drivers/acpi/pci_root.c

   1 /*
   2  *  pci_root.c - ACPI PCI Root Bridge Driver ($Revision: 40 $)
   3  *
   4  *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
   5  *  Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
   6  *
   7  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   8  *
   9  *  This program is free software; you can redistribute it and/or modify
  10  *  it under the terms of the GNU General Public License as published by
  11  *  the Free Software Foundation; either version 2 of the License, or (at
  12  *  your option) any later version.
  13  *
  14  *  This program is distributed in the hope that it will be useful, but
  15  *  WITHOUT ANY WARRANTY; without even the implied warranty of
  16  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  *  General Public License for more details.
  18  *
  19  *  You should have received a copy of the GNU General Public License along
  20  *  with this program; if not, write to the Free Software Foundation, Inc.,
  21  *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
  22  *
  23  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  24  */
  25
  26 #include <linux/kernel.h>
  27 #include <linux/module.h>
  28 #include <linux/init.h>
  29 #include <linux/types.h>
  30 #include <linux/mutex.h>
  31 #include <linux/pm.h>
  32 #include <linux/pm_runtime.h>
  33 #include <linux/pci.h>
  34 #include <linux/pci-acpi.h>
  35 #include <linux/pci-aspm.h>
  36 #include <linux/acpi.h>
  37 #include <linux/slab.h>
  38 #include <acpi/acpi_bus.h>
  39 #include <acpi/acpi_drivers.h>
  40 #include <acpi/apei.h>
  41
  42 #include "internal.h"
  43
  44 #define PREFIX "ACPI: "
  45
  46 #define _COMPONENT              ACPI_PCI_COMPONENT
  47 ACPI_MODULE_NAME("pci_root");
  48 #define ACPI_PCI_ROOT_CLASS             "pci_bridge"
  49 #define ACPI_PCI_ROOT_DEVICE_NAME       "PCI Root Bridge"
  50 static int acpi_pci_root_add(struct acpi_device *device,
  51                              const struct acpi_device_id *not_used);
  52 static void acpi_pci_root_remove(struct acpi_device *device);
  53
  54 #define ACPI_PCIE_REQ_SUPPORT (OSC_EXT_PCI_CONFIG_SUPPORT \
  55                                 | OSC_ACTIVE_STATE_PWR_SUPPORT \
  56                                 | OSC_CLOCK_PWR_CAPABILITY_SUPPORT \
  57                                 | OSC_MSI_SUPPORT)
  58
  59 static const struct acpi_device_id root_device_ids[] = {
  60         {"PNP0A03", 0},
  61         {"", 0},
  62 };
  63
  64 static struct acpi_scan_handler pci_root_handler = {
  65         .ids = root_device_ids,
  66         .attach = acpi_pci_root_add,
  67         .detach = acpi_pci_root_remove,
  68 };
  69
  70 static DEFINE_MUTEX(osc_lock);
  71
  72 /**
  73  * acpi_is_root_bridge - determine whether an ACPI CA node is a PCI root bridge
  74  * @handle - the ACPI CA node in question.
  75  *
  76  * Note: we could make this API take a struct acpi_device * instead, but
  77  * for now, it's more convenient to operate on an acpi_handle.
  78  */
  79 int acpi_is_root_bridge(acpi_handle handle)
  80 {
  81         int ret;
  82         struct acpi_device *device;
  83
  84         ret = acpi_bus_get_device(handle, &device);
  85         if (ret)
  86                 return 0;
  87
  88         ret = acpi_match_device_ids(device, root_device_ids);
  89         if (ret)
  90                 return 0;
  91         else
  92                 return 1;
  93 }
  94 EXPORT_SYMBOL_GPL(acpi_is_root_bridge);
  95
  96 static acpi_status
  97 get_root_bridge_busnr_callback(struct acpi_resource *resource, void *data)
  98 {
  99         struct resource *res = data;
 100         struct acpi_resource_address64 address;
 101         acpi_status status;
 102
 103         status = acpi_resource_to_address64(resource, &address);
 104         if (ACPI_FAILURE(status))
 105                 return AE_OK;
 106
 107         if ((address.address_length > 0) &&
 108             (address.resource_type == ACPI_BUS_NUMBER_RANGE)) {
 109                 res->start = address.minimum;
 110                 res->end = address.minimum + address.address_length - 1;
 111         }
 112
 113         return AE_OK;
 114 }
 115
 116 static acpi_status try_get_root_bridge_busnr(acpi_handle handle,
 117                                              struct resource *res)
 118 {
 119         acpi_status status;
 120
 121         res->start = -1;
 122         status =
 123             acpi_walk_resources(handle, METHOD_NAME__CRS,
 124                                 get_root_bridge_busnr_callback, res);
 125         if (ACPI_FAILURE(status))
 126                 return status;
 127         if (res->start == -1)
 128                 return AE_ERROR;
 129         return AE_OK;
 130 }
 131
 132 static u8 pci_osc_uuid_str[] = "33DB4D5B-1FF7-401C-9657-7441C03DD766";
 133
 134 static acpi_status acpi_pci_run_osc(acpi_handle handle,
 135                                     const u32 *capbuf, u32 *retval)
 136 {
 137         struct acpi_osc_context context = {
 138                 .uuid_str = pci_osc_uuid_str,
 139                 .rev = 1,
 140                 .cap.length = 12,
 141                 .cap.pointer = (void *)capbuf,
 142         };
 143         acpi_status status;
 144
 145         status = acpi_run_osc(handle, &context);
 146         if (ACPI_SUCCESS(status)) {
 147                 *retval = *((u32 *)(context.ret.pointer + 8));
 148                 kfree(context.ret.pointer);
 149         }
 150         return status;
 151 }
 152
 153 static acpi_status acpi_pci_query_osc(struct acpi_pci_root *root,
 154                                         u32 support,
 155                                         u32 *control)
 156 {
 157         acpi_status status;
 158         u32 result, capbuf[3];
 159
 160         support &= OSC_PCI_SUPPORT_MASKS;
 161         support |= root->osc_support_set;
 162
 163         capbuf[OSC_QUERY_TYPE] = OSC_QUERY_ENABLE;
 164         capbuf[OSC_SUPPORT_TYPE] = support;
 165         if (control) {
 166                 *control &= OSC_PCI_CONTROL_MASKS;
 167                 capbuf[OSC_CONTROL_TYPE] = *control | root->osc_control_set;
 168         } else {
 169                 /* Run _OSC query only with existing controls. */
 170                 capbuf[OSC_CONTROL_TYPE] = root->osc_control_set;
 171         }
 172
 173         status = acpi_pci_run_osc(root->device->handle, capbuf, &result);
 174         if (ACPI_SUCCESS(status)) {
 175                 root->osc_support_set = support;
 176                 if (control)
 177                         *control = result;
 178         }
 179         return status;
 180 }
 181
 182 static acpi_status acpi_pci_osc_support(struct acpi_pci_root *root, u32 flags)
 183 {
 184         acpi_status status;
 185         acpi_handle tmp;
 186
 187         status = acpi_get_handle(root->device->handle, "_OSC", &tmp);
 188         if (ACPI_FAILURE(status))
 189                 return status;
 190         mutex_lock(&osc_lock);
 191         status = acpi_pci_query_osc(root, flags, NULL);
 192         mutex_unlock(&osc_lock);
 193         return status;
 194 }
 195
 196 struct acpi_pci_root *acpi_pci_find_root(acpi_handle handle)
 197 {
 198         struct acpi_pci_root *root;
 199         struct acpi_device *device;
 200
 201         if (acpi_bus_get_device(handle, &device) ||
 202             acpi_match_device_ids(device, root_device_ids))
 203                 return NULL;
 204
 205         root = acpi_driver_data(device);
 206
 207         return root;
 208 }
 209 EXPORT_SYMBOL_GPL(acpi_pci_find_root);
 210
 211 struct acpi_handle_node {
 212         struct list_head node;
 213         acpi_handle handle;
 214 };
 215
 216 /**
 217  * acpi_get_pci_dev - convert ACPI CA handle to struct pci_dev
 218  * @handle: the handle in question
 219  *
 220  * Given an ACPI CA handle, the desired PCI device is located in the
 221  * list of PCI devices.
 222  *
 223  * If the device is found, its reference count is increased and this
 224  * function returns a pointer to its data structure.  The caller must
 225  * decrement the reference count by calling pci_dev_put().
 226  * If no device is found, %NULL is returned.
 227  */
 228 struct pci_dev *acpi_get_pci_dev(acpi_handle handle)
 229 {
 230         int dev, fn;
 231         unsigned long long adr;
 232         acpi_status status;
 233         acpi_handle phandle;
 234         struct pci_bus *pbus;
 235         struct pci_dev *pdev = NULL;
 236         struct acpi_handle_node *node, *tmp;
 237         struct acpi_pci_root *root;
 238         LIST_HEAD(device_list);
 239
 240         /*
 241          * Walk up the ACPI CA namespace until we reach a PCI root bridge.
 242          */
 243         phandle = handle;
 244         while (!acpi_is_root_bridge(phandle)) {
 245                 node = kzalloc(sizeof(struct acpi_handle_node), GFP_KERNEL);
 246                 if (!node)
 247                         goto out;
 248
 249                 INIT_LIST_HEAD(&node->node);
 250                 node->handle = phandle;
 251                 list_add(&node->node, &device_list);
 252
 253                 status = acpi_get_parent(phandle, &phandle);
 254                 if (ACPI_FAILURE(status))
 255                         goto out;
 256         }
 257
 258         root = acpi_pci_find_root(phandle);
 259         if (!root)
 260                 goto out;
 261
 262         pbus = root->bus;
 263
 264         /*
 265          * Now, walk back down the PCI device tree until we return to our
 266          * original handle. Assumes that everything between the PCI root
 267          * bridge and the device we're looking for must be a P2P bridge.
 268          */
 269         list_for_each_entry(node, &device_list, node) {
 270                 acpi_handle hnd = node->handle;
 271                 status = acpi_evaluate_integer(hnd, "_ADR", NULL, &adr);
 272                 if (ACPI_FAILURE(status))
 273                         goto out;
 274                 dev = (adr >> 16) & 0xffff;
 275                 fn  = adr & 0xffff;
 276
 277                 pdev = pci_get_slot(pbus, PCI_DEVFN(dev, fn));
 278                 if (!pdev || hnd == handle)
 279                         break;
 280
 281                 pbus = pdev->subordinate;
 282                 pci_dev_put(pdev);
 283
 284                 /*
 285                  * This function may be called for a non-PCI device that has a
 286                  * PCI parent (eg. a disk under a PCI SATA controller).  In that
 287                  * case pdev->subordinate will be NULL for the parent.
 288                  */
 289                 if (!pbus) {
 290                         dev_dbg(&pdev->dev, "Not a PCI-to-PCI bridge\n");
 291                         pdev = NULL;
 292                         break;
 293                 }
 294         }
 295 out:
 296         list_for_each_entry_safe(node, tmp, &device_list, node)
 297                 kfree(node);
 298
 299         return pdev;
 300 }
 301 EXPORT_SYMBOL_GPL(acpi_get_pci_dev);
 302
 303 /**
 304  * acpi_pci_osc_control_set - Request control of PCI root _OSC features.
 305  * @handle: ACPI handle of a PCI root bridge (or PCIe Root Complex).
 306  * @mask: Mask of _OSC bits to request control of, place to store control mask.
 307  * @req: Mask of _OSC bits the control of is essential to the caller.
 308  *
 309  * Run _OSC query for @mask and if that is successful, compare the returned
 310  * mask of control bits with @req.  If all of the @req bits are set in the
 311  * returned mask, run _OSC request for it.
 312  *
 313  * The variable at the @mask address may be modified regardless of whether or
 314  * not the function returns success.  On success it will contain the mask of
 315  * _OSC bits the BIOS has granted control of, but its contents are meaningless
 316  * on failure.
 317  **/
 318 acpi_status acpi_pci_osc_control_set(acpi_handle handle, u32 *mask, u32 req)
 319 {
 320         struct acpi_pci_root *root;
 321         acpi_status status;
 322         u32 ctrl, capbuf[3];
 323         acpi_handle tmp;
 324
 325         if (!mask)
 326                 return AE_BAD_PARAMETER;
 327
 328         ctrl = *mask & OSC_PCI_CONTROL_MASKS;
 329         if ((ctrl & req) != req)
 330                 return AE_TYPE;
 331
 332         root = acpi_pci_find_root(handle);
 333         if (!root)
 334                 return AE_NOT_EXIST;
 335
 336         status = acpi_get_handle(handle, "_OSC", &tmp);
 337         if (ACPI_FAILURE(status))
 338                 return status;
 339
 340         mutex_lock(&osc_lock);
 341
 342         *mask = ctrl | root->osc_control_set;
 343         /* No need to evaluate _OSC if the control was already granted. */
 344         if ((root->osc_control_set & ctrl) == ctrl)
 345                 goto out;
 346
 347         /* Need to check the available controls bits before requesting them. */
 348         while (*mask) {
 349                 status = acpi_pci_query_osc(root, root->osc_support_set, mask);
 350                 if (ACPI_FAILURE(status))
 351                         goto out;
 352                 if (ctrl == *mask)
 353                         break;
 354                 ctrl = *mask;
 355         }
 356
 357         if ((ctrl & req) != req) {
 358                 status = AE_SUPPORT;
 359                 goto out;
 360         }
 361
 362         capbuf[OSC_QUERY_TYPE] = 0;
 363         capbuf[OSC_SUPPORT_TYPE] = root->osc_support_set;
 364         capbuf[OSC_CONTROL_TYPE] = ctrl;
 365         status = acpi_pci_run_osc(handle, capbuf, mask);
 366         if (ACPI_SUCCESS(status))
 367                 root->osc_control_set = *mask;
 368 out:
 369         mutex_unlock(&osc_lock);
 370         return status;
 371 }
 372 EXPORT_SYMBOL(acpi_pci_osc_control_set);
 373
 374 static int acpi_pci_root_add(struct acpi_device *device,
 375                              const struct acpi_device_id *not_used)
 376 {
 377         unsigned long long segment, bus;
 378         acpi_status status;
 379         int result;
 380         struct acpi_pci_root *root;
 381         u32 flags, base_flags;
 382         acpi_handle handle = device->handle;
 383         bool no_aspm = false, clear_aspm = false;
 384
 385         root = kzalloc(sizeof(struct acpi_pci_root), GFP_KERNEL);
 386         if (!root)
 387                 return -ENOMEM;
 388
 389         segment = 0;
 390         status = acpi_evaluate_integer(handle, METHOD_NAME__SEG, NULL,
 391                                        &segment);
 392         if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) {
 393                 dev_err(&device->dev,  "can't evaluate _SEG\n");
 394                 result = -ENODEV;
 395                 goto end;
 396         }
 397
 398         /* Check _CRS first, then _BBN.  If no _BBN, default to zero. */
 399         root->secondary.flags = IORESOURCE_BUS;
 400         status = try_get_root_bridge_busnr(handle, &root->secondary);
 401         if (ACPI_FAILURE(status)) {
 402                 /*
 403                  * We need both the start and end of the downstream bus range
 404                  * to interpret _CBA (MMCONFIG base address), so it really is
 405                  * supposed to be in _CRS.  If we don't find it there, all we
 406                  * can do is assume [_BBN-0xFF] or [0-0xFF].
 407                  */
 408                 root->secondary.end = 0xFF;
 409                 dev_warn(&device->dev,
 410                          FW_BUG "no secondary bus range in _CRS\n");
 411                 status = acpi_evaluate_integer(handle, METHOD_NAME__BBN,
 412                                                NULL, &bus);
 413                 if (ACPI_SUCCESS(status))
 414                         root->secondary.start = bus;
 415                 else if (status == AE_NOT_FOUND)
 416                         root->secondary.start = 0;
 417                 else {
 418                         dev_err(&device->dev, "can't evaluate _BBN\n");
 419                         result = -ENODEV;
 420                         goto end;
 421                 }
 422         }
 423
 424         root->device = device;
 425         root->segment = segment & 0xFFFF;
 426         strcpy(acpi_device_name(device), ACPI_PCI_ROOT_DEVICE_NAME);
 427         strcpy(acpi_device_class(device), ACPI_PCI_ROOT_CLASS);
 428         device->driver_data = root;
 429
 430         pr_info(PREFIX "%s [%s] (domain %04x %pR)\n",
 431                acpi_device_name(device), acpi_device_bid(device),
 432                root->segment, &root->secondary);
 433
 434         root->mcfg_addr = acpi_pci_root_get_mcfg_addr(handle);
 435
 436         /*
 437          * All supported architectures that use ACPI have support for
 438          * PCI domains, so we indicate this in _OSC support capabilities.
 439          */
 440         flags = base_flags = OSC_PCI_SEGMENT_GROUPS_SUPPORT;
 441         acpi_pci_osc_support(root, flags);
 442
 443         if (pci_ext_cfg_avail())
 444                 flags |= OSC_EXT_PCI_CONFIG_SUPPORT;
 445         if (pcie_aspm_support_enabled()) {
 446                 flags |= OSC_ACTIVE_STATE_PWR_SUPPORT |
 447                 OSC_CLOCK_PWR_CAPABILITY_SUPPORT;
 448         }
 449         if (pci_msi_enabled())
 450                 flags |= OSC_MSI_SUPPORT;
 451         if (flags != base_flags) {
 452                 status = acpi_pci_osc_support(root, flags);
 453                 if (ACPI_FAILURE(status)) {
 454                         dev_info(&device->dev, "ACPI _OSC support "
 455                                 "notification failed, disabling PCIe ASPM\n");
 456                         no_aspm = true;
 457                         flags = base_flags;
 458                 }
 459         }
 460
 461         if (!pcie_ports_disabled
 462             && (flags & ACPI_PCIE_REQ_SUPPORT) == ACPI_PCIE_REQ_SUPPORT) {
 463                 flags = OSC_PCI_EXPRESS_CAP_STRUCTURE_CONTROL
 464                         | OSC_PCI_EXPRESS_NATIVE_HP_CONTROL
 465                         | OSC_PCI_EXPRESS_PME_CONTROL;
 466
 467                 if (pci_aer_available()) {
 468                         if (aer_acpi_firmware_first())
 469                                 dev_dbg(&device->dev,
 470                                         "PCIe errors handled by BIOS.\n");
 471                         else
 472                                 flags |= OSC_PCI_EXPRESS_AER_CONTROL;
 473                 }
 474
 475                 dev_info(&device->dev,
 476                         "Requesting ACPI _OSC control (0x%02x)\n", flags);
 477
 478                 status = acpi_pci_osc_control_set(handle, &flags,
 479                                        OSC_PCI_EXPRESS_CAP_STRUCTURE_CONTROL);
 480                 if (ACPI_SUCCESS(status)) {
 481                         dev_info(&device->dev,
 482                                 "ACPI _OSC control (0x%02x) granted\n", flags);
 483                         if (acpi_gbl_FADT.boot_flags & ACPI_FADT_NO_ASPM) {
 484                                 /*
 485                                  * We have ASPM control, but the FADT indicates
 486                                  * that it's unsupported. Clear it.
 487                                  */
 488                                 clear_aspm = true;
 489                         }
 490                 } else {
 491                         dev_info(&device->dev,
 492                                 "ACPI _OSC request failed (%s), "
 493                                 "returned control mask: 0x%02x\n",
 494                                 acpi_format_exception(status), flags);
 495                         dev_info(&device->dev,
 496                                  "ACPI _OSC control for PCIe not granted, disabling ASPM\n");
 497                         /*
 498                          * We want to disable ASPM here, but aspm_disabled
 499                          * needs to remain in its state from boot so that we
 500                          * properly handle PCIe 1.1 devices.  So we set this
 501                          * flag here, to defer the action until after the ACPI
 502                          * root scan.
 503                          */
 504                         no_aspm = true;
 505                 }
 506         } else {
 507                 dev_info(&device->dev,
 508                          "Unable to request _OSC control "
 509                          "(_OSC support mask: 0x%02x)\n", flags);
 510         }
 511
 512         /*
 513          * TBD: Need PCI interface for enumeration/configuration of roots.
 514          */
 515
 516         /*
 517          * Scan the Root Bridge
 518          * --------------------
 519          * Must do this prior to any attempt to bind the root device, as the
 520          * PCI namespace does not get created until this call is made (and
 521          * thus the root bridge's pci_dev does not exist).
 522          */
 523         root->bus = pci_acpi_scan_root(root);
 524         if (!root->bus) {
 525                 dev_err(&device->dev,
 526                         "Bus %04x:%02x not present in PCI namespace\n",
 527                         root->segment, (unsigned int)root->secondary.start);
 528                 result = -ENODEV;
 529                 goto end;
 530         }
 531
 532         if (clear_aspm) {
 533                 dev_info(&device->dev, "Disabling ASPM (FADT indicates it is unsupported)\n");
 534                 pcie_clear_aspm(root->bus);
 535         }
 536         if (no_aspm)
 537                 pcie_no_aspm();
 538
 539         pci_acpi_add_bus_pm_notifier(device, root->bus);
 540         if (device->wakeup.flags.run_wake)
 541                 device_set_run_wake(root->bus->bridge, true);
 542
 543         if (system_state != SYSTEM_BOOTING) {
 544                 pcibios_resource_survey_bus(root->bus);
 545                 pci_assign_unassigned_root_bus_resources(root->bus);
 546         }
 547
 548         pci_bus_add_devices(root->bus);
 549         return 1;
 550
 551 end:
 552         kfree(root);
 553         return result;
 554 }
 555
 556 static void acpi_pci_root_remove(struct acpi_device *device)
 557 {
 558         struct acpi_pci_root *root = acpi_driver_data(device);
 559
 560         pci_stop_root_bus(root->bus);
 561
 562         device_set_run_wake(root->bus->bridge, false);
 563         pci_acpi_remove_bus_pm_notifier(device);
 564
 565         pci_remove_root_bus(root->bus);
 566
 567         kfree(root);
 568 }
 569
 570 void __init acpi_pci_root_init(void)
 571 {
 572         acpi_hest_init();
 573
 574         if (!acpi_pci_disabled) {
 575                 pci_acpi_crs_quirks();
 576                 acpi_scan_add_handler(&pci_root_handler);
 577         }
 578 }
 579 /* Support root bridge hotplug */
 580
 581 static void handle_root_bridge_insertion(acpi_handle handle)
 582 {
 583         struct acpi_device *device;
 584
 585         if (!acpi_bus_get_device(handle, &device)) {
 586                 dev_printk(KERN_DEBUG, &device->dev,
 587                            "acpi device already exists; ignoring notify\n");
 588                 return;
 589         }
 590
 591         if (acpi_bus_scan(handle))
 592                 acpi_handle_err(handle, "cannot add bridge to acpi list\n");
 593 }
 594
 595 static void _handle_hotplug_event_root(struct work_struct *work)
 596 {
 597         struct acpi_pci_root *root;
 598         struct acpi_hp_work *hp_work;
 599         acpi_handle handle;
 600         u32 type;
 601
 602         hp_work = container_of(work, struct acpi_hp_work, work);
 603         handle = hp_work->handle;
 604         type = hp_work->type;
 605         kfree(hp_work); /* allocated in handle_hotplug_event_bridge */
 606
 607         acpi_scan_lock_acquire();
 608
 609         root = acpi_pci_find_root(handle);
 610
 611         switch (type) {
 612         case ACPI_NOTIFY_BUS_CHECK:
 613                 /* bus enumerate */
 614                 acpi_handle_printk(KERN_DEBUG, handle,
 615                                    "Bus check notify on %s\n", __func__);
 616                 if (root)
 617                         acpiphp_check_host_bridge(handle);
 618                 else
 619                         handle_root_bridge_insertion(handle);
 620
 621                 break;
 622
 623         case ACPI_NOTIFY_DEVICE_CHECK:
 624                 /* device check */
 625                 acpi_handle_printk(KERN_DEBUG, handle,
 626                                    "Device check notify on %s\n", __func__);
 627                 if (!root)
 628                         handle_root_bridge_insertion(handle);
 629                 break;
 630
 631         case ACPI_NOTIFY_EJECT_REQUEST:
 632                 /* request device eject */
 633                 acpi_handle_printk(KERN_DEBUG, handle,
 634                                    "Device eject notify on %s\n", __func__);
 635                 if (!root)
 636                         break;
 637
 638                 get_device(&root->device->dev);
 639
 640                 acpi_scan_lock_release();
 641
 642                 acpi_bus_device_eject(root->device, ACPI_NOTIFY_EJECT_REQUEST);
 643                 return;
 644         default:
 645                 acpi_handle_warn(handle,
 646                                  "notify_handler: unknown event type 0x%x\n",
 647                                  type);
 648                 break;
 649         }
 650
 651         acpi_scan_lock_release();
 652 }
 653
 654 static void handle_hotplug_event_root(acpi_handle handle, u32 type,
 655                                         void *context)
 656 {
 657         alloc_acpi_hp_work(handle, type, context,
 658                                 _handle_hotplug_event_root);
 659 }
 660
 661 static acpi_status __init
 662 find_root_bridges(acpi_handle handle, u32 lvl, void *context, void **rv)
 663 {
 664         acpi_status status;
 665         int *count = (int *)context;
 666
 667         if (!acpi_is_root_bridge(handle))
 668                 return AE_OK;
 669
 670         (*count)++;
 671
 672         status = acpi_install_notify_handler(handle, ACPI_SYSTEM_NOTIFY,
 673                                         handle_hotplug_event_root, NULL);
 674         if (ACPI_FAILURE(status))
 675                 acpi_handle_printk(KERN_DEBUG, handle,
 676                         "notify handler is not installed, exit status: %u\n",
 677                          (unsigned int)status);
 678         else
 679                 acpi_handle_printk(KERN_DEBUG, handle,
 680                                    "notify handler is installed\n");
 681
 682         return AE_OK;
 683 }
 684
 685 void __init acpi_pci_root_hp_init(void)
 686 {
 687         int num = 0;
 688
 689         acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
 690                 ACPI_UINT32_MAX, find_root_bridges, NULL, &num, NULL);
 691
 692         printk(KERN_DEBUG "Found %d acpi root devices\n", num);
 693 }