Root/drivers/pci/search.c

1/*
2 * PCI searching functions.
3 *
4 * Copyright (C) 1993 -- 1997 Drew Eckhardt, Frederic Potter,
5 * David Mosberger-Tang
6 * Copyright (C) 1997 -- 2000 Martin Mares <mj@ucw.cz>
7 * Copyright (C) 2003 -- 2004 Greg Kroah-Hartman <greg@kroah.com>
8 */
9
10#include <linux/init.h>
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
17DECLARE_RWSEM(pci_bus_sem);
18EXPORT_SYMBOL_GPL(pci_bus_sem);
19
20/*
21 * find the upstream PCIe-to-PCI bridge of a PCI device
22 * if the device is PCIE, return NULL
23 * if the device isn't connected to a PCIe bridge (that is its parent is a
24 * legacy PCI bridge and the bridge is directly connected to bus 0), return its
25 * parent
26 */
27struct pci_dev *
28pci_find_upstream_pcie_bridge(struct pci_dev *pdev)
29{
30    struct pci_dev *tmp = NULL;
31
32    if (pci_is_pcie(pdev))
33        return NULL;
34    while (1) {
35        if (pci_is_root_bus(pdev->bus))
36            break;
37        pdev = pdev->bus->self;
38        /* a p2p bridge */
39        if (!pci_is_pcie(pdev)) {
40            tmp = pdev;
41            continue;
42        }
43        /* PCI device should connect to a PCIe bridge */
44        if (pdev->pcie_type != PCI_EXP_TYPE_PCI_BRIDGE) {
45            /* Busted hardware? */
46            WARN_ON_ONCE(1);
47            return NULL;
48        }
49        return pdev;
50    }
51
52    return tmp;
53}
54
55static struct pci_bus *pci_do_find_bus(struct pci_bus *bus, unsigned char busnr)
56{
57    struct pci_bus* child;
58    struct list_head *tmp;
59
60    if(bus->number == busnr)
61        return bus;
62
63    list_for_each(tmp, &bus->children) {
64        child = pci_do_find_bus(pci_bus_b(tmp), busnr);
65        if(child)
66            return child;
67    }
68    return NULL;
69}
70
71/**
72 * pci_find_bus - locate PCI bus from a given domain and bus number
73 * @domain: number of PCI domain to search
74 * @busnr: number of desired PCI bus
75 *
76 * Given a PCI bus number and domain number, the desired PCI bus is located
77 * in the global list of PCI buses. If the bus is found, a pointer to its
78 * data structure is returned. If no bus is found, %NULL is returned.
79 */
80struct pci_bus * pci_find_bus(int domain, int busnr)
81{
82    struct pci_bus *bus = NULL;
83    struct pci_bus *tmp_bus;
84
85    while ((bus = pci_find_next_bus(bus)) != NULL) {
86        if (pci_domain_nr(bus) != domain)
87            continue;
88        tmp_bus = pci_do_find_bus(bus, busnr);
89        if (tmp_bus)
90            return tmp_bus;
91    }
92    return NULL;
93}
94
95/**
96 * pci_find_next_bus - begin or continue searching for a PCI bus
97 * @from: Previous PCI bus found, or %NULL for new search.
98 *
99 * Iterates through the list of known PCI busses. A new search is
100 * initiated by passing %NULL as the @from argument. Otherwise if
101 * @from is not %NULL, searches continue from next device on the
102 * global list.
103 */
104struct pci_bus *
105pci_find_next_bus(const struct pci_bus *from)
106{
107    struct list_head *n;
108    struct pci_bus *b = NULL;
109
110    WARN_ON(in_interrupt());
111    down_read(&pci_bus_sem);
112    n = from ? from->node.next : pci_root_buses.next;
113    if (n != &pci_root_buses)
114        b = pci_bus_b(n);
115    up_read(&pci_bus_sem);
116    return b;
117}
118
119/**
120 * pci_get_slot - locate PCI device for a given PCI slot
121 * @bus: PCI bus on which desired PCI device resides
122 * @devfn: encodes number of PCI slot in which the desired PCI
123 * device resides and the logical device number within that slot
124 * in case of multi-function devices.
125 *
126 * Given a PCI bus and slot/function number, the desired PCI device
127 * is located in the list of PCI devices.
128 * If the device is found, its reference count is increased and this
129 * function returns a pointer to its data structure. The caller must
130 * decrement the reference count by calling pci_dev_put().
131 * If no device is found, %NULL is returned.
132 */
133struct pci_dev * pci_get_slot(struct pci_bus *bus, unsigned int devfn)
134{
135    struct list_head *tmp;
136    struct pci_dev *dev;
137
138    WARN_ON(in_interrupt());
139    down_read(&pci_bus_sem);
140
141    list_for_each(tmp, &bus->devices) {
142        dev = pci_dev_b(tmp);
143        if (dev->devfn == devfn)
144            goto out;
145    }
146
147    dev = NULL;
148 out:
149    pci_dev_get(dev);
150    up_read(&pci_bus_sem);
151    return dev;
152}
153
154/**
155 * pci_get_domain_bus_and_slot - locate PCI device for a given PCI domain (segment), bus, and slot
156 * @domain: PCI domain/segment on which the PCI device resides.
157 * @bus: PCI bus on which desired PCI device resides
158 * @devfn: encodes number of PCI slot in which the desired PCI device
159 * resides and the logical device number within that slot in case of
160 * multi-function devices.
161 *
162 * Given a PCI domain, bus, and slot/function number, the desired PCI
163 * device is located in the list of PCI devices. If the device is
164 * found, its reference count is increased and this function returns a
165 * pointer to its data structure. The caller must decrement the
166 * reference count by calling pci_dev_put(). If no device is found,
167 * %NULL is returned.
168 */
169struct pci_dev *pci_get_domain_bus_and_slot(int domain, unsigned int bus,
170                        unsigned int devfn)
171{
172    struct pci_dev *dev = NULL;
173
174    for_each_pci_dev(dev) {
175        if (pci_domain_nr(dev->bus) == domain &&
176            (dev->bus->number == bus && dev->devfn == devfn))
177            return dev;
178    }
179    return NULL;
180}
181EXPORT_SYMBOL(pci_get_domain_bus_and_slot);
182
183static int match_pci_dev_by_id(struct device *dev, void *data)
184{
185    struct pci_dev *pdev = to_pci_dev(dev);
186    struct pci_device_id *id = data;
187
188    if (pci_match_one_device(id, pdev))
189        return 1;
190    return 0;
191}
192
193/*
194 * pci_get_dev_by_id - begin or continue searching for a PCI device by id
195 * @id: pointer to struct pci_device_id to match for the device
196 * @from: Previous PCI device found in search, or %NULL for new search.
197 *
198 * Iterates through the list of known PCI devices. If a PCI device is found
199 * with a matching id a pointer to its device structure is returned, and the
200 * reference count to the device is incremented. Otherwise, %NULL is returned.
201 * A new search is initiated by passing %NULL as the @from argument. Otherwise
202 * if @from is not %NULL, searches continue from next device on the global
203 * list. The reference count for @from is always decremented if it is not
204 * %NULL.
205 *
206 * This is an internal function for use by the other search functions in
207 * this file.
208 */
209static struct pci_dev *pci_get_dev_by_id(const struct pci_device_id *id,
210                     struct pci_dev *from)
211{
212    struct device *dev;
213    struct device *dev_start = NULL;
214    struct pci_dev *pdev = NULL;
215
216    WARN_ON(in_interrupt());
217    if (from)
218        dev_start = &from->dev;
219    dev = bus_find_device(&pci_bus_type, dev_start, (void *)id,
220                  match_pci_dev_by_id);
221    if (dev)
222        pdev = to_pci_dev(dev);
223    if (from)
224        pci_dev_put(from);
225    return pdev;
226}
227
228/**
229 * pci_get_subsys - begin or continue searching for a PCI device by vendor/subvendor/device/subdevice id
230 * @vendor: PCI vendor id to match, or %PCI_ANY_ID to match all vendor ids
231 * @device: PCI device id to match, or %PCI_ANY_ID to match all device ids
232 * @ss_vendor: PCI subsystem vendor id to match, or %PCI_ANY_ID to match all vendor ids
233 * @ss_device: PCI subsystem device id to match, or %PCI_ANY_ID to match all device ids
234 * @from: Previous PCI device found in search, or %NULL for new search.
235 *
236 * Iterates through the list of known PCI devices. If a PCI device is found
237 * with a matching @vendor, @device, @ss_vendor and @ss_device, a pointer to its
238 * device structure is returned, and the reference count to the device is
239 * incremented. Otherwise, %NULL is returned. A new search is initiated by
240 * passing %NULL as the @from argument. Otherwise if @from is not %NULL,
241 * searches continue from next device on the global list.
242 * The reference count for @from is always decremented if it is not %NULL.
243 */
244struct pci_dev *pci_get_subsys(unsigned int vendor, unsigned int device,
245                   unsigned int ss_vendor, unsigned int ss_device,
246                   struct pci_dev *from)
247{
248    struct pci_dev *pdev;
249    struct pci_device_id *id;
250
251    /*
252     * pci_find_subsys() can be called on the ide_setup() path,
253     * super-early in boot. But the down_read() will enable local
254     * interrupts, which can cause some machines to crash. So here we
255     * detect and flag that situation and bail out early.
256     */
257    if (unlikely(no_pci_devices()))
258        return NULL;
259
260    id = kzalloc(sizeof(*id), GFP_KERNEL);
261    if (!id)
262        return NULL;
263    id->vendor = vendor;
264    id->device = device;
265    id->subvendor = ss_vendor;
266    id->subdevice = ss_device;
267
268    pdev = pci_get_dev_by_id(id, from);
269    kfree(id);
270
271    return pdev;
272}
273
274/**
275 * pci_get_device - begin or continue searching for a PCI device by vendor/device id
276 * @vendor: PCI vendor id to match, or %PCI_ANY_ID to match all vendor ids
277 * @device: PCI device id to match, or %PCI_ANY_ID to match all device ids
278 * @from: Previous PCI device found in search, or %NULL for new search.
279 *
280 * Iterates through the list of known PCI devices. If a PCI device is
281 * found with a matching @vendor and @device, the reference count to the
282 * device is incremented and a pointer to its device structure is returned.
283 * Otherwise, %NULL is returned. A new search is initiated by passing %NULL
284 * as the @from argument. Otherwise if @from is not %NULL, searches continue
285 * from next device on the global list. The reference count for @from is
286 * always decremented if it is not %NULL.
287 */
288struct pci_dev *
289pci_get_device(unsigned int vendor, unsigned int device, struct pci_dev *from)
290{
291    return pci_get_subsys(vendor, device, PCI_ANY_ID, PCI_ANY_ID, from);
292}
293
294/**
295 * pci_get_class - begin or continue searching for a PCI device by class
296 * @class: search for a PCI device with this class designation
297 * @from: Previous PCI device found in search, or %NULL for new search.
298 *
299 * Iterates through the list of known PCI devices. If a PCI device is
300 * found with a matching @class, the reference count to the device is
301 * incremented and a pointer to its device structure is returned.
302 * Otherwise, %NULL is returned.
303 * A new search is initiated by passing %NULL as the @from argument.
304 * Otherwise if @from is not %NULL, searches continue from next device
305 * on the global list. The reference count for @from is always decremented
306 * if it is not %NULL.
307 */
308struct pci_dev *pci_get_class(unsigned int class, struct pci_dev *from)
309{
310    struct pci_dev *dev;
311    struct pci_device_id *id;
312
313    id = kzalloc(sizeof(*id), GFP_KERNEL);
314    if (!id)
315        return NULL;
316    id->vendor = id->device = id->subvendor = id->subdevice = PCI_ANY_ID;
317    id->class_mask = PCI_ANY_ID;
318    id->class = class;
319
320    dev = pci_get_dev_by_id(id, from);
321    kfree(id);
322    return dev;
323}
324
325/**
326 * pci_dev_present - Returns 1 if device matching the device list is present, 0 if not.
327 * @ids: A pointer to a null terminated list of struct pci_device_id structures
328 * that describe the type of PCI device the caller is trying to find.
329 *
330 * Obvious fact: You do not have a reference to any device that might be found
331 * by this function, so if that device is removed from the system right after
332 * this function is finished, the value will be stale. Use this function to
333 * find devices that are usually built into a system, or for a general hint as
334 * to if another device happens to be present at this specific moment in time.
335 */
336int pci_dev_present(const struct pci_device_id *ids)
337{
338    struct pci_dev *found = NULL;
339
340    WARN_ON(in_interrupt());
341    while (ids->vendor || ids->subvendor || ids->class_mask) {
342        found = pci_get_dev_by_id(ids, NULL);
343        if (found)
344            goto exit;
345        ids++;
346    }
347exit:
348    if (found)
349        return 1;
350    return 0;
351}
352EXPORT_SYMBOL(pci_dev_present);
353
354/* For boot time work */
355EXPORT_SYMBOL(pci_find_bus);
356EXPORT_SYMBOL(pci_find_next_bus);
357/* For everyone */
358EXPORT_SYMBOL(pci_get_device);
359EXPORT_SYMBOL(pci_get_subsys);
360EXPORT_SYMBOL(pci_get_slot);
361EXPORT_SYMBOL(pci_get_class);
362

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