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  */
pci_for_each_dma_alias(struct pci_dev * pdev,int (* fn)(struct pci_dev * pdev,u16 alias,void * data),void * data)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 
pci_do_find_bus(struct pci_bus * bus,unsigned char busnr)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  */
pci_find_bus(int domain,int busnr)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  */
pci_find_next_bus(const struct pci_bus * from)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  */
pci_get_slot(struct pci_bus * bus,unsigned int devfn)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  */
pci_get_domain_bus_and_slot(int domain,unsigned int bus,unsigned int devfn)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 
match_pci_dev_by_id(struct device * dev,const void * data)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  */
pci_get_dev_by_id(const struct pci_device_id * id,struct pci_dev * from)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  */
pci_get_subsys(unsigned int vendor,unsigned int device,unsigned int ss_vendor,unsigned int ss_device,struct pci_dev * from)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  */
pci_get_device(unsigned int vendor,unsigned int device,struct pci_dev * from)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  */
pci_get_class(unsigned int class,struct pci_dev * from)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  */
pci_dev_present(const struct pci_device_id * ids)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);
393