drivers/rpmsg/rpmsg_core.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * remote processor messaging bus
   4  *
   5  * Copyright (C) 2011 Texas Instruments, Inc.
   6  * Copyright (C) 2011 Google, Inc.
   7  *
   8  * Ohad Ben-Cohen <ohad@wizery.com>
   9  * Brian Swetland <swetland@google.com>
  10  */
  11
  12 #define pr_fmt(fmt) "%s: " fmt, __func__
  13
  14 #include <linux/kernel.h>
  15 #include <linux/module.h>
  16 #include <linux/rpmsg.h>
  17 #include <linux/of_device.h>
  18 #include <linux/pm_domain.h>
  19 #include <linux/slab.h>
  20
  21 #include "rpmsg_internal.h"
  22
  23 /**
  24  * rpmsg_create_channel() - create a new rpmsg channel
  25  * using its name and address info.
  26  * @rpdev: rpmsg device
  27  * @chinfo: channel_info to bind
  28  *
  29  * Returns a pointer to the new rpmsg device on success, or NULL on error.
  30  */
  31 struct rpmsg_device *rpmsg_create_channel(struct rpmsg_device *rpdev,
  32                                           struct rpmsg_channel_info *chinfo)
  33 {
  34         if (WARN_ON(!rpdev))
  35                 return NULL;
  36         if (!rpdev->ops || !rpdev->ops->create_channel) {
  37                 dev_err(&rpdev->dev, "no create_channel ops found\n");
  38                 return NULL;
  39         }
  40
  41         return rpdev->ops->create_channel(rpdev, chinfo);
  42 }
  43 EXPORT_SYMBOL(rpmsg_create_channel);
  44
  45 /**
  46  * rpmsg_release_channel() - release a rpmsg channel
  47  * using its name and address info.
  48  * @rpdev: rpmsg device
  49  * @chinfo: channel_info to bind
  50  *
  51  * Returns 0 on success or an appropriate error value.
  52  */
  53 int rpmsg_release_channel(struct rpmsg_device *rpdev,
  54                           struct rpmsg_channel_info *chinfo)
  55 {
  56         if (WARN_ON(!rpdev))
  57                 return -EINVAL;
  58         if (!rpdev->ops || !rpdev->ops->release_channel) {
  59                 dev_err(&rpdev->dev, "no release_channel ops found\n");
  60                 return -ENXIO;
  61         }
  62
  63         return rpdev->ops->release_channel(rpdev, chinfo);
  64 }
  65 EXPORT_SYMBOL(rpmsg_release_channel);
  66
  67 /**
  68  * rpmsg_create_ept() - create a new rpmsg_endpoint
  69  * @rpdev: rpmsg channel device
  70  * @cb: rx callback handler
  71  * @priv: private data for the driver's use
  72  * @chinfo: channel_info with the local rpmsg address to bind with @cb
  73  *
  74  * Every rpmsg address in the system is bound to an rx callback (so when
  75  * inbound messages arrive, they are dispatched by the rpmsg bus using the
  76  * appropriate callback handler) by means of an rpmsg_endpoint struct.
  77  *
  78  * This function allows drivers to create such an endpoint, and by that,
  79  * bind a callback, and possibly some private data too, to an rpmsg address
  80  * (either one that is known in advance, or one that will be dynamically
  81  * assigned for them).
  82  *
  83  * Simple rpmsg drivers need not call rpmsg_create_ept, because an endpoint
  84  * is already created for them when they are probed by the rpmsg bus
  85  * (using the rx callback provided when they registered to the rpmsg bus).
  86  *
  87  * So things should just work for simple drivers: they already have an
  88  * endpoint, their rx callback is bound to their rpmsg address, and when
  89  * relevant inbound messages arrive (i.e. messages which their dst address
  90  * equals to the src address of their rpmsg channel), the driver's handler
  91  * is invoked to process it.
  92  *
  93  * That said, more complicated drivers might need to allocate
  94  * additional rpmsg addresses, and bind them to different rx callbacks.
  95  * To accomplish that, those drivers need to call this function.
  96  *
  97  * Drivers should provide their @rpdev channel (so the new endpoint would belong
  98  * to the same remote processor their channel belongs to), an rx callback
  99  * function, an optional private data (which is provided back when the
 100  * rx callback is invoked), and an address they want to bind with the
 101  * callback. If @addr is RPMSG_ADDR_ANY, then rpmsg_create_ept will
 102  * dynamically assign them an available rpmsg address (drivers should have
 103  * a very good reason why not to always use RPMSG_ADDR_ANY here).
 104  *
 105  * Returns a pointer to the endpoint on success, or NULL on error.
 106  */
 107 struct rpmsg_endpoint *rpmsg_create_ept(struct rpmsg_device *rpdev,
 108                                         rpmsg_rx_cb_t cb, void *priv,
 109                                         struct rpmsg_channel_info chinfo)
 110 {
 111         if (WARN_ON(!rpdev))
 112                 return NULL;
 113
 114         return rpdev->ops->create_ept(rpdev, cb, priv, chinfo);
 115 }
 116 EXPORT_SYMBOL(rpmsg_create_ept);
 117
 118 /**
 119  * rpmsg_destroy_ept() - destroy an existing rpmsg endpoint
 120  * @ept: endpoing to destroy
 121  *
 122  * Should be used by drivers to destroy an rpmsg endpoint previously
 123  * created with rpmsg_create_ept(). As with other types of "free" NULL
 124  * is a valid parameter.
 125  */
 126 void rpmsg_destroy_ept(struct rpmsg_endpoint *ept)
 127 {
 128         if (ept && ept->ops)
 129                 ept->ops->destroy_ept(ept);
 130 }
 131 EXPORT_SYMBOL(rpmsg_destroy_ept);
 132
 133 /**
 134  * rpmsg_send() - send a message across to the remote processor
 135  * @ept: the rpmsg endpoint
 136  * @data: payload of message
 137  * @len: length of payload
 138  *
 139  * This function sends @data of length @len on the @ept endpoint.
 140  * The message will be sent to the remote processor which the @ept
 141  * endpoint belongs to, using @ept's address and its associated rpmsg
 142  * device destination addresses.
 143  * In case there are no TX buffers available, the function will block until
 144  * one becomes available, or a timeout of 15 seconds elapses. When the latter
 145  * happens, -ERESTARTSYS is returned.
 146  *
 147  * Can only be called from process context (for now).
 148  *
 149  * Returns 0 on success and an appropriate error value on failure.
 150  */
 151 int rpmsg_send(struct rpmsg_endpoint *ept, void *data, int len)
 152 {
 153         if (WARN_ON(!ept))
 154                 return -EINVAL;
 155         if (!ept->ops->send)
 156                 return -ENXIO;
 157
 158         return ept->ops->send(ept, data, len);
 159 }
 160 EXPORT_SYMBOL(rpmsg_send);
 161
 162 /**
 163  * rpmsg_sendto() - send a message across to the remote processor, specify dst
 164  * @ept: the rpmsg endpoint
 165  * @data: payload of message
 166  * @len: length of payload
 167  * @dst: destination address
 168  *
 169  * This function sends @data of length @len to the remote @dst address.
 170  * The message will be sent to the remote processor which the @ept
 171  * endpoint belongs to, using @ept's address as source.
 172  * In case there are no TX buffers available, the function will block until
 173  * one becomes available, or a timeout of 15 seconds elapses. When the latter
 174  * happens, -ERESTARTSYS is returned.
 175  *
 176  * Can only be called from process context (for now).
 177  *
 178  * Returns 0 on success and an appropriate error value on failure.
 179  */
 180 int rpmsg_sendto(struct rpmsg_endpoint *ept, void *data, int len, u32 dst)
 181 {
 182         if (WARN_ON(!ept))
 183                 return -EINVAL;
 184         if (!ept->ops->sendto)
 185                 return -ENXIO;
 186
 187         return ept->ops->sendto(ept, data, len, dst);
 188 }
 189 EXPORT_SYMBOL(rpmsg_sendto);
 190
 191 /**
 192  * rpmsg_send_offchannel() - send a message using explicit src/dst addresses
 193  * @ept: the rpmsg endpoint
 194  * @src: source address
 195  * @dst: destination address
 196  * @data: payload of message
 197  * @len: length of payload
 198  *
 199  * This function sends @data of length @len to the remote @dst address,
 200  * and uses @src as the source address.
 201  * The message will be sent to the remote processor which the @ept
 202  * endpoint belongs to.
 203  * In case there are no TX buffers available, the function will block until
 204  * one becomes available, or a timeout of 15 seconds elapses. When the latter
 205  * happens, -ERESTARTSYS is returned.
 206  *
 207  * Can only be called from process context (for now).
 208  *
 209  * Returns 0 on success and an appropriate error value on failure.
 210  */
 211 int rpmsg_send_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst,
 212                           void *data, int len)
 213 {
 214         if (WARN_ON(!ept))
 215                 return -EINVAL;
 216         if (!ept->ops->send_offchannel)
 217                 return -ENXIO;
 218
 219         return ept->ops->send_offchannel(ept, src, dst, data, len);
 220 }
 221 EXPORT_SYMBOL(rpmsg_send_offchannel);
 222
 223 /**
 224  * rpmsg_trysend() - send a message across to the remote processor
 225  * @ept: the rpmsg endpoint
 226  * @data: payload of message
 227  * @len: length of payload
 228  *
 229  * This function sends @data of length @len on the @ept endpoint.
 230  * The message will be sent to the remote processor which the @ept
 231  * endpoint belongs to, using @ept's address as source and its associated
 232  * rpdev's address as destination.
 233  * In case there are no TX buffers available, the function will immediately
 234  * return -ENOMEM without waiting until one becomes available.
 235  *
 236  * Can only be called from process context (for now).
 237  *
 238  * Returns 0 on success and an appropriate error value on failure.
 239  */
 240 int rpmsg_trysend(struct rpmsg_endpoint *ept, void *data, int len)
 241 {
 242         if (WARN_ON(!ept))
 243                 return -EINVAL;
 244         if (!ept->ops->trysend)
 245                 return -ENXIO;
 246
 247         return ept->ops->trysend(ept, data, len);
 248 }
 249 EXPORT_SYMBOL(rpmsg_trysend);
 250
 251 /**
 252  * rpmsg_trysendto() - send a message across to the remote processor, specify dst
 253  * @ept: the rpmsg endpoint
 254  * @data: payload of message
 255  * @len: length of payload
 256  * @dst: destination address
 257  *
 258  * This function sends @data of length @len to the remote @dst address.
 259  * The message will be sent to the remote processor which the @ept
 260  * endpoint belongs to, using @ept's address as source.
 261  * In case there are no TX buffers available, the function will immediately
 262  * return -ENOMEM without waiting until one becomes available.
 263  *
 264  * Can only be called from process context (for now).
 265  *
 266  * Returns 0 on success and an appropriate error value on failure.
 267  */
 268 int rpmsg_trysendto(struct rpmsg_endpoint *ept, void *data, int len, u32 dst)
 269 {
 270         if (WARN_ON(!ept))
 271                 return -EINVAL;
 272         if (!ept->ops->trysendto)
 273                 return -ENXIO;
 274
 275         return ept->ops->trysendto(ept, data, len, dst);
 276 }
 277 EXPORT_SYMBOL(rpmsg_trysendto);
 278
 279 /**
 280  * rpmsg_poll() - poll the endpoint's send buffers
 281  * @ept:        the rpmsg endpoint
 282  * @filp:       file for poll_wait()
 283  * @wait:       poll_table for poll_wait()
 284  *
 285  * Returns mask representing the current state of the endpoint's send buffers
 286  */
 287 __poll_t rpmsg_poll(struct rpmsg_endpoint *ept, struct file *filp,
 288                         poll_table *wait)
 289 {
 290         if (WARN_ON(!ept))
 291                 return 0;
 292         if (!ept->ops->poll)
 293                 return 0;
 294
 295         return ept->ops->poll(ept, filp, wait);
 296 }
 297 EXPORT_SYMBOL(rpmsg_poll);
 298
 299 /**
 300  * rpmsg_trysend_offchannel() - send a message using explicit src/dst addresses
 301  * @ept: the rpmsg endpoint
 302  * @src: source address
 303  * @dst: destination address
 304  * @data: payload of message
 305  * @len: length of payload
 306  *
 307  * This function sends @data of length @len to the remote @dst address,
 308  * and uses @src as the source address.
 309  * The message will be sent to the remote processor which the @ept
 310  * endpoint belongs to.
 311  * In case there are no TX buffers available, the function will immediately
 312  * return -ENOMEM without waiting until one becomes available.
 313  *
 314  * Can only be called from process context (for now).
 315  *
 316  * Returns 0 on success and an appropriate error value on failure.
 317  */
 318 int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst,
 319                              void *data, int len)
 320 {
 321         if (WARN_ON(!ept))
 322                 return -EINVAL;
 323         if (!ept->ops->trysend_offchannel)
 324                 return -ENXIO;
 325
 326         return ept->ops->trysend_offchannel(ept, src, dst, data, len);
 327 }
 328 EXPORT_SYMBOL(rpmsg_trysend_offchannel);
 329
 330 /*
 331  * match a rpmsg channel with a channel info struct.
 332  * this is used to make sure we're not creating rpmsg devices for channels
 333  * that already exist.
 334  */
 335 static int rpmsg_device_match(struct device *dev, void *data)
 336 {
 337         struct rpmsg_channel_info *chinfo = data;
 338         struct rpmsg_device *rpdev = to_rpmsg_device(dev);
 339
 340         if (chinfo->src != RPMSG_ADDR_ANY && chinfo->src != rpdev->src)
 341                 return 0;
 342
 343         if (chinfo->dst != RPMSG_ADDR_ANY && chinfo->dst != rpdev->dst)
 344                 return 0;
 345
 346         if (strncmp(chinfo->name, rpdev->id.name, RPMSG_NAME_SIZE))
 347                 return 0;
 348
 349         /* found a match ! */
 350         return 1;
 351 }
 352
 353 struct device *rpmsg_find_device(struct device *parent,
 354                                  struct rpmsg_channel_info *chinfo)
 355 {
 356         return device_find_child(parent, chinfo, rpmsg_device_match);
 357
 358 }
 359 EXPORT_SYMBOL(rpmsg_find_device);
 360
 361 /* sysfs show configuration fields */
 362 #define rpmsg_show_attr(field, path, format_string)                     \
 363 static ssize_t                                                          \
 364 field##_show(struct device *dev,                                        \
 365                         struct device_attribute *attr, char *buf)       \
 366 {                                                                       \
 367         struct rpmsg_device *rpdev = to_rpmsg_device(dev);              \
 368                                                                         \
 369         return sprintf(buf, format_string, rpdev->path);                \
 370 }                                                                       \
 371 static DEVICE_ATTR_RO(field);
 372
 373 #define rpmsg_string_attr(field, member)                                \
 374 static ssize_t                                                          \
 375 field##_store(struct device *dev, struct device_attribute *attr,        \
 376               const char *buf, size_t sz)                               \
 377 {                                                                       \
 378         struct rpmsg_device *rpdev = to_rpmsg_device(dev);              \
 379         char *new, *old;                                                \
 380                                                                         \
 381         new = kstrndup(buf, sz, GFP_KERNEL);                            \
 382         if (!new)                                                       \
 383                 return -ENOMEM;                                         \
 384         new[strcspn(new, "\n")] = '\0';                                 \
 385                                                                         \
 386         device_lock(dev);                                               \
 387         old = rpdev->member;                                            \
 388         if (strlen(new)) {                                              \
 389                 rpdev->member = new;                                    \
 390         } else {                                                        \
 391                 kfree(new);                                             \
 392                 rpdev->member = NULL;                                   \
 393         }                                                               \
 394         device_unlock(dev);                                             \
 395                                                                         \
 396         kfree(old);                                                     \
 397                                                                         \
 398         return sz;                                                      \
 399 }                                                                       \
 400 static ssize_t                                                          \
 401 field##_show(struct device *dev,                                        \
 402              struct device_attribute *attr, char *buf)                  \
 403 {                                                                       \
 404         struct rpmsg_device *rpdev = to_rpmsg_device(dev);              \
 405                                                                         \
 406         return sprintf(buf, "%s\n", rpdev->member);                     \
 407 }                                                                       \
 408 static DEVICE_ATTR_RW(field)
 409
 410 /* for more info, see Documentation/ABI/testing/sysfs-bus-rpmsg */
 411 rpmsg_show_attr(name, id.name, "%s\n");
 412 rpmsg_show_attr(src, src, "0x%x\n");
 413 rpmsg_show_attr(dst, dst, "0x%x\n");
 414 rpmsg_show_attr(announce, announce ? "true" : "false", "%s\n");
 415 rpmsg_string_attr(driver_override, driver_override);
 416
 417 static ssize_t modalias_show(struct device *dev,
 418                              struct device_attribute *attr, char *buf)
 419 {
 420         struct rpmsg_device *rpdev = to_rpmsg_device(dev);
 421         ssize_t len;
 422
 423         len = of_device_modalias(dev, buf, PAGE_SIZE);
 424         if (len != -ENODEV)
 425                 return len;
 426
 427         return sprintf(buf, RPMSG_DEVICE_MODALIAS_FMT "\n", rpdev->id.name);
 428 }
 429 static DEVICE_ATTR_RO(modalias);
 430
 431 static struct attribute *rpmsg_dev_attrs[] = {
 432         &dev_attr_name.attr,
 433         &dev_attr_modalias.attr,
 434         &dev_attr_dst.attr,
 435         &dev_attr_src.attr,
 436         &dev_attr_announce.attr,
 437         &dev_attr_driver_override.attr,
 438         NULL,
 439 };
 440 ATTRIBUTE_GROUPS(rpmsg_dev);
 441
 442 /* rpmsg devices and drivers are matched using the service name */
 443 static inline int rpmsg_id_match(const struct rpmsg_device *rpdev,
 444                                   const struct rpmsg_device_id *id)
 445 {
 446         return strncmp(id->name, rpdev->id.name, RPMSG_NAME_SIZE) == 0;
 447 }
 448
 449 /* match rpmsg channel and rpmsg driver */
 450 static int rpmsg_dev_match(struct device *dev, struct device_driver *drv)
 451 {
 452         struct rpmsg_device *rpdev = to_rpmsg_device(dev);
 453         struct rpmsg_driver *rpdrv = to_rpmsg_driver(drv);
 454         const struct rpmsg_device_id *ids = rpdrv->id_table;
 455         unsigned int i;
 456
 457         if (rpdev->driver_override)
 458                 return !strcmp(rpdev->driver_override, drv->name);
 459
 460         if (ids)
 461                 for (i = 0; ids[i].name[0]; i++)
 462                         if (rpmsg_id_match(rpdev, &ids[i]))
 463                                 return 1;
 464
 465         return of_driver_match_device(dev, drv);
 466 }
 467
 468 static int rpmsg_uevent(struct device *dev, struct kobj_uevent_env *env)
 469 {
 470         struct rpmsg_device *rpdev = to_rpmsg_device(dev);
 471         int ret;
 472
 473         ret = of_device_uevent_modalias(dev, env);
 474         if (ret != -ENODEV)
 475                 return ret;
 476
 477         return add_uevent_var(env, "MODALIAS=" RPMSG_DEVICE_MODALIAS_FMT,
 478                                         rpdev->id.name);
 479 }
 480
 481 /*
 482  * when an rpmsg driver is probed with a channel, we seamlessly create
 483  * it an endpoint, binding its rx callback to a unique local rpmsg
 484  * address.
 485  *
 486  * if we need to, we also announce about this channel to the remote
 487  * processor (needed in case the driver is exposing an rpmsg service).
 488  */
 489 static int rpmsg_dev_probe(struct device *dev)
 490 {
 491         struct rpmsg_device *rpdev = to_rpmsg_device(dev);
 492         struct rpmsg_driver *rpdrv = to_rpmsg_driver(rpdev->dev.driver);
 493         struct rpmsg_channel_info chinfo = {};
 494         struct rpmsg_endpoint *ept = NULL;
 495         int err;
 496
 497         err = dev_pm_domain_attach(dev, true);
 498         if (err)
 499                 goto out;
 500
 501         if (rpdrv->callback) {
 502                 strncpy(chinfo.name, rpdev->id.name, RPMSG_NAME_SIZE);
 503                 chinfo.src = rpdev->src;
 504                 chinfo.dst = RPMSG_ADDR_ANY;
 505
 506                 ept = rpmsg_create_ept(rpdev, rpdrv->callback, NULL, chinfo);
 507                 if (!ept) {
 508                         dev_err(dev, "failed to create endpoint\n");
 509                         err = -ENOMEM;
 510                         goto out;
 511                 }
 512
 513                 rpdev->ept = ept;
 514                 rpdev->src = ept->addr;
 515         }
 516
 517         err = rpdrv->probe(rpdev);
 518         if (err) {
 519                 dev_err(dev, "%s: failed: %d\n", __func__, err);
 520                 if (ept)
 521                         rpmsg_destroy_ept(ept);
 522                 goto out;
 523         }
 524
 525         if (ept && rpdev->ops->announce_create)
 526                 err = rpdev->ops->announce_create(rpdev);
 527 out:
 528         return err;
 529 }
 530
 531 static int rpmsg_dev_remove(struct device *dev)
 532 {
 533         struct rpmsg_device *rpdev = to_rpmsg_device(dev);
 534         struct rpmsg_driver *rpdrv = to_rpmsg_driver(rpdev->dev.driver);
 535         int err = 0;
 536
 537         if (rpdev->ops->announce_destroy)
 538                 err = rpdev->ops->announce_destroy(rpdev);
 539
 540         if (rpdrv->remove)
 541                 rpdrv->remove(rpdev);
 542
 543         dev_pm_domain_detach(dev, true);
 544
 545         if (rpdev->ept)
 546                 rpmsg_destroy_ept(rpdev->ept);
 547
 548         return err;
 549 }
 550
 551 static struct bus_type rpmsg_bus = {
 552         .name           = "rpmsg",
 553         .match          = rpmsg_dev_match,
 554         .dev_groups     = rpmsg_dev_groups,
 555         .uevent         = rpmsg_uevent,
 556         .probe          = rpmsg_dev_probe,
 557         .remove         = rpmsg_dev_remove,
 558 };
 559
 560 int rpmsg_register_device(struct rpmsg_device *rpdev)
 561 {
 562         struct device *dev = &rpdev->dev;
 563         int ret;
 564
 565         dev_set_name(&rpdev->dev, "%s.%s.%d.%d", dev_name(dev->parent),
 566                      rpdev->id.name, rpdev->src, rpdev->dst);
 567
 568         rpdev->dev.bus = &rpmsg_bus;
 569
 570         ret = device_register(&rpdev->dev);
 571         if (ret) {
 572                 dev_err(dev, "device_register failed: %d\n", ret);
 573                 put_device(&rpdev->dev);
 574         }
 575
 576         return ret;
 577 }
 578 EXPORT_SYMBOL(rpmsg_register_device);
 579
 580 /*
 581  * find an existing channel using its name + address properties,
 582  * and destroy it
 583  */
 584 int rpmsg_unregister_device(struct device *parent,
 585                             struct rpmsg_channel_info *chinfo)
 586 {
 587         struct device *dev;
 588
 589         dev = rpmsg_find_device(parent, chinfo);
 590         if (!dev)
 591                 return -EINVAL;
 592
 593         device_unregister(dev);
 594
 595         put_device(dev);
 596
 597         return 0;
 598 }
 599 EXPORT_SYMBOL(rpmsg_unregister_device);
 600
 601 /**
 602  * __register_rpmsg_driver() - register an rpmsg driver with the rpmsg bus
 603  * @rpdrv: pointer to a struct rpmsg_driver
 604  * @owner: owning module/driver
 605  *
 606  * Returns 0 on success, and an appropriate error value on failure.
 607  */
 608 int __register_rpmsg_driver(struct rpmsg_driver *rpdrv, struct module *owner)
 609 {
 610         rpdrv->drv.bus = &rpmsg_bus;
 611         rpdrv->drv.owner = owner;
 612         return driver_register(&rpdrv->drv);
 613 }
 614 EXPORT_SYMBOL(__register_rpmsg_driver);
 615
 616 /**
 617  * unregister_rpmsg_driver() - unregister an rpmsg driver from the rpmsg bus
 618  * @rpdrv: pointer to a struct rpmsg_driver
 619  *
 620  * Returns 0 on success, and an appropriate error value on failure.
 621  */
 622 void unregister_rpmsg_driver(struct rpmsg_driver *rpdrv)
 623 {
 624         driver_unregister(&rpdrv->drv);
 625 }
 626 EXPORT_SYMBOL(unregister_rpmsg_driver);
 627
 628
 629 static int __init rpmsg_init(void)
 630 {
 631         int ret;
 632
 633         ret = bus_register(&rpmsg_bus);
 634         if (ret)
 635                 pr_err("failed to register rpmsg bus: %d\n", ret);
 636
 637         return ret;
 638 }
 639 postcore_initcall(rpmsg_init);
 640
 641 static void __exit rpmsg_fini(void)
 642 {
 643         bus_unregister(&rpmsg_bus);
 644 }
 645 module_exit(rpmsg_fini);
 646
 647 MODULE_DESCRIPTION("remote processor messaging bus");
 648 MODULE_LICENSE("GPL v2");