drivers/pci/search.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * PCI searching functions
   4  *
   5  * Copyright (C) 1993 -- 1997 Drew Eckhardt, Frederic Potter,
   6  *                                      David Mosberger-Tang
   7  * Copyright (C) 1997 -- 2000 Martin Mares <mj@ucw.cz>
   8  * Copyright (C) 2003 -- 2004 Greg Kroah-Hartman <greg@kroah.com>
   9  */
  10
  11 #include <linux/pci.h>
  12 #include <linux/slab.h>
  13 #include <linux/module.h>
  14 #include <linux/interrupt.h>
  15 #include "pci.h"
  16
  17 DECLARE_RWSEM(pci_bus_sem);
  18 EXPORT_SYMBOL_GPL(pci_bus_sem);
  19
  20 /*
  21  * pci_for_each_dma_alias - Iterate over DMA aliases for a device
  22  * @pdev: starting downstream device
  23  * @fn: function to call for each alias
  24  * @data: opaque data to pass to @fn
  25  *
  26  * Starting @pdev, walk up the bus calling @fn for each possible alias
  27  * of @pdev at the root bus.
  28  */
  29 int pci_for_each_dma_alias(struct pci_dev *pdev,
  30                            int (*fn)(struct pci_dev *pdev,
  31                                      u16 alias, void *data), void *data)
  32 {
  33         struct pci_bus *bus;
  34         int ret;
  35
  36         ret = fn(pdev, PCI_DEVID(pdev->bus->number, pdev->devfn), data);
  37         if (ret)
  38                 return ret;
  39
  40         /*
  41          * If the device is broken and uses an alias requester ID for
  42          * DMA, iterate over that too.
  43          */
  44         if (unlikely(pdev->dma_alias_mask)) {
  45                 u8 devfn;
  46
  47                 for_each_set_bit(devfn, pdev->dma_alias_mask, U8_MAX) {
  48                         ret = fn(pdev, PCI_DEVID(pdev->bus->number, devfn),
  49                                  data);
  50                         if (ret)
  51                                 return ret;
  52                 }
  53         }
  54
  55         for (bus = pdev->bus; !pci_is_root_bus(bus); bus = bus->parent) {
  56                 struct pci_dev *tmp;
  57
  58                 /* Skip virtual buses */
  59                 if (!bus->self)
  60                         continue;
  61
  62                 tmp = bus->self;
  63
  64                 /* stop at bridge where translation unit is associated */
  65                 if (tmp->dev_flags & PCI_DEV_FLAGS_BRIDGE_XLATE_ROOT)
  66                         return ret;
  67
  68                 /*
  69                  * PCIe-to-PCI/X bridges alias transactions from downstream
  70                  * devices using the subordinate bus number (PCI Express to
  71                  * PCI/PCI-X Bridge Spec, rev 1.0, sec 2.3).  For all cases
  72                  * where the upstream bus is PCI/X we alias to the bridge
  73                  * (there are various conditions in the previous reference
  74                  * where the bridge may take ownership of transactions, even
  75                  * when the secondary interface is PCI-X).
  76                  */
  77                 if (pci_is_pcie(tmp)) {
  78                         switch (pci_pcie_type(tmp)) {
  79                         case PCI_EXP_TYPE_ROOT_PORT:
  80                         case PCI_EXP_TYPE_UPSTREAM:
  81                         case PCI_EXP_TYPE_DOWNSTREAM:
  82                                 continue;
  83                         case PCI_EXP_TYPE_PCI_BRIDGE:
  84                                 ret = fn(tmp,
  85                                          PCI_DEVID(tmp->subordinate->number,
  86                                                    PCI_DEVFN(0, 0)), data);
  87                                 if (ret)
  88                                         return ret;
  89                                 continue;
  90                         case PCI_EXP_TYPE_PCIE_BRIDGE:
  91                                 ret = fn(tmp,
  92                                          PCI_DEVID(tmp->bus->number,
  93                                                    tmp->devfn), data);
  94                                 if (ret)
  95                                         return ret;
  96                                 continue;
  97                         }
  98                 } else {
  99                         if (tmp->dev_flags & PCI_DEV_FLAG_PCIE_BRIDGE_ALIAS)
 100                                 ret = fn(tmp,
 101                                          PCI_DEVID(tmp->subordinate->number,
 102                                                    PCI_DEVFN(0, 0)), data);
 103                         else
 104                                 ret = fn(tmp,
 105                                          PCI_DEVID(tmp->bus->number,
 106                                                    tmp->devfn), data);
 107                         if (ret)
 108                                 return ret;
 109                 }
 110         }
 111
 112         return ret;
 113 }
 114
 115 static struct pci_bus *pci_do_find_bus(struct pci_bus *bus, unsigned char busnr)
 116 {
 117         struct pci_bus *child;
 118         struct pci_bus *tmp;
 119
 120         if (bus->number == busnr)
 121                 return bus;
 122
 123         list_for_each_entry(tmp, &bus->children, node) {
 124                 child = pci_do_find_bus(tmp, busnr);
 125                 if (child)
 126                         return child;
 127         }
 128         return NULL;
 129 }
 130
 131 /**
 132  * pci_find_bus - locate PCI bus from a given domain and bus number
 133  * @domain: number of PCI domain to search
 134  * @busnr: number of desired PCI bus
 135  *
 136  * Given a PCI bus number and domain number, the desired PCI bus is located
 137  * in the global list of PCI buses.  If the bus is found, a pointer to its
 138  * data structure is returned.  If no bus is found, %NULL is returned.
 139  */
 140 struct pci_bus *pci_find_bus(int domain, int busnr)
 141 {
 142         struct pci_bus *bus = NULL;
 143         struct pci_bus *tmp_bus;
 144
 145         while ((bus = pci_find_next_bus(bus)) != NULL)  {
 146                 if (pci_domain_nr(bus) != domain)
 147                         continue;
 148                 tmp_bus = pci_do_find_bus(bus, busnr);
 149                 if (tmp_bus)
 150                         return tmp_bus;
 151         }
 152         return NULL;
 153 }
 154 EXPORT_SYMBOL(pci_find_bus);
 155
 156 /**
 157  * pci_find_next_bus - begin or continue searching for a PCI bus
 158  * @from: Previous PCI bus found, or %NULL for new search.
 159  *
 160  * Iterates through the list of known PCI buses.  A new search is
 161  * initiated by passing %NULL as the @from argument.  Otherwise if
 162  * @from is not %NULL, searches continue from next device on the
 163  * global list.
 164  */
 165 struct pci_bus *pci_find_next_bus(const struct pci_bus *from)
 166 {
 167         struct list_head *n;
 168         struct pci_bus *b = NULL;
 169
 170         WARN_ON(in_interrupt());
 171         down_read(&pci_bus_sem);
 172         n = from ? from->node.next : pci_root_buses.next;
 173         if (n != &pci_root_buses)
 174                 b = list_entry(n, struct pci_bus, node);
 175         up_read(&pci_bus_sem);
 176         return b;
 177 }
 178 EXPORT_SYMBOL(pci_find_next_bus);
 179
 180 /**
 181  * pci_get_slot - locate PCI device for a given PCI slot
 182  * @bus: PCI bus on which desired PCI device resides
 183  * @devfn: encodes number of PCI slot in which the desired PCI
 184  * device resides and the logical device number within that slot
 185  * in case of multi-function devices.
 186  *
 187  * Given a PCI bus and slot/function number, the desired PCI device
 188  * is located in the list of PCI devices.
 189  * If the device is found, its reference count is increased and this
 190  * function returns a pointer to its data structure.  The caller must
 191  * decrement the reference count by calling pci_dev_put().
 192  * If no device is found, %NULL is returned.
 193  */
 194 struct pci_dev *pci_get_slot(struct pci_bus *bus, unsigned int devfn)
 195 {
 196         struct pci_dev *dev;
 197
 198         WARN_ON(in_interrupt());
 199         down_read(&pci_bus_sem);
 200
 201         list_for_each_entry(dev, &bus->devices, bus_list) {
 202                 if (dev->devfn == devfn)
 203                         goto out;
 204         }
 205
 206         dev = NULL;
 207  out:
 208         pci_dev_get(dev);
 209         up_read(&pci_bus_sem);
 210         return dev;
 211 }
 212 EXPORT_SYMBOL(pci_get_slot);
 213
 214 /**
 215  * pci_get_domain_bus_and_slot - locate PCI device for a given PCI domain (segment), bus, and slot
 216  * @domain: PCI domain/segment on which the PCI device resides.
 217  * @bus: PCI bus on which desired PCI device resides
 218  * @devfn: encodes number of PCI slot in which the desired PCI device
 219  * resides and the logical device number within that slot in case of
 220  * multi-function devices.
 221  *
 222  * Given a PCI domain, bus, and slot/function number, the desired PCI
 223  * device is located in the list of PCI devices. If the device is
 224  * found, its reference count is increased and this function returns a
 225  * pointer to its data structure.  The caller must decrement the
 226  * reference count by calling pci_dev_put().  If no device is found,
 227  * %NULL is returned.
 228  */
 229 struct pci_dev *pci_get_domain_bus_and_slot(int domain, unsigned int bus,
 230                                             unsigned int devfn)
 231 {
 232         struct pci_dev *dev = NULL;
 233
 234         for_each_pci_dev(dev) {
 235                 if (pci_domain_nr(dev->bus) == domain &&
 236                     (dev->bus->number == bus && dev->devfn == devfn))
 237                         return dev;
 238         }
 239         return NULL;
 240 }
 241 EXPORT_SYMBOL(pci_get_domain_bus_and_slot);
 242
 243 static int match_pci_dev_by_id(struct device *dev, void *data)
 244 {
 245         struct pci_dev *pdev = to_pci_dev(dev);
 246         struct pci_device_id *id = data;
 247
 248         if (pci_match_one_device(id, pdev))
 249                 return 1;
 250         return 0;
 251 }
 252
 253 /*
 254  * pci_get_dev_by_id - begin or continue searching for a PCI device by id
 255  * @id: pointer to struct pci_device_id to match for the device
 256  * @from: Previous PCI device found in search, or %NULL for new search.
 257  *
 258  * Iterates through the list of known PCI devices.  If a PCI device is found
 259  * with a matching id a pointer to its device structure is returned, and the
 260  * reference count to the device is incremented.  Otherwise, %NULL is returned.
 261  * A new search is initiated by passing %NULL as the @from argument.  Otherwise
 262  * if @from is not %NULL, searches continue from next device on the global
 263  * list.  The reference count for @from is always decremented if it is not
 264  * %NULL.
 265  *
 266  * This is an internal function for use by the other search functions in
 267  * this file.
 268  */
 269 static struct pci_dev *pci_get_dev_by_id(const struct pci_device_id *id,
 270                                          struct pci_dev *from)
 271 {
 272         struct device *dev;
 273         struct device *dev_start = NULL;
 274         struct pci_dev *pdev = NULL;
 275
 276         WARN_ON(in_interrupt());
 277         if (from)
 278                 dev_start = &from->dev;
 279         dev = bus_find_device(&pci_bus_type, dev_start, (void *)id,
 280                               match_pci_dev_by_id);
 281         if (dev)
 282                 pdev = to_pci_dev(dev);
 283         pci_dev_put(from);
 284         return pdev;
 285 }
 286
 287 /**
 288  * pci_get_subsys - begin or continue searching for a PCI device by vendor/subvendor/device/subdevice id
 289  * @vendor: PCI vendor id to match, or %PCI_ANY_ID to match all vendor ids
 290  * @device: PCI device id to match, or %PCI_ANY_ID to match all device ids
 291  * @ss_vendor: PCI subsystem vendor id to match, or %PCI_ANY_ID to match all vendor ids
 292  * @ss_device: PCI subsystem device id to match, or %PCI_ANY_ID to match all device ids
 293  * @from: Previous PCI device found in search, or %NULL for new search.
 294  *
 295  * Iterates through the list of known PCI devices.  If a PCI device is found
 296  * with a matching @vendor, @device, @ss_vendor and @ss_device, a pointer to its
 297  * device structure is returned, and the reference count to the device is
 298  * incremented.  Otherwise, %NULL is returned.  A new search is initiated by
 299  * passing %NULL as the @from argument.  Otherwise if @from is not %NULL,
 300  * searches continue from next device on the global list.
 301  * The reference count for @from is always decremented if it is not %NULL.
 302  */
 303 struct pci_dev *pci_get_subsys(unsigned int vendor, unsigned int device,
 304                                unsigned int ss_vendor, unsigned int ss_device,
 305                                struct pci_dev *from)
 306 {
 307         struct pci_device_id id = {
 308                 .vendor = vendor,
 309                 .device = device,
 310                 .subvendor = ss_vendor,
 311                 .subdevice = ss_device,
 312         };
 313
 314         return pci_get_dev_by_id(&id, from);
 315 }
 316 EXPORT_SYMBOL(pci_get_subsys);
 317
 318 /**
 319  * pci_get_device - begin or continue searching for a PCI device by vendor/device id
 320  * @vendor: PCI vendor id to match, or %PCI_ANY_ID to match all vendor ids
 321  * @device: PCI device id to match, or %PCI_ANY_ID to match all device ids
 322  * @from: Previous PCI device found in search, or %NULL for new search.
 323  *
 324  * Iterates through the list of known PCI devices.  If a PCI device is
 325  * found with a matching @vendor and @device, the reference count to the
 326  * device is incremented and a pointer to its device structure is returned.
 327  * Otherwise, %NULL is returned.  A new search is initiated by passing %NULL
 328  * as the @from argument.  Otherwise if @from is not %NULL, searches continue
 329  * from next device on the global list.  The reference count for @from is
 330  * always decremented if it is not %NULL.
 331  */
 332 struct pci_dev *pci_get_device(unsigned int vendor, unsigned int device,
 333                                struct pci_dev *from)
 334 {
 335         return pci_get_subsys(vendor, device, PCI_ANY_ID, PCI_ANY_ID, from);
 336 }
 337 EXPORT_SYMBOL(pci_get_device);
 338
 339 /**
 340  * pci_get_class - begin or continue searching for a PCI device by class
 341  * @class: search for a PCI device with this class designation
 342  * @from: Previous PCI device found in search, or %NULL for new search.
 343  *
 344  * Iterates through the list of known PCI devices.  If a PCI device is
 345  * found with a matching @class, the reference count to the device is
 346  * incremented and a pointer to its device structure is returned.
 347  * Otherwise, %NULL is returned.
 348  * A new search is initiated by passing %NULL as the @from argument.
 349  * Otherwise if @from is not %NULL, searches continue from next device
 350  * on the global list.  The reference count for @from is always decremented
 351  * if it is not %NULL.
 352  */
 353 struct pci_dev *pci_get_class(unsigned int class, struct pci_dev *from)
 354 {
 355         struct pci_device_id id = {
 356                 .vendor = PCI_ANY_ID,
 357                 .device = PCI_ANY_ID,
 358                 .subvendor = PCI_ANY_ID,
 359                 .subdevice = PCI_ANY_ID,
 360                 .class_mask = PCI_ANY_ID,
 361                 .class = class,
 362         };
 363
 364         return pci_get_dev_by_id(&id, from);
 365 }
 366 EXPORT_SYMBOL(pci_get_class);
 367
 368 /**
 369  * pci_dev_present - Returns 1 if device matching the device list is present, 0 if not.
 370  * @ids: A pointer to a null terminated list of struct pci_device_id structures
 371  * that describe the type of PCI device the caller is trying to find.
 372  *
 373  * Obvious fact: You do not have a reference to any device that might be found
 374  * by this function, so if that device is removed from the system right after
 375  * this function is finished, the value will be stale.  Use this function to
 376  * find devices that are usually built into a system, or for a general hint as
 377  * to if another device happens to be present at this specific moment in time.
 378  */
 379 int pci_dev_present(const struct pci_device_id *ids)
 380 {
 381         struct pci_dev *found = NULL;
 382
 383         WARN_ON(in_interrupt());
 384         while (ids->vendor || ids->subvendor || ids->class_mask) {
 385                 found = pci_get_dev_by_id(ids, NULL);
 386                 if (found) {
 387                         pci_dev_put(found);
 388                         return 1;
 389                 }
 390                 ids++;
 391         }
 392
 393         return 0;
 394 }
 395 EXPORT_SYMBOL(pci_dev_present);