions);
 359 static DEVICE_ATTR_RO(available_datatypes);
 360 static DEVICE_ATTR_RO(number_of_packet_buffers);
 361 static DEVICE_ATTR_RO(number_of_stream_buffers);
 362 static DEVICE_ATTR_RO(size_of_stream_buffer);
 363 static DEVICE_ATTR_RO(size_of_packet_buffer);
 364 static DEVICE_ATTR_RO(channel_starving);
 365 static DEVICE_ATTR_RO(set_buffer_size);
 366 static DEVICE_ATTR_RO(set_number_of_buffers);
 367 static DEVICE_ATTR_RO(set_direction);
 368 static DEVICE_ATTR_RO(set_datatype);
 369 static DEVICE_ATTR_RO(set_subbuffer_size);
 370 static DEVICE_ATTR_RO(set_packets_per_xact);
 371 static DEVICE_ATTR_RO(set_dbr_size);
 372
 373 static struct attribute *channel_attrs[] = {
 374         DEV_ATTR(available_directions),
 375         DEV_ATTR(available_datatypes),
 376         DEV_ATTR(number_of_packet_buffers),
 377         DEV_ATTR(number_of_stream_buffers),
 378         DEV_ATTR(size_of_stream_buffer),
 379         DEV_ATTR(size_of_packet_buffer),
 380         DEV_ATTR(channel_starving),
 381         DEV_ATTR(set_buffer_size),
 382         DEV_ATTR(set_number_of_buffers),
 383         DEV_ATTR(set_direction),
 384         DEV_ATTR(set_datatype),
 385         DEV_ATTR(set_subbuffer_size),
 386         DEV_ATTR(set_packets_per_xact),
 387         DEV_ATTR(set_dbr_size),
 388         NULL,
 389 };
 390
 391 static struct attribute_group channel_attr_group = {
 392         .attrs = channel_attrs,
 393         .is_visible = channel_attr_is_visible,
 394 };
 395
 396 static const struct attribute_group *channel_attr_groups[] = {
 397         &channel_attr_group,
 398         NULL,
 399 };
 400
 401 static ssize_t description_show(struct device *dev,
 402                                 struct device_attribute *attr,
 403                                 char *buf)
 404 {
 405         struct most_interface *iface = to_most_interface(dev);
 406
 407         return snprintf(buf, PAGE_SIZE, "%s\n", iface->description);
 408 }
 409
 410 static ssize_t interface_show(struct device *dev,
 411                               struct device_attribute *attr,
 412                               char *buf)
 413 {
 414         struct most_interface *iface = to_most_interface(dev);
 415
 416         switch (iface->interface) {
 417         case ITYPE_LOOPBACK:
 418                 return snprintf(buf, PAGE_SIZE, "loopback\n");
 419         case ITYPE_I2C:
 420                 return snprintf(buf, PAGE_SIZE, "i2c\n");
 421         case ITYPE_I2S:
 422                 return snprintf(buf, PAGE_SIZE, "i2s\n");
 423         case ITYPE_TSI:
 424                 return snprintf(buf, PAGE_SIZE, "tsi\n");
 425         case ITYPE_HBI:
 426                 return snprintf(buf, PAGE_SIZE, "hbi\n");
 427         case ITYPE_MEDIALB_DIM:
 428                 return snprintf(buf, PAGE_SIZE, "mlb_dim\n");
 429         case ITYPE_MEDIALB_DIM2:
 430                 return snprintf(buf, PAGE_SIZE, "mlb_dim2\n");
 431         case ITYPE_USB:
 432                 return snprintf(buf, PAGE_SIZE, "usb\n");
 433         case ITYPE_PCIE:
 434                 return snprintf(buf, PAGE_SIZE, "pcie\n");
 435         }
 436         return snprintf(buf, PAGE_SIZE, "unknown\n");
 437 }
 438
 439 static DEVICE_ATTR_RO(description);
 440 static DEVICE_ATTR_RO(interface);
 441
 442 static struct attribute *interface_attrs[] = {
 443         DEV_ATTR(description),
 444         DEV_ATTR(interface),
 445         NULL,
 446 };
 447
 448 static struct attribute_group interface_attr_group = {
 449         .attrs = interface_attrs,
 450 };
 451
 452 static const struct attribute_group *interface_attr_groups[] = {
 453         &interface_attr_group,
 454         NULL,
 455 };
 456
 457 static struct most_component *match_component(char *name)
 458 {
 459         struct most_component *comp;
 460
 461         list_for_each_entry(comp, &mc.comp_list, list) {
 462                 if (!strcmp(comp->name, name))
 463                         return comp;
 464         }
 465         return NULL;
 466 }
 467
 468 struct show_links_data {
 469         int offs;
 470         char *buf;
 471 };
 472
 473 static int print_links(struct device *dev, void *data)
 474 {
 475         struct show_links_data *d = data;
 476         int offs = d->offs;
 477         char *buf = d->buf;
 478         struct most_channel *c;
 479         struct most_interface *iface = to_most_interface(dev);
 480
 481         list_for_each_entry(c, &iface->p->channel_list, list) {
 482                 if (c->pipe0.comp) {
 483                         offs += snprintf(buf + offs,
 484                                          PAGE_SIZE - offs,
 485                                          "%s:%s:%s\n",
 486                                          c->pipe0.comp->name,
 487                                          dev_name(&iface->dev),
 488                                          dev_name(&c->dev));
 489                 }
 490                 if (c->pipe1.comp) {
 491                         offs += snprintf(buf + offs,
 492                                          PAGE_SIZE - offs,
 493                                          "%s:%s:%s\n",
 494                                          c->pipe1.comp->name,
 495                                          dev_name(&iface->dev),
 496                                          dev_name(&c->dev));
 497                 }
 498         }
 499         d->offs = offs;
 500         return 0;
 501 }
 502
 503 static ssize_t links_show(struct device_driver *drv, char *buf)
 504 {
 505         struct show_links_data d = { .buf = buf };
 506
 507         bus_for_each_dev(&mc.bus, NULL, &d, print_links);
 508         return d.offs;
 509 }
 510
 511 static ssize_t components_show(struct device_driver *drv, char *buf)
 512 {
 513         struct most_component *comp;
 514         int offs = 0;
 515
 516         list_for_each_entry(comp, &mc.comp_list, list) {
 517                 offs += snprintf(buf + offs, PAGE_SIZE - offs, "%s\n",
 518                                  comp->name);
 519         }
 520         return offs;
 521 }
 522
 523 /**
 524  * get_channel - get pointer to channel
 525  * @mdev: name of the device interface
 526  * @mdev_ch: name of channel
 527  */
 528 static struct most_channel *get_channel(char *mdev, char *mdev_ch)
 529 {
 530         struct device *dev = NULL;
 531         struct most_interface *iface;
 532         struct most_channel *c, *tmp;
 533
 534         dev = bus_find_device_by_name(&mc.bus, NULL, mdev);
 535         if (!dev)
 536                 return NULL;
 537         iface = to_most_interface(dev);
 538         list_for_each_entry_safe(c, tmp, &iface->p->channel_list, list) {
 539                 if (!strcmp(dev_name(&c->dev), mdev_ch))
 540                         return c;
 541         }
 542         return NULL;
 543 }
 544
 545 static
 546 inline int link_channel_to_component(struct most_channel *c,
 547                                      struct most_component *comp,
 548                                      char *name,
 549                                      char *comp_param)
 550 {
 551         int ret;
 552         struct most_component **comp_ptr;
 553
 554         if (!c->pipe0.comp)
 555                 comp_ptr = &c->pipe0.comp;
 556         else if (!c->pipe1.comp)
 557                 comp_ptr = &c->pipe1.comp;
 558         else
 559                 return -ENOSPC;
 560
 561         *comp_ptr = comp;
 562         ret = comp->probe_channel(c->iface, c->channel_id, &c->cfg, name,
 563                                   comp_param);
 564         if (ret) {
 565                 *comp_ptr = NULL;
 566                 return ret;
 567         }
 568         return 0;
 569 }
 570
 571 int most_set_cfg_buffer_size(char *mdev, char *mdev_ch, u16 val)
 572 {
 573         struct most_channel *c = get_channel(mdev, mdev_ch);
 574
 575         if (!c)
 576                 return -ENODEV;
 577         c->cfg.buffer_size = val;
 578         return 0;
 579 }
 580
 581 int most_set_cfg_subbuffer_size(char *mdev, char *mdev_ch, u16 val)
 582 {
 583         struct most_channel *c = get_channel(mdev, mdev_ch);
 584
 585         if (!c)
 586                 return -ENODEV;
 587         c->cfg.subbuffer_size = val;
 588         return 0;
 589 }
 590
 591 int most_set_cfg_dbr_size(char *mdev, char *mdev_ch, u16 val)
 592 {
 593         struct most_channel *c = get_channel(mdev, mdev_ch);
 594
 595         if (!c)
 596                 return -ENODEV;
 597         c->cfg.dbr_size = val;
 598         return 0;
 599 }
 600
 601 int most_set_cfg_num_buffers(char *mdev, char *mdev_ch, u16 val)
 602 {
 603         struct most_channel *c = get_channel(mdev, mdev_ch);
 604
 605         if (!c)
 606                 return -ENODEV;
 607         c->cfg.num_buffers = val;
 608         return 0;
 609 }
 610
 611 int most_set_cfg_datatype(char *mdev, char *mdev_ch, char *buf)
 612 {
 613         int i;
 614         struct most_channel *c = get_channel(mdev, mdev_ch);
 615
 616         if (!c)
 617                 return -ENODEV;
 618         for (i = 0; i < ARRAY_SIZE(ch_data_type); i++) {
 619                 if (!strcmp(buf, ch_data_type[i].name)) {
 620                         c->cfg.data_type = ch_data_type[i].most_ch_data_type;
 621                         break;
 622                 }
 623         }
 624
 625         if (i == ARRAY_SIZE(ch_data_type))
 626                 dev_warn(&mc.dev, "invalid attribute settings\n");
 627         return 0;
 628 }
 629
 630 int most_set_cfg_direction(char *mdev, char *mdev_ch, char *buf)
 631 {
 632         struct most_channel *c = get_channel(mdev, mdev_ch);
 633
 634         if (!c)
 635                 return -ENODEV;
 636         if (!strcmp(buf, "dir_rx")) {
 637                 c->cfg.direction = MOST_CH_RX;
 638         } else if (!strcmp(buf, "rx")) {
 639                 c->cfg.direction = MOST_CH_RX;
 640         } else if (!strcmp(buf, "dir_tx")) {
 641                 c->cfg.direction = MOST_CH_TX;
 642         } else if (!strcmp(buf, "tx")) {
 643                 c->cfg.direction = MOST_CH_TX;
 644         } else {
 645                 dev_err(&mc.dev, "Invalid direction\n");
 646                 return -ENODATA;
 647         }
 648         return 0;
 649 }
 650
 651 int most_set_cfg_packets_xact(char *mdev, char *mdev_ch, u16 val)
 652 {
 653         struct most_channel *c = get_channel(mdev, mdev_ch);
 654
 655         if (!c)
 656                 return -ENODEV;
 657         c->cfg.packets_per_xact = val;
 658         return 0;
 659 }
 660
 661 int most_cfg_complete(char *comp_name)
 662 {
 663         struct most_component *comp;
 664
 665         comp = match_component(comp_name);
 666         if (!comp)
 667                 return -ENODEV;
 668
 669         return comp->cfg_complete();
 670 }
 671
 672 int most_add_link(char *mdev, char *mdev_ch, char *comp_name, char *link_name,
 673                   char *comp_param)
 674 {
 675         struct most_channel *c = get_channel(mdev, mdev_ch);
 676         struct most_component *comp = match_component(comp_name);
 677
 678         if (!c || !comp)
 679                 return -ENODEV;
 680
 681         return link_channel_to_component(c, comp, link_name, comp_param);
 682 }
 683
 684 int most_remove_link(char *mdev, char *mdev_ch, char *comp_name)
 685 {
 686         struct most_channel *c;
 687         struct most_component *comp;
 688
 689         comp = match_component(comp_name);
 690         if (!comp)
 691                 return -ENODEV;
 692         c = get_channel(mdev, mdev_ch);
 693         if (!c)
 694                 return -ENODEV;
 695
 696         if (comp->disconnect_channel(c->iface, c->channel_id))
 697                 return -EIO;
 698         if (c->pipe0.comp == comp)
 699                 c->pipe0.comp = NULL;
 700         if (c->pipe1.comp == comp)
 701                 c->pipe1.comp = NULL;
 702         return 0;
 703 }
 704
 705 #define DRV_ATTR(_name)  (&driver_attr_##_name.attr)
 706
 707 static DRIVER_ATTR_RO(links);
 708 static DRIVER_ATTR_RO(components);
 709
 710 static struct attribute *mc_attrs[] = {
 711         DRV_ATTR(links),
 712         DRV_ATTR(components),
 713         NULL,
 714 };
 715
 716 static struct attribute_group mc_attr_group = {
 717         .attrs = mc_attrs,
 718 };
 719
 720 static const struct attribute_group *mc_attr_groups[] = {
 721         &mc_attr_group,
 722         NULL,
 723 };
 724
 725 static int most_match(struct device *dev, struct device_driver *drv)
 726 {
 727         if (!strcmp(dev_name(dev), "most"))
 728                 return 0;
 729         else
 730                 return 1;
 731 }
 732
 733 static inline void trash_mbo(struct mbo *mbo)
 734 {
 735         unsigned long flags;
 736         struct most_channel *c = mbo->context;
 737
 738         spin_lock_irqsave(&c->fifo_lock, flags);
 739         list_add(&mbo->list, &c->trash_fifo);
 740         spin_unlock_irqrestore(&c->fifo_lock, flags);
 741 }
 742
 743 static bool hdm_mbo_ready(struct most_channel *c)
 744 {
 745         bool empty;
 746
 747         if (c->enqueue_halt)
 748                 return false;
 749
 750         spin_lock_irq(&c->fifo_lock);
 751         empty = list_empty(&c->halt_fifo);
 752         spin_unlock_irq(&c->fifo_lock);
 753
 754         return !empty;
 755 }
 756
 757 static void nq_hdm_mbo(struct mbo *mbo)
 758 {
 759         unsigned long flags;
 760         struct most_channel *c = mbo->context;
 761
 762         spin_lock_irqsave(&c->fifo_lock, flags);
 763         list_add_tail(&mbo->list, &c->halt_fifo);
 764         spin_unlock_irqrestore(&c->fifo_lock, flags);
 765         wake_up_interruptible(&c->hdm_fifo_wq);
 766 }
 767
 768 static int hdm_enqueue_thread(void *data)
 769 {
 770         struct most_channel *c = data;
 771         struct mbo *mbo;
 772         int ret;
 773         typeof(c->iface->enqueue) enqueue = c->iface->enqueue;
 774
 775         while (likely(!kthread_should_stop())) {
 776                 wait_event_interruptible(c->hdm_fifo_wq,
 777                                          hdm_mbo_ready(c) ||
 778                                          kthread_should_stop());
 779
 780                 mutex_lock(&c->nq_mutex);
 781                 spin_lock_irq(&c->fifo_lock);
 782                 if (unlikely(c->enqueue_halt || list_empty(&c->halt_fifo))) {
 783                         spin_unlock_irq(&c->fifo_lock);
 784                         mutex_unlock(&c->nq_mutex);
 785                         continue;
 786                 }
 787
 788                 mbo = list_pop_mbo(&c->halt_fifo);
 789                 spin_unlock_irq(&c->fifo_lock);
 790
 791                 if (c->cfg.direction == MOST_CH_RX)
 792                         mbo->buffer_length = c->cfg.buffer_size;
 793
 794                 ret = enqueue(mbo->ifp, mbo->hdm_channel_id, mbo);
 795                 mutex_unlock(&c->nq_mutex);
 796
 797                 if (unlikely(ret)) {
 798                         dev_err(&mc.dev, "hdm enqueue failed\n");
 799                         nq_hdm_mbo(mbo);
 800                         c->hdm_enqueue_task = NULL;
 801                         return 0;
 802                 }
 803         }
 804
 805         return 0;
 806 }
 807
 808 static int run_enqueue_thread(struct most_channel *c, int channel_id)
 809 {
 810         struct task_struct *task =
 811                 kthread_run(hdm_enqueue_thread, c, "hdm_fifo_%d",
 812                             channel_id);
 813
 814         if (IS_ERR(task))
 815                 return PTR_ERR(task);
 816
 817         c->hdm_enqueue_task = task;
 818         return 0;
 819 }
 820
 821 /**
 822  * arm_mbo - recycle MBO for further usage
 823  * @mbo: most buffer
 824  *
 825  * This puts an MBO back to the list to have it ready for up coming
 826  * tx transactions.
 827  *
 828  * In case the MBO belongs to a channel that recently has been
 829  * poisoned, the MBO is scheduled to be trashed.
 830  * Calls the completion handler of an attached component.
 831  */
 832 static void arm_mbo(struct mbo *mbo)
 833 {
 834         unsigned long flags;
 835         struct most_channel *c;
 836
 837         c = mbo->context;
 838
 839         if (c->is_poisoned) {
 840                 trash_mbo(mbo);
 841                 return;
 842         }
 843
 844         spin_lock_irqsave(&c->fifo_lock, flags);
 845         ++*mbo->num_buffers_ptr;
 846         list_add_tail(&mbo->list, &c->fifo);
 847         spin_unlock_irqrestore(&c->fifo_lock, flags);
 848
 849         if (c->pipe0.refs && c->pipe0.comp->tx_completion)
 850                 c->pipe0.comp->tx_completion(c->iface, c->channel_id);
 851
 852         if (c->pipe1.refs && c->pipe1.comp->tx_completion)
 853                 c->pipe1.comp->tx_completion(c->iface, c->channel_id);
 854 }
 855
 856 /**
 857  * arm_mbo_chain - helper function that arms an MBO chain for the HDM
 858  * @c: pointer to interface channel
 859  * @dir: direction of the channel
 860  * @compl: pointer to completion function
 861  *
 862  * This allocates buffer objects including the containing DMA coherent
 863  * buffer and puts them in the fifo.
 864  * Buffers of Rx channels are put in the kthread fifo, hence immediately
 865  * submitted to the HDM.
 866  *
 867  * Returns the number of allocated and enqueued MBOs.
 868  */
 869 static int arm_mbo_chain(struct most_channel *c, int dir,
 870                          void (*compl)(struct mbo *))
 871 {
 872         unsigned int i;
 873         struct mbo *mbo;
 874         unsigned long flags;
 875         u32 coherent_buf_size = c->cfg.buffer_size + c->cfg.extra_len;
 876
 877         atomic_set(&c->mbo_nq_level, 0);
 878
 879         for (i = 0; i < c->cfg.num_buffers; i++) {
 880                 mbo = kzalloc(sizeof(*mbo), GFP_KERNEL);
 881                 if (!mbo)
 882                         goto flush_fifos;
 883
 884                 mbo->context = c;
 885                 mbo->ifp = c->iface;
 886                 mbo->hdm_channel_id = c->channel_id;
 887                 if (c->iface->dma_alloc) {
 888                         mbo->virt_address =
 889                                 c->iface->dma_alloc(mbo, coherent_buf_size);
 890                 } else {
 891                         mbo->virt_address =
 892                                 kzalloc(coherent_buf_size, GFP_KERNEL);
 893                 }
 894                 if (!mbo->virt_address)
 895                         goto release_mbo;
 896
 897                 mbo->complete = compl;
 898                 mbo->num_buffers_ptr = &dummy_num_buffers;
 899                 if (dir == MOST_CH_RX) {
 900                         nq_hdm_mbo(mbo);
 901                         atomic_inc(&c->mbo_nq_level);
 902                 } else {
 903                         spin_lock_irqsave(&c->fifo_lock, flags);
 904                         list_add_tail(&mbo->list, &c->fifo);
 905                         spin_unlock_irqrestore(&c->fifo_lock, flags);
 906                 }
 907         }
 908         return c->cfg.num_buffers;
 909
 910 release_mbo:
 911         kfree(mbo);
 912
 913 flush_fifos:
 914         flush_channel_fifos(c);
 915         return 0;
 916 }
 917
 918 /**
 919  * most_submit_mbo - submits an MBO to fifo
 920  * @mbo: most buffer
 921  */
 922 void most_submit_mbo(struct mbo *mbo)
 923 {
 924         if (WARN_ONCE(!mbo || !mbo->context,
 925                       "bad mbo or missing channel reference\n"))
 926                 return;
 927
 928         nq_hdm_mbo(mbo);
 929 }
 930 EXPORT_SYMBOL_GPL(most_submit_mbo);
 931
 932 /**
 933  * most_write_completion - write completion handler
 934  * @mbo: most buffer
 935  *
 936  * This recycles the MBO for further usage. In case the channel has been
 937  * poisoned, the MBO is scheduled to be trashed.
 938  */
 939 static void most_write_completion(struct mbo *mbo)
 940 {
 941         struct most_channel *c;
 942
 943         c = mbo->context;
 944         if (mbo->status == MBO_E_INVAL)
 945                 dev_warn(&mc.dev, "Tx MBO status: invalid\n");
 946         if (unlikely(c->is_poisoned || (mbo->status == MBO_E_CLOSE)))
 947                 trash_mbo(mbo);
 948         else
 949                 arm_mbo(mbo);
 950 }
 951
 952 int channel_has_mbo(struct most_interface *iface, int id,
 953                     struct most_component *comp)
 954 {
 955         struct most_channel *c = iface->p->channel[id];
 956         unsigned long flags;
 957         int empty;
 958
 959         if (unlikely(!c))
 960                 return -EINVAL;
 961
 962         if (c->pipe0.refs && c->pipe1.refs &&
 963             ((comp == c->pipe0.comp && c->pipe0.num_buffers <= 0) ||
 964              (comp == c->pipe1.comp && c->pipe1.num_buffers <= 0)))
 965                 return 0;
 966
 967         spin_lock_irqsave(&c->fifo_lock, flags);
 968         empty = list_empty(&c->fifo);
 969         spin_unlock_irqrestore(&c->fifo_lock, flags);
 970         return !empty;
 971 }
 972 EXPORT_SYMBOL_GPL(channel_has_mbo);
 973
 974 /**
 975  * most_get_mbo - get pointer to an MBO of pool
 976  * @iface: pointer to interface instance
 977  * @id: channel ID
 978  * @comp: driver component
 979  *
 980  * This attempts to get a free buffer out of the channel fifo.
 981  * Returns a pointer to MBO on success or NULL otherwise.
 982  */
 983 struct mbo *most_get_mbo(struct most_interface *iface, int id,
 984                          struct most_component *comp)
 985 {
 986         struct mbo *mbo;
 987         struct most_channel *c;
 988         unsigned long flags;
 989         int *num_buffers_ptr;
 990
 991         c = iface->p->channel[id];
 992         if (unlikely(!c))
 993                 return NULL;
 994
 995         if (c->pipe0.refs && c->pipe1.refs &&
 996             ((comp == c->pipe0.comp && c->pipe0.num_buffers <= 0) ||
 997              (comp == c->pipe1.comp && c->pipe1.num_buffers <= 0)))
 998                 return NULL;
 999
1000         if (comp == c->pipe0.comp)
1001                 num_buffers_ptr = &c->pipe0.num_buffers;
1002         else if (comp == c->pipe1.comp)
1003                 num_buffers_ptr = &c->pipe1.num_buffers;
1004         else
1005                 num_buffers_ptr = &dummy_num_buffers;
1006
1007         spin_lock_irqsave(&c->fifo_lock, flags);
1008         if (list_empty(&c->fifo)) {
1009                 spin_unlock_irqrestore(&c->fifo_lock, flags);
1010                 return NULL;
1011         }
1012         mbo = list_pop_mbo(&c->fifo);
1013         --*num_buffers_ptr;
1014         spin_unlock_irqrestore(&c->fifo_lock, flags);
1015
1016         mbo->num_buffers_ptr = num_buffers_ptr;
1017         mbo->buffer_length = c->cfg.buffer_size;
1018         return mbo;
1019 }
1020 EXPORT_SYMBOL_GPL(most_get_mbo);
1021
1022 /**
1023  * most_put_mbo - return buffer to pool
1024  * @mbo: most buffer
1025  */
1026 void most_put_mbo(struct mbo *mbo)
1027 {
1028         struct most_channel *c = mbo->context;
1029
1030         if (c->cfg.direction == MOST_CH_TX) {
1031                 arm_mbo(mbo);
1032                 return;
1033         }
1034         nq_hdm_mbo(mbo);
1035         atomic_inc(&c->mbo_nq_level);
1036 }
1037 EXPORT_SYMBOL_GPL(most_put_mbo);
1038
1039 /**
1040  * most_read_completion - read completion handler
1041  * @mbo: most buffer
1042  *
1043  * This function is called by the HDM when data has been received from the
1044  * hardware and copied to the buffer of the MBO.
1045  *
1046  * In case the channel has been poisoned it puts the buffer in the trash queue.
1047  * Otherwise, it passes the buffer to an component for further processing.
1048  */
1049 static void most_read_completion(struct mbo *mbo)
1050 {
1051         struct most_channel *c = mbo->context;
1052
1053         if (unlikely(c->is_poisoned || (mbo->status == MBO_E_CLOSE))) {
1054                 trash_mbo(mbo);
1055                 return;
1056         }
1057
1058         if (mbo->status == MBO_E_INVAL) {
1059                 nq_hdm_mbo(mbo);
1060                 atomic_inc(&c->mbo_nq_level);
1061                 return;
1062         }
1063
1064         if (atomic_sub_and_test(1, &c->mbo_nq_level))
1065                 c->is_starving = 1;
1066
1067         if (c->pipe0.refs && c->pipe0.comp->rx_completion &&
1068             c->pipe0.comp->rx_completion(mbo) == 0)
1069                 return;
1070
1071         if (c->pipe1.refs && c->pipe1.comp->rx_completion &&
1072             c->pipe1.comp->rx_completion(mbo) == 0)
1073                 return;
1074
1075         most_put_mbo(mbo);
1076 }
1077
1078 /**
1079  * most_start_channel - prepares a channel for communication
1080  * @iface: pointer to interface instance
1081  * @id: channel ID
1082  * @comp: driver component
1083  *
1084  * This prepares the channel for usage. Cross-checks whether the
1085  * channel's been properly configured.
1086  *
1087  * Returns 0 on success or error code otherwise.
1088  */
1089 int most_start_channel(struct most_interface *iface, int id,
1090                        struct most_component *comp)
1091 {
1092         int num_buffer;
1093         int ret;
1094         struct most_channel *c = iface->p->channel[id];
1095
1096         if (unlikely(!c))
1097                 return -EINVAL;
1098
1099         mutex_lock(&c->start_mutex);
1100         if (c->pipe0.refs + c->pipe1.refs > 0)
1101                 goto out; /* already started by another component */
1102
1103         if (!try_module_get(iface->mod)) {
1104                 dev_err(&mc.dev, "failed to acquire HDM lock\n");
1105                 mutex_unlock(&c->start_mutex);
1106                 return -ENOLCK;
1107         }
1108
1109         c->cfg.extra_len = 0;
1110         if (c->iface->configure(c->iface, c->channel_id, &c->cfg)) {
1111                 dev_err(&mc.dev, "channel configuration failed. Go check settings...\n");
1112                 ret = -EINVAL;
1113                 goto err_put_module;
1114         }
1115
1116         init_waitqueue_head(&c->hdm_fifo_wq);
1117
1118         if (c->cfg.direction == MOST_CH_RX)
1119                 num_buffer = arm_mbo_chain(c, c->cfg.direction,
1120                                            most_read_completion);
1121         else
1122                 num_buffer = arm_mbo_chain(c, c->cfg.direction,
1123                                            most_write_completion);
1124         if (unlikely(!num_buffer)) {
1125                 ret = -ENOMEM;
1126                 goto err_put_module;
1127         }
1128
1129         ret = run_enqueue_thread(c, id);
1130         if (ret)
1131                 goto err_put_module;
1132
1133         c->is_starving = 0;
1134         c->pipe0.num_buffers = c->cfg.num_buffers / 2;
1135         c->pipe1.num_buffers = c->cfg.num_buffers - c->pipe0.num_buffers;
1136         atomic_set(&c->mbo_ref, num_buffer);
1137
1138 out:
1139         if (comp == c->pipe0.comp)
1140                 c->pipe0.refs++;
1141         if (comp == c->pipe1.comp)
1142                 c->pipe1.refs++;
1143         mutex_unlock(&c->start_mutex);
1144         return 0;
1145
1146 err_put_module:
1147         module_put(iface->mod);
1148         mutex_unlock(&c->start_mutex);
1149         return ret;
1150 }
1151 EXPORT_SYMBOL_GPL(most_start_channel);
1152
1153 /**
1154  * most_stop_channel - stops a running channel
1155  * @iface: pointer to interface instance
1156  * @id: channel ID
1157  * @comp: driver component
1158  */
1159 int most_stop_channel(struct most_interface *iface, int id,
1160                       struct most_component *comp)
1161 {
1162         struct most_channel *c;
1163
1164         if (unlikely((!iface) || (id >= iface->num_channels) || (id < 0))) {
1165                 dev_err(&mc.dev, "Bad interface or index out of range\n");
1166                 return -EINVAL;
1167         }
1168         c = iface->p->channel[id];
1169         if (unlikely(!c))
1170                 return -EINVAL;
1171
1172         mutex_lock(&c->start_mutex);
1173         if (c->pipe0.refs + c->pipe1.refs >= 2)
1174                 goto out;
1175
1176         if (c->hdm_enqueue_task)
1177                 kthread_stop(c->hdm_enqueue_task);
1178         c->hdm_enqueue_task = NULL;
1179
1180         if (iface->mod)
1181                 module_put(iface->mod);
1182
1183         c->is_poisoned = true;
1184         if (c->iface->poison_channel(c->iface, c->channel_id)) {
1185                 dev_err(&mc.dev, "Cannot stop channel %d of mdev %s\n", c->channel_id,
1186                         c->iface->description);
1187                 mutex_unlock(&c->start_mutex);
1188                 return -EAGAIN;
1189         }
1190         flush_trash_fifo(c);
1191         flush_channel_fifos(c);
1192
1193 #ifdef CMPL_INTERRUPTIBLE
1194         if (wait_for_completion_interruptible(&c->cleanup)) {
1195                 dev_err(&mc.dev, "Interrupted while clean up ch %d\n", c->channel_id);
1196                 mutex_unlock(&c->start_mutex);
1197                 return -EINTR;
1198         }
1199 #else
1200         wait_for_completion(&c->cleanup);
1201 #endif
1202         c->is_poisoned = false;
1203
1204 out:
1205         if (comp == c->pipe0.comp)
1206                 c->pipe0.refs--;
1207         if (comp == c->pipe1.comp)
1208                 c->pipe1.refs--;
1209         mutex_unlock(&c->start_mutex);
1210         return 0;
1211 }
1212 EXPORT_SYMBOL_GPL(most_stop_channel);
1213
1214 /**
1215  * most_register_component - registers a driver component with the core
1216  * @comp: driver component
1217  */
1218 int most_register_component(struct most_component *comp)
1219 {
1220         if (!comp) {
1221                 dev_err(&mc.dev, "Bad component\n");
1222                 return -EINVAL;
1223         }
1224         list_add_tail(&comp->list, &mc.comp_list);
1225         return 0;
1226 }
1227 EXPORT_SYMBOL_GPL(most_register_component);
1228
1229 static int disconnect_channels(struct device *dev, void *data)
1230 {
1231         struct most_interface *iface;
1232         struct most_channel *c, *tmp;
1233         struct most_component *comp = data;
1234
1235         iface = to_most_interface(dev);
1236         list_for_each_entry_safe(c, tmp, &iface->p->channel_list, list) {
1237                 if (c->pipe0.comp == comp || c->pipe1.comp == comp)
1238                         comp->disconnect_channel(c->iface, c->channel_id);
1239                 if (c->pipe0.comp == comp)
1240                         c->pipe0.comp = NULL;
1241                 if (c->pipe1.comp == comp)
1242                         c->pipe1.comp = NULL;
1243         }
1244         return 0;
1245 }
1246
1247 /**
1248  * most_deregister_component - deregisters a driver component with the core
1249  * @comp: driver component
1250  */
1251 int most_deregister_component(struct most_component *comp)
1252 {
1253         if (!comp) {
1254                 dev_err(&mc.dev, "Bad component\n");
1255                 return -EINVAL;
1256         }
1257
1258         bus_for_each_dev(&mc.bus, NULL, comp, disconnect_channels);
1259         list_del(&comp->list);
1260         return 0;
1261 }
1262 EXPORT_SYMBOL_GPL(most_deregister_component);
1263
1264 static void release_interface(struct device *dev)
1265 {
1266         dev_info(&mc.dev, "releasing interface dev %s...\n", dev_name(dev));
1267 }
1268
1269 static void release_channel(struct device *dev)
1270 {
1271         dev_info(&mc.dev, "releasing channel dev %s...\n", dev_name(dev));
1272 }
1273
1274 /**
1275  * most_register_interface - registers an interface with core
1276  * @iface: device interface
1277  *
1278  * Allocates and initializes a new interface instance and all of its channels.
1279  * Returns a pointer to kobject or an error pointer.
1280  */
1281 int most_register_interface(struct most_interface *iface)
1282 {
1283         unsigned int i;
1284         int id;
1285         struct most_channel *c;
1286
1287         if (!iface || !iface->enqueue || !iface->configure ||
1288             !iface->poison_channel || (iface->num_channels > MAX_CHANNELS)) {
1289                 dev_err(&mc.dev, "Bad interface or channel overflow\n");
1290                 return -EINVAL;
1291         }
1292
1293         id = ida_simple_get(&mdev_id, 0, 0, GFP_KERNEL);
1294         if (id < 0) {
1295                 dev_err(&mc.dev, "Failed to alloc mdev ID\n");
1296                 return id;
1297         }
1298
1299         iface->p = kzalloc(sizeof(*iface->p), GFP_KERNEL);
1300         if (!iface->p) {
1301                 ida_simple_remove(&mdev_id, id);
1302                 return -ENOMEM;
1303         }
1304
1305         INIT_LIST_HEAD(&iface->p->channel_list);
1306         iface->p->dev_id = id;
1307         strscpy(iface->p->name, iface->description, sizeof(iface->p->name));
1308         iface->dev.init_name = iface->p->name;
1309         iface->dev.bus = &mc.bus;
1310         iface->dev.parent = &mc.dev;
1311         iface->dev.groups = interface_attr_groups;
1312         iface->dev.release = release_interface;
1313         if (device_register(&iface->dev)) {
1314                 dev_err(&mc.dev, "registering iface->dev failed\n");
1315                 kfree(iface->p);
1316                 ida_simple_remove(&mdev_id, id);
1317                 return -ENOMEM;
1318         }
1319
1320         for (i = 0; i < iface->num_channels; i++) {
1321                 const char *name_suffix = iface->channel_vector[i].name_suffix;
1322
1323                 c = kzalloc(sizeof(*c), GFP_KERNEL);
1324                 if (!c)
1325                         goto err_free_resources;
1326                 if (!name_suffix)
1327                         snprintf(c->name, STRING_SIZE, "ch%d", i);
1328                 else
1329                         snprintf(c->name, STRING_SIZE, "%s", name_suffix);
1330                 c->dev.init_name = c->name;
1331                 c->dev.parent = &iface->dev;
1332                 c->dev.groups = channel_attr_groups;
1333                 c->dev.release = release_channel;
1334                 iface->p->channel[i] = c;
1335                 c->is_starving = 0;
1336                 c->iface = iface;
1337                 c->channel_id = i;
1338                 c->keep_mbo = false;
1339                 c->enqueue_halt = false;
1340                 c->is_poisoned = false;
1341                 c->cfg.direction = 0;
1342                 c->cfg.data_type = 0;
1343                 c->cfg.num_buffers = 0;
1344                 c->cfg.buffer_size = 0;
1345                 c->cfg.subbuffer_size = 0;
1346                 c->cfg.packets_per_xact = 0;
1347                 spin_lock_init(&c->fifo_lock);
1348                 INIT_LIST_HEAD(&c->fifo);
1349                 INIT_LIST_HEAD(&c->trash_fifo);
1350                 INIT_LIST_HEAD(&c->halt_fifo);
1351                 init_completion(&c->cleanup);
1352                 atomic_set(&c->mbo_ref, 0);
1353                 mutex_init(&c->start_mutex);
1354                 mutex_init(&c->nq_mutex);
1355                 list_add_tail(&c->list, &iface->p->channel_list);
1356                 if (device_register(&c->dev)) {
1357                         dev_err(&mc.dev, "registering c->dev failed\n");
1358                         goto err_free_most_channel;
1359                 }
1360         }
1361         most_interface_register_notify(iface->description);
1362         return 0;
1363
1364 err_free_most_channel:
1365         kfree(c);
1366
1367 err_free_resources:
1368         while (i > 0) {
1369                 c = iface->p->channel[--i];
1370                 device_unregister(&c->dev);
1371                 kfree(c);
1372         }
1373         kfree(iface->p);
1374         device_unregister(&iface->dev);
1375         ida_simple_remove(&mdev_id, id);
1376         return -ENOMEM;
1377 }
1378 EXPORT_SYMBOL_GPL(most_register_interface);
1379
1380 /**
1381  * most_deregister_interface - deregisters an interface with core
1382  * @iface: device interface
1383  *
1384  * Before removing an interface instance from the list, all running
1385  * channels are stopped and poisoned.
1386  */
1387 void most_deregister_interface(struct most_interface *iface)
1388 {
1389         int i;
1390         struct most_channel *c;
1391
1392         for (i = 0; i < iface->num_channels; i++) {
1393                 c = iface->p->channel[i];
1394                 if (c->pipe0.comp)
1395                         c->pipe0.comp->disconnect_channel(c->iface,
1396                                                         c->channel_id);
1397                 if (c->pipe1.comp)
1398                         c->pipe1.comp->disconnect_channel(c->iface,
1399                                                         c->channel_id);
1400                 c->pipe0.comp = NULL;
1401                 c->pipe1.comp = NULL;
1402                 list_del(&c->list);
1403                 device_unregister(&c->dev);
1404                 kfree(c);
1405         }
1406
1407         ida_simple_remove(&mdev_id, iface->p->dev_id);
1408         kfree(iface->p);
1409         device_unregister(&iface->dev);
1410 }
1411 EXPORT_SYMBOL_GPL(most_deregister_interface);
1412
1413 /**
1414  * most_stop_enqueue - prevents core from enqueueing MBOs
1415  * @iface: pointer to interface
1416  * @id: channel id
1417  *
1418  * This is called by an HDM that _cannot_ attend to its duties and
1419  * is imminent to get run over by the core. The core is not going to
1420  * enqueue any further packets unless the flagging HDM calls
1421  * most_resume enqueue().
1422  */
1423 void most_stop_enqueue(struct most_interface *iface, int id)
1424 {
1425         struct most_channel *c = iface->p->channel[id];
1426
1427         if (!c)
1428                 return;
1429
1430         mutex_lock(&c->nq_mutex);
1431         c->enqueue_halt = true;
1432         mutex_unlock(&c->nq_mutex);
1433 }
1434 EXPORT_SYMBOL_GPL(most_stop_enqueue);
1435
1436 /**
1437  * most_resume_enqueue - allow core to enqueue MBOs again
1438  * @iface: pointer to interface
1439  * @id: channel id
1440  *
1441  * This clears the enqueue halt flag and enqueues all MBOs currently
1442  * sitting in the wait fifo.
1443  */
1444 void most_resume_enqueue(struct most_interface *iface, int id)
1445 {
1446         struct most_channel *c = iface->p->channel[id];
1447
1448         if (!c)
1449                 return;
1450
1451         mutex_lock(&c->nq_mutex);
1452         c->enqueue_halt = false;
1453         mutex_unlock(&c->nq_mutex);
1454
1455         wake_up_interruptible(&c->hdm_fifo_wq);
1456 }
1457 EXPORT_SYMBOL_GPL(most_resume_enqueue);
1458
1459 static void release_most_sub(struct device *dev)
1460 {
1461         dev_info(&mc.dev, "releasing most_subsystem\n");
1462 }
1463
1464 static int __init most_init(void)
1465 {
1466         int err;
1467
1468         INIT_LIST_HEAD(&mc.comp_list);
1469         ida_init(&mdev_id);
1470
1471         mc.bus.name = "most",
1472         mc.bus.match = most_match,
1473         mc.drv.name = "most_core",
1474         mc.drv.bus = &mc.bus,
1475         mc.drv.groups = mc_attr_groups;
1476
1477         err = bus_register(&mc.bus);
1478         if (err) {
1479                 dev_err(&mc.dev, "Cannot register most bus\n");
1480                 return err;
1481         }
1482         err = driver_register(&mc.drv);
1483         if (err) {
1484                 dev_err(&mc.dev, "Cannot register core driver\n");
1485                 goto err_unregister_bus;
1486         }
1487         mc.dev.init_name = "most_bus";
1488         mc.dev.release = release_most_sub;
1489         if (device_register(&mc.dev)) {
1490                 err = -ENOMEM;
1491                 goto err_unregister_driver;
1492         }
1493         configfs_init();
1494         return 0;
1495
1496 err_unregister_driver:
1497         driver_unregister(&mc.drv);
1498 err_unregister_bus:
1499         bus_unregister(&mc.bus);
1500         return err;
1501 }
1502
1503 static void __exit most_exit(void)
1504 {
1505         device_unregister(&mc.dev);
1506         driver_unregister(&mc.drv);
1507         bus_unregister(&mc.bus);
1508         ida_destroy(&mdev_id);
1509 }
1510
1511 module_init(most_init);
1512 module_exit(most_exit);
1513 MODULE_LICENSE("GPL");
1514 MODULE_AUTHOR("Christian Gromm <christian.gromm@microchip.com>");
1515 MODULE_DESCRIPTION("Core module of stacked MOST Linux driver");