drivers/acpi/dock.c

   1 /*
   2  *  dock.c - ACPI dock station driver
   3  *
   4  *  Copyright (C) 2006 Kristen Carlson Accardi <kristen.c.accardi@intel.com>
   5  *
   6  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   7  *
   8  *  This program is free software; you can redistribute it and/or modify
   9  *  it under the terms of the GNU General Public License as published by
  10  *  the Free Software Foundation; either version 2 of the License, or (at
  11  *  your option) any later version.
  12  *
  13  *  This program is distributed in the hope that it will be useful, but
  14  *  WITHOUT ANY WARRANTY; without even the implied warranty of
  15  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  *  General Public License for more details.
  17  *
  18  *  You should have received a copy of the GNU General Public License along
  19  *  with this program; if not, write to the Free Software Foundation, Inc.,
  20  *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
  21  *
  22  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  23  */
  24
  25 #include <linux/kernel.h>
  26 #include <linux/module.h>
  27 #include <linux/init.h>
  28 #include <linux/types.h>
  29 #include <linux/notifier.h>
  30 #include <linux/platform_device.h>
  31 #include <linux/jiffies.h>
  32 #include <acpi/acpi_bus.h>
  33 #include <acpi/acpi_drivers.h>
  34
  35 #define ACPI_DOCK_DRIVER_NAME "ACPI Dock Station Driver"
  36
  37 ACPI_MODULE_NAME("dock")
  38 MODULE_AUTHOR("Kristen Carlson Accardi");
  39 MODULE_DESCRIPTION(ACPI_DOCK_DRIVER_NAME);
  40 MODULE_LICENSE("GPL");
  41
  42 static struct atomic_notifier_head dock_notifier_list;
  43 static struct platform_device dock_device;
  44 static char dock_device_name[] = "dock";
  45
  46 struct dock_station {
  47         acpi_handle handle;
  48         unsigned long last_dock_time;
  49         u32 flags;
  50         spinlock_t dd_lock;
  51         spinlock_t hp_lock;
  52         struct list_head dependent_devices;
  53         struct list_head hotplug_devices;
  54 };
  55
  56 struct dock_dependent_device {
  57         struct list_head list;
  58         struct list_head hotplug_list;
  59         acpi_handle handle;
  60         acpi_notify_handler handler;
  61         void *context;
  62 };
  63
  64 #define DOCK_DOCKING    0x00000001
  65 #define DOCK_EVENT      3
  66 #define UNDOCK_EVENT    2
  67
  68 static struct dock_station *dock_station;
  69
  70 /*****************************************************************************
  71  *                         Dock Dependent device functions                   *
  72  *****************************************************************************/
  73 /**
  74  *  alloc_dock_dependent_device - allocate and init a dependent device
  75  *  @handle: the acpi_handle of the dependent device
  76  *
  77  *  Allocate memory for a dependent device structure for a device referenced
  78  *  by the acpi handle
  79  */
  80 static struct dock_dependent_device *
  81 alloc_dock_dependent_device(acpi_handle handle)
  82 {
  83         struct dock_dependent_device *dd;
  84
  85         dd = kzalloc(sizeof(*dd), GFP_KERNEL);
  86         if (dd) {
  87                 dd->handle = handle;
  88                 INIT_LIST_HEAD(&dd->list);
  89                 INIT_LIST_HEAD(&dd->hotplug_list);
  90         }
  91         return dd;
  92 }
  93
  94 /**
  95  * add_dock_dependent_device - associate a device with the dock station
  96  * @ds: The dock station
  97  * @dd: The dependent device
  98  *
  99  * Add the dependent device to the dock's dependent device list.
 100  */
 101 static void
 102 add_dock_dependent_device(struct dock_station *ds,
 103                           struct dock_dependent_device *dd)
 104 {
 105         spin_lock(&ds->dd_lock);
 106         list_add_tail(&dd->list, &ds->dependent_devices);
 107         spin_unlock(&ds->dd_lock);
 108 }
 109
 110 /**
 111  * dock_add_hotplug_device - associate a hotplug handler with the dock station
 112  * @ds: The dock station
 113  * @dd: The dependent device struct
 114  *
 115  * Add the dependent device to the dock's hotplug device list
 116  */
 117 static void
 118 dock_add_hotplug_device(struct dock_station *ds,
 119                         struct dock_dependent_device *dd)
 120 {
 121         spin_lock(&ds->hp_lock);
 122         list_add_tail(&dd->hotplug_list, &ds->hotplug_devices);
 123         spin_unlock(&ds->hp_lock);
 124 }
 125
 126 /**
 127  * dock_del_hotplug_device - remove a hotplug handler from the dock station
 128  * @ds: The dock station
 129  * @dd: the dependent device struct
 130  *
 131  * Delete the dependent device from the dock's hotplug device list
 132  */
 133 static void
 134 dock_del_hotplug_device(struct dock_station *ds,
 135                         struct dock_dependent_device *dd)
 136 {
 137         spin_lock(&ds->hp_lock);
 138         list_del(&dd->hotplug_list);
 139         spin_unlock(&ds->hp_lock);
 140 }
 141
 142 /**
 143  * find_dock_dependent_device - get a device dependent on this dock
 144  * @ds: the dock station
 145  * @handle: the acpi_handle of the device we want
 146  *
 147  * iterate over the dependent device list for this dock.  If the
 148  * dependent device matches the handle, return.
 149  */
 150 static struct dock_dependent_device *
 151 find_dock_dependent_device(struct dock_station *ds, acpi_handle handle)
 152 {
 153         struct dock_dependent_device *dd;
 154
 155         spin_lock(&ds->dd_lock);
 156         list_for_each_entry(dd, &ds->dependent_devices, list) {
 157                 if (handle == dd->handle) {
 158                         spin_unlock(&ds->dd_lock);
 159                         return dd;
 160                 }
 161         }
 162         spin_unlock(&ds->dd_lock);
 163         return NULL;
 164 }
 165
 166 /*****************************************************************************
 167  *                         Dock functions                                    *
 168  *****************************************************************************/
 169 /**
 170  * is_dock - see if a device is a dock station
 171  * @handle: acpi handle of the device
 172  *
 173  * If an acpi object has a _DCK method, then it is by definition a dock
 174  * station, so return true.
 175  */
 176 static int is_dock(acpi_handle handle)
 177 {
 178         acpi_status status;
 179         acpi_handle tmp;
 180
 181         status = acpi_get_handle(handle, "_DCK", &tmp);
 182         if (ACPI_FAILURE(status))
 183                 return 0;
 184         return 1;
 185 }
 186
 187 /**
 188  * is_dock_device - see if a device is on a dock station
 189  * @handle: acpi handle of the device
 190  *
 191  * If this device is either the dock station itself,
 192  * or is a device dependent on the dock station, then it
 193  * is a dock device
 194  */
 195 int is_dock_device(acpi_handle handle)
 196 {
 197         if (!dock_station)
 198                 return 0;
 199
 200         if (is_dock(handle) || find_dock_dependent_device(dock_station, handle))
 201                 return 1;
 202
 203         return 0;
 204 }
 205
 206 EXPORT_SYMBOL_GPL(is_dock_device);
 207
 208 /**
 209  * dock_present - see if the dock station is present.
 210  * @ds: the dock station
 211  *
 212  * execute the _STA method.  note that present does not
 213  * imply that we are docked.
 214  */
 215 static int dock_present(struct dock_station *ds)
 216 {
 217         unsigned long sta;
 218         acpi_status status;
 219
 220         if (ds) {
 221                 status = acpi_evaluate_integer(ds->handle, "_STA", NULL, &sta);
 222                 if (ACPI_SUCCESS(status) && sta)
 223                         return 1;
 224         }
 225         return 0;
 226 }
 227
 228
 229
 230 /**
 231  * dock_create_acpi_device - add new devices to acpi
 232  * @handle - handle of the device to add
 233  *
 234  *  This function will create a new acpi_device for the given
 235  *  handle if one does not exist already.  This should cause
 236  *  acpi to scan for drivers for the given devices, and call
 237  *  matching driver's add routine.
 238  *
 239  *  Returns a pointer to the acpi_device corresponding to the handle.
 240  */
 241 static struct acpi_device * dock_create_acpi_device(acpi_handle handle)
 242 {
 243         struct acpi_device *device = NULL;
 244         struct acpi_device *parent_device;
 245         acpi_handle parent;
 246         int ret;
 247
 248         if (acpi_bus_get_device(handle, &device)) {
 249                 /*
 250                  * no device created for this object,
 251                  * so we should create one.
 252                  */
 253                 acpi_get_parent(handle, &parent);
 254                 if (acpi_bus_get_device(parent, &parent_device))
 255                         parent_device = NULL;
 256
 257                 ret = acpi_bus_add(&device, parent_device, handle,
 258                         ACPI_BUS_TYPE_DEVICE);
 259                 if (ret) {
 260                         pr_debug("error adding bus, %x\n",
 261                                 -ret);
 262                         return NULL;
 263                 }
 264         }
 265         return device;
 266 }
 267
 268 /**
 269  * dock_remove_acpi_device - remove the acpi_device struct from acpi
 270  * @handle - the handle of the device to remove
 271  *
 272  *  Tell acpi to remove the acpi_device.  This should cause any loaded
 273  *  driver to have it's remove routine called.
 274  */
 275 static void dock_remove_acpi_device(acpi_handle handle)
 276 {
 277         struct acpi_device *device;
 278         int ret;
 279
 280         if (!acpi_bus_get_device(handle, &device)) {
 281                 ret = acpi_bus_trim(device, 1);
 282                 if (ret)
 283                         pr_debug("error removing bus, %x\n", -ret);
 284         }
 285 }
 286
 287
 288 /**
 289  * hotplug_dock_devices - insert or remove devices on the dock station
 290  * @ds: the dock station
 291  * @event: either bus check or eject request
 292  *
 293  * Some devices on the dock station need to have drivers called
 294  * to perform hotplug operations after a dock event has occurred.
 295  * Traverse the list of dock devices that have registered a
 296  * hotplug handler, and call the handler.
 297  */
 298 static void hotplug_dock_devices(struct dock_station *ds, u32 event)
 299 {
 300         struct dock_dependent_device *dd;
 301
 302         spin_lock(&ds->hp_lock);
 303
 304         /*
 305          * First call driver specific hotplug functions
 306          */
 307         list_for_each_entry(dd, &ds->hotplug_devices, hotplug_list) {
 308                 if (dd->handler)
 309                         dd->handler(dd->handle, event, dd->context);
 310         }
 311
 312         /*
 313          * Now make sure that an acpi_device is created for each
 314          * dependent device, or removed if this is an eject request.
 315          * This will cause acpi_drivers to be stopped/started if they
 316          * exist
 317          */
 318         list_for_each_entry(dd, &ds->dependent_devices, list) {
 319                 if (event == ACPI_NOTIFY_EJECT_REQUEST)
 320                         dock_remove_acpi_device(dd->handle);
 321                 else
 322                         dock_create_acpi_device(dd->handle);
 323         }
 324         spin_unlock(&ds->hp_lock);
 325 }
 326
 327 static void dock_event(struct dock_station *ds, u32 event, int num)
 328 {
 329         /*
 330          * we don't do events until someone tells me that
 331          * they would like to have them.
 332          */
 333 }
 334
 335 /**
 336  * eject_dock - respond to a dock eject request
 337  * @ds: the dock station
 338  *
 339  * This is called after _DCK is called, to execute the dock station's
 340  * _EJ0 method.
 341  */
 342 static void eject_dock(struct dock_station *ds)
 343 {
 344         struct acpi_object_list arg_list;
 345         union acpi_object arg;
 346         acpi_status status;
 347         acpi_handle tmp;
 348
 349         /* all dock devices should have _EJ0, but check anyway */
 350         status = acpi_get_handle(ds->handle, "_EJ0", &tmp);
 351         if (ACPI_FAILURE(status)) {
 352                 pr_debug("No _EJ0 support for dock device\n");
 353                 return;
 354         }
 355
 356         arg_list.count = 1;
 357         arg_list.pointer = &arg;
 358         arg.type = ACPI_TYPE_INTEGER;
 359         arg.integer.value = 1;
 360
 361         if (ACPI_FAILURE(acpi_evaluate_object(ds->handle, "_EJ0",
 362                                               &arg_list, NULL)))
 363                 pr_debug("Failed to evaluate _EJ0!\n");
 364 }
 365
 366 /**
 367  * handle_dock - handle a dock event
 368  * @ds: the dock station
 369  * @dock: to dock, or undock - that is the question
 370  *
 371  * Execute the _DCK method in response to an acpi event
 372  */
 373 static void handle_dock(struct dock_station *ds, int dock)
 374 {
 375         acpi_status status;
 376         struct acpi_object_list arg_list;
 377         union acpi_object arg;
 378         struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
 379         struct acpi_buffer name_buffer = { ACPI_ALLOCATE_BUFFER, NULL };
 380         union acpi_object *obj;
 381
 382         acpi_get_name(ds->handle, ACPI_FULL_PATHNAME, &name_buffer);
 383         obj = name_buffer.pointer;
 384
 385         printk(KERN_INFO PREFIX "%s\n", dock ? "docking" : "undocking");
 386
 387         /* _DCK method has one argument */
 388         arg_list.count = 1;
 389         arg_list.pointer = &arg;
 390         arg.type = ACPI_TYPE_INTEGER;
 391         arg.integer.value = dock;
 392         status = acpi_evaluate_object(ds->handle, "_DCK", &arg_list, &buffer);
 393         if (ACPI_FAILURE(status))
 394                 pr_debug("%s: failed to execute _DCK\n", obj->string.pointer);
 395         kfree(buffer.pointer);
 396         kfree(name_buffer.pointer);
 397 }
 398
 399 static inline void dock(struct dock_station *ds)
 400 {
 401         handle_dock(ds, 1);
 402 }
 403
 404 static inline void undock(struct dock_station *ds)
 405 {
 406         handle_dock(ds, 0);
 407 }
 408
 409 static inline void begin_dock(struct dock_station *ds)
 410 {
 411         ds->flags |= DOCK_DOCKING;
 412 }
 413
 414 static inline void complete_dock(struct dock_station *ds)
 415 {
 416         ds->flags &= ~(DOCK_DOCKING);
 417         ds->last_dock_time = jiffies;
 418 }
 419
 420 /**
 421  * dock_in_progress - see if we are in the middle of handling a dock event
 422  * @ds: the dock station
 423  *
 424  * Sometimes while docking, false dock events can be sent to the driver
 425  * because good connections aren't made or some other reason.  Ignore these
 426  * if we are in the middle of doing something.
 427  */
 428 static int dock_in_progress(struct dock_station *ds)
 429 {
 430         if ((ds->flags & DOCK_DOCKING) ||
 431             time_before(jiffies, (ds->last_dock_time + HZ)))
 432                 return 1;
 433         return 0;
 434 }
 435
 436 /**
 437  * register_dock_notifier - add yourself to the dock notifier list
 438  * @nb: the callers notifier block
 439  *
 440  * If a driver wishes to be notified about dock events, they can
 441  * use this function to put a notifier block on the dock notifier list.
 442  * this notifier call chain will be called after a dock event, but
 443  * before hotplugging any new devices.
 444  */
 445 int register_dock_notifier(struct notifier_block *nb)
 446 {
 447         return atomic_notifier_chain_register(&dock_notifier_list, nb);
 448 }
 449
 450 EXPORT_SYMBOL_GPL(register_dock_notifier);
 451
 452 /**
 453  * unregister_dock_notifier - remove yourself from the dock notifier list
 454  * @nb: the callers notifier block
 455  */
 456 void unregister_dock_notifier(struct notifier_block *nb)
 457 {
 458         atomic_notifier_chain_unregister(&dock_notifier_list, nb);
 459 }
 460
 461 EXPORT_SYMBOL_GPL(unregister_dock_notifier);
 462
 463 /**
 464  * register_hotplug_dock_device - register a hotplug function
 465  * @handle: the handle of the device
 466  * @handler: the acpi_notifier_handler to call after docking
 467  * @context: device specific data
 468  *
 469  * If a driver would like to perform a hotplug operation after a dock
 470  * event, they can register an acpi_notifiy_handler to be called by
 471  * the dock driver after _DCK is executed.
 472  */
 473 int
 474 register_hotplug_dock_device(acpi_handle handle, acpi_notify_handler handler,
 475                              void *context)
 476 {
 477         struct dock_dependent_device *dd;
 478
 479         if (!dock_station)
 480                 return -ENODEV;
 481
 482         /*
 483          * make sure this handle is for a device dependent on the dock,
 484          * this would include the dock station itself
 485          */
 486         dd = find_dock_dependent_device(dock_station, handle);
 487         if (dd) {
 488                 dd->handler = handler;
 489                 dd->context = context;
 490                 dock_add_hotplug_device(dock_station, dd);
 491                 return 0;
 492         }
 493
 494         return -EINVAL;
 495 }
 496
 497 EXPORT_SYMBOL_GPL(register_hotplug_dock_device);
 498
 499 /**
 500  * unregister_hotplug_dock_device - remove yourself from the hotplug list
 501  * @handle: the acpi handle of the device
 502  */
 503 void unregister_hotplug_dock_device(acpi_handle handle)
 504 {
 505         struct dock_dependent_device *dd;
 506
 507         if (!dock_station)
 508                 return;
 509
 510         dd = find_dock_dependent_device(dock_station, handle);
 511         if (dd)
 512                 dock_del_hotplug_device(dock_station, dd);
 513 }
 514
 515 EXPORT_SYMBOL_GPL(unregister_hotplug_dock_device);
 516
 517 /**
 518  * handle_eject_request - handle an undock request checking for error conditions
 519  *
 520  * Check to make sure the dock device is still present, then undock and
 521  * hotremove all the devices that may need removing.
 522  */
 523 static int handle_eject_request(struct dock_station *ds, u32 event)
 524 {
 525         if (!dock_present(ds))
 526                 return -ENODEV;
 527
 528         if (dock_in_progress(ds))
 529                 return -EBUSY;
 530
 531         /*
 532          * here we need to generate the undock
 533          * event prior to actually doing the undock
 534          * so that the device struct still exists.
 535          */
 536         dock_event(ds, event, UNDOCK_EVENT);
 537         hotplug_dock_devices(ds, ACPI_NOTIFY_EJECT_REQUEST);
 538         undock(ds);
 539         eject_dock(ds);
 540         if (dock_present(ds)) {
 541                 printk(KERN_ERR PREFIX "Unable to undock!\n");
 542                 return -EBUSY;
 543         }
 544
 545         return 0;
 546 }
 547
 548 /**
 549  * dock_notify - act upon an acpi dock notification
 550  * @handle: the dock station handle
 551  * @event: the acpi event
 552  * @data: our driver data struct
 553  *
 554  * If we are notified to dock, then check to see if the dock is
 555  * present and then dock.  Notify all drivers of the dock event,
 556  * and then hotplug and devices that may need hotplugging.
 557  */
 558 static void dock_notify(acpi_handle handle, u32 event, void *data)
 559 {
 560         struct dock_station *ds = (struct dock_station *)data;
 561
 562         switch (event) {
 563         case ACPI_NOTIFY_BUS_CHECK:
 564                 if (!dock_in_progress(ds) && dock_present(ds)) {
 565                         begin_dock(ds);
 566                         dock(ds);
 567                         if (!dock_present(ds)) {
 568                                 printk(KERN_ERR PREFIX "Unable to dock!\n");
 569                                 break;
 570                         }
 571                         atomic_notifier_call_chain(&dock_notifier_list,
 572                                                    event, NULL);
 573                         hotplug_dock_devices(ds, event);
 574                         complete_dock(ds);
 575                         dock_event(ds, event, DOCK_EVENT);
 576                 }
 577                 break;
 578         case ACPI_NOTIFY_DEVICE_CHECK:
 579         /*
 580          * According to acpi spec 3.0a, if a DEVICE_CHECK notification
 581          * is sent and _DCK is present, it is assumed to mean an
 582          * undock request.  This notify routine will only be called
 583          * for objects defining _DCK, so we will fall through to eject
 584          * request here.  However, we will pass an eject request through
 585          * to the driver who wish to hotplug.
 586          */
 587         case ACPI_NOTIFY_EJECT_REQUEST:
 588                 handle_eject_request(ds, event);
 589                 break;
 590         default:
 591                 printk(KERN_ERR PREFIX "Unknown dock event %d\n", event);
 592         }
 593 }
 594
 595 /**
 596  * find_dock_devices - find devices on the dock station
 597  * @handle: the handle of the device we are examining
 598  * @lvl: unused
 599  * @context: the dock station private data
 600  * @rv: unused
 601  *
 602  * This function is called by acpi_walk_namespace.  It will
 603  * check to see if an object has an _EJD method.  If it does, then it
 604  * will see if it is dependent on the dock station.
 605  */
 606 static acpi_status
 607 find_dock_devices(acpi_handle handle, u32 lvl, void *context, void **rv)
 608 {
 609         acpi_status status;
 610         acpi_handle tmp;
 611         struct dock_station *ds = (struct dock_station *)context;
 612         struct dock_dependent_device *dd;
 613
 614         status = acpi_bus_get_ejd(handle, &tmp);
 615         if (ACPI_FAILURE(status))
 616                 return AE_OK;
 617
 618         if (tmp == ds->handle) {
 619                 dd = alloc_dock_dependent_device(handle);
 620                 if (dd)
 621                         add_dock_dependent_device(ds, dd);
 622         }
 623
 624         return AE_OK;
 625 }
 626
 627 /*
 628  * show_docked - read method for "docked" file in sysfs
 629  */
 630 static ssize_t show_docked(struct device *dev,
 631                            struct device_attribute *attr, char *buf)
 632 {
 633         return snprintf(buf, PAGE_SIZE, "%d\n", dock_present(dock_station));
 634
 635 }
 636 DEVICE_ATTR(docked, S_IRUGO, show_docked, NULL);
 637
 638 /*
 639  * write_undock - write method for "undock" file in sysfs
 640  */
 641 static ssize_t write_undock(struct device *dev, struct device_attribute *attr,
 642                            const char *buf, size_t count)
 643 {
 644         int ret;
 645
 646         if (!count)
 647                 return -EINVAL;
 648
 649         ret = handle_eject_request(dock_station, ACPI_NOTIFY_EJECT_REQUEST);
 650         return ret ? ret: count;
 651 }
 652 DEVICE_ATTR(undock, S_IWUSR, NULL, write_undock);
 653
 654 /**
 655  * dock_add - add a new dock station
 656  * @handle: the dock station handle
 657  *
 658  * allocated and initialize a new dock station device.  Find all devices
 659  * that are on the dock station, and register for dock event notifications.
 660  */
 661 static int dock_add(acpi_handle handle)
 662 {
 663         int ret;
 664         acpi_status status;
 665         struct dock_dependent_device *dd;
 666
 667         /* allocate & initialize the dock_station private data */
 668         dock_station = kzalloc(sizeof(*dock_station), GFP_KERNEL);
 669         if (!dock_station)
 670                 return -ENOMEM;
 671         dock_station->handle = handle;
 672         dock_station->last_dock_time = jiffies - HZ;
 673         INIT_LIST_HEAD(&dock_station->dependent_devices);
 674         INIT_LIST_HEAD(&dock_station->hotplug_devices);
 675         spin_lock_init(&dock_station->dd_lock);
 676         spin_lock_init(&dock_station->hp_lock);
 677         ATOMIC_INIT_NOTIFIER_HEAD(&dock_notifier_list);
 678
 679         /* initialize platform device stuff */
 680         dock_device.name = dock_device_name;
 681         ret = platform_device_register(&dock_device);
 682         if (ret) {
 683                 printk(KERN_ERR PREFIX "Error %d registering dock device\n", ret);
 684                 kfree(dock_station);
 685                 return ret;
 686         }
 687         ret = device_create_file(&dock_device.dev, &dev_attr_docked);
 688         if (ret) {
 689                 printk("Error %d adding sysfs file\n", ret);
 690                 platform_device_unregister(&dock_device);
 691                 kfree(dock_station);
 692                 return ret;
 693         }
 694         ret = device_create_file(&dock_device.dev, &dev_attr_undock);
 695         if (ret) {
 696                 printk("Error %d adding sysfs file\n", ret);
 697                 device_remove_file(&dock_device.dev, &dev_attr_docked);
 698                 platform_device_unregister(&dock_device);
 699                 kfree(dock_station);
 700                 return ret;
 701         }
 702
 703         /* Find dependent devices */
 704         acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
 705                             ACPI_UINT32_MAX, find_dock_devices, dock_station,
 706                             NULL);
 707
 708         /* add the dock station as a device dependent on itself */
 709         dd = alloc_dock_dependent_device(handle);
 710         if (!dd) {
 711                 kfree(dock_station);
 712                 ret = -ENOMEM;
 713                 goto dock_add_err_unregister;
 714         }
 715         add_dock_dependent_device(dock_station, dd);
 716
 717         /* register for dock events */
 718         status = acpi_install_notify_handler(dock_station->handle,
 719                                              ACPI_SYSTEM_NOTIFY,
 720                                              dock_notify, dock_station);
 721
 722         if (ACPI_FAILURE(status)) {
 723                 printk(KERN_ERR PREFIX "Error installing notify handler\n");
 724                 ret = -ENODEV;
 725                 goto dock_add_err;
 726         }
 727
 728         printk(KERN_INFO PREFIX "%s \n", ACPI_DOCK_DRIVER_NAME);
 729
 730         return 0;
 731
 732 dock_add_err:
 733         kfree(dd);
 734 dock_add_err_unregister:
 735         device_remove_file(&dock_device.dev, &dev_attr_docked);
 736         device_remove_file(&dock_device.dev, &dev_attr_undock);
 737         platform_device_unregister(&dock_device);
 738         kfree(dock_station);
 739         return ret;
 740 }
 741
 742 /**
 743  * dock_remove - free up resources related to the dock station
 744  */
 745 static int dock_remove(void)
 746 {
 747         struct dock_dependent_device *dd, *tmp;
 748         acpi_status status;
 749
 750         if (!dock_station)
 751                 return 0;
 752
 753         /* remove dependent devices */
 754         list_for_each_entry_safe(dd, tmp, &dock_station->dependent_devices,
 755                                  list)
 756             kfree(dd);
 757
 758         /* remove dock notify handler */
 759         status = acpi_remove_notify_handler(dock_station->handle,
 760                                             ACPI_SYSTEM_NOTIFY,
 761                                             dock_notify);
 762         if (ACPI_FAILURE(status))
 763                 printk(KERN_ERR "Error removing notify handler\n");
 764
 765         /* cleanup sysfs */
 766         device_remove_file(&dock_device.dev, &dev_attr_docked);
 767         device_remove_file(&dock_device.dev, &dev_attr_undock);
 768         platform_device_unregister(&dock_device);
 769
 770         /* free dock station memory */
 771         kfree(dock_station);
 772         return 0;
 773 }
 774
 775 /**
 776  * find_dock - look for a dock station
 777  * @handle: acpi handle of a device
 778  * @lvl: unused
 779  * @context: counter of dock stations found
 780  * @rv: unused
 781  *
 782  * This is called by acpi_walk_namespace to look for dock stations.
 783  */
 784 static acpi_status
 785 find_dock(acpi_handle handle, u32 lvl, void *context, void **rv)
 786 {
 787         int *count = (int *)context;
 788         acpi_status status = AE_OK;
 789
 790         if (is_dock(handle)) {
 791                 if (dock_add(handle) >= 0) {
 792                         (*count)++;
 793                         status = AE_CTRL_TERMINATE;
 794                 }
 795         }
 796         return status;
 797 }
 798
 799 static int __init dock_init(void)
 800 {
 801         int num = 0;
 802
 803         dock_station = NULL;
 804
 805         /* look for a dock station */
 806         acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
 807                             ACPI_UINT32_MAX, find_dock, &num, NULL);
 808
 809         if (!num)
 810                 return -ENODEV;
 811
 812         return 0;
 813 }
 814
 815 static void __exit dock_exit(void)
 816 {
 817         dock_remove();
 818 }
 819
 820 postcore_initcall(dock_init);
 821 module_exit(dock_exit);