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/apei.h>  /* for acpi_hest_init() */
  39
  40 #include "internal.h"
  41
  42 #define _COMPONENT              ACPI_PCI_COMPONENT
  43 ACPI_MODULE_NAME("pci_root");
  44 #define ACPI_PCI_ROOT_CLASS             "pci_bridge"
  45 #define ACPI_PCI_ROOT_DEVICE_NAME       "PCI Root Bridge"
  46 static int acpi_pci_root_add(struct acpi_device *device,
  47                              const struct acpi_device_id *not_used);
  48 static void acpi_pci_root_remove(struct acpi_device *device);
  49
  50 static int acpi_pci_root_scan_dependent(struct acpi_device *adev)
  51 {
  52         acpiphp_check_host_bridge(adev);
  53         return 0;
  54 }
  55
  56 #define ACPI_PCIE_REQ_SUPPORT (OSC_PCI_EXT_CONFIG_SUPPORT \
  57                                 | OSC_PCI_ASPM_SUPPORT \
  58                                 | OSC_PCI_CLOCK_PM_SUPPORT \
  59                                 | OSC_PCI_MSI_SUPPORT)
  60
  61 static const struct acpi_device_id root_device_ids[] = {
  62         {"PNP0A03", 0},
  63         {"", 0},
  64 };
  65
  66 static struct acpi_scan_handler pci_root_handler = {
  67         .ids = root_device_ids,
  68         .attach = acpi_pci_root_add,
  69         .detach = acpi_pci_root_remove,
  70         .hotplug = {
  71                 .enabled = true,
  72                 .scan_dependent = acpi_pci_root_scan_dependent,
  73         },
  74 };
  75
  76 static DEFINE_MUTEX(osc_lock);
  77
  78 /**
  79  * acpi_is_root_bridge - determine whether an ACPI CA node is a PCI root bridge
  80  * @handle - the ACPI CA node in question.
  81  *
  82  * Note: we could make this API take a struct acpi_device * instead, but
  83  * for now, it's more convenient to operate on an acpi_handle.
  84  */
  85 int acpi_is_root_bridge(acpi_handle handle)
  86 {
  87         int ret;
  88         struct acpi_device *device;
  89
  90         ret = acpi_bus_get_device(handle, &device);
  91         if (ret)
  92                 return 0;
  93
  94         ret = acpi_match_device_ids(device, root_device_ids);
  95         if (ret)
  96                 return 0;
  97         else
  98                 return 1;
  99 }
 100 EXPORT_SYMBOL_GPL(acpi_is_root_bridge);
 101
 102 static acpi_status
 103 get_root_bridge_busnr_callback(struct acpi_resource *resource, void *data)
 104 {
 105         struct resource *res = data;
 106         struct acpi_resource_address64 address;
 107         acpi_status status;
 108
 109         status = acpi_resource_to_address64(resource, &address);
 110         if (ACPI_FAILURE(status))
 111                 return AE_OK;
 112
 113         if ((address.address_length > 0) &&
 114             (address.resource_type == ACPI_BUS_NUMBER_RANGE)) {
 115                 res->start = address.minimum;
 116                 res->end = address.minimum + address.address_length - 1;
 117         }
 118
 119         return AE_OK;
 120 }
 121
 122 static acpi_status try_get_root_bridge_busnr(acpi_handle handle,
 123                                              struct resource *res)
 124 {
 125         acpi_status status;
 126
 127         res->start = -1;
 128         status =
 129             acpi_walk_resources(handle, METHOD_NAME__CRS,
 130                                 get_root_bridge_busnr_callback, res);
 131         if (ACPI_FAILURE(status))
 132                 return status;
 133         if (res->start == -1)
 134                 return AE_ERROR;
 135         return AE_OK;
 136 }
 137
 138 struct pci_osc_bit_struct {
 139         u32 bit;
 140         char *desc;
 141 };
 142
 143 static struct pci_osc_bit_struct pci_osc_support_bit[] = {
 144         { OSC_PCI_EXT_CONFIG_SUPPORT, "ExtendedConfig" },
 145         { OSC_PCI_ASPM_SUPPORT, "ASPM" },
 146         { OSC_PCI_CLOCK_PM_SUPPORT, "ClockPM" },
 147         { OSC_PCI_SEGMENT_GROUPS_SUPPORT, "Segments" },
 148         { OSC_PCI_MSI_SUPPORT, "MSI" },
 149 };
 150
 151 static struct pci_osc_bit_struct pci_osc_control_bit[] = {
 152         { OSC_PCI_EXPRESS_NATIVE_HP_CONTROL, "PCIeHotplug" },
 153         { OSC_PCI_SHPC_NATIVE_HP_CONTROL, "SHPCHotplug" },
 154         { OSC_PCI_EXPRESS_PME_CONTROL, "PME" },
 155         { OSC_PCI_EXPRESS_AER_CONTROL, "AER" },
 156         { OSC_PCI_EXPRESS_CAPABILITY_CONTROL, "PCIeCapability" },
 157 };
 158
 159 static void decode_osc_bits(struct acpi_pci_root *root, char *msg, u32 word,
 160                             struct pci_osc_bit_struct *table, int size)
 161 {
 162         char buf[80];
 163         int i, len = 0;
 164         struct pci_osc_bit_struct *entry;
 165
 166         buf[0] = '\0';
 167         for (i = 0, entry = table; i < size; i++, entry++)
 168                 if (word & entry->bit)
 169                         len += snprintf(buf + len, sizeof(buf) - len, "%s%s",
 170                                         len ? " " : "", entry->desc);
 171
 172         dev_info(&root->device->dev, "_OSC: %s [%s]\n", msg, buf);
 173 }
 174
 175 static void decode_osc_support(struct acpi_pci_root *root, char *msg, u32 word)
 176 {
 177         decode_osc_bits(root, msg, word, pci_osc_support_bit,
 178                         ARRAY_SIZE(pci_osc_support_bit));
 179 }
 180
 181 static void decode_osc_control(struct acpi_pci_root *root, char *msg, u32 word)
 182 {
 183         decode_osc_bits(root, msg, word, pci_osc_control_bit,
 184                         ARRAY_SIZE(pci_osc_control_bit));
 185 }
 186
 187 static u8 pci_osc_uuid_str[] = "33DB4D5B-1FF7-401C-9657-7441C03DD766";
 188
 189 static acpi_status acpi_pci_run_osc(acpi_handle handle,
 190                                     const u32 *capbuf, u32 *retval)
 191 {
 192         struct acpi_osc_context context = {
 193                 .uuid_str = pci_osc_uuid_str,
 194                 .rev = 1,
 195                 .cap.length = 12,
 196                 .cap.pointer = (void *)capbuf,
 197         };
 198         acpi_status status;
 199
 200         status = acpi_run_osc(handle, &context);
 201         if (ACPI_SUCCESS(status)) {
 202                 *retval = *((u32 *)(context.ret.pointer + 8));
 203                 kfree(context.ret.pointer);
 204         }
 205         return status;
 206 }
 207
 208 static acpi_status acpi_pci_query_osc(struct acpi_pci_root *root,
 209                                         u32 support,
 210                                         u32 *control)
 211 {
 212         acpi_status status;
 213         u32 result, capbuf[3];
 214
 215         support &= OSC_PCI_SUPPORT_MASKS;
 216         support |= root->osc_support_set;
 217
 218         capbuf[OSC_QUERY_DWORD] = OSC_QUERY_ENABLE;
 219         capbuf[OSC_SUPPORT_DWORD] = support;
 220         if (control) {
 221                 *control &= OSC_PCI_CONTROL_MASKS;
 222                 capbuf[OSC_CONTROL_DWORD] = *control | root->osc_control_set;
 223         } else {
 224                 /* Run _OSC query only with existing controls. */
 225                 capbuf[OSC_CONTROL_DWORD] = root->osc_control_set;
 226         }
 227
 228         status = acpi_pci_run_osc(root->device->handle, capbuf, &result);
 229         if (ACPI_SUCCESS(status)) {
 230                 root->osc_support_set = support;
 231                 if (control)
 232                         *control = result;
 233         }
 234         return status;
 235 }
 236
 237 static acpi_status acpi_pci_osc_support(struct acpi_pci_root *root, u32 flags)
 238 {
 239         acpi_status status;
 240
 241         mutex_lock(&osc_lock);
 242         status = acpi_pci_query_osc(root, flags, NULL);
 243         mutex_unlock(&osc_lock);
 244         return status;
 245 }
 246
 247 struct acpi_pci_root *acpi_pci_find_root(acpi_handle handle)
 248 {
 249         struct acpi_pci_root *root;
 250         struct acpi_device *device;
 251
 252         if (acpi_bus_get_device(handle, &device) ||
 253             acpi_match_device_ids(device, root_device_ids))
 254                 return NULL;
 255
 256         root = acpi_driver_data(device);
 257
 258         return root;
 259 }
 260 EXPORT_SYMBOL_GPL(acpi_pci_find_root);
 261
 262 struct acpi_handle_node {
 263         struct list_head node;
 264         acpi_handle handle;
 265 };
 266
 267 /**
 268  * acpi_get_pci_dev - convert ACPI CA handle to struct pci_dev
 269  * @handle: the handle in question
 270  *
 271  * Given an ACPI CA handle, the desired PCI device is located in the
 272  * list of PCI devices.
 273  *
 274  * If the device is found, its reference count is increased and this
 275  * function returns a pointer to its data structure.  The caller must
 276  * decrement the reference count by calling pci_dev_put().
 277  * If no device is found, %NULL is returned.
 278  */
 279 struct pci_dev *acpi_get_pci_dev(acpi_handle handle)
 280 {
 281         int dev, fn;
 282         unsigned long long adr;
 283         acpi_status status;
 284         acpi_handle phandle;
 285         struct pci_bus *pbus;
 286         struct pci_dev *pdev = NULL;
 287         struct acpi_handle_node *node, *tmp;
 288         struct acpi_pci_root *root;
 289         LIST_HEAD(device_list);
 290
 291         /*
 292          * Walk up the ACPI CA namespace until we reach a PCI root bridge.
 293          */
 294         phandle = handle;
 295         while (!acpi_is_root_bridge(phandle)) {
 296                 node = kzalloc(sizeof(struct acpi_handle_node), GFP_KERNEL);
 297                 if (!node)
 298                         goto out;
 299
 300                 INIT_LIST_HEAD(&node->node);
 301                 node->handle = phandle;
 302                 list_add(&node->node, &device_list);
 303
 304                 status = acpi_get_parent(phandle, &phandle);
 305                 if (ACPI_FAILURE(status))
 306                         goto out;
 307         }
 308
 309         root = acpi_pci_find_root(phandle);
 310         if (!root)
 311                 goto out;
 312
 313         pbus = root->bus;
 314
 315         /*
 316          * Now, walk back down the PCI device tree until we return to our
 317          * original handle. Assumes that everything between the PCI root
 318          * bridge and the device we're looking for must be a P2P bridge.
 319          */
 320         list_for_each_entry(node, &device_list, node) {
 321                 acpi_handle hnd = node->handle;
 322                 status = acpi_evaluate_integer(hnd, "_ADR", NULL, &adr);
 323                 if (ACPI_FAILURE(status))
 324                         goto out;
 325                 dev = (adr >> 16) & 0xffff;
 326                 fn  = adr & 0xffff;
 327
 328                 pdev = pci_get_slot(pbus, PCI_DEVFN(dev, fn));
 329                 if (!pdev || hnd == handle)
 330                         break;
 331
 332                 pbus = pdev->subordinate;
 333                 pci_dev_put(pdev);
 334
 335                 /*
 336                  * This function may be called for a non-PCI device that has a
 337                  * PCI parent (eg. a disk under a PCI SATA controller).  In that
 338                  * case pdev->subordinate will be NULL for the parent.
 339                  */
 340                 if (!pbus) {
 341                         dev_dbg(&pdev->dev, "Not a PCI-to-PCI bridge\n");
 342                         pdev = NULL;
 343                         break;
 344                 }
 345         }
 346 out:
 347         list_for_each_entry_safe(node, tmp, &device_list, node)
 348                 kfree(node);
 349
 350         return pdev;
 351 }
 352 EXPORT_SYMBOL_GPL(acpi_get_pci_dev);
 353
 354 /**
 355  * acpi_pci_osc_control_set - Request control of PCI root _OSC features.
 356  * @handle: ACPI handle of a PCI root bridge (or PCIe Root Complex).
 357  * @mask: Mask of _OSC bits to request control of, place to store control mask.
 358  * @req: Mask of _OSC bits the control of is essential to the caller.
 359  *
 360  * Run _OSC query for @mask and if that is successful, compare the returned
 361  * mask of control bits with @req.  If all of the @req bits are set in the
 362  * returned mask, run _OSC request for it.
 363  *
 364  * The variable at the @mask address may be modified regardless of whether or
 365  * not the function returns success.  On success it will contain the mask of
 366  * _OSC bits the BIOS has granted control of, but its contents are meaningless
 367  * on failure.
 368  **/
 369 acpi_status acpi_pci_osc_control_set(acpi_handle handle, u32 *mask, u32 req)
 370 {
 371         struct acpi_pci_root *root;
 372         acpi_status status = AE_OK;
 373         u32 ctrl, capbuf[3];
 374
 375         if (!mask)
 376                 return AE_BAD_PARAMETER;
 377
 378         ctrl = *mask & OSC_PCI_CONTROL_MASKS;
 379         if ((ctrl & req) != req)
 380                 return AE_TYPE;
 381
 382         root = acpi_pci_find_root(handle);
 383         if (!root)
 384                 return AE_NOT_EXIST;
 385
 386         mutex_lock(&osc_lock);
 387
 388         *mask = ctrl | root->osc_control_set;
 389         /* No need to evaluate _OSC if the control was already granted. */
 390         if ((root->osc_control_set & ctrl) == ctrl)
 391                 goto out;
 392
 393         /* Need to check the available controls bits before requesting them. */
 394         while (*mask) {
 395                 status = acpi_pci_query_osc(root, root->osc_support_set, mask);
 396                 if (ACPI_FAILURE(status))
 397                         goto out;
 398                 if (ctrl == *mask)
 399                         break;
 400                 decode_osc_control(root, "platform does not support",
 401                                    ctrl & ~(*mask));
 402                 ctrl = *mask;
 403         }
 404
 405         if ((ctrl & req) != req) {
 406                 decode_osc_control(root, "not requesting control; platform does not support",
 407                                    req & ~(ctrl));
 408                 status = AE_SUPPORT;
 409                 goto out;
 410         }
 411
 412         capbuf[OSC_QUERY_DWORD] = 0;
 413         capbuf[OSC_SUPPORT_DWORD] = root->osc_support_set;
 414         capbuf[OSC_CONTROL_DWORD] = ctrl;
 415         status = acpi_pci_run_osc(handle, capbuf, mask);
 416         if (ACPI_SUCCESS(status))
 417                 root->osc_control_set = *mask;
 418 out:
 419         mutex_unlock(&osc_lock);
 420         return status;
 421 }
 422 EXPORT_SYMBOL(acpi_pci_osc_control_set);
 423
 424 static void negotiate_os_control(struct acpi_pci_root *root, int *no_aspm,
 425                                  int *clear_aspm)
 426 {
 427         u32 support, control, requested;
 428         acpi_status status;
 429         struct acpi_device *device = root->device;
 430         acpi_handle handle = device->handle;
 431
 432         /*
 433          * All supported architectures that use ACPI have support for
 434          * PCI domains, so we indicate this in _OSC support capabilities.
 435          */
 436         support = OSC_PCI_SEGMENT_GROUPS_SUPPORT;
 437         if (pci_ext_cfg_avail())
 438                 support |= OSC_PCI_EXT_CONFIG_SUPPORT;
 439         if (pcie_aspm_support_enabled())
 440                 support |= OSC_PCI_ASPM_SUPPORT | OSC_PCI_CLOCK_PM_SUPPORT;
 441         if (pci_msi_enabled())
 442                 support |= OSC_PCI_MSI_SUPPORT;
 443
 444         decode_osc_support(root, "OS supports", support);
 445         status = acpi_pci_osc_support(root, support);
 446         if (ACPI_FAILURE(status)) {
 447                 dev_info(&device->dev, "_OSC failed (%s); disabling ASPM\n",
 448                          acpi_format_exception(status));
 449                 *no_aspm = 1;
 450                 return;
 451         }
 452
 453         if (pcie_ports_disabled) {
 454                 dev_info(&device->dev, "PCIe port services disabled; not requesting _OSC control\n");
 455                 return;
 456         }
 457
 458         if ((support & ACPI_PCIE_REQ_SUPPORT) != ACPI_PCIE_REQ_SUPPORT) {
 459                 decode_osc_support(root, "not requesting OS control; OS requires",
 460                                    ACPI_PCIE_REQ_SUPPORT);
 461                 return;
 462         }
 463
 464         control = OSC_PCI_EXPRESS_CAPABILITY_CONTROL
 465                 | OSC_PCI_EXPRESS_NATIVE_HP_CONTROL
 466                 | OSC_PCI_EXPRESS_PME_CONTROL;
 467
 468         if (pci_aer_available()) {
 469                 if (aer_acpi_firmware_first())
 470                         dev_info(&device->dev,
 471                                  "PCIe AER handled by firmware\n");
 472                 else
 473                         control |= OSC_PCI_EXPRESS_AER_CONTROL;
 474         }
 475
 476         requested = control;
 477         status = acpi_pci_osc_control_set(handle, &control,
 478                                           OSC_PCI_EXPRESS_CAPABILITY_CONTROL);
 479         if (ACPI_SUCCESS(status)) {
 480                 decode_osc_control(root, "OS now controls", control);
 481                 if (acpi_gbl_FADT.boot_flags & ACPI_FADT_NO_ASPM) {
 482                         /*
 483                          * We have ASPM control, but the FADT indicates
 484                          * that it's unsupported. Clear it.
 485                          */
 486                         *clear_aspm = 1;
 487                 }
 488         } else {
 489                 decode_osc_control(root, "OS requested", requested);
 490                 decode_osc_control(root, "platform willing to grant", control);
 491                 dev_info(&device->dev, "_OSC failed (%s); disabling ASPM\n",
 492                         acpi_format_exception(status));
 493
 494                 /*
 495                  * We want to disable ASPM here, but aspm_disabled
 496                  * needs to remain in its state from boot so that we
 497                  * properly handle PCIe 1.1 devices.  So we set this
 498                  * flag here, to defer the action until after the ACPI
 499                  * root scan.
 500                  */
 501                 *no_aspm = 1;
 502         }
 503 }
 504
 505 static int acpi_pci_root_add(struct acpi_device *device,
 506                              const struct acpi_device_id *not_used)
 507 {
 508         unsigned long long segment, bus;
 509         acpi_status status;
 510         int result;
 511         struct acpi_pci_root *root;
 512         acpi_handle handle = device->handle;
 513         int no_aspm = 0, clear_aspm = 0;
 514
 515         root = kzalloc(sizeof(struct acpi_pci_root), GFP_KERNEL);
 516         if (!root)
 517                 return -ENOMEM;
 518
 519         segment = 0;
 520         status = acpi_evaluate_integer(handle, METHOD_NAME__SEG, NULL,
 521                                        &segment);
 522         if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) {
 523                 dev_err(&device->dev,  "can't evaluate _SEG\n");
 524                 result = -ENODEV;
 525                 goto end;
 526         }
 527
 528         /* Check _CRS first, then _BBN.  If no _BBN, default to zero. */
 529         root->secondary.flags = IORESOURCE_BUS;
 530         status = try_get_root_bridge_busnr(handle, &root->secondary);
 531         if (ACPI_FAILURE(status)) {
 532                 /*
 533                  * We need both the start and end of the downstream bus range
 534                  * to interpret _CBA (MMCONFIG base address), so it really is
 535                  * supposed to be in _CRS.  If we don't find it there, all we
 536                  * can do is assume [_BBN-0xFF] or [0-0xFF].
 537                  */
 538                 root->secondary.end = 0xFF;
 539                 dev_warn(&device->dev,
 540                          FW_BUG "no secondary bus range in _CRS\n");
 541                 status = acpi_evaluate_integer(handle, METHOD_NAME__BBN,
 542                                                NULL, &bus);
 543                 if (ACPI_SUCCESS(status))
 544                         root->secondary.start = bus;
 545                 else if (status == AE_NOT_FOUND)
 546                         root->secondary.start = 0;
 547                 else {
 548                         dev_err(&device->dev, "can't evaluate _BBN\n");
 549                         result = -ENODEV;
 550                         goto end;
 551                 }
 552         }
 553
 554         root->device = device;
 555         root->segment = segment & 0xFFFF;
 556         strcpy(acpi_device_name(device), ACPI_PCI_ROOT_DEVICE_NAME);
 557         strcpy(acpi_device_class(device), ACPI_PCI_ROOT_CLASS);
 558         device->driver_data = root;
 559
 560         pr_info(PREFIX "%s [%s] (domain %04x %pR)\n",
 561                acpi_device_name(device), acpi_device_bid(device),
 562                root->segment, &root->secondary);
 563
 564         root->mcfg_addr = acpi_pci_root_get_mcfg_addr(handle);
 565
 566         negotiate_os_control(root, &no_aspm, &clear_aspm);
 567
 568         /*
 569          * TBD: Need PCI interface for enumeration/configuration of roots.
 570          */
 571
 572         /*
 573          * Scan the Root Bridge
 574          * --------------------
 575          * Must do this prior to any attempt to bind the root device, as the
 576          * PCI namespace does not get created until this call is made (and
 577          * thus the root bridge's pci_dev does not exist).
 578          */
 579         root->bus = pci_acpi_scan_root(root);
 580         if (!root->bus) {
 581                 dev_err(&device->dev,
 582                         "Bus %04x:%02x not present in PCI namespace\n",
 583                         root->segment, (unsigned int)root->secondary.start);
 584                 device->driver_data = NULL;
 585                 result = -ENODEV;
 586                 goto end;
 587         }
 588
 589         if (clear_aspm) {
 590                 dev_info(&device->dev, "Disabling ASPM (FADT indicates it is unsupported)\n");
 591                 pcie_clear_aspm(root->bus);
 592         }
 593         if (no_aspm)
 594                 pcie_no_aspm();
 595
 596         pci_acpi_add_bus_pm_notifier(device);
 597         if (device->wakeup.flags.run_wake)
 598                 device_set_run_wake(root->bus->bridge, true);
 599
 600         if (system_state != SYSTEM_BOOTING) {
 601                 pcibios_resource_survey_bus(root->bus);
 602                 pci_assign_unassigned_root_bus_resources(root->bus);
 603         }
 604
 605         pci_lock_rescan_remove();
 606         pci_bus_add_devices(root->bus);
 607         pci_unlock_rescan_remove();
 608         return 1;
 609
 610 end:
 611         kfree(root);
 612         return result;
 613 }
 614
 615 static void acpi_pci_root_remove(struct acpi_device *device)
 616 {
 617         struct acpi_pci_root *root = acpi_driver_data(device);
 618
 619         pci_lock_rescan_remove();
 620
 621         pci_stop_root_bus(root->bus);
 622
 623         device_set_run_wake(root->bus->bridge, false);
 624         pci_acpi_remove_bus_pm_notifier(device);
 625
 626         pci_remove_root_bus(root->bus);
 627
 628         pci_unlock_rescan_remove();
 629
 630         kfree(root);
 631 }
 632
 633 void __init acpi_pci_root_init(void)
 634 {
 635         acpi_hest_init();
 636         if (acpi_pci_disabled)
 637                 return;
 638
 639         pci_acpi_crs_quirks();
 640         acpi_scan_add_handler_with_hotplug(&pci_root_handler, "pci_root");
 641 }