drivers/staging/greybus/loopback.c

   1 /*
   2  * Loopback bridge driver for the Greybus loopback module.
   3  *
   4  * Copyright 2014 Google Inc.
   5  * Copyright 2014 Linaro Ltd.
   6  *
   7  * Released under the GPLv2 only.
   8  */
   9
  10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  11
  12 #include <linux/kernel.h>
  13 #include <linux/module.h>
  14 #include <linux/mutex.h>
  15 #include <linux/slab.h>
  16 #include <linux/kthread.h>
  17 #include <linux/delay.h>
  18 #include <linux/random.h>
  19 #include <linux/sizes.h>
  20 #include <linux/cdev.h>
  21 #include <linux/fs.h>
  22 #include <linux/kfifo.h>
  23 #include <linux/debugfs.h>
  24 #include <linux/list_sort.h>
  25 #include <linux/spinlock.h>
  26 #include <linux/workqueue.h>
  27 #include <linux/atomic.h>
  28 #include <linux/pm_runtime.h>
  29
  30 #include <asm/div64.h>
  31
  32 #include "greybus.h"
  33 #include "connection.h"
  34
  35 #define NSEC_PER_DAY 86400000000000ULL
  36
  37 struct gb_loopback_stats {
  38         u32 min;
  39         u32 max;
  40         u64 sum;
  41         u32 count;
  42 };
  43
  44 struct gb_loopback_device {
  45         struct dentry *root;
  46         u32 count;
  47         size_t size_max;
  48
  49         /* We need to take a lock in atomic context */
  50         spinlock_t lock;
  51         struct list_head list;
  52         struct list_head list_op_async;
  53         wait_queue_head_t wq;
  54 };
  55
  56 static struct gb_loopback_device gb_dev;
  57
  58 struct gb_loopback_async_operation {
  59         struct gb_loopback *gb;
  60         struct gb_operation *operation;
  61         struct timeval ts;
  62         struct timer_list timer;
  63         struct list_head entry;
  64         struct work_struct work;
  65         struct kref kref;
  66         bool pending;
  67         int (*completion)(struct gb_loopback_async_operation *op_async);
  68 };
  69
  70 struct gb_loopback {
  71         struct gb_connection *connection;
  72
  73         struct dentry *file;
  74         struct kfifo kfifo_lat;
  75         struct kfifo kfifo_ts;
  76         struct mutex mutex;
  77         struct task_struct *task;
  78         struct list_head entry;
  79         struct device *dev;
  80         wait_queue_head_t wq;
  81         wait_queue_head_t wq_completion;
  82         atomic_t outstanding_operations;
  83
  84         /* Per connection stats */
  85         struct timeval ts;
  86         struct gb_loopback_stats latency;
  87         struct gb_loopback_stats throughput;
  88         struct gb_loopback_stats requests_per_second;
  89         struct gb_loopback_stats apbridge_unipro_latency;
  90         struct gb_loopback_stats gbphy_firmware_latency;
  91
  92         int type;
  93         int async;
  94         int id;
  95         u32 size;
  96         u32 iteration_max;
  97         u32 iteration_count;
  98         int us_wait;
  99         u32 error;
 100         u32 requests_completed;
 101         u32 requests_timedout;
 102         u32 timeout;
 103         u32 jiffy_timeout;
 104         u32 timeout_min;
 105         u32 timeout_max;
 106         u32 outstanding_operations_max;
 107         u32 lbid;
 108         u64 elapsed_nsecs;
 109         u32 apbridge_latency_ts;
 110         u32 gbphy_latency_ts;
 111
 112         u32 send_count;
 113 };
 114
 115 static struct class loopback_class = {
 116         .name           = "gb_loopback",
 117         .owner          = THIS_MODULE,
 118 };
 119 static DEFINE_IDA(loopback_ida);
 120
 121 /* Min/max values in jiffies */
 122 #define GB_LOOPBACK_TIMEOUT_MIN                         1
 123 #define GB_LOOPBACK_TIMEOUT_MAX                         10000
 124
 125 #define GB_LOOPBACK_FIFO_DEFAULT                        8192
 126
 127 static unsigned kfifo_depth = GB_LOOPBACK_FIFO_DEFAULT;
 128 module_param(kfifo_depth, uint, 0444);
 129
 130 /* Maximum size of any one send data buffer we support */
 131 #define MAX_PACKET_SIZE (PAGE_SIZE * 2)
 132
 133 #define GB_LOOPBACK_US_WAIT_MAX                         1000000
 134
 135 /* interface sysfs attributes */
 136 #define gb_loopback_ro_attr(field)                              \
 137 static ssize_t field##_show(struct device *dev,                 \
 138                             struct device_attribute *attr,              \
 139                             char *buf)                                  \
 140 {                                                                       \
 141         struct gb_loopback *gb = dev_get_drvdata(dev);                  \
 142         return sprintf(buf, "%u\n", gb->field);                 \
 143 }                                                                       \
 144 static DEVICE_ATTR_RO(field)
 145
 146 #define gb_loopback_ro_stats_attr(name, field, type)            \
 147 static ssize_t name##_##field##_show(struct device *dev,        \
 148                             struct device_attribute *attr,              \
 149                             char *buf)                                  \
 150 {                                                                       \
 151         struct gb_loopback *gb = dev_get_drvdata(dev);                  \
 152         /* Report 0 for min and max if no transfer successed */         \
 153         if (!gb->requests_completed)                                    \
 154                 return sprintf(buf, "0\n");                             \
 155         return sprintf(buf, "%"#type"\n", gb->name.field);      \
 156 }                                                                       \
 157 static DEVICE_ATTR_RO(name##_##field)
 158
 159 #define gb_loopback_ro_avg_attr(name)                   \
 160 static ssize_t name##_avg_show(struct device *dev,              \
 161                             struct device_attribute *attr,              \
 162                             char *buf)                                  \
 163 {                                                                       \
 164         struct gb_loopback_stats *stats;                                \
 165         struct gb_loopback *gb;                                         \
 166         u64 avg, rem;                                                   \
 167         u32 count;                                                      \
 168         gb = dev_get_drvdata(dev);                      \
 169         stats = &gb->name;                                      \
 170         count = stats->count ? stats->count : 1;                        \
 171         avg = stats->sum + count / 2000000; /* round closest */         \
 172         rem = do_div(avg, count);                                       \
 173         rem *= 1000000;                                                 \
 174         do_div(rem, count);                                             \
 175         return sprintf(buf, "%llu.%06u\n", avg, (u32)rem);              \
 176 }                                                                       \
 177 static DEVICE_ATTR_RO(name##_avg)
 178
 179 #define gb_loopback_stats_attrs(field)                          \
 180         gb_loopback_ro_stats_attr(field, min, u);               \
 181         gb_loopback_ro_stats_attr(field, max, u);               \
 182         gb_loopback_ro_avg_attr(field)
 183
 184 #define gb_loopback_attr(field, type)                                   \
 185 static ssize_t field##_show(struct device *dev,                         \
 186                             struct device_attribute *attr,              \
 187                             char *buf)                                  \
 188 {                                                                       \
 189         struct gb_loopback *gb = dev_get_drvdata(dev);                  \
 190         return sprintf(buf, "%"#type"\n", gb->field);                   \
 191 }                                                                       \
 192 static ssize_t field##_store(struct device *dev,                        \
 193                             struct device_attribute *attr,              \
 194                             const char *buf,                            \
 195                             size_t len)                                 \
 196 {                                                                       \
 197         int ret;                                                        \
 198         struct gb_loopback *gb = dev_get_drvdata(dev);                  \
 199         mutex_lock(&gb->mutex);                                         \
 200         ret = sscanf(buf, "%"#type, &gb->field);                        \
 201         if (ret != 1)                                                   \
 202                 len = -EINVAL;                                          \
 203         else                                                            \
 204                 gb_loopback_check_attr(gb, bundle);                     \
 205         mutex_unlock(&gb->mutex);                                       \
 206         return len;                                                     \
 207 }                                                                       \
 208 static DEVICE_ATTR_RW(field)
 209
 210 #define gb_dev_loopback_ro_attr(field, conn)                            \
 211 static ssize_t field##_show(struct device *dev,         \
 212                             struct device_attribute *attr,              \
 213                             char *buf)                                  \
 214 {                                                                       \
 215         struct gb_loopback *gb = dev_get_drvdata(dev);                  \
 216         return sprintf(buf, "%u\n", gb->field);                         \
 217 }                                                                       \
 218 static DEVICE_ATTR_RO(field)
 219
 220 #define gb_dev_loopback_rw_attr(field, type)                            \
 221 static ssize_t field##_show(struct device *dev,                         \
 222                             struct device_attribute *attr,              \
 223                             char *buf)                                  \
 224 {                                                                       \
 225         struct gb_loopback *gb = dev_get_drvdata(dev);                  \
 226         return sprintf(buf, "%"#type"\n", gb->field);                   \
 227 }                                                                       \
 228 static ssize_t field##_store(struct device *dev,                        \
 229                             struct device_attribute *attr,              \
 230                             const char *buf,                            \
 231                             size_t len)                                 \
 232 {                                                                       \
 233         int ret;                                                        \
 234         struct gb_loopback *gb = dev_get_drvdata(dev);                  \
 235         mutex_lock(&gb->mutex);                                         \
 236         ret = sscanf(buf, "%"#type, &gb->field);                        \
 237         if (ret != 1)                                                   \
 238                 len = -EINVAL;                                          \
 239         else                                                            \
 240                 gb_loopback_check_attr(gb);             \
 241         mutex_unlock(&gb->mutex);                                       \
 242         return len;                                                     \
 243 }                                                                       \
 244 static DEVICE_ATTR_RW(field)
 245
 246 static void gb_loopback_reset_stats(struct gb_loopback *gb);
 247 static void gb_loopback_check_attr(struct gb_loopback *gb)
 248 {
 249         if (gb->us_wait > GB_LOOPBACK_US_WAIT_MAX)
 250                 gb->us_wait = GB_LOOPBACK_US_WAIT_MAX;
 251         if (gb->size > gb_dev.size_max)
 252                 gb->size = gb_dev.size_max;
 253         gb->requests_timedout = 0;
 254         gb->requests_completed = 0;
 255         gb->iteration_count = 0;
 256         gb->send_count = 0;
 257         gb->error = 0;
 258
 259         if (kfifo_depth < gb->iteration_max) {
 260                 dev_warn(gb->dev,
 261                          "cannot log bytes %u kfifo_depth %u\n",
 262                          gb->iteration_max, kfifo_depth);
 263         }
 264         kfifo_reset_out(&gb->kfifo_lat);
 265         kfifo_reset_out(&gb->kfifo_ts);
 266
 267         switch (gb->type) {
 268         case GB_LOOPBACK_TYPE_PING:
 269         case GB_LOOPBACK_TYPE_TRANSFER:
 270         case GB_LOOPBACK_TYPE_SINK:
 271                 gb->jiffy_timeout = usecs_to_jiffies(gb->timeout);
 272                 if (!gb->jiffy_timeout)
 273                         gb->jiffy_timeout = GB_LOOPBACK_TIMEOUT_MIN;
 274                 else if (gb->jiffy_timeout > GB_LOOPBACK_TIMEOUT_MAX)
 275                         gb->jiffy_timeout = GB_LOOPBACK_TIMEOUT_MAX;
 276                 gb_loopback_reset_stats(gb);
 277                 wake_up(&gb->wq);
 278                 break;
 279         default:
 280                 gb->type = 0;
 281                 break;
 282         }
 283 }
 284
 285 /* Time to send and receive one message */
 286 gb_loopback_stats_attrs(latency);
 287 /* Number of requests sent per second on this cport */
 288 gb_loopback_stats_attrs(requests_per_second);
 289 /* Quantity of data sent and received on this cport */
 290 gb_loopback_stats_attrs(throughput);
 291 /* Latency across the UniPro link from APBridge's perspective */
 292 gb_loopback_stats_attrs(apbridge_unipro_latency);
 293 /* Firmware induced overhead in the GPBridge */
 294 gb_loopback_stats_attrs(gbphy_firmware_latency);
 295
 296 /* Number of errors encountered during loop */
 297 gb_loopback_ro_attr(error);
 298 /* Number of requests successfully completed async */
 299 gb_loopback_ro_attr(requests_completed);
 300 /* Number of requests timed out async */
 301 gb_loopback_ro_attr(requests_timedout);
 302 /* Timeout minimum in useconds */
 303 gb_loopback_ro_attr(timeout_min);
 304 /* Timeout minimum in useconds */
 305 gb_loopback_ro_attr(timeout_max);
 306
 307 /*
 308  * Type of loopback message to send based on protocol type definitions
 309  * 0 => Don't send message
 310  * 2 => Send ping message continuously (message without payload)
 311  * 3 => Send transfer message continuously (message with payload,
 312  *                                         payload returned in response)
 313  * 4 => Send a sink message (message with payload, no payload in response)
 314  */
 315 gb_dev_loopback_rw_attr(type, d);
 316 /* Size of transfer message payload: 0-4096 bytes */
 317 gb_dev_loopback_rw_attr(size, u);
 318 /* Time to wait between two messages: 0-1000 ms */
 319 gb_dev_loopback_rw_attr(us_wait, d);
 320 /* Maximum iterations for a given operation: 1-(2^32-1), 0 implies infinite */
 321 gb_dev_loopback_rw_attr(iteration_max, u);
 322 /* The current index of the for (i = 0; i < iteration_max; i++) loop */
 323 gb_dev_loopback_ro_attr(iteration_count, false);
 324 /* A flag to indicate synchronous or asynchronous operations */
 325 gb_dev_loopback_rw_attr(async, u);
 326 /* Timeout of an individual asynchronous request */
 327 gb_dev_loopback_rw_attr(timeout, u);
 328 /* Maximum number of in-flight operations before back-off */
 329 gb_dev_loopback_rw_attr(outstanding_operations_max, u);
 330
 331 static struct attribute *loopback_attrs[] = {
 332         &dev_attr_latency_min.attr,
 333         &dev_attr_latency_max.attr,
 334         &dev_attr_latency_avg.attr,
 335         &dev_attr_requests_per_second_min.attr,
 336         &dev_attr_requests_per_second_max.attr,
 337         &dev_attr_requests_per_second_avg.attr,
 338         &dev_attr_throughput_min.attr,
 339         &dev_attr_throughput_max.attr,
 340         &dev_attr_throughput_avg.attr,
 341         &dev_attr_apbridge_unipro_latency_min.attr,
 342         &dev_attr_apbridge_unipro_latency_max.attr,
 343         &dev_attr_apbridge_unipro_latency_avg.attr,
 344         &dev_attr_gbphy_firmware_latency_min.attr,
 345         &dev_attr_gbphy_firmware_latency_max.attr,
 346         &dev_attr_gbphy_firmware_latency_avg.attr,
 347         &dev_attr_type.attr,
 348         &dev_attr_size.attr,
 349         &dev_attr_us_wait.attr,
 350         &dev_attr_iteration_count.attr,
 351         &dev_attr_iteration_max.attr,
 352         &dev_attr_async.attr,
 353         &dev_attr_error.attr,
 354         &dev_attr_requests_completed.attr,
 355         &dev_attr_requests_timedout.attr,
 356         &dev_attr_timeout.attr,
 357         &dev_attr_outstanding_operations_max.attr,
 358         &dev_attr_timeout_min.attr,
 359         &dev_attr_timeout_max.attr,
 360         NULL,
 361 };
 362 ATTRIBUTE_GROUPS(loopback);
 363
 364 static void gb_loopback_calculate_stats(struct gb_loopback *gb, bool error);
 365
 366 static u32 gb_loopback_nsec_to_usec_latency(u64 elapsed_nsecs)
 367 {
 368         u32 lat;
 369
 370         do_div(elapsed_nsecs, NSEC_PER_USEC);
 371         lat = elapsed_nsecs;
 372         return lat;
 373 }
 374
 375 static u64 __gb_loopback_calc_latency(u64 t1, u64 t2)
 376 {
 377         if (t2 > t1)
 378                 return t2 - t1;
 379         else
 380                 return NSEC_PER_DAY - t2 + t1;
 381 }
 382
 383 static u64 gb_loopback_calc_latency(struct timeval *ts, struct timeval *te)
 384 {
 385         u64 t1, t2;
 386
 387         t1 = timeval_to_ns(ts);
 388         t2 = timeval_to_ns(te);
 389
 390         return __gb_loopback_calc_latency(t1, t2);
 391 }
 392
 393 static void gb_loopback_push_latency_ts(struct gb_loopback *gb,
 394                                         struct timeval *ts, struct timeval *te)
 395 {
 396         kfifo_in(&gb->kfifo_ts, (unsigned char *)ts, sizeof(*ts));
 397         kfifo_in(&gb->kfifo_ts, (unsigned char *)te, sizeof(*te));
 398 }
 399
 400 static int gb_loopback_operation_sync(struct gb_loopback *gb, int type,
 401                                       void *request, int request_size,
 402                                       void *response, int response_size)
 403 {
 404         struct gb_operation *operation;
 405         struct timeval ts, te;
 406         int ret;
 407
 408         do_gettimeofday(&ts);
 409         operation = gb_operation_create(gb->connection, type, request_size,
 410                                         response_size, GFP_KERNEL);
 411         if (!operation)
 412                 return -ENOMEM;
 413
 414         if (request_size)
 415                 memcpy(operation->request->payload, request, request_size);
 416
 417         ret = gb_operation_request_send_sync(operation);
 418         if (ret) {
 419                 dev_err(&gb->connection->bundle->dev,
 420                         "synchronous operation failed: %d\n", ret);
 421                 goto out_put_operation;
 422         } else {
 423                 if (response_size == operation->response->payload_size) {
 424                         memcpy(response, operation->response->payload,
 425                                response_size);
 426                 } else {
 427                         dev_err(&gb->connection->bundle->dev,
 428                                 "response size %zu expected %d\n",
 429                                 operation->response->payload_size,
 430                                 response_size);
 431                         ret = -EINVAL;
 432                         goto out_put_operation;
 433                 }
 434         }
 435
 436         do_gettimeofday(&te);
 437
 438         /* Calculate the total time the message took */
 439         gb_loopback_push_latency_ts(gb, &ts, &te);
 440         gb->elapsed_nsecs = gb_loopback_calc_latency(&ts, &te);
 441
 442 out_put_operation:
 443         gb_operation_put(operation);
 444
 445         return ret;
 446 }
 447
 448 static void __gb_loopback_async_operation_destroy(struct kref *kref)
 449 {
 450         struct gb_loopback_async_operation *op_async;
 451
 452         op_async = container_of(kref, struct gb_loopback_async_operation, kref);
 453
 454         list_del(&op_async->entry);
 455         if (op_async->operation)
 456                 gb_operation_put(op_async->operation);
 457         atomic_dec(&op_async->gb->outstanding_operations);
 458         wake_up(&op_async->gb->wq_completion);
 459         kfree(op_async);
 460 }
 461
 462 static void gb_loopback_async_operation_get(struct gb_loopback_async_operation
 463                                             *op_async)
 464 {
 465         kref_get(&op_async->kref);
 466 }
 467
 468 static void gb_loopback_async_operation_put(struct gb_loopback_async_operation
 469                                             *op_async)
 470 {
 471         unsigned long flags;
 472
 473         spin_lock_irqsave(&gb_dev.lock, flags);
 474         kref_put(&op_async->kref, __gb_loopback_async_operation_destroy);
 475         spin_unlock_irqrestore(&gb_dev.lock, flags);
 476 }
 477
 478 static struct gb_loopback_async_operation *
 479         gb_loopback_operation_find(u16 id)
 480 {
 481         struct gb_loopback_async_operation *op_async;
 482         bool found = false;
 483         unsigned long flags;
 484
 485         spin_lock_irqsave(&gb_dev.lock, flags);
 486         list_for_each_entry(op_async, &gb_dev.list_op_async, entry) {
 487                 if (op_async->operation->id == id) {
 488                         gb_loopback_async_operation_get(op_async);
 489                         found = true;
 490                         break;
 491                 }
 492         }
 493         spin_unlock_irqrestore(&gb_dev.lock, flags);
 494
 495         return found ? op_async : NULL;
 496 }
 497
 498 static void gb_loopback_async_wait_all(struct gb_loopback *gb)
 499 {
 500         wait_event(gb->wq_completion,
 501                    !atomic_read(&gb->outstanding_operations));
 502 }
 503
 504 static void gb_loopback_async_operation_callback(struct gb_operation *operation)
 505 {
 506         struct gb_loopback_async_operation *op_async;
 507         struct gb_loopback *gb;
 508         struct timeval te;
 509         bool err = false;
 510
 511         do_gettimeofday(&te);
 512         op_async = gb_loopback_operation_find(operation->id);
 513         if (!op_async)
 514                 return;
 515
 516         gb = op_async->gb;
 517         mutex_lock(&gb->mutex);
 518
 519         if (!op_async->pending || gb_operation_result(operation)) {
 520                 err = true;
 521         } else {
 522                 if (op_async->completion)
 523                         if (op_async->completion(op_async))
 524                                 err = true;
 525         }
 526
 527         if (!err) {
 528                 gb_loopback_push_latency_ts(gb, &op_async->ts, &te);
 529                 gb->elapsed_nsecs = gb_loopback_calc_latency(&op_async->ts,
 530                                                              &te);
 531         }
 532
 533         if (op_async->pending) {
 534                 if (err)
 535                         gb->error++;
 536                 gb->iteration_count++;
 537                 op_async->pending = false;
 538                 del_timer_sync(&op_async->timer);
 539                 gb_loopback_async_operation_put(op_async);
 540                 gb_loopback_calculate_stats(gb, err);
 541         }
 542         mutex_unlock(&gb->mutex);
 543
 544         dev_dbg(&gb->connection->bundle->dev, "complete operation %d\n",
 545                 operation->id);
 546
 547         gb_loopback_async_operation_put(op_async);
 548 }
 549
 550 static void gb_loopback_async_operation_work(struct work_struct *work)
 551 {
 552         struct gb_loopback *gb;
 553         struct gb_operation *operation;
 554         struct gb_loopback_async_operation *op_async;
 555
 556         op_async = container_of(work, struct gb_loopback_async_operation, work);
 557         gb = op_async->gb;
 558         operation = op_async->operation;
 559
 560         mutex_lock(&gb->mutex);
 561         if (op_async->pending) {
 562                 gb->requests_timedout++;
 563                 gb->error++;
 564                 gb->iteration_count++;
 565                 op_async->pending = false;
 566                 gb_loopback_async_operation_put(op_async);
 567                 gb_loopback_calculate_stats(gb, true);
 568         }
 569         mutex_unlock(&gb->mutex);
 570
 571         dev_dbg(&gb->connection->bundle->dev, "timeout operation %d\n",
 572                 operation->id);
 573
 574         gb_operation_cancel(operation, -ETIMEDOUT);
 575         gb_loopback_async_operation_put(op_async);
 576 }
 577
 578 static void gb_loopback_async_operation_timeout(unsigned long data)
 579 {
 580         struct gb_loopback_async_operation *op_async;
 581         u16 id = data;
 582
 583         op_async = gb_loopback_operation_find(id);
 584         if (!op_async) {
 585                 pr_err("operation %d not found - time out ?\n", id);
 586                 return;
 587         }
 588         schedule_work(&op_async->work);
 589 }
 590
 591 static int gb_loopback_async_operation(struct gb_loopback *gb, int type,
 592                                        void *request, int request_size,
 593                                        int response_size,
 594                                        void *completion)
 595 {
 596         struct gb_loopback_async_operation *op_async;
 597         struct gb_operation *operation;
 598         int ret;
 599         unsigned long flags;
 600
 601         op_async = kzalloc(sizeof(*op_async), GFP_KERNEL);
 602         if (!op_async)
 603                 return -ENOMEM;
 604
 605         INIT_WORK(&op_async->work, gb_loopback_async_operation_work);
 606         kref_init(&op_async->kref);
 607
 608         operation = gb_operation_create(gb->connection, type, request_size,
 609                                         response_size, GFP_KERNEL);
 610         if (!operation) {
 611                 kfree(op_async);
 612                 return -ENOMEM;
 613         }
 614
 615         if (request_size)
 616                 memcpy(operation->request->payload, request, request_size);
 617
 618         op_async->gb = gb;
 619         op_async->operation = operation;
 620         op_async->completion = completion;
 621
 622         spin_lock_irqsave(&gb_dev.lock, flags);
 623         list_add_tail(&op_async->entry, &gb_dev.list_op_async);
 624         spin_unlock_irqrestore(&gb_dev.lock, flags);
 625
 626         do_gettimeofday(&op_async->ts);
 627         op_async->pending = true;
 628         atomic_inc(&gb->outstanding_operations);
 629         mutex_lock(&gb->mutex);
 630         ret = gb_operation_request_send(operation,
 631                                         gb_loopback_async_operation_callback,
 632                                         GFP_KERNEL);
 633         if (ret)
 634                 goto error;
 635
 636         setup_timer(&op_async->timer, gb_loopback_async_operation_timeout,
 637                         (unsigned long)operation->id);
 638         op_async->timer.expires = jiffies + gb->jiffy_timeout;
 639         add_timer(&op_async->timer);
 640
 641         goto done;
 642 error:
 643         gb_loopback_async_operation_put(op_async);
 644 done:
 645         mutex_unlock(&gb->mutex);
 646         return ret;
 647 }
 648
 649 static int gb_loopback_sync_sink(struct gb_loopback *gb, u32 len)
 650 {
 651         struct gb_loopback_transfer_request *request;
 652         int retval;
 653
 654         request = kmalloc(len + sizeof(*request), GFP_KERNEL);
 655         if (!request)
 656                 return -ENOMEM;
 657
 658         request->len = cpu_to_le32(len);
 659         retval = gb_loopback_operation_sync(gb, GB_LOOPBACK_TYPE_SINK,
 660                                             request, len + sizeof(*request),
 661                                             NULL, 0);
 662         kfree(request);
 663         return retval;
 664 }
 665
 666 static int gb_loopback_sync_transfer(struct gb_loopback *gb, u32 len)
 667 {
 668         struct gb_loopback_transfer_request *request;
 669         struct gb_loopback_transfer_response *response;
 670         int retval;
 671
 672         gb->apbridge_latency_ts = 0;
 673         gb->gbphy_latency_ts = 0;
 674
 675         request = kmalloc(len + sizeof(*request), GFP_KERNEL);
 676         if (!request)
 677                 return -ENOMEM;
 678         response = kmalloc(len + sizeof(*response), GFP_KERNEL);
 679         if (!response) {
 680                 kfree(request);
 681                 return -ENOMEM;
 682         }
 683
 684         memset(request->data, 0x5A, len);
 685
 686         request->len = cpu_to_le32(len);
 687         retval = gb_loopback_operation_sync(gb, GB_LOOPBACK_TYPE_TRANSFER,
 688                                             request, len + sizeof(*request),
 689                                             response, len + sizeof(*response));
 690         if (retval)
 691                 goto gb_error;
 692
 693         if (memcmp(request->data, response->data, len)) {
 694                 dev_err(&gb->connection->bundle->dev,
 695                         "Loopback Data doesn't match\n");
 696                 retval = -EREMOTEIO;
 697         }
 698         gb->apbridge_latency_ts = (u32)__le32_to_cpu(response->reserved0);
 699         gb->gbphy_latency_ts = (u32)__le32_to_cpu(response->reserved1);
 700
 701 gb_error:
 702         kfree(request);
 703         kfree(response);
 704
 705         return retval;
 706 }
 707
 708 static int gb_loopback_sync_ping(struct gb_loopback *gb)
 709 {
 710         return gb_loopback_operation_sync(gb, GB_LOOPBACK_TYPE_PING,
 711                                           NULL, 0, NULL, 0);
 712 }
 713
 714 static int gb_loopback_async_sink(struct gb_loopback *gb, u32 len)
 715 {
 716         struct gb_loopback_transfer_request *request;
 717         int retval;
 718
 719         request = kmalloc(len + sizeof(*request), GFP_KERNEL);
 720         if (!request)
 721                 return -ENOMEM;
 722
 723         request->len = cpu_to_le32(len);
 724         retval = gb_loopback_async_operation(gb, GB_LOOPBACK_TYPE_SINK,
 725                                              request, len + sizeof(*request),
 726                                              0, NULL);
 727         kfree(request);
 728         return retval;
 729 }
 730
 731 static int gb_loopback_async_transfer_complete(
 732                                 struct gb_loopback_async_operation *op_async)
 733 {
 734         struct gb_loopback *gb;
 735         struct gb_operation *operation;
 736         struct gb_loopback_transfer_request *request;
 737         struct gb_loopback_transfer_response *response;
 738         size_t len;
 739         int retval = 0;
 740
 741         gb = op_async->gb;
 742         operation = op_async->operation;
 743         request = operation->request->payload;
 744         response = operation->response->payload;
 745         len = le32_to_cpu(request->len);
 746
 747         if (memcmp(request->data, response->data, len)) {
 748                 dev_err(&gb->connection->bundle->dev,
 749                         "Loopback Data doesn't match operation id %d\n",
 750                         operation->id);
 751                 retval = -EREMOTEIO;
 752         } else {
 753                 gb->apbridge_latency_ts =
 754                         (u32)__le32_to_cpu(response->reserved0);
 755                 gb->gbphy_latency_ts =
 756                         (u32)__le32_to_cpu(response->reserved1);
 757         }
 758
 759         return retval;
 760 }
 761
 762 static int gb_loopback_async_transfer(struct gb_loopback *gb, u32 len)
 763 {
 764         struct gb_loopback_transfer_request *request;
 765         int retval, response_len;
 766
 767         request = kmalloc(len + sizeof(*request), GFP_KERNEL);
 768         if (!request)
 769                 return -ENOMEM;
 770
 771         memset(request->data, 0x5A, len);
 772
 773         request->len = cpu_to_le32(len);
 774         response_len = sizeof(struct gb_loopback_transfer_response);
 775         retval = gb_loopback_async_operation(gb, GB_LOOPBACK_TYPE_TRANSFER,
 776                                              request, len + sizeof(*request),
 777                                              len + response_len,
 778                                              gb_loopback_async_transfer_complete);
 779         if (retval)
 780                 goto gb_error;
 781
 782 gb_error:
 783         kfree(request);
 784         return retval;
 785 }
 786
 787 static int gb_loopback_async_ping(struct gb_loopback *gb)
 788 {
 789         return gb_loopback_async_operation(gb, GB_LOOPBACK_TYPE_PING,
 790                                            NULL, 0, 0, NULL);
 791 }
 792
 793 static int gb_loopback_request_handler(struct gb_operation *operation)
 794 {
 795         struct gb_connection *connection = operation->connection;
 796         struct gb_loopback_transfer_request *request;
 797         struct gb_loopback_transfer_response *response;
 798         struct device *dev = &connection->bundle->dev;
 799         size_t len;
 800
 801         /* By convention, the AP initiates the version operation */
 802         switch (operation->type) {
 803         case GB_LOOPBACK_TYPE_PING:
 804         case GB_LOOPBACK_TYPE_SINK:
 805                 return 0;
 806         case GB_LOOPBACK_TYPE_TRANSFER:
 807                 if (operation->request->payload_size < sizeof(*request)) {
 808                         dev_err(dev, "transfer request too small (%zu < %zu)\n",
 809                                 operation->request->payload_size,
 810                                 sizeof(*request));
 811                         return -EINVAL; /* -EMSGSIZE */
 812                 }
 813                 request = operation->request->payload;
 814                 len = le32_to_cpu(request->len);
 815                 if (len > gb_dev.size_max) {
 816                         dev_err(dev, "transfer request too large (%zu > %zu)\n",
 817                                 len, gb_dev.size_max);
 818                         return -EINVAL;
 819                 }
 820
 821                 if (!gb_operation_response_alloc(operation,
 822                                 len + sizeof(*response), GFP_KERNEL)) {
 823                         dev_err(dev, "error allocating response\n");
 824                         return -ENOMEM;
 825                 }
 826                 response = operation->response->payload;
 827                 response->len = cpu_to_le32(len);
 828                 if (len)
 829                         memcpy(response->data, request->data, len);
 830
 831                 return 0;
 832         default:
 833                 dev_err(dev, "unsupported request: %u\n", operation->type);
 834                 return -EINVAL;
 835         }
 836 }
 837
 838 static void gb_loopback_reset_stats(struct gb_loopback *gb)
 839 {
 840         struct gb_loopback_stats reset = {
 841                 .min = U32_MAX,
 842         };
 843
 844         /* Reset per-connection stats */
 845         memcpy(&gb->latency, &reset,
 846                sizeof(struct gb_loopback_stats));
 847         memcpy(&gb->throughput, &reset,
 848                sizeof(struct gb_loopback_stats));
 849         memcpy(&gb->requests_per_second, &reset,
 850                sizeof(struct gb_loopback_stats));
 851         memcpy(&gb->apbridge_unipro_latency, &reset,
 852                sizeof(struct gb_loopback_stats));
 853         memcpy(&gb->gbphy_firmware_latency, &reset,
 854                sizeof(struct gb_loopback_stats));
 855
 856         /* Should be initialized at least once per transaction set */
 857         gb->apbridge_latency_ts = 0;
 858         gb->gbphy_latency_ts = 0;
 859         memset(&gb->ts, 0, sizeof(struct timeval));
 860 }
 861
 862 static void gb_loopback_update_stats(struct gb_loopback_stats *stats, u32 val)
 863 {
 864         if (stats->min > val)
 865                 stats->min = val;
 866         if (stats->max < val)
 867                 stats->max = val;
 868         stats->sum += val;
 869         stats->count++;
 870 }
 871
 872 static void gb_loopback_update_stats_window(struct gb_loopback_stats *stats,
 873                                             u64 val, u32 count)
 874 {
 875         stats->sum += val;
 876         stats->count += count;
 877
 878         do_div(val, count);
 879         if (stats->min > val)
 880                 stats->min = val;
 881         if (stats->max < val)
 882                 stats->max = val;
 883 }
 884
 885 static void gb_loopback_requests_update(struct gb_loopback *gb, u32 latency)
 886 {
 887         u64 req = gb->requests_completed * USEC_PER_SEC;
 888
 889         gb_loopback_update_stats_window(&gb->requests_per_second, req, latency);
 890 }
 891
 892 static void gb_loopback_throughput_update(struct gb_loopback *gb, u32 latency)
 893 {
 894         u64 aggregate_size = sizeof(struct gb_operation_msg_hdr) * 2;
 895
 896         switch (gb->type) {
 897         case GB_LOOPBACK_TYPE_PING:
 898                 break;
 899         case GB_LOOPBACK_TYPE_SINK:
 900                 aggregate_size += sizeof(struct gb_loopback_transfer_request) +
 901                                   gb->size;
 902                 break;
 903         case GB_LOOPBACK_TYPE_TRANSFER:
 904                 aggregate_size += sizeof(struct gb_loopback_transfer_request) +
 905                                   sizeof(struct gb_loopback_transfer_response) +
 906                                   gb->size * 2;
 907                 break;
 908         default:
 909                 return;
 910         }
 911
 912         aggregate_size *= gb->requests_completed;
 913         aggregate_size *= USEC_PER_SEC;
 914         gb_loopback_update_stats_window(&gb->throughput, aggregate_size,
 915                                         latency);
 916 }
 917
 918 static void gb_loopback_calculate_latency_stats(struct gb_loopback *gb)
 919 {
 920         u32 lat;
 921
 922         /* Express latency in terms of microseconds */
 923         lat = gb_loopback_nsec_to_usec_latency(gb->elapsed_nsecs);
 924
 925         /* Log latency stastic */
 926         gb_loopback_update_stats(&gb->latency, lat);
 927
 928         /* Raw latency log on a per thread basis */
 929         kfifo_in(&gb->kfifo_lat, (unsigned char *)&lat, sizeof(lat));
 930
 931         /* Log the firmware supplied latency values */
 932         gb_loopback_update_stats(&gb->apbridge_unipro_latency,
 933                                  gb->apbridge_latency_ts);
 934         gb_loopback_update_stats(&gb->gbphy_firmware_latency,
 935                                  gb->gbphy_latency_ts);
 936 }
 937
 938 static void gb_loopback_calculate_stats(struct gb_loopback *gb, bool error)
 939 {
 940         u64 nlat;
 941         u32 lat;
 942         struct timeval te;
 943
 944         if (!error) {
 945                 gb->requests_completed++;
 946                 gb_loopback_calculate_latency_stats(gb);
 947         }
 948
 949         do_gettimeofday(&te);
 950         nlat = gb_loopback_calc_latency(&gb->ts, &te);
 951         if (nlat >= NSEC_PER_SEC || gb->iteration_count == gb->iteration_max) {
 952                 lat = gb_loopback_nsec_to_usec_latency(nlat);
 953
 954                 gb_loopback_throughput_update(gb, lat);
 955                 gb_loopback_requests_update(gb, lat);
 956
 957                 if (gb->iteration_count != gb->iteration_max) {
 958                         gb->ts = te;
 959                         gb->requests_completed = 0;
 960                 }
 961         }
 962 }
 963
 964 static void gb_loopback_async_wait_to_send(struct gb_loopback *gb)
 965 {
 966         if (!(gb->async && gb->outstanding_operations_max))
 967                 return;
 968         wait_event_interruptible(gb->wq_completion,
 969                                  (atomic_read(&gb->outstanding_operations) <
 970                                   gb->outstanding_operations_max) ||
 971                                   kthread_should_stop());
 972 }
 973
 974 static int gb_loopback_fn(void *data)
 975 {
 976         int error = 0;
 977         int us_wait = 0;
 978         int type;
 979         int ret;
 980         u32 size;
 981
 982         struct gb_loopback *gb = data;
 983         struct gb_bundle *bundle = gb->connection->bundle;
 984
 985         ret = gb_pm_runtime_get_sync(bundle);
 986         if (ret)
 987                 return ret;
 988
 989         while (1) {
 990                 if (!gb->type) {
 991                         gb_pm_runtime_put_autosuspend(bundle);
 992                         wait_event_interruptible(gb->wq, gb->type ||
 993                                                  kthread_should_stop());
 994                         ret = gb_pm_runtime_get_sync(bundle);
 995                         if (ret)
 996                                 return ret;
 997                 }
 998
 999                 if (kthread_should_stop())
1000                         break;
1001
1002                 /* Limit the maximum number of in-flight async operations */
1003                 gb_loopback_async_wait_to_send(gb);
1004                 if (kthread_should_stop())
1005                         break;
1006
1007                 mutex_lock(&gb->mutex);
1008
1009                 /* Optionally terminate */
1010                 if (gb->send_count == gb->iteration_max) {
1011                         if (gb->iteration_count == gb->iteration_max) {
1012                                 gb->type = 0;
1013                                 gb->send_count = 0;
1014                                 sysfs_notify(&gb->dev->kobj,  NULL,
1015                                                 "iteration_count");
1016                         }
1017                         mutex_unlock(&gb->mutex);
1018                         continue;
1019                 }
1020                 size = gb->size;
1021                 us_wait = gb->us_wait;
1022                 type = gb->type;
1023                 if (gb->ts.tv_usec == 0 && gb->ts.tv_sec == 0)
1024                         do_gettimeofday(&gb->ts);
1025                 mutex_unlock(&gb->mutex);
1026
1027                 /* Else operations to perform */
1028                 if (gb->async) {
1029                         if (type == GB_LOOPBACK_TYPE_PING) {
1030                                 error = gb_loopback_async_ping(gb);
1031                         } else if (type == GB_LOOPBACK_TYPE_TRANSFER) {
1032                                 error = gb_loopback_async_transfer(gb, size);
1033                         } else if (type == GB_LOOPBACK_TYPE_SINK) {
1034                                 error = gb_loopback_async_sink(gb, size);
1035                         }
1036
1037                         if (error)
1038                                 gb->error++;
1039                 } else {
1040                         /* We are effectively single threaded here */
1041                         if (type == GB_LOOPBACK_TYPE_PING)
1042                                 error = gb_loopback_sync_ping(gb);
1043                         else if (type == GB_LOOPBACK_TYPE_TRANSFER)
1044                                 error = gb_loopback_sync_transfer(gb, size);
1045                         else if (type == GB_LOOPBACK_TYPE_SINK)
1046                                 error = gb_loopback_sync_sink(gb, size);
1047
1048                         if (error)
1049                                 gb->error++;
1050                         gb->iteration_count++;
1051                         gb_loopback_calculate_stats(gb, !!error);
1052                 }
1053                 gb->send_count++;
1054                 if (us_wait)
1055                         udelay(us_wait);
1056         }
1057
1058         gb_pm_runtime_put_autosuspend(bundle);
1059
1060         return 0;
1061 }
1062
1063 static int gb_loopback_dbgfs_latency_show_common(struct seq_file *s,
1064                                                  struct kfifo *kfifo,
1065                                                  struct mutex *mutex)
1066 {
1067         u32 latency;
1068         int retval;
1069
1070         if (kfifo_len(kfifo) == 0) {
1071                 retval = -EAGAIN;
1072                 goto done;
1073         }
1074
1075         mutex_lock(mutex);
1076         retval = kfifo_out(kfifo, &latency, sizeof(latency));
1077         if (retval > 0) {
1078                 seq_printf(s, "%u", latency);
1079                 retval = 0;
1080         }
1081         mutex_unlock(mutex);
1082 done:
1083         return retval;
1084 }
1085
1086 static int gb_loopback_dbgfs_latency_show(struct seq_file *s, void *unused)
1087 {
1088         struct gb_loopback *gb = s->private;
1089
1090         return gb_loopback_dbgfs_latency_show_common(s, &gb->kfifo_lat,
1091                                                      &gb->mutex);
1092 }
1093
1094 static int gb_loopback_latency_open(struct inode *inode, struct file *file)
1095 {
1096         return single_open(file, gb_loopback_dbgfs_latency_show,
1097                            inode->i_private);
1098 }
1099
1100 static const struct file_operations gb_loopback_debugfs_latency_ops = {
1101         .open           = gb_loopback_latency_open,
1102         .read           = seq_read,
1103         .llseek         = seq_lseek,
1104         .release        = single_release,
1105 };
1106
1107 static int gb_loopback_bus_id_compare(void *priv, struct list_head *lha,
1108                                       struct list_head *lhb)
1109 {
1110         struct gb_loopback *a = list_entry(lha, struct gb_loopback, entry);
1111         struct gb_loopback *b = list_entry(lhb, struct gb_loopback, entry);
1112         struct gb_connection *ca = a->connection;
1113         struct gb_connection *cb = b->connection;
1114
1115         if (ca->bundle->intf->interface_id < cb->bundle->intf->interface_id)
1116                 return -1;
1117         if (cb->bundle->intf->interface_id < ca->bundle->intf->interface_id)
1118                 return 1;
1119         if (ca->bundle->id < cb->bundle->id)
1120                 return -1;
1121         if (cb->bundle->id < ca->bundle->id)
1122                 return 1;
1123         if (ca->intf_cport_id < cb->intf_cport_id)
1124                 return -1;
1125         else if (cb->intf_cport_id < ca->intf_cport_id)
1126                 return 1;
1127
1128         return 0;
1129 }
1130
1131 static void gb_loopback_insert_id(struct gb_loopback *gb)
1132 {
1133         struct gb_loopback *gb_list;
1134         u32 new_lbid = 0;
1135
1136         /* perform an insertion sort */
1137         list_add_tail(&gb->entry, &gb_dev.list);
1138         list_sort(NULL, &gb_dev.list, gb_loopback_bus_id_compare);
1139         list_for_each_entry(gb_list, &gb_dev.list, entry) {
1140                 gb_list->lbid = 1 << new_lbid;
1141                 new_lbid++;
1142         }
1143 }
1144
1145 #define DEBUGFS_NAMELEN 32
1146
1147 static int gb_loopback_probe(struct gb_bundle *bundle,
1148                              const struct greybus_bundle_id *id)
1149 {
1150         struct greybus_descriptor_cport *cport_desc;
1151         struct gb_connection *connection;
1152         struct gb_loopback *gb;
1153         struct device *dev;
1154         int retval;
1155         char name[DEBUGFS_NAMELEN];
1156         unsigned long flags;
1157
1158         if (bundle->num_cports != 1)
1159                 return -ENODEV;
1160
1161         cport_desc = &bundle->cport_desc[0];
1162         if (cport_desc->protocol_id != GREYBUS_PROTOCOL_LOOPBACK)
1163                 return -ENODEV;
1164
1165         gb = kzalloc(sizeof(*gb), GFP_KERNEL);
1166         if (!gb)
1167                 return -ENOMEM;
1168
1169         connection = gb_connection_create(bundle, le16_to_cpu(cport_desc->id),
1170                                           gb_loopback_request_handler);
1171         if (IS_ERR(connection)) {
1172                 retval = PTR_ERR(connection);
1173                 goto out_kzalloc;
1174         }
1175
1176         gb->connection = connection;
1177         greybus_set_drvdata(bundle, gb);
1178
1179         init_waitqueue_head(&gb->wq);
1180         init_waitqueue_head(&gb->wq_completion);
1181         atomic_set(&gb->outstanding_operations, 0);
1182         gb_loopback_reset_stats(gb);
1183
1184         /* Reported values to user-space for min/max timeouts */
1185         gb->timeout_min = jiffies_to_usecs(GB_LOOPBACK_TIMEOUT_MIN);
1186         gb->timeout_max = jiffies_to_usecs(GB_LOOPBACK_TIMEOUT_MAX);
1187
1188         if (!gb_dev.count) {
1189                 /* Calculate maximum payload */
1190                 gb_dev.size_max = gb_operation_get_payload_size_max(connection);
1191                 if (gb_dev.size_max <=
1192                         sizeof(struct gb_loopback_transfer_request)) {
1193                         retval = -EINVAL;
1194                         goto out_connection_destroy;
1195                 }
1196                 gb_dev.size_max -= sizeof(struct gb_loopback_transfer_request);
1197         }
1198
1199         /* Create per-connection sysfs and debugfs data-points */
1200         snprintf(name, sizeof(name), "raw_latency_%s",
1201                  dev_name(&connection->bundle->dev));
1202         gb->file = debugfs_create_file(name, S_IFREG | S_IRUGO, gb_dev.root, gb,
1203                                        &gb_loopback_debugfs_latency_ops);
1204
1205         gb->id = ida_simple_get(&loopback_ida, 0, 0, GFP_KERNEL);
1206         if (gb->id < 0) {
1207                 retval = gb->id;
1208                 goto out_debugfs_remove;
1209         }
1210
1211         retval = gb_connection_enable(connection);
1212         if (retval)
1213                 goto out_ida_remove;
1214
1215         dev = device_create_with_groups(&loopback_class,
1216                                         &connection->bundle->dev,
1217                                         MKDEV(0, 0), gb, loopback_groups,
1218                                         "gb_loopback%d", gb->id);
1219         if (IS_ERR(dev)) {
1220                 retval = PTR_ERR(dev);
1221                 goto out_connection_disable;
1222         }
1223         gb->dev = dev;
1224
1225         /* Allocate kfifo */
1226         if (kfifo_alloc(&gb->kfifo_lat, kfifo_depth * sizeof(u32),
1227                           GFP_KERNEL)) {
1228                 retval = -ENOMEM;
1229                 goto out_conn;
1230         }
1231         if (kfifo_alloc(&gb->kfifo_ts, kfifo_depth * sizeof(struct timeval) * 2,
1232                           GFP_KERNEL)) {
1233                 retval = -ENOMEM;
1234                 goto out_kfifo0;
1235         }
1236
1237         /* Fork worker thread */
1238         mutex_init(&gb->mutex);
1239         gb->task = kthread_run(gb_loopback_fn, gb, "gb_loopback");
1240         if (IS_ERR(gb->task)) {
1241                 retval = PTR_ERR(gb->task);
1242                 goto out_kfifo1;
1243         }
1244
1245         spin_lock_irqsave(&gb_dev.lock, flags);
1246         gb_loopback_insert_id(gb);
1247         gb_dev.count++;
1248         spin_unlock_irqrestore(&gb_dev.lock, flags);
1249
1250         gb_connection_latency_tag_enable(connection);
1251
1252         gb_pm_runtime_put_autosuspend(bundle);
1253
1254         return 0;
1255
1256 out_kfifo1:
1257         kfifo_free(&gb->kfifo_ts);
1258 out_kfifo0:
1259         kfifo_free(&gb->kfifo_lat);
1260 out_conn:
1261         device_unregister(dev);
1262 out_connection_disable:
1263         gb_connection_disable(connection);
1264 out_ida_remove:
1265         ida_simple_remove(&loopback_ida, gb->id);
1266 out_debugfs_remove:
1267         debugfs_remove(gb->file);
1268 out_connection_destroy:
1269         gb_connection_destroy(connection);
1270 out_kzalloc:
1271         kfree(gb);
1272
1273         return retval;
1274 }
1275
1276 static void gb_loopback_disconnect(struct gb_bundle *bundle)
1277 {
1278         struct gb_loopback *gb = greybus_get_drvdata(bundle);
1279         unsigned long flags;
1280         int ret;
1281
1282         ret = gb_pm_runtime_get_sync(bundle);
1283         if (ret)
1284                 gb_pm_runtime_get_noresume(bundle);
1285
1286         gb_connection_disable(gb->connection);
1287
1288         if (!IS_ERR_OR_NULL(gb->task))
1289                 kthread_stop(gb->task);
1290
1291         kfifo_free(&gb->kfifo_lat);
1292         kfifo_free(&gb->kfifo_ts);
1293         gb_connection_latency_tag_disable(gb->connection);
1294         debugfs_remove(gb->file);
1295
1296         /*
1297          * FIXME: gb_loopback_async_wait_all() is redundant now, as connection
1298          * is disabled at the beginning and so we can't have any more
1299          * incoming/outgoing requests.
1300          */
1301         gb_loopback_async_wait_all(gb);
1302
1303         spin_lock_irqsave(&gb_dev.lock, flags);
1304         gb_dev.count--;
1305         list_del(&gb->entry);
1306         spin_unlock_irqrestore(&gb_dev.lock, flags);
1307
1308         device_unregister(gb->dev);
1309         ida_simple_remove(&loopback_ida, gb->id);
1310
1311         gb_connection_destroy(gb->connection);
1312         kfree(gb);
1313 }
1314
1315 static const struct greybus_bundle_id gb_loopback_id_table[] = {
1316         { GREYBUS_DEVICE_CLASS(GREYBUS_CLASS_LOOPBACK) },
1317         { }
1318 };
1319 MODULE_DEVICE_TABLE(greybus, gb_loopback_id_table);
1320
1321 static struct greybus_driver gb_loopback_driver = {
1322         .name           = "loopback",
1323         .probe          = gb_loopback_probe,
1324         .disconnect     = gb_loopback_disconnect,
1325         .id_table       = gb_loopback_id_table,
1326 };
1327
1328 static int loopback_init(void)
1329 {
1330         int retval;
1331
1332         INIT_LIST_HEAD(&gb_dev.list);
1333         INIT_LIST_HEAD(&gb_dev.list_op_async);
1334         spin_lock_init(&gb_dev.lock);
1335         gb_dev.root = debugfs_create_dir("gb_loopback", NULL);
1336
1337         retval = class_register(&loopback_class);
1338         if (retval)
1339                 goto err;
1340
1341         retval = greybus_register(&gb_loopback_driver);
1342         if (retval)
1343                 goto err_unregister;
1344
1345         return 0;
1346
1347 err_unregister:
1348         class_unregister(&loopback_class);
1349 err:
1350         debugfs_remove_recursive(gb_dev.root);
1351         return retval;
1352 }
1353 module_init(loopback_init);
1354
1355 static void __exit loopback_exit(void)
1356 {
1357         debugfs_remove_recursive(gb_dev.root);
1358         greybus_deregister(&gb_loopback_driver);
1359         class_unregister(&loopback_class);
1360         ida_destroy(&loopback_ida);
1361 }
1362 module_exit(loopback_exit);
1363
1364 MODULE_LICENSE("GPL v2");