Linux Audio

Check our new training course

Loading...
v3.5.6
  1/*
  2 *	drivers/pci/bus.c
  3 *
  4 * From setup-res.c, by:
  5 *	Dave Rusling (david.rusling@reo.mts.dec.com)
  6 *	David Mosberger (davidm@cs.arizona.edu)
  7 *	David Miller (davem@redhat.com)
  8 *	Ivan Kokshaysky (ink@jurassic.park.msu.ru)
  9 */
 10#include <linux/module.h>
 11#include <linux/kernel.h>
 12#include <linux/pci.h>
 13#include <linux/errno.h>
 14#include <linux/ioport.h>
 15#include <linux/proc_fs.h>
 16#include <linux/init.h>
 17#include <linux/slab.h>
 18
 19#include "pci.h"
 20
 21void pci_add_resource_offset(struct list_head *resources, struct resource *res,
 22			     resource_size_t offset)
 23{
 24	struct pci_host_bridge_window *window;
 25
 26	window = kzalloc(sizeof(struct pci_host_bridge_window), GFP_KERNEL);
 27	if (!window) {
 28		printk(KERN_ERR "PCI: can't add host bridge window %pR\n", res);
 29		return;
 30	}
 31
 32	window->res = res;
 33	window->offset = offset;
 34	list_add_tail(&window->list, resources);
 35}
 36EXPORT_SYMBOL(pci_add_resource_offset);
 37
 38void pci_add_resource(struct list_head *resources, struct resource *res)
 39{
 40	pci_add_resource_offset(resources, res, 0);
 41}
 42EXPORT_SYMBOL(pci_add_resource);
 43
 44void pci_free_resource_list(struct list_head *resources)
 45{
 46	struct pci_host_bridge_window *window, *tmp;
 47
 48	list_for_each_entry_safe(window, tmp, resources, list) {
 49		list_del(&window->list);
 50		kfree(window);
 51	}
 52}
 53EXPORT_SYMBOL(pci_free_resource_list);
 54
 55void pci_bus_add_resource(struct pci_bus *bus, struct resource *res,
 56			  unsigned int flags)
 57{
 58	struct pci_bus_resource *bus_res;
 59
 60	bus_res = kzalloc(sizeof(struct pci_bus_resource), GFP_KERNEL);
 61	if (!bus_res) {
 62		dev_err(&bus->dev, "can't add %pR resource\n", res);
 63		return;
 64	}
 65
 66	bus_res->res = res;
 67	bus_res->flags = flags;
 68	list_add_tail(&bus_res->list, &bus->resources);
 69}
 70
 71struct resource *pci_bus_resource_n(const struct pci_bus *bus, int n)
 72{
 73	struct pci_bus_resource *bus_res;
 74
 75	if (n < PCI_BRIDGE_RESOURCE_NUM)
 76		return bus->resource[n];
 77
 78	n -= PCI_BRIDGE_RESOURCE_NUM;
 79	list_for_each_entry(bus_res, &bus->resources, list) {
 80		if (n-- == 0)
 81			return bus_res->res;
 82	}
 83	return NULL;
 84}
 85EXPORT_SYMBOL_GPL(pci_bus_resource_n);
 86
 87void pci_bus_remove_resources(struct pci_bus *bus)
 88{
 89	int i;
 
 90
 91	for (i = 0; i < PCI_BRIDGE_RESOURCE_NUM; i++)
 92		bus->resource[i] = NULL;
 93
 94	pci_free_resource_list(&bus->resources);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 95}
 96
 97/**
 98 * pci_bus_alloc_resource - allocate a resource from a parent bus
 99 * @bus: PCI bus
100 * @res: resource to allocate
101 * @size: size of resource to allocate
102 * @align: alignment of resource to allocate
103 * @min: minimum /proc/iomem address to allocate
104 * @type_mask: IORESOURCE_* type flags
105 * @alignf: resource alignment function
106 * @alignf_data: data argument for resource alignment function
107 *
108 * Given the PCI bus a device resides on, the size, minimum address,
109 * alignment and type, try to find an acceptable resource allocation
110 * for a specific device resource.
111 */
112int
113pci_bus_alloc_resource(struct pci_bus *bus, struct resource *res,
114		resource_size_t size, resource_size_t align,
115		resource_size_t min, unsigned int type_mask,
116		resource_size_t (*alignf)(void *,
117					  const struct resource *,
118					  resource_size_t,
119					  resource_size_t),
120		void *alignf_data)
121{
122	int i, ret = -ENOMEM;
123	struct resource *r;
124	resource_size_t max = -1;
 
 
 
 
 
 
 
 
 
 
 
 
125
126	type_mask |= IORESOURCE_IO | IORESOURCE_MEM;
 
 
 
 
127
128	/* don't allocate too high if the pref mem doesn't support 64bit*/
129	if (!(res->flags & IORESOURCE_MEM_64))
130		max = PCIBIOS_MAX_MEM_32;
 
 
 
 
 
 
 
 
 
 
131
132	pci_bus_for_each_resource(bus, r, i) {
 
 
133		if (!r)
134			continue;
135
136		/* type_mask must match */
137		if ((res->flags ^ r->flags) & type_mask)
138			continue;
139
140		/* We cannot allocate a non-prefetching resource
141		   from a pre-fetching area */
142		if ((r->flags & IORESOURCE_PREFETCH) &&
143		    !(res->flags & IORESOURCE_PREFETCH))
144			continue;
145
146		/* Ok, try it out.. */
147		ret = allocate_resource(r, res, size,
148					r->start ? : min,
149					max, align,
150					alignf, alignf_data);
151		if (ret == 0)
152			break;
 
 
 
 
 
 
 
153	}
154	return ret;
 
155}
156
157/**
158 * pci_bus_add_device - add a single device
159 * @dev: device to add
160 *
161 * This adds a single pci device to the global
162 * device list and adds sysfs and procfs entries
163 */
164int pci_bus_add_device(struct pci_dev *dev)
165{
166	int retval;
167	retval = device_add(&dev->dev);
168	if (retval)
169		return retval;
170
171	dev->is_added = 1;
172	pci_proc_attach_device(dev);
173	pci_create_sysfs_dev_files(dev);
174	return 0;
175}
176
177/**
178 * pci_bus_add_child - add a child bus
179 * @bus: bus to add
180 *
181 * This adds sysfs entries for a single bus
182 */
183int pci_bus_add_child(struct pci_bus *bus)
184{
185	int retval;
186
187	if (bus->bridge)
188		bus->dev.parent = bus->bridge;
189
190	retval = device_register(&bus->dev);
191	if (retval)
192		return retval;
193
194	bus->is_added = 1;
 
195
196	/* Create legacy_io and legacy_mem files for this bus */
197	pci_create_legacy_files(bus);
 
 
 
 
 
 
198
199	return retval;
200}
 
201
202/**
203 * pci_bus_add_devices - insert newly discovered PCI devices
204 * @bus: bus to check for new devices
205 *
206 * Add newly discovered PCI devices (which are on the bus->devices
207 * list) to the global PCI device list, add the sysfs and procfs
208 * entries.  Where a bridge is found, add the discovered bus to
209 * the parents list of child buses, and recurse (breadth-first
210 * to be compatible with 2.4)
211 *
212 * Call hotplug for each new devices.
213 */
214void pci_bus_add_devices(const struct pci_bus *bus)
215{
216	struct pci_dev *dev;
217	struct pci_bus *child;
218	int retval;
219
220	list_for_each_entry(dev, &bus->devices, bus_list) {
221		/* Skip already-added devices */
222		if (dev->is_added)
223			continue;
224		retval = pci_bus_add_device(dev);
225		if (retval)
226			dev_err(&dev->dev, "Error adding device, continuing\n");
227	}
228
229	list_for_each_entry(dev, &bus->devices, bus_list) {
230		BUG_ON(!dev->is_added);
231
232		child = dev->subordinate;
233		/*
234		 * If there is an unattached subordinate bus, attach
235		 * it and then scan for unattached PCI devices.
236		 */
237		if (!child)
238			continue;
239		if (list_empty(&child->node)) {
240			down_write(&pci_bus_sem);
241			list_add_tail(&child->node, &dev->bus->children);
242			up_write(&pci_bus_sem);
243		}
244		pci_bus_add_devices(child);
245
246		/*
247		 * register the bus with sysfs as the parent is now
248		 * properly registered.
249		 */
250		if (child->is_added)
251			continue;
252		retval = pci_bus_add_child(child);
253		if (retval)
254			dev_err(&dev->dev, "Error adding bus, continuing\n");
255	}
256}
257
258void pci_enable_bridges(struct pci_bus *bus)
259{
260	struct pci_dev *dev;
261	int retval;
262
263	list_for_each_entry(dev, &bus->devices, bus_list) {
264		if (dev->subordinate) {
265			if (!pci_is_enabled(dev)) {
266				retval = pci_enable_device(dev);
267				if (retval)
268					dev_err(&dev->dev, "Error enabling bridge (%d), continuing\n", retval);
269				pci_set_master(dev);
270			}
271			pci_enable_bridges(dev->subordinate);
272		}
273	}
274}
 
275
276/** pci_walk_bus - walk devices on/under bus, calling callback.
277 *  @top      bus whose devices should be walked
278 *  @cb       callback to be called for each device found
279 *  @userdata arbitrary pointer to be passed to callback.
280 *
281 *  Walk the given bus, including any bridged devices
282 *  on buses under this bus.  Call the provided callback
283 *  on each device found.
284 *
285 *  We check the return of @cb each time. If it returns anything
286 *  other than 0, we break out.
287 *
288 */
289void pci_walk_bus(struct pci_bus *top, int (*cb)(struct pci_dev *, void *),
290		  void *userdata)
291{
292	struct pci_dev *dev;
293	struct pci_bus *bus;
294	struct list_head *next;
295	int retval;
296
297	bus = top;
298	down_read(&pci_bus_sem);
299	next = top->devices.next;
300	for (;;) {
301		if (next == &bus->devices) {
302			/* end of this bus, go up or finish */
303			if (bus == top)
304				break;
305			next = bus->self->bus_list.next;
306			bus = bus->self->bus;
307			continue;
308		}
309		dev = list_entry(next, struct pci_dev, bus_list);
310		if (dev->subordinate) {
311			/* this is a pci-pci bridge, do its devices next */
312			next = dev->subordinate->devices.next;
313			bus = dev->subordinate;
314		} else
315			next = dev->bus_list.next;
316
317		/* Run device routines with the device locked */
318		device_lock(&dev->dev);
319		retval = cb(dev, userdata);
320		device_unlock(&dev->dev);
321		if (retval)
322			break;
323	}
324	up_read(&pci_bus_sem);
325}
326EXPORT_SYMBOL_GPL(pci_walk_bus);
327
328EXPORT_SYMBOL(pci_bus_alloc_resource);
329EXPORT_SYMBOL_GPL(pci_bus_add_device);
330EXPORT_SYMBOL(pci_bus_add_devices);
331EXPORT_SYMBOL(pci_enable_bridges);
 
 
 
 
 
 
 
 
 
 
v4.10.11
  1/*
  2 *	drivers/pci/bus.c
  3 *
  4 * From setup-res.c, by:
  5 *	Dave Rusling (david.rusling@reo.mts.dec.com)
  6 *	David Mosberger (davidm@cs.arizona.edu)
  7 *	David Miller (davem@redhat.com)
  8 *	Ivan Kokshaysky (ink@jurassic.park.msu.ru)
  9 */
 10#include <linux/module.h>
 11#include <linux/kernel.h>
 12#include <linux/pci.h>
 13#include <linux/errno.h>
 14#include <linux/ioport.h>
 15#include <linux/proc_fs.h>
 
 16#include <linux/slab.h>
 17
 18#include "pci.h"
 19
 20void pci_add_resource_offset(struct list_head *resources, struct resource *res,
 21			     resource_size_t offset)
 22{
 23	struct resource_entry *entry;
 24
 25	entry = resource_list_create_entry(res, 0);
 26	if (!entry) {
 27		printk(KERN_ERR "PCI: can't add host bridge window %pR\n", res);
 28		return;
 29	}
 30
 31	entry->offset = offset;
 32	resource_list_add_tail(entry, resources);
 
 33}
 34EXPORT_SYMBOL(pci_add_resource_offset);
 35
 36void pci_add_resource(struct list_head *resources, struct resource *res)
 37{
 38	pci_add_resource_offset(resources, res, 0);
 39}
 40EXPORT_SYMBOL(pci_add_resource);
 41
 42void pci_free_resource_list(struct list_head *resources)
 43{
 44	resource_list_free(resources);
 
 
 
 
 
 45}
 46EXPORT_SYMBOL(pci_free_resource_list);
 47
 48void pci_bus_add_resource(struct pci_bus *bus, struct resource *res,
 49			  unsigned int flags)
 50{
 51	struct pci_bus_resource *bus_res;
 52
 53	bus_res = kzalloc(sizeof(struct pci_bus_resource), GFP_KERNEL);
 54	if (!bus_res) {
 55		dev_err(&bus->dev, "can't add %pR resource\n", res);
 56		return;
 57	}
 58
 59	bus_res->res = res;
 60	bus_res->flags = flags;
 61	list_add_tail(&bus_res->list, &bus->resources);
 62}
 63
 64struct resource *pci_bus_resource_n(const struct pci_bus *bus, int n)
 65{
 66	struct pci_bus_resource *bus_res;
 67
 68	if (n < PCI_BRIDGE_RESOURCE_NUM)
 69		return bus->resource[n];
 70
 71	n -= PCI_BRIDGE_RESOURCE_NUM;
 72	list_for_each_entry(bus_res, &bus->resources, list) {
 73		if (n-- == 0)
 74			return bus_res->res;
 75	}
 76	return NULL;
 77}
 78EXPORT_SYMBOL_GPL(pci_bus_resource_n);
 79
 80void pci_bus_remove_resources(struct pci_bus *bus)
 81{
 82	int i;
 83	struct pci_bus_resource *bus_res, *tmp;
 84
 85	for (i = 0; i < PCI_BRIDGE_RESOURCE_NUM; i++)
 86		bus->resource[i] = NULL;
 87
 88	list_for_each_entry_safe(bus_res, tmp, &bus->resources, list) {
 89		list_del(&bus_res->list);
 90		kfree(bus_res);
 91	}
 92}
 93
 94int devm_request_pci_bus_resources(struct device *dev,
 95				   struct list_head *resources)
 96{
 97	struct resource_entry *win;
 98	struct resource *parent, *res;
 99	int err;
100
101	resource_list_for_each_entry(win, resources) {
102		res = win->res;
103		switch (resource_type(res)) {
104		case IORESOURCE_IO:
105			parent = &ioport_resource;
106			break;
107		case IORESOURCE_MEM:
108			parent = &iomem_resource;
109			break;
110		default:
111			continue;
112		}
113
114		err = devm_request_resource(dev, parent, res);
115		if (err)
116			return err;
117	}
118
119	return 0;
120}
121EXPORT_SYMBOL_GPL(devm_request_pci_bus_resources);
122
123static struct pci_bus_region pci_32_bit = {0, 0xffffffffULL};
124#ifdef CONFIG_PCI_BUS_ADDR_T_64BIT
125static struct pci_bus_region pci_64_bit = {0,
126				(pci_bus_addr_t) 0xffffffffffffffffULL};
127static struct pci_bus_region pci_high = {(pci_bus_addr_t) 0x100000000ULL,
128				(pci_bus_addr_t) 0xffffffffffffffffULL};
129#endif
130
131/*
132 * @res contains CPU addresses.  Clip it so the corresponding bus addresses
133 * on @bus are entirely within @region.  This is used to control the bus
134 * addresses of resources we allocate, e.g., we may need a resource that
135 * can be mapped by a 32-bit BAR.
136 */
137static void pci_clip_resource_to_region(struct pci_bus *bus,
138					struct resource *res,
139					struct pci_bus_region *region)
140{
141	struct pci_bus_region r;
142
143	pcibios_resource_to_bus(bus, &r, res);
144	if (r.start < region->start)
145		r.start = region->start;
146	if (r.end > region->end)
147		r.end = region->end;
148
149	if (r.end < r.start)
150		res->end = res->start - 1;
151	else
152		pcibios_bus_to_resource(bus, res, &r);
153}
154
155static int pci_bus_alloc_from_region(struct pci_bus *bus, struct resource *res,
156		resource_size_t size, resource_size_t align,
157		resource_size_t min, unsigned long type_mask,
158		resource_size_t (*alignf)(void *,
159					  const struct resource *,
160					  resource_size_t,
161					  resource_size_t),
162		void *alignf_data,
163		struct pci_bus_region *region)
164{
165	int i, ret;
166	struct resource *r, avail;
167	resource_size_t max;
168
169	type_mask |= IORESOURCE_TYPE_BITS;
170
171	pci_bus_for_each_resource(bus, r, i) {
172		resource_size_t min_used = min;
173
174		if (!r)
175			continue;
176
177		/* type_mask must match */
178		if ((res->flags ^ r->flags) & type_mask)
179			continue;
180
181		/* We cannot allocate a non-prefetching resource
182		   from a pre-fetching area */
183		if ((r->flags & IORESOURCE_PREFETCH) &&
184		    !(res->flags & IORESOURCE_PREFETCH))
185			continue;
186
187		avail = *r;
188		pci_clip_resource_to_region(bus, &avail, region);
189
190		/*
191		 * "min" is typically PCIBIOS_MIN_IO or PCIBIOS_MIN_MEM to
192		 * protect badly documented motherboard resources, but if
193		 * this is an already-configured bridge window, its start
194		 * overrides "min".
195		 */
196		if (avail.start)
197			min_used = avail.start;
198
199		max = avail.end;
200
201		/* Ok, try it out.. */
202		ret = allocate_resource(r, res, size, min_used, max,
203					align, alignf, alignf_data);
204		if (ret == 0)
205			return 0;
206	}
207	return -ENOMEM;
208}
209
210/**
211 * pci_bus_alloc_resource - allocate a resource from a parent bus
212 * @bus: PCI bus
213 * @res: resource to allocate
214 * @size: size of resource to allocate
215 * @align: alignment of resource to allocate
216 * @min: minimum /proc/iomem address to allocate
217 * @type_mask: IORESOURCE_* type flags
218 * @alignf: resource alignment function
219 * @alignf_data: data argument for resource alignment function
220 *
221 * Given the PCI bus a device resides on, the size, minimum address,
222 * alignment and type, try to find an acceptable resource allocation
223 * for a specific device resource.
224 */
225int pci_bus_alloc_resource(struct pci_bus *bus, struct resource *res,
 
226		resource_size_t size, resource_size_t align,
227		resource_size_t min, unsigned long type_mask,
228		resource_size_t (*alignf)(void *,
229					  const struct resource *,
230					  resource_size_t,
231					  resource_size_t),
232		void *alignf_data)
233{
234#ifdef CONFIG_PCI_BUS_ADDR_T_64BIT
235	int rc;
236
237	if (res->flags & IORESOURCE_MEM_64) {
238		rc = pci_bus_alloc_from_region(bus, res, size, align, min,
239					       type_mask, alignf, alignf_data,
240					       &pci_high);
241		if (rc == 0)
242			return 0;
243
244		return pci_bus_alloc_from_region(bus, res, size, align, min,
245						 type_mask, alignf, alignf_data,
246						 &pci_64_bit);
247	}
248#endif
249
250	return pci_bus_alloc_from_region(bus, res, size, align, min,
251					 type_mask, alignf, alignf_data,
252					 &pci_32_bit);
253}
254EXPORT_SYMBOL(pci_bus_alloc_resource);
255
256/*
257 * The @idx resource of @dev should be a PCI-PCI bridge window.  If this
258 * resource fits inside a window of an upstream bridge, do nothing.  If it
259 * overlaps an upstream window but extends outside it, clip the resource so
260 * it fits completely inside.
261 */
262bool pci_bus_clip_resource(struct pci_dev *dev, int idx)
263{
264	struct pci_bus *bus = dev->bus;
265	struct resource *res = &dev->resource[idx];
266	struct resource orig_res = *res;
267	struct resource *r;
268	int i;
269
270	pci_bus_for_each_resource(bus, r, i) {
271		resource_size_t start, end;
272
273		if (!r)
274			continue;
275
276		if (resource_type(res) != resource_type(r))
 
277			continue;
278
279		start = max(r->start, res->start);
280		end = min(r->end, res->end);
 
 
 
281
282		if (start > end)
283			continue;	/* no overlap */
284
285		if (res->start == start && res->end == end)
286			return false;	/* no change */
287
288		res->start = start;
289		res->end = end;
290		res->flags &= ~IORESOURCE_UNSET;
291		orig_res.flags &= ~IORESOURCE_UNSET;
292		dev_printk(KERN_DEBUG, &dev->dev, "%pR clipped to %pR\n",
293				 &orig_res, res);
294
295		return true;
296	}
297
298	return false;
299}
300
301void __weak pcibios_resource_survey_bus(struct pci_bus *bus) { }
 
 
 
 
 
 
 
 
 
 
 
 
302
303void __weak pcibios_bus_add_device(struct pci_dev *pdev) { }
 
 
 
 
304
305/**
306 * pci_bus_add_device - start driver for a single device
307 * @dev: device to add
308 *
309 * This adds add sysfs entries and start device drivers
310 */
311void pci_bus_add_device(struct pci_dev *dev)
312{
313	int retval;
314
315	/*
316	 * Can not put in pci_device_add yet because resources
317	 * are not assigned yet for some devices.
318	 */
319	pcibios_bus_add_device(dev);
320	pci_fixup_device(pci_fixup_final, dev);
321	pci_create_sysfs_dev_files(dev);
322	pci_proc_attach_device(dev);
323	pci_bridge_d3_update(dev);
324
325	dev->match_driver = true;
326	retval = device_attach(&dev->dev);
327	if (retval < 0 && retval != -EPROBE_DEFER) {
328		dev_warn(&dev->dev, "device attach failed (%d)\n", retval);
329		pci_proc_detach_device(dev);
330		pci_remove_sysfs_dev_files(dev);
331		return;
332	}
333
334	dev->is_added = 1;
335}
336EXPORT_SYMBOL_GPL(pci_bus_add_device);
337
338/**
339 * pci_bus_add_devices - start driver for PCI devices
340 * @bus: bus to check for new devices
341 *
342 * Start driver for PCI devices and add some sysfs entries.
 
 
 
 
 
 
343 */
344void pci_bus_add_devices(const struct pci_bus *bus)
345{
346	struct pci_dev *dev;
347	struct pci_bus *child;
 
348
349	list_for_each_entry(dev, &bus->devices, bus_list) {
350		/* Skip already-added devices */
351		if (dev->is_added)
352			continue;
353		pci_bus_add_device(dev);
 
 
354	}
355
356	list_for_each_entry(dev, &bus->devices, bus_list) {
357		/* Skip if device attach failed */
358		if (!dev->is_added)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
359			continue;
360		child = dev->subordinate;
361		if (child)
362			pci_bus_add_devices(child);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
363	}
364}
365EXPORT_SYMBOL(pci_bus_add_devices);
366
367/** pci_walk_bus - walk devices on/under bus, calling callback.
368 *  @top      bus whose devices should be walked
369 *  @cb       callback to be called for each device found
370 *  @userdata arbitrary pointer to be passed to callback.
371 *
372 *  Walk the given bus, including any bridged devices
373 *  on buses under this bus.  Call the provided callback
374 *  on each device found.
375 *
376 *  We check the return of @cb each time. If it returns anything
377 *  other than 0, we break out.
378 *
379 */
380void pci_walk_bus(struct pci_bus *top, int (*cb)(struct pci_dev *, void *),
381		  void *userdata)
382{
383	struct pci_dev *dev;
384	struct pci_bus *bus;
385	struct list_head *next;
386	int retval;
387
388	bus = top;
389	down_read(&pci_bus_sem);
390	next = top->devices.next;
391	for (;;) {
392		if (next == &bus->devices) {
393			/* end of this bus, go up or finish */
394			if (bus == top)
395				break;
396			next = bus->self->bus_list.next;
397			bus = bus->self->bus;
398			continue;
399		}
400		dev = list_entry(next, struct pci_dev, bus_list);
401		if (dev->subordinate) {
402			/* this is a pci-pci bridge, do its devices next */
403			next = dev->subordinate->devices.next;
404			bus = dev->subordinate;
405		} else
406			next = dev->bus_list.next;
407
 
 
408		retval = cb(dev, userdata);
 
409		if (retval)
410			break;
411	}
412	up_read(&pci_bus_sem);
413}
414EXPORT_SYMBOL_GPL(pci_walk_bus);
415
416struct pci_bus *pci_bus_get(struct pci_bus *bus)
417{
418	if (bus)
419		get_device(&bus->dev);
420	return bus;
421}
422EXPORT_SYMBOL(pci_bus_get);
423
424void pci_bus_put(struct pci_bus *bus)
425{
426	if (bus)
427		put_device(&bus->dev);
428}
429EXPORT_SYMBOL(pci_bus_put);