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