drivers/acpi/pci_irq.c

   1 /*
   2  *  pci_irq.c - ACPI PCI Interrupt Routing ($Revision: 11 $)
   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  *  Copyright (C) 2002       Dominik Brodowski <devel@brodo.de>
   7  *
   8  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   9  *
  10  *  This program is free software; you can redistribute it and/or modify
  11  *  it under the terms of the GNU General Public License as published by
  12  *  the Free Software Foundation; either version 2 of the License, or (at
  13  *  your option) any later version.
  14  *
  15  *  This program is distributed in the hope that it will be useful, but
  16  *  WITHOUT ANY WARRANTY; without even the implied warranty of
  17  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  18  *  General Public License for more details.
  19  *
  20  *  You should have received a copy of the GNU General Public License along
  21  *  with this program; if not, write to the Free Software Foundation, Inc.,
  22  *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
  23  *
  24  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  25  */
  26
  27
  28 #include <linux/dmi.h>
  29 #include <linux/kernel.h>
  30 #include <linux/module.h>
  31 #include <linux/init.h>
  32 #include <linux/types.h>
  33 #include <linux/proc_fs.h>
  34 #include <linux/spinlock.h>
  35 #include <linux/pm.h>
  36 #include <linux/pci.h>
  37 #include <linux/acpi.h>
  38 #include <acpi/acpi_bus.h>
  39 #include <acpi/acpi_drivers.h>
  40
  41 #define _COMPONENT              ACPI_PCI_COMPONENT
  42 ACPI_MODULE_NAME("pci_irq");
  43
  44 static struct acpi_prt_list acpi_prt;
  45 static DEFINE_SPINLOCK(acpi_prt_lock);
  46
  47 /* --------------------------------------------------------------------------
  48                          PCI IRQ Routing Table (PRT) Support
  49    -------------------------------------------------------------------------- */
  50
  51 static struct acpi_prt_entry *acpi_pci_irq_find_prt_entry(int segment,
  52                                                           int bus,
  53                                                           int device, int pin)
  54 {
  55         struct acpi_prt_entry *entry = NULL;
  56
  57         if (!acpi_prt.count)
  58                 return NULL;
  59
  60         /*
  61          * Parse through all PRT entries looking for a match on the specified
  62          * PCI device's segment, bus, device, and pin (don't care about func).
  63          *
  64          */
  65         spin_lock(&acpi_prt_lock);
  66         list_for_each_entry(entry, &acpi_prt.entries, node) {
  67                 if ((segment == entry->id.segment)
  68                     && (bus == entry->id.bus)
  69                     && (device == entry->id.device)
  70                     && (pin == entry->pin)) {
  71                         spin_unlock(&acpi_prt_lock);
  72                         return entry;
  73                 }
  74         }
  75
  76         spin_unlock(&acpi_prt_lock);
  77         return NULL;
  78 }
  79
  80 /* http://bugzilla.kernel.org/show_bug.cgi?id=4773 */
  81 static struct dmi_system_id medion_md9580[] = {
  82         {
  83                 .ident = "Medion MD9580-F laptop",
  84                 .matches = {
  85                         DMI_MATCH(DMI_SYS_VENDOR, "MEDIONNB"),
  86                         DMI_MATCH(DMI_PRODUCT_NAME, "A555"),
  87                 },
  88         },
  89         { }
  90 };
  91
  92 /* http://bugzilla.kernel.org/show_bug.cgi?id=5044 */
  93 static struct dmi_system_id dell_optiplex[] = {
  94         {
  95                 .ident = "Dell Optiplex GX1",
  96                 .matches = {
  97                         DMI_MATCH(DMI_SYS_VENDOR, "Dell Computer Corporation"),
  98                         DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex GX1 600S+"),
  99                 },
 100         },
 101         { }
 102 };
 103
 104 /* http://bugzilla.kernel.org/show_bug.cgi?id=10138 */
 105 static struct dmi_system_id hp_t5710[] = {
 106         {
 107                 .ident = "HP t5710",
 108                 .matches = {
 109                         DMI_MATCH(DMI_SYS_VENDOR, "Hewlett-Packard"),
 110                         DMI_MATCH(DMI_PRODUCT_NAME, "hp t5000 series"),
 111                         DMI_MATCH(DMI_BOARD_NAME, "098Ch"),
 112                 },
 113         },
 114         { }
 115 };
 116
 117 struct prt_quirk {
 118         struct dmi_system_id    *system;
 119         unsigned int            segment;
 120         unsigned int            bus;
 121         unsigned int            device;
 122         unsigned char           pin;
 123         char                    *source;        /* according to BIOS */
 124         char                    *actual_source;
 125 };
 126
 127 /*
 128  * These systems have incorrect _PRT entries.  The BIOS claims the PCI
 129  * interrupt at the listed segment/bus/device/pin is connected to the first
 130  * link device, but it is actually connected to the second.
 131  */
 132 static struct prt_quirk prt_quirks[] = {
 133         { medion_md9580, 0, 0, 9, 'A',
 134                 "\\_SB_.PCI0.ISA_.LNKA",
 135                 "\\_SB_.PCI0.ISA_.LNKB"},
 136         { dell_optiplex, 0, 0, 0xd, 'A',
 137                 "\\_SB_.LNKB",
 138                 "\\_SB_.LNKA"},
 139         { hp_t5710, 0, 0, 1, 'A',
 140                 "\\_SB_.PCI0.LNK1",
 141                 "\\_SB_.PCI0.LNK3"},
 142 };
 143
 144 static void
 145 do_prt_fixups(struct acpi_prt_entry *entry, struct acpi_pci_routing_table *prt)
 146 {
 147         int i;
 148         struct prt_quirk *quirk;
 149
 150         for (i = 0; i < ARRAY_SIZE(prt_quirks); i++) {
 151                 quirk = &prt_quirks[i];
 152
 153                 /* All current quirks involve link devices, not GSIs */
 154                 if (!prt->source)
 155                         continue;
 156
 157                 if (dmi_check_system(quirk->system) &&
 158                     entry->id.segment == quirk->segment &&
 159                     entry->id.bus == quirk->bus &&
 160                     entry->id.device == quirk->device &&
 161                     entry->pin + 'A' == quirk->pin &&
 162                     !strcmp(prt->source, quirk->source) &&
 163                     strlen(prt->source) >= strlen(quirk->actual_source)) {
 164                         printk(KERN_WARNING PREFIX "firmware reports "
 165                                 "%04x:%02x:%02x PCI INT %c connected to %s; "
 166                                 "changing to %s\n",
 167                                 entry->id.segment, entry->id.bus,
 168                                 entry->id.device, 'A' + entry->pin,
 169                                 prt->source, quirk->actual_source);
 170                         strcpy(prt->source, quirk->actual_source);
 171                 }
 172         }
 173 }
 174
 175 static int
 176 acpi_pci_irq_add_entry(acpi_handle handle,
 177                        int segment, int bus, struct acpi_pci_routing_table *prt)
 178 {
 179         struct acpi_prt_entry *entry = NULL;
 180
 181
 182         if (!prt)
 183                 return -EINVAL;
 184
 185         entry = kzalloc(sizeof(struct acpi_prt_entry), GFP_KERNEL);
 186         if (!entry)
 187                 return -ENOMEM;
 188
 189         entry->id.segment = segment;
 190         entry->id.bus = bus;
 191         entry->id.device = (prt->address >> 16) & 0xFFFF;
 192         entry->id.function = prt->address & 0xFFFF;
 193         entry->pin = prt->pin;
 194
 195         do_prt_fixups(entry, prt);
 196
 197         /*
 198          * Type 1: Dynamic
 199          * ---------------
 200          * The 'source' field specifies the PCI interrupt link device used to
 201          * configure the IRQ assigned to this slot|dev|pin.  The 'source_index'
 202          * indicates which resource descriptor in the resource template (of
 203          * the link device) this interrupt is allocated from.
 204          *
 205          * NOTE: Don't query the Link Device for IRQ information at this time
 206          *       because Link Device enumeration may not have occurred yet
 207          *       (e.g. exists somewhere 'below' this _PRT entry in the ACPI
 208          *       namespace).
 209          */
 210         if (prt->source[0]) {
 211                 acpi_get_handle(handle, prt->source, &entry->link.handle);
 212                 entry->link.index = prt->source_index;
 213         }
 214         /*
 215          * Type 2: Static
 216          * --------------
 217          * The 'source' field is NULL, and the 'source_index' field specifies
 218          * the IRQ value, which is hardwired to specific interrupt inputs on
 219          * the interrupt controller.
 220          */
 221         else
 222                 entry->link.index = prt->source_index;
 223
 224         ACPI_DEBUG_PRINT_RAW((ACPI_DB_INFO,
 225                               "      %02X:%02X:%02X[%c] -> %s[%d]\n",
 226                               entry->id.segment, entry->id.bus,
 227                               entry->id.device, ('A' + entry->pin), prt->source,
 228                               entry->link.index));
 229
 230         spin_lock(&acpi_prt_lock);
 231         list_add_tail(&entry->node, &acpi_prt.entries);
 232         acpi_prt.count++;
 233         spin_unlock(&acpi_prt_lock);
 234
 235         return 0;
 236 }
 237
 238 static void
 239 acpi_pci_irq_del_entry(int segment, int bus, struct acpi_prt_entry *entry)
 240 {
 241         if (segment == entry->id.segment && bus == entry->id.bus) {
 242                 acpi_prt.count--;
 243                 list_del(&entry->node);
 244                 kfree(entry);
 245         }
 246 }
 247
 248 int acpi_pci_irq_add_prt(acpi_handle handle, int segment, int bus)
 249 {
 250         acpi_status status = AE_OK;
 251         char *pathname = NULL;
 252         struct acpi_buffer buffer = { 0, NULL };
 253         struct acpi_pci_routing_table *prt = NULL;
 254         struct acpi_pci_routing_table *entry = NULL;
 255         static int first_time = 1;
 256
 257
 258         pathname = kzalloc(ACPI_PATHNAME_MAX, GFP_KERNEL);
 259         if (!pathname)
 260                 return -ENOMEM;
 261
 262         if (first_time) {
 263                 acpi_prt.count = 0;
 264                 INIT_LIST_HEAD(&acpi_prt.entries);
 265                 first_time = 0;
 266         }
 267
 268         /*
 269          * NOTE: We're given a 'handle' to the _PRT object's parent device
 270          *       (either a PCI root bridge or PCI-PCI bridge).
 271          */
 272
 273         buffer.length = ACPI_PATHNAME_MAX;
 274         buffer.pointer = pathname;
 275         acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
 276
 277         printk(KERN_DEBUG "ACPI: PCI Interrupt Routing Table [%s._PRT]\n",
 278                pathname);
 279
 280         /*
 281          * Evaluate this _PRT and add its entries to our global list (acpi_prt).
 282          */
 283
 284         buffer.length = 0;
 285         buffer.pointer = NULL;
 286         kfree(pathname);
 287         status = acpi_get_irq_routing_table(handle, &buffer);
 288         if (status != AE_BUFFER_OVERFLOW) {
 289                 ACPI_EXCEPTION((AE_INFO, status, "Evaluating _PRT [%s]",
 290                                 acpi_format_exception(status)));
 291                 return -ENODEV;
 292         }
 293
 294         prt = kzalloc(buffer.length, GFP_KERNEL);
 295         if (!prt) {
 296                 return -ENOMEM;
 297         }
 298         buffer.pointer = prt;
 299
 300         status = acpi_get_irq_routing_table(handle, &buffer);
 301         if (ACPI_FAILURE(status)) {
 302                 ACPI_EXCEPTION((AE_INFO, status, "Evaluating _PRT [%s]",
 303                                 acpi_format_exception(status)));
 304                 kfree(buffer.pointer);
 305                 return -ENODEV;
 306         }
 307
 308         entry = prt;
 309
 310         while (entry && (entry->length > 0)) {
 311                 acpi_pci_irq_add_entry(handle, segment, bus, entry);
 312                 entry = (struct acpi_pci_routing_table *)
 313                     ((unsigned long)entry + entry->length);
 314         }
 315
 316         kfree(prt);
 317
 318         return 0;
 319 }
 320
 321 void acpi_pci_irq_del_prt(int segment, int bus)
 322 {
 323         struct list_head *node = NULL, *n = NULL;
 324         struct acpi_prt_entry *entry = NULL;
 325
 326         if (!acpi_prt.count) {
 327                 return;
 328         }
 329
 330         printk(KERN_DEBUG
 331                "ACPI: Delete PCI Interrupt Routing Table for %x:%x\n", segment,
 332                bus);
 333         spin_lock(&acpi_prt_lock);
 334         list_for_each_safe(node, n, &acpi_prt.entries) {
 335                 entry = list_entry(node, struct acpi_prt_entry, node);
 336
 337                 acpi_pci_irq_del_entry(segment, bus, entry);
 338         }
 339         spin_unlock(&acpi_prt_lock);
 340 }
 341
 342 /* --------------------------------------------------------------------------
 343                           PCI Interrupt Routing Support
 344    -------------------------------------------------------------------------- */
 345 typedef int (*irq_lookup_func) (struct acpi_prt_entry *, int *, int *, char **);
 346
 347 static int
 348 acpi_pci_allocate_irq(struct acpi_prt_entry *entry,
 349                       int *triggering, int *polarity, char **link)
 350 {
 351         int irq;
 352
 353
 354         if (entry->link.handle) {
 355                 irq = acpi_pci_link_allocate_irq(entry->link.handle,
 356                                                  entry->link.index, triggering,
 357                                                  polarity, link);
 358                 if (irq < 0) {
 359                         printk(KERN_WARNING PREFIX
 360                                       "Invalid IRQ link routing entry\n");
 361                         return -1;
 362                 }
 363         } else {
 364                 irq = entry->link.index;
 365                 *triggering = ACPI_LEVEL_SENSITIVE;
 366                 *polarity = ACPI_ACTIVE_LOW;
 367         }
 368
 369         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found IRQ %d\n", irq));
 370         return irq;
 371 }
 372
 373 static int
 374 acpi_pci_free_irq(struct acpi_prt_entry *entry,
 375                   int *triggering, int *polarity, char **link)
 376 {
 377         int irq;
 378
 379         if (entry->link.handle) {
 380                 irq = acpi_pci_link_free_irq(entry->link.handle);
 381         } else {
 382                 irq = entry->link.index;
 383         }
 384         return irq;
 385 }
 386
 387 #ifdef CONFIG_X86_IO_APIC
 388 extern int noioapicquirk;
 389
 390 static int bridge_has_boot_interrupt_variant(struct pci_bus *bus)
 391 {
 392         struct pci_bus *bus_it;
 393
 394         for (bus_it = bus ; bus_it ; bus_it = bus_it->parent) {
 395                 if (!bus_it->self)
 396                         return 0;
 397
 398                 printk(KERN_INFO "vendor=%04x device=%04x\n", bus_it->self->vendor,
 399                                 bus_it->self->device);
 400
 401                 if (bus_it->self->irq_reroute_variant)
 402                         return bus_it->self->irq_reroute_variant;
 403         }
 404         return 0;
 405 }
 406 #endif /* CONFIG_X86_IO_APIC */
 407
 408 /*
 409  * acpi_pci_irq_lookup
 410  * success: return IRQ >= 0
 411  * failure: return -1
 412  */
 413 static int
 414 acpi_pci_irq_lookup(struct pci_bus *bus,
 415                     int device,
 416                     int pin,
 417                     int *triggering,
 418                     int *polarity, char **link, irq_lookup_func func)
 419 {
 420         struct acpi_prt_entry *entry = NULL;
 421         int segment = pci_domain_nr(bus);
 422         int bus_nr = bus->number;
 423         int ret;
 424
 425
 426         ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 427                           "Searching for PRT entry for %02x:%02x:%02x[%c]\n",
 428                           segment, bus_nr, device, ('A' + pin)));
 429
 430         entry = acpi_pci_irq_find_prt_entry(segment, bus_nr, device, pin);
 431         if (!entry) {
 432                 ACPI_DEBUG_PRINT((ACPI_DB_INFO, "PRT entry not found\n"));
 433                 return -1;
 434         }
 435
 436         ret = func(entry, triggering, polarity, link);
 437
 438 #ifdef CONFIG_X86_IO_APIC
 439         /*
 440          * Some chipsets (e.g. intel 6700PXH) generate a legacy INTx when the
 441          * IRQ entry in the chipset's IO-APIC is masked (as, e.g. the RT kernel
 442          * does during interrupt handling). When this INTx generation cannot be
 443          * disabled, we reroute these interrupts to their legacy equivalent to
 444          * get rid of spurious interrupts.
 445          */
 446         if (!noioapicquirk) {
 447                 switch (bridge_has_boot_interrupt_variant(bus)) {
 448                 case 0:
 449                         /* no rerouting necessary */
 450                         break;
 451
 452                 case INTEL_IRQ_REROUTE_VARIANT:
 453                         /*
 454                          * Remap according to INTx routing table in 6700PXH
 455                          * specs, intel order number 302628-002, section
 456                          * 2.15.2. Other chipsets (80332, ...) have the same
 457                          * mapping and are handled here as well.
 458                          */
 459                         printk(KERN_INFO "pci irq %d -> rerouted to legacy "
 460                                          "irq %d\n", ret, (ret % 4) + 16);
 461                         ret = (ret % 4) + 16;
 462                         break;
 463
 464                 default:
 465                         printk(KERN_INFO "not rerouting irq %d to legacy irq: "
 466                                          "unknown mapping\n", ret);
 467                         break;
 468                 }
 469         }
 470 #endif /* CONFIG_X86_IO_APIC */
 471
 472         return ret;
 473 }
 474
 475 /*
 476  * acpi_pci_irq_derive
 477  * success: return IRQ >= 0
 478  * failure: return < 0
 479  */
 480 static int
 481 acpi_pci_irq_derive(struct pci_dev *dev,
 482                     int pin,
 483                     int *triggering,
 484                     int *polarity, char **link, irq_lookup_func func)
 485 {
 486         struct pci_dev *bridge = dev;
 487         int irq = -1;
 488         u8 bridge_pin = 0, orig_pin = pin;
 489
 490
 491         if (!dev)
 492                 return -EINVAL;
 493
 494         /*
 495          * Attempt to derive an IRQ for this device from a parent bridge's
 496          * PCI interrupt routing entry (eg. yenta bridge and add-in card bridge).
 497          */
 498         while (irq < 0 && bridge->bus->self) {
 499                 pin = (pin + PCI_SLOT(bridge->devfn)) % 4;
 500                 bridge = bridge->bus->self;
 501
 502                 if ((bridge->class >> 8) == PCI_CLASS_BRIDGE_CARDBUS) {
 503                         /* PC card has the same IRQ as its cardbridge */
 504                         bridge_pin = bridge->pin;
 505                         if (!bridge_pin) {
 506                                 ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 507                                                   "No interrupt pin configured for device %s\n",
 508                                                   pci_name(bridge)));
 509                                 return -1;
 510                         }
 511                         /* Pin is from 0 to 3 */
 512                         bridge_pin--;
 513                         pin = bridge_pin;
 514                 }
 515
 516                 irq = acpi_pci_irq_lookup(bridge->bus, PCI_SLOT(bridge->devfn),
 517                                           pin, triggering, polarity,
 518                                           link, func);
 519         }
 520
 521         if (irq < 0) {
 522                 dev_warn(&dev->dev, "can't derive routing for PCI INT %c\n",
 523                          'A' + orig_pin);
 524                 return -1;
 525         }
 526
 527         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Derive IRQ %d for device %s from %s\n",
 528                           irq, pci_name(dev), pci_name(bridge)));
 529
 530         return irq;
 531 }
 532
 533 /*
 534  * acpi_pci_irq_enable
 535  * success: return 0
 536  * failure: return < 0
 537  */
 538
 539 int acpi_pci_irq_enable(struct pci_dev *dev)
 540 {
 541         int irq = 0;
 542         u8 pin = 0;
 543         int triggering = ACPI_LEVEL_SENSITIVE;
 544         int polarity = ACPI_ACTIVE_LOW;
 545         char *link = NULL;
 546         char link_desc[16];
 547         int rc;
 548
 549
 550         if (!dev)
 551                 return -EINVAL;
 552
 553         pin = dev->pin;
 554         if (!pin) {
 555                 ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 556                                   "No interrupt pin configured for device %s\n",
 557                                   pci_name(dev)));
 558                 return 0;
 559         }
 560         pin--;
 561
 562         if (!dev->bus) {
 563                 dev_err(&dev->dev, "invalid (NULL) 'bus' field\n");
 564                 return -ENODEV;
 565         }
 566
 567         /*
 568          * First we check the PCI IRQ routing table (PRT) for an IRQ.  PRT
 569          * values override any BIOS-assigned IRQs set during boot.
 570          */
 571         irq = acpi_pci_irq_lookup(dev->bus, PCI_SLOT(dev->devfn), pin,
 572                                   &triggering, &polarity, &link,
 573                                   acpi_pci_allocate_irq);
 574
 575         /*
 576          * If no PRT entry was found, we'll try to derive an IRQ from the
 577          * device's parent bridge.
 578          */
 579         if (irq < 0)
 580                 irq = acpi_pci_irq_derive(dev, pin, &triggering,
 581                                           &polarity, &link,
 582                                           acpi_pci_allocate_irq);
 583
 584         if (irq < 0) {
 585                 /*
 586                  * IDE legacy mode controller IRQs are magic. Why do compat
 587                  * extensions always make such a nasty mess.
 588                  */
 589                 if (dev->class >> 8 == PCI_CLASS_STORAGE_IDE &&
 590                                 (dev->class & 0x05) == 0)
 591                         return 0;
 592         }
 593         /*
 594          * No IRQ known to the ACPI subsystem - maybe the BIOS /
 595          * driver reported one, then use it. Exit in any case.
 596          */
 597         if (irq < 0) {
 598                 dev_warn(&dev->dev, "PCI INT %c: no GSI", 'A' + pin);
 599                 /* Interrupt Line values above 0xF are forbidden */
 600                 if (dev->irq > 0 && (dev->irq <= 0xF)) {
 601                         printk(" - using IRQ %d\n", dev->irq);
 602                         acpi_register_gsi(dev->irq, ACPI_LEVEL_SENSITIVE,
 603                                           ACPI_ACTIVE_LOW);
 604                         return 0;
 605                 } else {
 606                         printk("\n");
 607                         return 0;
 608                 }
 609         }
 610
 611         rc = acpi_register_gsi(irq, triggering, polarity);
 612         if (rc < 0) {
 613                 dev_warn(&dev->dev, "PCI INT %c: failed to register GSI\n",
 614                          'A' + pin);
 615                 return rc;
 616         }
 617         dev->irq = rc;
 618
 619         if (link)
 620                 snprintf(link_desc, sizeof(link_desc), " -> Link[%s]", link);
 621         else
 622                 link_desc[0] = '\0';
 623
 624         dev_info(&dev->dev, "PCI INT %c%s -> GSI %u (%s, %s) -> IRQ %d\n",
 625                  'A' + pin, link_desc, irq,
 626                  (triggering == ACPI_LEVEL_SENSITIVE) ? "level" : "edge",
 627                  (polarity == ACPI_ACTIVE_LOW) ? "low" : "high", dev->irq);
 628
 629         return 0;
 630 }
 631
 632 /* FIXME: implement x86/x86_64 version */
 633 void __attribute__ ((weak)) acpi_unregister_gsi(u32 i)
 634 {
 635 }
 636
 637 void acpi_pci_irq_disable(struct pci_dev *dev)
 638 {
 639         int gsi = 0;
 640         u8 pin = 0;
 641         int triggering = ACPI_LEVEL_SENSITIVE;
 642         int polarity = ACPI_ACTIVE_LOW;
 643
 644
 645         if (!dev || !dev->bus)
 646                 return;
 647
 648         pin = dev->pin;
 649         if (!pin)
 650                 return;
 651         pin--;
 652
 653         /*
 654          * First we check the PCI IRQ routing table (PRT) for an IRQ.
 655          */
 656         gsi = acpi_pci_irq_lookup(dev->bus, PCI_SLOT(dev->devfn), pin,
 657                                   &triggering, &polarity, NULL,
 658                                   acpi_pci_free_irq);
 659         /*
 660          * If no PRT entry was found, we'll try to derive an IRQ from the
 661          * device's parent bridge.
 662          */
 663         if (gsi < 0)
 664                 gsi = acpi_pci_irq_derive(dev, pin,
 665                                           &triggering, &polarity, NULL,
 666                                           acpi_pci_free_irq);
 667         if (gsi < 0)
 668                 return;
 669
 670         /*
 671          * TBD: It might be worth clearing dev->irq by magic constant
 672          * (e.g. PCI_UNDEFINED_IRQ).
 673          */
 674
 675         dev_info(&dev->dev, "PCI INT %c disabled\n", 'A' + pin);
 676         acpi_unregister_gsi(gsi);
 677 }