drivers/gpu/host1x/bus.c

   1 /*
   2  * Copyright (C) 2012 Avionic Design GmbH
   3  * Copyright (C) 2012-2013, NVIDIA Corporation
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms and conditions of the GNU General Public License,
   7  * version 2, as published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  12  * more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 #include <linux/debugfs.h>
  19 #include <linux/host1x.h>
  20 #include <linux/of.h>
  21 #include <linux/seq_file.h>
  22 #include <linux/slab.h>
  23 #include <linux/of_device.h>
  24
  25 #include "bus.h"
  26 #include "dev.h"
  27
  28 static DEFINE_MUTEX(clients_lock);
  29 static LIST_HEAD(clients);
  30
  31 static DEFINE_MUTEX(drivers_lock);
  32 static LIST_HEAD(drivers);
  33
  34 static DEFINE_MUTEX(devices_lock);
  35 static LIST_HEAD(devices);
  36
  37 struct host1x_subdev {
  38         struct host1x_client *client;
  39         struct device_node *np;
  40         struct list_head list;
  41 };
  42
  43 /**
  44  * host1x_subdev_add() - add a new subdevice with an associated device node
  45  * @device: host1x device to add the subdevice to
  46  * @np: device node
  47  */
  48 static int host1x_subdev_add(struct host1x_device *device,
  49                              struct host1x_driver *driver,
  50                              struct device_node *np)
  51 {
  52         struct host1x_subdev *subdev;
  53         struct device_node *child;
  54         int err;
  55
  56         subdev = kzalloc(sizeof(*subdev), GFP_KERNEL);
  57         if (!subdev)
  58                 return -ENOMEM;
  59
  60         INIT_LIST_HEAD(&subdev->list);
  61         subdev->np = of_node_get(np);
  62
  63         mutex_lock(&device->subdevs_lock);
  64         list_add_tail(&subdev->list, &device->subdevs);
  65         mutex_unlock(&device->subdevs_lock);
  66
  67         /* recursively add children */
  68         for_each_child_of_node(np, child) {
  69                 if (of_match_node(driver->subdevs, child) &&
  70                     of_device_is_available(child)) {
  71                         err = host1x_subdev_add(device, driver, child);
  72                         if (err < 0) {
  73                                 /* XXX cleanup? */
  74                                 of_node_put(child);
  75                                 return err;
  76                         }
  77                 }
  78         }
  79
  80         return 0;
  81 }
  82
  83 /**
  84  * host1x_subdev_del() - remove subdevice
  85  * @subdev: subdevice to remove
  86  */
  87 static void host1x_subdev_del(struct host1x_subdev *subdev)
  88 {
  89         list_del(&subdev->list);
  90         of_node_put(subdev->np);
  91         kfree(subdev);
  92 }
  93
  94 /**
  95  * host1x_device_parse_dt() - scan device tree and add matching subdevices
  96  * @device: host1x logical device
  97  * @driver: host1x driver
  98  */
  99 static int host1x_device_parse_dt(struct host1x_device *device,
 100                                   struct host1x_driver *driver)
 101 {
 102         struct device_node *np;
 103         int err;
 104
 105         for_each_child_of_node(device->dev.parent->of_node, np) {
 106                 if (of_match_node(driver->subdevs, np) &&
 107                     of_device_is_available(np)) {
 108                         err = host1x_subdev_add(device, driver, np);
 109                         if (err < 0) {
 110                                 of_node_put(np);
 111                                 return err;
 112                         }
 113                 }
 114         }
 115
 116         return 0;
 117 }
 118
 119 static void host1x_subdev_register(struct host1x_device *device,
 120                                    struct host1x_subdev *subdev,
 121                                    struct host1x_client *client)
 122 {
 123         int err;
 124
 125         /*
 126          * Move the subdevice to the list of active (registered) subdevices
 127          * and associate it with a client. At the same time, associate the
 128          * client with its parent device.
 129          */
 130         mutex_lock(&device->subdevs_lock);
 131         mutex_lock(&device->clients_lock);
 132         list_move_tail(&client->list, &device->clients);
 133         list_move_tail(&subdev->list, &device->active);
 134         client->parent = &device->dev;
 135         subdev->client = client;
 136         mutex_unlock(&device->clients_lock);
 137         mutex_unlock(&device->subdevs_lock);
 138
 139         if (list_empty(&device->subdevs)) {
 140                 err = device_add(&device->dev);
 141                 if (err < 0)
 142                         dev_err(&device->dev, "failed to add: %d\n", err);
 143                 else
 144                         device->registered = true;
 145         }
 146 }
 147
 148 static void __host1x_subdev_unregister(struct host1x_device *device,
 149                                        struct host1x_subdev *subdev)
 150 {
 151         struct host1x_client *client = subdev->client;
 152
 153         /*
 154          * If all subdevices have been activated, we're about to remove the
 155          * first active subdevice, so unload the driver first.
 156          */
 157         if (list_empty(&device->subdevs)) {
 158                 if (device->registered) {
 159                         device->registered = false;
 160                         device_del(&device->dev);
 161                 }
 162         }
 163
 164         /*
 165          * Move the subdevice back to the list of idle subdevices and remove
 166          * it from list of clients.
 167          */
 168         mutex_lock(&device->clients_lock);
 169         subdev->client = NULL;
 170         client->parent = NULL;
 171         list_move_tail(&subdev->list, &device->subdevs);
 172         /*
 173          * XXX: Perhaps don't do this here, but rather explicitly remove it
 174          * when the device is about to be deleted.
 175          *
 176          * This is somewhat complicated by the fact that this function is
 177          * used to remove the subdevice when a client is unregistered but
 178          * also when the composite device is about to be removed.
 179          */
 180         list_del_init(&client->list);
 181         mutex_unlock(&device->clients_lock);
 182 }
 183
 184 static void host1x_subdev_unregister(struct host1x_device *device,
 185                                      struct host1x_subdev *subdev)
 186 {
 187         mutex_lock(&device->subdevs_lock);
 188         __host1x_subdev_unregister(device, subdev);
 189         mutex_unlock(&device->subdevs_lock);
 190 }
 191
 192 /**
 193  * host1x_device_init() - initialize a host1x logical device
 194  * @device: host1x logical device
 195  *
 196  * The driver for the host1x logical device can call this during execution of
 197  * its &host1x_driver.probe implementation to initialize each of its clients.
 198  * The client drivers access the subsystem specific driver data using the
 199  * &host1x_client.parent field and driver data associated with it (usually by
 200  * calling dev_get_drvdata()).
 201  */
 202 int host1x_device_init(struct host1x_device *device)
 203 {
 204         struct host1x_client *client;
 205         int err;
 206
 207         mutex_lock(&device->clients_lock);
 208
 209         list_for_each_entry(client, &device->clients, list) {
 210                 if (client->ops && client->ops->init) {
 211                         err = client->ops->init(client);
 212                         if (err < 0) {
 213                                 dev_err(&device->dev,
 214                                         "failed to initialize %s: %d\n",
 215                                         dev_name(client->dev), err);
 216                                 goto teardown;
 217                         }
 218                 }
 219         }
 220
 221         mutex_unlock(&device->clients_lock);
 222
 223         return 0;
 224
 225 teardown:
 226         list_for_each_entry_continue_reverse(client, &device->clients, list)
 227                 if (client->ops->exit)
 228                         client->ops->exit(client);
 229
 230         mutex_unlock(&device->clients_lock);
 231         return err;
 232 }
 233 EXPORT_SYMBOL(host1x_device_init);
 234
 235 /**
 236  * host1x_device_exit() - uninitialize host1x logical device
 237  * @device: host1x logical device
 238  *
 239  * When the driver for a host1x logical device is unloaded, it can call this
 240  * function to tear down each of its clients. Typically this is done after a
 241  * subsystem-specific data structure is removed and the functionality can no
 242  * longer be used.
 243  */
 244 int host1x_device_exit(struct host1x_device *device)
 245 {
 246         struct host1x_client *client;
 247         int err;
 248
 249         mutex_lock(&device->clients_lock);
 250
 251         list_for_each_entry_reverse(client, &device->clients, list) {
 252                 if (client->ops && client->ops->exit) {
 253                         err = client->ops->exit(client);
 254                         if (err < 0) {
 255                                 dev_err(&device->dev,
 256                                         "failed to cleanup %s: %d\n",
 257                                         dev_name(client->dev), err);
 258                                 mutex_unlock(&device->clients_lock);
 259                                 return err;
 260                         }
 261                 }
 262         }
 263
 264         mutex_unlock(&device->clients_lock);
 265
 266         return 0;
 267 }
 268 EXPORT_SYMBOL(host1x_device_exit);
 269
 270 static int host1x_add_client(struct host1x *host1x,
 271                              struct host1x_client *client)
 272 {
 273         struct host1x_device *device;
 274         struct host1x_subdev *subdev;
 275
 276         mutex_lock(&host1x->devices_lock);
 277
 278         list_for_each_entry(device, &host1x->devices, list) {
 279                 list_for_each_entry(subdev, &device->subdevs, list) {
 280                         if (subdev->np == client->dev->of_node) {
 281                                 host1x_subdev_register(device, subdev, client);
 282                                 mutex_unlock(&host1x->devices_lock);
 283                                 return 0;
 284                         }
 285                 }
 286         }
 287
 288         mutex_unlock(&host1x->devices_lock);
 289         return -ENODEV;
 290 }
 291
 292 static int host1x_del_client(struct host1x *host1x,
 293                              struct host1x_client *client)
 294 {
 295         struct host1x_device *device, *dt;
 296         struct host1x_subdev *subdev;
 297
 298         mutex_lock(&host1x->devices_lock);
 299
 300         list_for_each_entry_safe(device, dt, &host1x->devices, list) {
 301                 list_for_each_entry(subdev, &device->active, list) {
 302                         if (subdev->client == client) {
 303                                 host1x_subdev_unregister(device, subdev);
 304                                 mutex_unlock(&host1x->devices_lock);
 305                                 return 0;
 306                         }
 307                 }
 308         }
 309
 310         mutex_unlock(&host1x->devices_lock);
 311         return -ENODEV;
 312 }
 313
 314 static int host1x_device_match(struct device *dev, struct device_driver *drv)
 315 {
 316         return strcmp(dev_name(dev), drv->name) == 0;
 317 }
 318
 319 static int host1x_dma_configure(struct device *dev)
 320 {
 321         return of_dma_configure(dev, dev->of_node, true);
 322 }
 323
 324 static const struct dev_pm_ops host1x_device_pm_ops = {
 325         .suspend = pm_generic_suspend,
 326         .resume = pm_generic_resume,
 327         .freeze = pm_generic_freeze,
 328         .thaw = pm_generic_thaw,
 329         .poweroff = pm_generic_poweroff,
 330         .restore = pm_generic_restore,
 331 };
 332
 333 struct bus_type host1x_bus_type = {
 334         .name = "host1x",
 335         .match = host1x_device_match,
 336         .dma_configure = host1x_dma_configure,
 337         .pm = &host1x_device_pm_ops,
 338 };
 339
 340 static void __host1x_device_del(struct host1x_device *device)
 341 {
 342         struct host1x_subdev *subdev, *sd;
 343         struct host1x_client *client, *cl;
 344
 345         mutex_lock(&device->subdevs_lock);
 346
 347         /* unregister subdevices */
 348         list_for_each_entry_safe(subdev, sd, &device->active, list) {
 349                 /*
 350                  * host1x_subdev_unregister() will remove the client from
 351                  * any lists, so we'll need to manually add it back to the
 352                  * list of idle clients.
 353                  *
 354                  * XXX: Alternatively, perhaps don't remove the client from
 355                  * any lists in host1x_subdev_unregister() and instead do
 356                  * that explicitly from host1x_unregister_client()?
 357                  */
 358                 client = subdev->client;
 359
 360                 __host1x_subdev_unregister(device, subdev);
 361
 362                 /* add the client to the list of idle clients */
 363                 mutex_lock(&clients_lock);
 364                 list_add_tail(&client->list, &clients);
 365                 mutex_unlock(&clients_lock);
 366         }
 367
 368         /* remove subdevices */
 369         list_for_each_entry_safe(subdev, sd, &device->subdevs, list)
 370                 host1x_subdev_del(subdev);
 371
 372         mutex_unlock(&device->subdevs_lock);
 373
 374         /* move clients to idle list */
 375         mutex_lock(&clients_lock);
 376         mutex_lock(&device->clients_lock);
 377
 378         list_for_each_entry_safe(client, cl, &device->clients, list)
 379                 list_move_tail(&client->list, &clients);
 380
 381         mutex_unlock(&device->clients_lock);
 382         mutex_unlock(&clients_lock);
 383
 384         /* finally remove the device */
 385         list_del_init(&device->list);
 386 }
 387
 388 static void host1x_device_release(struct device *dev)
 389 {
 390         struct host1x_device *device = to_host1x_device(dev);
 391
 392         __host1x_device_del(device);
 393         kfree(device);
 394 }
 395
 396 static int host1x_device_add(struct host1x *host1x,
 397                              struct host1x_driver *driver)
 398 {
 399         struct host1x_client *client, *tmp;
 400         struct host1x_subdev *subdev;
 401         struct host1x_device *device;
 402         int err;
 403
 404         device = kzalloc(sizeof(*device), GFP_KERNEL);
 405         if (!device)
 406                 return -ENOMEM;
 407
 408         device_initialize(&device->dev);
 409
 410         mutex_init(&device->subdevs_lock);
 411         INIT_LIST_HEAD(&device->subdevs);
 412         INIT_LIST_HEAD(&device->active);
 413         mutex_init(&device->clients_lock);
 414         INIT_LIST_HEAD(&device->clients);
 415         INIT_LIST_HEAD(&device->list);
 416         device->driver = driver;
 417
 418         device->dev.coherent_dma_mask = host1x->dev->coherent_dma_mask;
 419         device->dev.dma_mask = &device->dev.coherent_dma_mask;
 420         dev_set_name(&device->dev, "%s", driver->driver.name);
 421         device->dev.release = host1x_device_release;
 422         device->dev.of_node = host1x->dev->of_node;
 423         device->dev.bus = &host1x_bus_type;
 424         device->dev.parent = host1x->dev;
 425
 426         of_dma_configure(&device->dev, host1x->dev->of_node, true);
 427
 428         err = host1x_device_parse_dt(device, driver);
 429         if (err < 0) {
 430                 kfree(device);
 431                 return err;
 432         }
 433
 434         list_add_tail(&device->list, &host1x->devices);
 435
 436         mutex_lock(&clients_lock);
 437
 438         list_for_each_entry_safe(client, tmp, &clients, list) {
 439                 list_for_each_entry(subdev, &device->subdevs, list) {
 440                         if (subdev->np == client->dev->of_node) {
 441                                 host1x_subdev_register(device, subdev, client);
 442                                 break;
 443                         }
 444                 }
 445         }
 446
 447         mutex_unlock(&clients_lock);
 448
 449         return 0;
 450 }
 451
 452 /*
 453  * Removes a device by first unregistering any subdevices and then removing
 454  * itself from the list of devices.
 455  *
 456  * This function must be called with the host1x->devices_lock held.
 457  */
 458 static void host1x_device_del(struct host1x *host1x,
 459                               struct host1x_device *device)
 460 {
 461         if (device->registered) {
 462                 device->registered = false;
 463                 device_del(&device->dev);
 464         }
 465
 466         put_device(&device->dev);
 467 }
 468
 469 static void host1x_attach_driver(struct host1x *host1x,
 470                                  struct host1x_driver *driver)
 471 {
 472         struct host1x_device *device;
 473         int err;
 474
 475         mutex_lock(&host1x->devices_lock);
 476
 477         list_for_each_entry(device, &host1x->devices, list) {
 478                 if (device->driver == driver) {
 479                         mutex_unlock(&host1x->devices_lock);
 480                         return;
 481                 }
 482         }
 483
 484         err = host1x_device_add(host1x, driver);
 485         if (err < 0)
 486                 dev_err(host1x->dev, "failed to allocate device: %d\n", err);
 487
 488         mutex_unlock(&host1x->devices_lock);
 489 }
 490
 491 static void host1x_detach_driver(struct host1x *host1x,
 492                                  struct host1x_driver *driver)
 493 {
 494         struct host1x_device *device, *tmp;
 495
 496         mutex_lock(&host1x->devices_lock);
 497
 498         list_for_each_entry_safe(device, tmp, &host1x->devices, list)
 499                 if (device->driver == driver)
 500                         host1x_device_del(host1x, device);
 501
 502         mutex_unlock(&host1x->devices_lock);
 503 }
 504
 505 static int host1x_devices_show(struct seq_file *s, void *data)
 506 {
 507         struct host1x *host1x = s->private;
 508         struct host1x_device *device;
 509
 510         mutex_lock(&host1x->devices_lock);
 511
 512         list_for_each_entry(device, &host1x->devices, list) {
 513                 struct host1x_subdev *subdev;
 514
 515                 seq_printf(s, "%s\n", dev_name(&device->dev));
 516
 517                 mutex_lock(&device->subdevs_lock);
 518
 519                 list_for_each_entry(subdev, &device->active, list)
 520                         seq_printf(s, "  %pOFf: %s\n", subdev->np,
 521                                    dev_name(subdev->client->dev));
 522
 523                 list_for_each_entry(subdev, &device->subdevs, list)
 524                         seq_printf(s, "  %pOFf:\n", subdev->np);
 525
 526                 mutex_unlock(&device->subdevs_lock);
 527         }
 528
 529         mutex_unlock(&host1x->devices_lock);
 530
 531         return 0;
 532 }
 533 DEFINE_SHOW_ATTRIBUTE(host1x_devices);
 534
 535 /**
 536  * host1x_register() - register a host1x controller
 537  * @host1x: host1x controller
 538  *
 539  * The host1x controller driver uses this to register a host1x controller with
 540  * the infrastructure. Note that all Tegra SoC generations have only ever come
 541  * with a single host1x instance, so this function is somewhat academic.
 542  */
 543 int host1x_register(struct host1x *host1x)
 544 {
 545         struct host1x_driver *driver;
 546
 547         mutex_lock(&devices_lock);
 548         list_add_tail(&host1x->list, &devices);
 549         mutex_unlock(&devices_lock);
 550
 551         mutex_lock(&drivers_lock);
 552
 553         list_for_each_entry(driver, &drivers, list)
 554                 host1x_attach_driver(host1x, driver);
 555
 556         mutex_unlock(&drivers_lock);
 557
 558         debugfs_create_file("devices", S_IRUGO, host1x->debugfs, host1x,
 559                             &host1x_devices_fops);
 560
 561         return 0;
 562 }
 563
 564 /**
 565  * host1x_unregister() - unregister a host1x controller
 566  * @host1x: host1x controller
 567  *
 568  * The host1x controller driver uses this to remove a host1x controller from
 569  * the infrastructure.
 570  */
 571 int host1x_unregister(struct host1x *host1x)
 572 {
 573         struct host1x_driver *driver;
 574
 575         mutex_lock(&drivers_lock);
 576
 577         list_for_each_entry(driver, &drivers, list)
 578                 host1x_detach_driver(host1x, driver);
 579
 580         mutex_unlock(&drivers_lock);
 581
 582         mutex_lock(&devices_lock);
 583         list_del_init(&host1x->list);
 584         mutex_unlock(&devices_lock);
 585
 586         return 0;
 587 }
 588
 589 static int host1x_device_probe(struct device *dev)
 590 {
 591         struct host1x_driver *driver = to_host1x_driver(dev->driver);
 592         struct host1x_device *device = to_host1x_device(dev);
 593
 594         if (driver->probe)
 595                 return driver->probe(device);
 596
 597         return 0;
 598 }
 599
 600 static int host1x_device_remove(struct device *dev)
 601 {
 602         struct host1x_driver *driver = to_host1x_driver(dev->driver);
 603         struct host1x_device *device = to_host1x_device(dev);
 604
 605         if (driver->remove)
 606                 return driver->remove(device);
 607
 608         return 0;
 609 }
 610
 611 static void host1x_device_shutdown(struct device *dev)
 612 {
 613         struct host1x_driver *driver = to_host1x_driver(dev->driver);
 614         struct host1x_device *device = to_host1x_device(dev);
 615
 616         if (driver->shutdown)
 617                 driver->shutdown(device);
 618 }
 619
 620 /**
 621  * host1x_driver_register_full() - register a host1x driver
 622  * @driver: host1x driver
 623  * @owner: owner module
 624  *
 625  * Drivers for host1x logical devices call this function to register a driver
 626  * with the infrastructure. Note that since these drive logical devices, the
 627  * registration of the driver actually triggers tho logical device creation.
 628  * A logical device will be created for each host1x instance.
 629  */
 630 int host1x_driver_register_full(struct host1x_driver *driver,
 631                                 struct module *owner)
 632 {
 633         struct host1x *host1x;
 634
 635         INIT_LIST_HEAD(&driver->list);
 636
 637         mutex_lock(&drivers_lock);
 638         list_add_tail(&driver->list, &drivers);
 639         mutex_unlock(&drivers_lock);
 640
 641         mutex_lock(&devices_lock);
 642
 643         list_for_each_entry(host1x, &devices, list)
 644                 host1x_attach_driver(host1x, driver);
 645
 646         mutex_unlock(&devices_lock);
 647
 648         driver->driver.bus = &host1x_bus_type;
 649         driver->driver.owner = owner;
 650         driver->driver.probe = host1x_device_probe;
 651         driver->driver.remove = host1x_device_remove;
 652         driver->driver.shutdown = host1x_device_shutdown;
 653
 654         return driver_register(&driver->driver);
 655 }
 656 EXPORT_SYMBOL(host1x_driver_register_full);
 657
 658 /**
 659  * host1x_driver_unregister() - unregister a host1x driver
 660  * @driver: host1x driver
 661  *
 662  * Unbinds the driver from each of the host1x logical devices that it is
 663  * bound to, effectively removing the subsystem devices that they represent.
 664  */
 665 void host1x_driver_unregister(struct host1x_driver *driver)
 666 {
 667         driver_unregister(&driver->driver);
 668
 669         mutex_lock(&drivers_lock);
 670         list_del_init(&driver->list);
 671         mutex_unlock(&drivers_lock);
 672 }
 673 EXPORT_SYMBOL(host1x_driver_unregister);
 674
 675 /**
 676  * host1x_client_register() - register a host1x client
 677  * @client: host1x client
 678  *
 679  * Registers a host1x client with each host1x controller instance. Note that
 680  * each client will only match their parent host1x controller and will only be
 681  * associated with that instance. Once all clients have been registered with
 682  * their parent host1x controller, the infrastructure will set up the logical
 683  * device and call host1x_device_init(), which will in turn call each client's
 684  * &host1x_client_ops.init implementation.
 685  */
 686 int host1x_client_register(struct host1x_client *client)
 687 {
 688         struct host1x *host1x;
 689         int err;
 690
 691         mutex_lock(&devices_lock);
 692
 693         list_for_each_entry(host1x, &devices, list) {
 694                 err = host1x_add_client(host1x, client);
 695                 if (!err) {
 696                         mutex_unlock(&devices_lock);
 697                         return 0;
 698                 }
 699         }
 700
 701         mutex_unlock(&devices_lock);
 702
 703         mutex_lock(&clients_lock);
 704         list_add_tail(&client->list, &clients);
 705         mutex_unlock(&clients_lock);
 706
 707         return 0;
 708 }
 709 EXPORT_SYMBOL(host1x_client_register);
 710
 711 /**
 712  * host1x_client_unregister() - unregister a host1x client
 713  * @client: host1x client
 714  *
 715  * Removes a host1x client from its host1x controller instance. If a logical
 716  * device has already been initialized, it will be torn down.
 717  */
 718 int host1x_client_unregister(struct host1x_client *client)
 719 {
 720         struct host1x_client *c;
 721         struct host1x *host1x;
 722         int err;
 723
 724         mutex_lock(&devices_lock);
 725
 726         list_for_each_entry(host1x, &devices, list) {
 727                 err = host1x_del_client(host1x, client);
 728                 if (!err) {
 729                         mutex_unlock(&devices_lock);
 730                         return 0;
 731                 }
 732         }
 733
 734         mutex_unlock(&devices_lock);
 735         mutex_lock(&clients_lock);
 736
 737         list_for_each_entry(c, &clients, list) {
 738                 if (c == client) {
 739                         list_del_init(&c->list);
 740                         break;
 741                 }
 742         }
 743
 744         mutex_unlock(&clients_lock);
 745
 746         return 0;
 747 }
 748 EXPORT_SYMBOL(host1x_client_unregister);