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 WARN_ON(in_interrupt()); 172 down_read(&pci_bus_sem); 173 n = from ? from->node.next : pci_root_buses.next; 174 if (n != &pci_root_buses) 175 b = list_entry(n, struct pci_bus, node); 176 up_read(&pci_bus_sem); 177 return b; 178 } 179 EXPORT_SYMBOL(pci_find_next_bus); 180 181 /** 182 * pci_get_slot - locate PCI device for a given PCI slot 183 * @bus: PCI bus on which desired PCI device resides 184 * @devfn: encodes number of PCI slot in which the desired PCI 185 * device resides and the logical device number within that slot 186 * in case of multi-function devices. 187 * 188 * Given a PCI bus and slot/function number, the desired PCI device 189 * is located in the list of PCI devices. 190 * If the device is found, its reference count is increased and this 191 * function returns a pointer to its data structure. The caller must 192 * decrement the reference count by calling pci_dev_put(). 193 * If no device is found, %NULL is returned. 194 */ 195 struct pci_dev *pci_get_slot(struct pci_bus *bus, unsigned int devfn) 196 { 197 struct pci_dev *dev; 198 199 WARN_ON(in_interrupt()); 200 down_read(&pci_bus_sem); 201 202 list_for_each_entry(dev, &bus->devices, bus_list) { 203 if (dev->devfn == devfn) 204 goto out; 205 } 206 207 dev = NULL; 208 out: 209 pci_dev_get(dev); 210 up_read(&pci_bus_sem); 211 return dev; 212 } 213 EXPORT_SYMBOL(pci_get_slot); 214 215 /** 216 * pci_get_domain_bus_and_slot - locate PCI device for a given PCI domain (segment), bus, and slot 217 * @domain: PCI domain/segment on which the PCI device resides. 218 * @bus: PCI bus on which desired PCI device resides 219 * @devfn: encodes number of PCI slot in which the desired PCI device 220 * resides and the logical device number within that slot in case of 221 * multi-function devices. 222 * 223 * Given a PCI domain, bus, and slot/function number, the desired PCI 224 * device is located in the list of PCI devices. If the device is 225 * found, its reference count is increased and this function returns a 226 * pointer to its data structure. The caller must decrement the 227 * reference count by calling pci_dev_put(). If no device is found, 228 * %NULL is returned. 229 */ 230 struct pci_dev *pci_get_domain_bus_and_slot(int domain, unsigned int bus, 231 unsigned int devfn) 232 { 233 struct pci_dev *dev = NULL; 234 235 for_each_pci_dev(dev) { 236 if (pci_domain_nr(dev->bus) == domain && 237 (dev->bus->number == bus && dev->devfn == devfn)) 238 return dev; 239 } 240 return NULL; 241 } 242 EXPORT_SYMBOL(pci_get_domain_bus_and_slot); 243 244 static int match_pci_dev_by_id(struct device *dev, const void *data) 245 { 246 struct pci_dev *pdev = to_pci_dev(dev); 247 const struct pci_device_id *id = data; 248 249 if (pci_match_one_device(id, pdev)) 250 return 1; 251 return 0; 252 } 253 254 /* 255 * pci_get_dev_by_id - begin or continue searching for a PCI device by id 256 * @id: pointer to struct pci_device_id to match for the device 257 * @from: Previous PCI device found in search, or %NULL for new search. 258 * 259 * Iterates through the list of known PCI devices. If a PCI device is found 260 * with a matching id a pointer to its device structure is returned, and the 261 * reference count to the device is incremented. Otherwise, %NULL is returned. 262 * A new search is initiated by passing %NULL as the @from argument. Otherwise 263 * if @from is not %NULL, searches continue from next device on the global 264 * list. The reference count for @from is always decremented if it is not 265 * %NULL. 266 * 267 * This is an internal function for use by the other search functions in 268 * this file. 269 */ 270 static struct pci_dev *pci_get_dev_by_id(const struct pci_device_id *id, 271 struct pci_dev *from) 272 { 273 struct device *dev; 274 struct device *dev_start = NULL; 275 struct pci_dev *pdev = NULL; 276 277 WARN_ON(in_interrupt()); 278 if (from) 279 dev_start = &from->dev; 280 dev = bus_find_device(&pci_bus_type, dev_start, (void *)id, 281 match_pci_dev_by_id); 282 if (dev) 283 pdev = to_pci_dev(dev); 284 pci_dev_put(from); 285 return pdev; 286 } 287 288 /** 289 * pci_get_subsys - begin or continue searching for a PCI device by vendor/subvendor/device/subdevice id 290 * @vendor: PCI vendor id to match, or %PCI_ANY_ID to match all vendor ids 291 * @device: PCI device id to match, or %PCI_ANY_ID to match all device ids 292 * @ss_vendor: PCI subsystem vendor id to match, or %PCI_ANY_ID to match all vendor ids 293 * @ss_device: PCI subsystem device id to match, or %PCI_ANY_ID to match all device ids 294 * @from: Previous PCI device found in search, or %NULL for new search. 295 * 296 * Iterates through the list of known PCI devices. If a PCI device is found 297 * with a matching @vendor, @device, @ss_vendor and @ss_device, a pointer to its 298 * device structure is returned, and the reference count to the device is 299 * incremented. Otherwise, %NULL is returned. A new search is initiated by 300 * passing %NULL as the @from argument. Otherwise if @from is not %NULL, 301 * searches continue from next device on the global list. 302 * The reference count for @from is always decremented if it is not %NULL. 303 */ 304 struct pci_dev *pci_get_subsys(unsigned int vendor, unsigned int device, 305 unsigned int ss_vendor, unsigned int ss_device, 306 struct pci_dev *from) 307 { 308 struct pci_device_id id = { 309 .vendor = vendor, 310 .device = device, 311 .subvendor = ss_vendor, 312 .subdevice = ss_device, 313 }; 314 315 return pci_get_dev_by_id(&id, from); 316 } 317 EXPORT_SYMBOL(pci_get_subsys); 318 319 /** 320 * pci_get_device - begin or continue searching for a PCI device by vendor/device id 321 * @vendor: PCI vendor id to match, or %PCI_ANY_ID to match all vendor ids 322 * @device: PCI device id to match, or %PCI_ANY_ID to match all device ids 323 * @from: Previous PCI device found in search, or %NULL for new search. 324 * 325 * Iterates through the list of known PCI devices. If a PCI device is 326 * found with a matching @vendor and @device, the reference count to the 327 * device is incremented and a pointer to its device structure is returned. 328 * Otherwise, %NULL is returned. A new search is initiated by passing %NULL 329 * as the @from argument. Otherwise if @from is not %NULL, searches continue 330 * from next device on the global list. The reference count for @from is 331 * always decremented if it is not %NULL. 332 */ 333 struct pci_dev *pci_get_device(unsigned int vendor, unsigned int device, 334 struct pci_dev *from) 335 { 336 return pci_get_subsys(vendor, device, PCI_ANY_ID, PCI_ANY_ID, from); 337 } 338 EXPORT_SYMBOL(pci_get_device); 339 340 /** 341 * pci_get_class - begin or continue searching for a PCI device by class 342 * @class: search for a PCI device with this class designation 343 * @from: Previous PCI device found in search, or %NULL for new search. 344 * 345 * Iterates through the list of known PCI devices. If a PCI device is 346 * found with a matching @class, the reference count to the device is 347 * incremented and a pointer to its device structure is returned. 348 * Otherwise, %NULL is returned. 349 * A new search is initiated by passing %NULL as the @from argument. 350 * Otherwise if @from is not %NULL, searches continue from next device 351 * on the global list. The reference count for @from is always decremented 352 * if it is not %NULL. 353 */ 354 struct pci_dev *pci_get_class(unsigned int class, struct pci_dev *from) 355 { 356 struct pci_device_id id = { 357 .vendor = PCI_ANY_ID, 358 .device = PCI_ANY_ID, 359 .subvendor = PCI_ANY_ID, 360 .subdevice = PCI_ANY_ID, 361 .class_mask = PCI_ANY_ID, 362 .class = class, 363 }; 364 365 return pci_get_dev_by_id(&id, from); 366 } 367 EXPORT_SYMBOL(pci_get_class); 368 369 /** 370 * pci_dev_present - Returns 1 if device matching the device list is present, 0 if not. 371 * @ids: A pointer to a null terminated list of struct pci_device_id structures 372 * that describe the type of PCI device the caller is trying to find. 373 * 374 * Obvious fact: You do not have a reference to any device that might be found 375 * by this function, so if that device is removed from the system right after 376 * this function is finished, the value will be stale. Use this function to 377 * find devices that are usually built into a system, or for a general hint as 378 * to if another device happens to be present at this specific moment in time. 379 */ 380 int pci_dev_present(const struct pci_device_id *ids) 381 { 382 struct pci_dev *found = NULL; 383 384 WARN_ON(in_interrupt()); 385 while (ids->vendor || ids->subvendor || ids->class_mask) { 386 found = pci_get_dev_by_id(ids, NULL); 387 if (found) { 388 pci_dev_put(found); 389 return 1; 390 } 391 ids++; 392 } 393 394 return 0; 395 } 396 EXPORT_SYMBOL(pci_dev_present); 397