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
  28static struct ida mdev_id;
  29static int dummy_num_buffers;
  30static struct list_head comp_list;
  31
  32struct pipe {
  33	struct most_component *comp;
  34	int refs;
  35	int num_buffers;
  36};
  37
  38struct 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
  67struct 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
  74static 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 */
 100static 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 */
 118static 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 */
 152static 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
 168static 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
 184static 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
 204static 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
 215static 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
 226static 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
 237static 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
 248static 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
 257static 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
 266static 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
 275static 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
 288static 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
 303static 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
 312static 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
 321static 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)
 330static 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
 349static DEVICE_ATTR_RO(available_directions);
 350static DEVICE_ATTR_RO(available_datatypes);
 351static DEVICE_ATTR_RO(number_of_packet_buffers);
 352static DEVICE_ATTR_RO(number_of_stream_buffers);
 353static DEVICE_ATTR_RO(size_of_stream_buffer);
 354static DEVICE_ATTR_RO(size_of_packet_buffer);
 355static DEVICE_ATTR_RO(channel_starving);
 356static DEVICE_ATTR_RO(set_buffer_size);
 357static DEVICE_ATTR_RO(set_number_of_buffers);
 358static DEVICE_ATTR_RO(set_direction);
 359static DEVICE_ATTR_RO(set_datatype);
 360static DEVICE_ATTR_RO(set_subbuffer_size);
 361static DEVICE_ATTR_RO(set_packets_per_xact);
 362static DEVICE_ATTR_RO(set_dbr_size);
 363
 364static 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
 382static const struct attribute_group channel_attr_group = {
 383	.attrs = channel_attrs,
 384	.is_visible = channel_attr_is_visible,
 385};
 386
 387static const struct attribute_group *channel_attr_groups[] = {
 388	&channel_attr_group,
 389	NULL,
 390};
 391
 392static 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
 401static 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
 430static DEVICE_ATTR_RO(description);
 431static DEVICE_ATTR_RO(interface);
 432
 433static struct attribute *interface_attrs[] = {
 434	DEV_ATTR(description),
 435	DEV_ATTR(interface),
 436	NULL,
 437};
 438
 439static const struct attribute_group interface_attr_group = {
 440	.attrs = interface_attrs,
 441};
 442
 443static const struct attribute_group *interface_attr_groups[] = {
 444	&interface_attr_group,
 445	NULL,
 446};
 447
 448static 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
 459struct show_links_data {
 460	int offs;
 461	char *buf;
 462};
 463
 464static 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
 494static 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
 502static struct bus_type mostbus = {
 503	.name = "most",
 504	.match = most_match,
 505};
 506
 507static 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
 515static 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 */
 532static 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
 550static
 551inline 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
 576int 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
 586int 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
 596int 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
 606int 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
 616int 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
 635int 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
 656int 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
 666int 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
 677int 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
 689int 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
 712static DRIVER_ATTR_RO(links);
 713static DRIVER_ATTR_RO(components);
 714
 715static struct attribute *mc_attrs[] = {
 716	DRV_ATTR(links),
 717	DRV_ATTR(components),
 718	NULL,
 719};
 720
 721static const struct attribute_group mc_attr_group = {
 722	.attrs = mc_attrs,
 723};
 724
 725static const struct attribute_group *mc_attr_groups[] = {
 726	&mc_attr_group,
 727	NULL,
 728};
 729
 730static struct device_driver mostbus_driver = {
 731	.name = "most_core",
 732	.bus = &mostbus,
 733	.groups = mc_attr_groups,
 734};
 735
 736static 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
 746static 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
 760static 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
 771static 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
 811static 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 */
 835static 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 */
 872static 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
 913release_mbo:
 914	kfree(mbo);
 915
 916flush_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 */
 925void 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}
 933EXPORT_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 */
 942static 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
 953int 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}
 973EXPORT_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 */
 984struct 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}
1021EXPORT_SYMBOL_GPL(most_get_mbo);
1022
1023/**
1024 * most_put_mbo - return buffer to pool
1025 * @mbo: most buffer
1026 */
1027void 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}
1038EXPORT_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 */
1050static 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 */
1090int 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
1139out:
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
1147err_put_module:
1148	module_put(iface->mod);
1149	mutex_unlock(&c->start_mutex);
1150	return ret;
1151}
1152EXPORT_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 */
1160int 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
1205out:
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}
1213EXPORT_SYMBOL_GPL(most_stop_channel);
1214
1215/**
1216 * most_register_component - registers a driver component with the core
1217 * @comp: driver component
1218 */
1219int 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}
1228EXPORT_SYMBOL_GPL(most_register_component);
1229
1230static 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 */
1252int 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}
1263EXPORT_SYMBOL_GPL(most_deregister_component);
1264
1265static 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 */
1279int 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
1359err_free_most_channel:
1360	put_device(&c->dev);
1361
1362err_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}
1372EXPORT_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 */
1381void 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}
1404EXPORT_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 */
1416void 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}
1427EXPORT_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 */
1437void 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}
1450EXPORT_SYMBOL_GPL(most_resume_enqueue);
1451
1452static 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
1472err_unregister_bus:
1473	bus_unregister(&mostbus);
1474	return err;
1475}
1476
1477static void __exit most_exit(void)
1478{
1479	driver_unregister(&mostbus_driver);
1480	bus_unregister(&mostbus);
1481	ida_destroy(&mdev_id);
1482}
1483
1484subsys_initcall(most_init);
1485module_exit(most_exit);
1486MODULE_LICENSE("GPL");
1487MODULE_AUTHOR("Christian Gromm <christian.gromm@microchip.com>");
1488MODULE_DESCRIPTION("Core module of stacked MOST Linux driver");