[linux-2.6-block.git] / drivers / pci / bus.c

/*
 *	drivers/pci/bus.c
 *
 * From setup-res.c, by:
 *	Dave Rusling (david.rusling@reo.mts.dec.com)
 *	David Mosberger (davidm@cs.arizona.edu)
 *	David Miller (davem@redhat.com)
 *	Ivan Kokshaysky (ink@jurassic.park.msu.ru)
 */
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/pci.h>
#include <linux/errno.h>
#include <linux/ioport.h>
#include <linux/proc_fs.h>
#include <linux/slab.h>

#include "pci.h"

void pci_add_resource_offset(struct list_head *resources, struct resource *res,
			     resource_size_t offset)
{
	struct resource_entry *entry;

	entry = resource_list_create_entry(res, 0);
	if (!entry) {
		printk(KERN_ERR "PCI: can't add host bridge window %pR\n", res);
		return;
	}

	entry->offset = offset;
	resource_list_add_tail(entry, resources);
}
EXPORT_SYMBOL(pci_add_resource_offset);

void pci_add_resource(struct list_head *resources, struct resource *res)
{
	pci_add_resource_offset(resources, res, 0);
}
EXPORT_SYMBOL(pci_add_resource);

void pci_free_resource_list(struct list_head *resources)
{
	resource_list_free(resources);
}
EXPORT_SYMBOL(pci_free_resource_list);

void pci_bus_add_resource(struct pci_bus *bus, struct resource *res,
			  unsigned int flags)
{
	struct pci_bus_resource *bus_res;

	bus_res = kzalloc(sizeof(struct pci_bus_resource), GFP_KERNEL);
	if (!bus_res) {
		dev_err(&bus->dev, "can't add %pR resource\n", res);
		return;
	}

	bus_res->res = res;
	bus_res->flags = flags;
	list_add_tail(&bus_res->list, &bus->resources);
}

struct resource *pci_bus_resource_n(const struct pci_bus *bus, int n)
{
	struct pci_bus_resource *bus_res;

	if (n < PCI_BRIDGE_RESOURCE_NUM)
		return bus->resource[n];

	n -= PCI_BRIDGE_RESOURCE_NUM;
	list_for_each_entry(bus_res, &bus->resources, list) {
		if (n-- == 0)
			return bus_res->res;
	}
	return NULL;
}
EXPORT_SYMBOL_GPL(pci_bus_resource_n);

void pci_bus_remove_resources(struct pci_bus *bus)
{
	int i;
	struct pci_bus_resource *bus_res, *tmp;

	for (i = 0; i < PCI_BRIDGE_RESOURCE_NUM; i++)
		bus->resource[i] = NULL;

	list_for_each_entry_safe(bus_res, tmp, &bus->resources, list) {
		list_del(&bus_res->list);
		kfree(bus_res);
	}
}

static struct pci_bus_region pci_32_bit = {0, 0xffffffffULL};
#ifdef CONFIG_PCI_BUS_ADDR_T_64BIT
static struct pci_bus_region pci_64_bit = {0,
				(pci_bus_addr_t) 0xffffffffffffffffULL};
static struct pci_bus_region pci_high = {(pci_bus_addr_t) 0x100000000ULL,
				(pci_bus_addr_t) 0xffffffffffffffffULL};
#endif

/*
 * @res contains CPU addresses.  Clip it so the corresponding bus addresses
 * on @bus are entirely within @region.  This is used to control the bus
 * addresses of resources we allocate, e.g., we may need a resource that
 * can be mapped by a 32-bit BAR.
 */
static void pci_clip_resource_to_region(struct pci_bus *bus,
					struct resource *res,
					struct pci_bus_region *region)
{
	struct pci_bus_region r;

	pcibios_resource_to_bus(bus, &r, res);
	if (r.start < region->start)
		r.start = region->start;
	if (r.end > region->end)
		r.end = region->end;

	if (r.end < r.start)
		res->end = res->start - 1;
	else
		pcibios_bus_to_resource(bus, res, &r);
}

static int pci_bus_alloc_from_region(struct pci_bus *bus, struct resource *res,
		resource_size_t size, resource_size_t align,
		resource_size_t min, unsigned long type_mask,
		resource_size_t (*alignf)(void *,
					  const struct resource *,
					  resource_size_t,
					  resource_size_t),
		void *alignf_data,
		struct pci_bus_region *region)
{
	int i, ret;
	struct resource *r, avail;
	resource_size_t max;

	type_mask |= IORESOURCE_TYPE_BITS;

	pci_bus_for_each_resource(bus, r, i) {
		if (!r)
			continue;

		/* type_mask must match */
		if ((res->flags ^ r->flags) & type_mask)
			continue;

		/* We cannot allocate a non-prefetching resource
		   from a pre-fetching area */
		if ((r->flags & IORESOURCE_PREFETCH) &&
		    !(res->flags & IORESOURCE_PREFETCH))
			continue;

		avail = *r;
		pci_clip_resource_to_region(bus, &avail, region);

		/*
		 * "min" is typically PCIBIOS_MIN_IO or PCIBIOS_MIN_MEM to
		 * protect badly documented motherboard resources, but if
		 * this is an already-configured bridge window, its start
		 * overrides "min".
		 */
		if (avail.start)
			min = avail.start;

		max = avail.end;

		/* Ok, try it out.. */
		ret = allocate_resource(r, res, size, min, max,
					align, alignf, alignf_data);
		if (ret == 0)
			return 0;
	}
	return -ENOMEM;
}

/**
 * pci_bus_alloc_resource - allocate a resource from a parent bus
 * @bus: PCI bus
 * @res: resource to allocate
 * @size: size of resource to allocate
 * @align: alignment of resource to allocate
 * @min: minimum /proc/iomem address to allocate
 * @type_mask: IORESOURCE_* type flags
 * @alignf: resource alignment function
 * @alignf_data: data argument for resource alignment function
 *
 * Given the PCI bus a device resides on, the size, minimum address,
 * alignment and type, try to find an acceptable resource allocation
 * for a specific device resource.
 */
int pci_bus_alloc_resource(struct pci_bus *bus, struct resource *res,
		resource_size_t size, resource_size_t align,
		resource_size_t min, unsigned long type_mask,
		resource_size_t (*alignf)(void *,
					  const struct resource *,
					  resource_size_t,
					  resource_size_t),
		void *alignf_data)
{
#ifdef CONFIG_PCI_BUS_ADDR_T_64BIT
	int rc;

	if (res->flags & IORESOURCE_MEM_64) {
		rc = pci_bus_alloc_from_region(bus, res, size, align, min,
					       type_mask, alignf, alignf_data,
					       &pci_high);
		if (rc == 0)
			return 0;

		return pci_bus_alloc_from_region(bus, res, size, align, min,
						 type_mask, alignf, alignf_data,
						 &pci_64_bit);
	}
#endif

	return pci_bus_alloc_from_region(bus, res, size, align, min,
					 type_mask, alignf, alignf_data,
					 &pci_32_bit);
}
EXPORT_SYMBOL(pci_bus_alloc_resource);

/*
 * The @idx resource of @dev should be a PCI-PCI bridge window.  If this
 * resource fits inside a window of an upstream bridge, do nothing.  If it
 * overlaps an upstream window but extends outside it, clip the resource so
 * it fits completely inside.
 */
bool pci_bus_clip_resource(struct pci_dev *dev, int idx)
{
	struct pci_bus *bus = dev->bus;
	struct resource *res = &dev->resource[idx];
	struct resource orig_res = *res;
	struct resource *r;
	int i;

	pci_bus_for_each_resource(bus, r, i) {
		resource_size_t start, end;

		if (!r)
			continue;

		if (resource_type(res) != resource_type(r))
			continue;

		start = max(r->start, res->start);
		end = min(r->end, res->end);

		if (start > end)
			continue;	/* no overlap */

		if (res->start == start && res->end == end)
			return false;	/* no change */

		res->start = start;
		res->end = end;
		res->flags &= ~IORESOURCE_UNSET;
		orig_res.flags &= ~IORESOURCE_UNSET;
		dev_printk(KERN_DEBUG, &dev->dev, "%pR clipped to %pR\n",
				 &orig_res, res);

		return true;
	}

	return false;
}

void __weak pcibios_resource_survey_bus(struct pci_bus *bus) { }

/**
 * pci_bus_add_device - start driver for a single device
 * @dev: device to add
 *
 * This adds add sysfs entries and start device drivers
 */
void pci_bus_add_device(struct pci_dev *dev)
{
	int retval;

	/*
	 * Can not put in pci_device_add yet because resources
	 * are not assigned yet for some devices.
	 */
	pci_fixup_device(pci_fixup_final, dev);
	pci_create_sysfs_dev_files(dev);
	pci_proc_attach_device(dev);

	dev->match_driver = true;
	retval = device_attach(&dev->dev);
	WARN_ON(retval < 0);

	dev->is_added = 1;
}
EXPORT_SYMBOL_GPL(pci_bus_add_device);

/**
 * pci_bus_add_devices - start driver for PCI devices
 * @bus: bus to check for new devices
 *
 * Start driver for PCI devices and add some sysfs entries.
 */
void pci_bus_add_devices(const struct pci_bus *bus)
{
	struct pci_dev *dev;
	struct pci_bus *child;

	list_for_each_entry(dev, &bus->devices, bus_list) {
		/* Skip already-added devices */
		if (dev->is_added)
			continue;
		pci_bus_add_device(dev);
	}

	list_for_each_entry(dev, &bus->devices, bus_list) {
		BUG_ON(!dev->is_added);
		child = dev->subordinate;
		if (child)
			pci_bus_add_devices(child);
	}
}
EXPORT_SYMBOL(pci_bus_add_devices);

/** pci_walk_bus - walk devices on/under bus, calling callback.
 *  @top      bus whose devices should be walked
 *  @cb       callback to be called for each device found
 *  @userdata arbitrary pointer to be passed to callback.
 *
 *  Walk the given bus, including any bridged devices
 *  on buses under this bus.  Call the provided callback
 *  on each device found.
 *
 *  We check the return of @cb each time. If it returns anything
 *  other than 0, we break out.
 *
 */
void pci_walk_bus(struct pci_bus *top, int (*cb)(struct pci_dev *, void *),
		  void *userdata)
{
	struct pci_dev *dev;
	struct pci_bus *bus;
	struct list_head *next;
	int retval;

	bus = top;
	down_read(&pci_bus_sem);
	next = top->devices.next;
	for (;;) {
		if (next == &bus->devices) {
			/* end of this bus, go up or finish */
			if (bus == top)
				break;
			next = bus->self->bus_list.next;
			bus = bus->self->bus;
			continue;
		}
		dev = list_entry(next, struct pci_dev, bus_list);
		if (dev->subordinate) {
			/* this is a pci-pci bridge, do its devices next */
			next = dev->subordinate->devices.next;
			bus = dev->subordinate;
		} else
			next = dev->bus_list.next;

		retval = cb(dev, userdata);
		if (retval)
			break;
	}
	up_read(&pci_bus_sem);
}
EXPORT_SYMBOL_GPL(pci_walk_bus);

struct pci_bus *pci_bus_get(struct pci_bus *bus)
{
	if (bus)
		get_device(&bus->dev);
	return bus;
}
EXPORT_SYMBOL(pci_bus_get);

void pci_bus_put(struct pci_bus *bus)
{
	if (bus)
		put_device(&bus->dev);
}
EXPORT_SYMBOL(pci_bus_put);
Commit	Line	Data
1da177e4 LT	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>
5a0e3ad6	16	#include <linux/slab.h>
1da177e4 LT	17
	18	#include "pci.h"
	19
0efd5aab BH	20	void pci_add_resource_offset(struct list_head resources, struct resource res,
0efd5aab BH	21	resource_size_t offset)
45ca9e97	22	{
14d76b68	23	struct resource_entry *entry;
45ca9e97	24
14d76b68 JL	25	entry = resource_list_create_entry(res, 0);
14d76b68 JL	26	if (!entry) {
0efd5aab	27	printk(KERN_ERR "PCI: can't add host bridge window %pR\n", res);
45ca9e97 BH	28	return;
	29	}
	30
14d76b68 JL	31	entry->offset = offset;
14d76b68 JL	32	resource_list_add_tail(entry, resources);
0efd5aab BH	33	}
	34	EXPORT_SYMBOL(pci_add_resource_offset);
	35
	36	void pci_add_resource(struct list_head resources, struct resource res)
	37	{
	38	pci_add_resource_offset(resources, res, 0);
45ca9e97 BH	39	}
	40	EXPORT_SYMBOL(pci_add_resource);
	41
	42	void pci_free_resource_list(struct list_head *resources)
	43	{
14d76b68	44	resource_list_free(resources);
45ca9e97 BH	45	}
	46	EXPORT_SYMBOL(pci_free_resource_list);
	47
2fe2abf8 BH	48	void 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
	64	struct 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	}
	78	EXPORT_SYMBOL_GPL(pci_bus_resource_n);
	79
	80	void pci_bus_remove_resources(struct pci_bus *bus)
	81	{
2fe2abf8	82	int i;
817a2685	83	struct pci_bus_resource bus_res, tmp;
2fe2abf8 BH	84
2fe2abf8 BH	85	for (i = 0; i < PCI_BRIDGE_RESOURCE_NUM; i++)
7736a05a	86	bus->resource[i] = NULL;
2fe2abf8	87
817a2685 YL	88	list_for_each_entry_safe(bus_res, tmp, &bus->resources, list) {
	89	list_del(&bus_res->list);
	90	kfree(bus_res);
	91	}
2fe2abf8 BH	92	}
2fe2abf8 BH	93
f75b99d5	94	static struct pci_bus_region pci_32_bit = {0, 0xffffffffULL};
3a9ad0b4	95	#ifdef CONFIG_PCI_BUS_ADDR_T_64BIT
f75b99d5	96	static struct pci_bus_region pci_64_bit = {0,
3a9ad0b4 YL	97	(pci_bus_addr_t) 0xffffffffffffffffULL};
	98	static struct pci_bus_region pci_high = {(pci_bus_addr_t) 0x100000000ULL,
	99	(pci_bus_addr_t) 0xffffffffffffffffULL};
f75b99d5 YL	100	#endif
	101
	102	/*
	103	* @res contains CPU addresses. Clip it so the corresponding bus addresses
	104	* on @bus are entirely within @region. This is used to control the bus
	105	* addresses of resources we allocate, e.g., we may need a resource that
	106	* can be mapped by a 32-bit BAR.
1da177e4	107	*/
f75b99d5 YL	108	static void pci_clip_resource_to_region(struct pci_bus *bus,
	109	struct resource *res,
	110	struct pci_bus_region *region)
	111	{
	112	struct pci_bus_region r;
	113
	114	pcibios_resource_to_bus(bus, &r, res);
	115	if (r.start < region->start)
	116	r.start = region->start;
	117	if (r.end > region->end)
	118	r.end = region->end;
	119
	120	if (r.end < r.start)
	121	res->end = res->start - 1;
	122	else
	123	pcibios_bus_to_resource(bus, res, &r);
	124	}
	125
	126	static int pci_bus_alloc_from_region(struct pci_bus bus, struct resource res,
e31dd6e4	127	resource_size_t size, resource_size_t align,
664c2848	128	resource_size_t min, unsigned long type_mask,
b26b2d49	129	resource_size_t (alignf)(void ,
3b7a17fc	130	const struct resource *,
b26b2d49 DB	131	resource_size_t,
b26b2d49 DB	132	resource_size_t),
f75b99d5 YL	133	void *alignf_data,
f75b99d5 YL	134	struct pci_bus_region *region)
1da177e4	135	{
f75b99d5 YL	136	int i, ret;
	137	struct resource *r, avail;
	138	resource_size_t max;
1da177e4	139
aa11fc58	140	type_mask \|= IORESOURCE_TYPE_BITS;
1da177e4	141
6db45b76 BH	142	pci_bus_for_each_resource(bus, r, i) {
	143	if (!r)
	144	continue;
	145
1da177e4 LT	146	/* type_mask must match */
	147	if ((res->flags ^ r->flags) & type_mask)
	148	continue;
	149
	150	/* We cannot allocate a non-prefetching resource
	151	from a pre-fetching area */
	152	if ((r->flags & IORESOURCE_PREFETCH) &&
	153	!(res->flags & IORESOURCE_PREFETCH))
	154	continue;
	155
f75b99d5 YL	156	avail = *r;
f75b99d5 YL	157	pci_clip_resource_to_region(bus, &avail, region);
f75b99d5	158
36e097a8 BH	159	/*
	160	* "min" is typically PCIBIOS_MIN_IO or PCIBIOS_MIN_MEM to
	161	* protect badly documented motherboard resources, but if
	162	* this is an already-configured bridge window, its start
	163	* overrides "min".
	164	*/
f75b99d5 YL	165	if (avail.start)
	166	min = avail.start;
	167
	168	max = avail.end;
36e097a8	169
1da177e4	170	/* Ok, try it out.. */
36e097a8 BH	171	ret = allocate_resource(r, res, size, min, max,
36e097a8 BH	172	align, alignf, alignf_data);
1da177e4	173	if (ret == 0)
f75b99d5	174	return 0;
1da177e4	175	}
f75b99d5 YL	176	return -ENOMEM;
	177	}
	178
	179	/**
	180	* pci_bus_alloc_resource - allocate a resource from a parent bus
	181	* @bus: PCI bus
	182	* @res: resource to allocate
	183	* @size: size of resource to allocate
	184	* @align: alignment of resource to allocate
	185	* @min: minimum /proc/iomem address to allocate
	186	* @type_mask: IORESOURCE_* type flags
	187	* @alignf: resource alignment function
	188	* @alignf_data: data argument for resource alignment function
	189	*
	190	* Given the PCI bus a device resides on, the size, minimum address,
	191	* alignment and type, try to find an acceptable resource allocation
	192	* for a specific device resource.
	193	*/
d56dbf5b	194	int pci_bus_alloc_resource(struct pci_bus bus, struct resource res,
f75b99d5	195	resource_size_t size, resource_size_t align,
664c2848	196	resource_size_t min, unsigned long type_mask,
f75b99d5 YL	197	resource_size_t (alignf)(void ,
	198	const struct resource *,
	199	resource_size_t,
	200	resource_size_t),
	201	void *alignf_data)
	202	{
3a9ad0b4	203	#ifdef CONFIG_PCI_BUS_ADDR_T_64BIT
d56dbf5b YL	204	int rc;
	205
	206	if (res->flags & IORESOURCE_MEM_64) {
	207	rc = pci_bus_alloc_from_region(bus, res, size, align, min,
	208	type_mask, alignf, alignf_data,
	209	&pci_high);
	210	if (rc == 0)
	211	return 0;
	212
f75b99d5 YL	213	return pci_bus_alloc_from_region(bus, res, size, align, min,
	214	type_mask, alignf, alignf_data,
	215	&pci_64_bit);
1da177e4	216	}
f75b99d5 YL	217	#endif
	218
	219	return pci_bus_alloc_from_region(bus, res, size, align, min,
	220	type_mask, alignf, alignf_data,
	221	&pci_32_bit);
1da177e4	222	}
b7fe9434	223	EXPORT_SYMBOL(pci_bus_alloc_resource);
1da177e4	224
0f7e7aee YL	225	/*
	226	* The @idx resource of @dev should be a PCI-PCI bridge window. If this
	227	* resource fits inside a window of an upstream bridge, do nothing. If it
	228	* overlaps an upstream window but extends outside it, clip the resource so
	229	* it fits completely inside.
	230	*/
	231	bool pci_bus_clip_resource(struct pci_dev *dev, int idx)
	232	{
	233	struct pci_bus *bus = dev->bus;
	234	struct resource *res = &dev->resource[idx];
	235	struct resource orig_res = *res;
	236	struct resource *r;
	237	int i;
	238
	239	pci_bus_for_each_resource(bus, r, i) {
	240	resource_size_t start, end;
	241
	242	if (!r)
	243	continue;
	244
	245	if (resource_type(res) != resource_type(r))
	246	continue;
	247
	248	start = max(r->start, res->start);
	249	end = min(r->end, res->end);
	250
	251	if (start > end)
	252	continue; /* no overlap */
	253
	254	if (res->start == start && res->end == end)
	255	return false; /* no change */
	256
	257	res->start = start;
	258	res->end = end;
b838b39e BH	259	res->flags &= ~IORESOURCE_UNSET;
b838b39e BH	260	orig_res.flags &= ~IORESOURCE_UNSET;
0f7e7aee YL	261	dev_printk(KERN_DEBUG, &dev->dev, "%pR clipped to %pR\n",
	262	&orig_res, res);
	263
	264	return true;
	265	}
	266
	267	return false;
	268	}
	269
3c449ed0 YL	270	void __weak pcibios_resource_survey_bus(struct pci_bus *bus) { }
3c449ed0 YL	271
1da177e4	272	/**
4f535093	273	* pci_bus_add_device - start driver for a single device
1da177e4 LT	274	* @dev: device to add
1da177e4 LT	275	*
4f535093	276	* This adds add sysfs entries and start device drivers
1da177e4	277	*/
c893d133	278	void pci_bus_add_device(struct pci_dev *dev)
1da177e4	279	{
b19441af	280	int retval;
735bff10	281
4f535093 YL	282	/*
	283	* Can not put in pci_device_add yet because resources
	284	* are not assigned yet for some devices.
	285	*/
e253aaf0	286	pci_fixup_device(pci_fixup_final, dev);
4f535093	287	pci_create_sysfs_dev_files(dev);
ef37702e	288	pci_proc_attach_device(dev);
1da177e4	289
58d9a38f YL	290	dev->match_driver = true;
	291	retval = device_attach(&dev->dev);
	292	WARN_ON(retval < 0);
	293
8a1bc901	294	dev->is_added = 1;
876e501a	295	}
b7fe9434	296	EXPORT_SYMBOL_GPL(pci_bus_add_device);
876e501a	297
1da177e4	298	/**
4f535093	299	* pci_bus_add_devices - start driver for PCI devices
1da177e4 LT	300	* @bus: bus to check for new devices
1da177e4 LT	301	*
4f535093	302	* Start driver for PCI devices and add some sysfs entries.
1da177e4	303	*/
c48f1670	304	void pci_bus_add_devices(const struct pci_bus *bus)
1da177e4 LT	305	{
1da177e4 LT	306	struct pci_dev *dev;
3fa16fdb	307	struct pci_bus *child;
1da177e4 LT	308
1da177e4 LT	309	list_for_each_entry(dev, &bus->devices, bus_list) {
8a1bc901 GKH	310	/* Skip already-added devices */
8a1bc901 GKH	311	if (dev->is_added)
1da177e4	312	continue;
c893d133	313	pci_bus_add_device(dev);
1da177e4 LT	314	}
	315
	316	list_for_each_entry(dev, &bus->devices, bus_list) {
8a1bc901	317	BUG_ON(!dev->is_added);
3fa16fdb	318	child = dev->subordinate;
981cf9ea JL	319	if (child)
981cf9ea JL	320	pci_bus_add_devices(child);
1da177e4 LT	321	}
1da177e4 LT	322	}
b7fe9434	323	EXPORT_SYMBOL(pci_bus_add_devices);
1da177e4	324
cecf4864 PM	325	/** pci_walk_bus - walk devices on/under bus, calling callback.
	326	* @top bus whose devices should be walked
	327	* @cb callback to be called for each device found
	328	* @userdata arbitrary pointer to be passed to callback.
	329	*
	330	* Walk the given bus, including any bridged devices
	331	* on buses under this bus. Call the provided callback
	332	* on each device found.
70298c6e ZY	333	*
	334	* We check the return of @cb each time. If it returns anything
	335	* other than 0, we break out.
	336	*
cecf4864	337	*/
70298c6e	338	void pci_walk_bus(struct pci_bus top, int (cb)(struct pci_dev , void ),
cecf4864 PM	339	void *userdata)
	340	{
	341	struct pci_dev *dev;
	342	struct pci_bus *bus;
	343	struct list_head *next;
70298c6e	344	int retval;
cecf4864 PM	345
cecf4864 PM	346	bus = top;
d71374da	347	down_read(&pci_bus_sem);
cecf4864 PM	348	next = top->devices.next;
	349	for (;;) {
	350	if (next == &bus->devices) {
	351	/* end of this bus, go up or finish */
	352	if (bus == top)
	353	break;
	354	next = bus->self->bus_list.next;
	355	bus = bus->self->bus;
	356	continue;
	357	}
	358	dev = list_entry(next, struct pci_dev, bus_list);
cecf4864 PM	359	if (dev->subordinate) {
	360	/* this is a pci-pci bridge, do its devices next */
	361	next = dev->subordinate->devices.next;
	362	bus = dev->subordinate;
	363	} else
	364	next = dev->bus_list.next;
cecf4864	365
70298c6e	366	retval = cb(dev, userdata);
70298c6e ZY	367	if (retval)
70298c6e ZY	368	break;
cecf4864	369	}
d71374da	370	up_read(&pci_bus_sem);
cecf4864	371	}
7c94def8	372	EXPORT_SYMBOL_GPL(pci_walk_bus);
cecf4864	373
fe830ef6 JL	374	struct pci_bus pci_bus_get(struct pci_bus bus)
	375	{
	376	if (bus)
	377	get_device(&bus->dev);
	378	return bus;
	379	}
	380	EXPORT_SYMBOL(pci_bus_get);
	381
	382	void pci_bus_put(struct pci_bus *bus)
	383	{
	384	if (bus)
	385	put_device(&bus->dev);
	386	}
	387	EXPORT_SYMBOL(pci_bus_put);
	388