linux/arch/sparc64/kernel/pci.c

812 lines
20 KiB
C
Raw Normal View History

/* $Id: pci.c,v 1.39 2002/01/05 01:13:43 davem Exp $
* pci.c: UltraSparc PCI controller support.
*
* Copyright (C) 1997, 1998, 1999 David S. Miller (davem@redhat.com)
* Copyright (C) 1998, 1999 Eddie C. Dost (ecd@skynet.be)
* Copyright (C) 1999 Jakub Jelinek (jj@ultra.linux.cz)
*/
#include <linux/config.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/sched.h>
#include <linux/capability.h>
#include <linux/errno.h>
#include <linux/smp_lock.h>
#include <linux/init.h>
#include <asm/uaccess.h>
#include <asm/pbm.h>
#include <asm/pgtable.h>
#include <asm/irq.h>
#include <asm/ebus.h>
#include <asm/isa.h>
unsigned long pci_memspace_mask = 0xffffffffUL;
#ifndef CONFIG_PCI
/* A "nop" PCI implementation. */
asmlinkage int sys_pciconfig_read(unsigned long bus, unsigned long dfn,
unsigned long off, unsigned long len,
unsigned char *buf)
{
return 0;
}
asmlinkage int sys_pciconfig_write(unsigned long bus, unsigned long dfn,
unsigned long off, unsigned long len,
unsigned char *buf)
{
return 0;
}
#else
/* List of all PCI controllers found in the system. */
struct pci_controller_info *pci_controller_root = NULL;
/* Each PCI controller found gets a unique index. */
int pci_num_controllers = 0;
/* At boot time the user can give the kernel a command
* line option which controls if and how PCI devices
* are reordered at PCI bus probing time.
*/
int pci_device_reorder = 0;
volatile int pci_poke_in_progress;
volatile int pci_poke_cpu = -1;
volatile int pci_poke_faulted;
static DEFINE_SPINLOCK(pci_poke_lock);
void pci_config_read8(u8 *addr, u8 *ret)
{
unsigned long flags;
u8 byte;
spin_lock_irqsave(&pci_poke_lock, flags);
pci_poke_cpu = smp_processor_id();
pci_poke_in_progress = 1;
pci_poke_faulted = 0;
__asm__ __volatile__("membar #Sync\n\t"
"lduba [%1] %2, %0\n\t"
"membar #Sync"
: "=r" (byte)
: "r" (addr), "i" (ASI_PHYS_BYPASS_EC_E_L)
: "memory");
pci_poke_in_progress = 0;
pci_poke_cpu = -1;
if (!pci_poke_faulted)
*ret = byte;
spin_unlock_irqrestore(&pci_poke_lock, flags);
}
void pci_config_read16(u16 *addr, u16 *ret)
{
unsigned long flags;
u16 word;
spin_lock_irqsave(&pci_poke_lock, flags);
pci_poke_cpu = smp_processor_id();
pci_poke_in_progress = 1;
pci_poke_faulted = 0;
__asm__ __volatile__("membar #Sync\n\t"
"lduha [%1] %2, %0\n\t"
"membar #Sync"
: "=r" (word)
: "r" (addr), "i" (ASI_PHYS_BYPASS_EC_E_L)
: "memory");
pci_poke_in_progress = 0;
pci_poke_cpu = -1;
if (!pci_poke_faulted)
*ret = word;
spin_unlock_irqrestore(&pci_poke_lock, flags);
}
void pci_config_read32(u32 *addr, u32 *ret)
{
unsigned long flags;
u32 dword;
spin_lock_irqsave(&pci_poke_lock, flags);
pci_poke_cpu = smp_processor_id();
pci_poke_in_progress = 1;
pci_poke_faulted = 0;
__asm__ __volatile__("membar #Sync\n\t"
"lduwa [%1] %2, %0\n\t"
"membar #Sync"
: "=r" (dword)
: "r" (addr), "i" (ASI_PHYS_BYPASS_EC_E_L)
: "memory");
pci_poke_in_progress = 0;
pci_poke_cpu = -1;
if (!pci_poke_faulted)
*ret = dword;
spin_unlock_irqrestore(&pci_poke_lock, flags);
}
void pci_config_write8(u8 *addr, u8 val)
{
unsigned long flags;
spin_lock_irqsave(&pci_poke_lock, flags);
pci_poke_cpu = smp_processor_id();
pci_poke_in_progress = 1;
pci_poke_faulted = 0;
__asm__ __volatile__("membar #Sync\n\t"
"stba %0, [%1] %2\n\t"
"membar #Sync"
: /* no outputs */
: "r" (val), "r" (addr), "i" (ASI_PHYS_BYPASS_EC_E_L)
: "memory");
pci_poke_in_progress = 0;
pci_poke_cpu = -1;
spin_unlock_irqrestore(&pci_poke_lock, flags);
}
void pci_config_write16(u16 *addr, u16 val)
{
unsigned long flags;
spin_lock_irqsave(&pci_poke_lock, flags);
pci_poke_cpu = smp_processor_id();
pci_poke_in_progress = 1;
pci_poke_faulted = 0;
__asm__ __volatile__("membar #Sync\n\t"
"stha %0, [%1] %2\n\t"
"membar #Sync"
: /* no outputs */
: "r" (val), "r" (addr), "i" (ASI_PHYS_BYPASS_EC_E_L)
: "memory");
pci_poke_in_progress = 0;
pci_poke_cpu = -1;
spin_unlock_irqrestore(&pci_poke_lock, flags);
}
void pci_config_write32(u32 *addr, u32 val)
{
unsigned long flags;
spin_lock_irqsave(&pci_poke_lock, flags);
pci_poke_cpu = smp_processor_id();
pci_poke_in_progress = 1;
pci_poke_faulted = 0;
__asm__ __volatile__("membar #Sync\n\t"
"stwa %0, [%1] %2\n\t"
"membar #Sync"
: /* no outputs */
: "r" (val), "r" (addr), "i" (ASI_PHYS_BYPASS_EC_E_L)
: "memory");
pci_poke_in_progress = 0;
pci_poke_cpu = -1;
spin_unlock_irqrestore(&pci_poke_lock, flags);
}
/* Probe for all PCI controllers in the system. */
extern void sabre_init(int, char *);
extern void psycho_init(int, char *);
extern void schizo_init(int, char *);
extern void schizo_plus_init(int, char *);
extern void tomatillo_init(int, char *);
static struct {
char *model_name;
void (*init)(int, char *);
} pci_controller_table[] __initdata = {
{ "SUNW,sabre", sabre_init },
{ "pci108e,a000", sabre_init },
{ "pci108e,a001", sabre_init },
{ "SUNW,psycho", psycho_init },
{ "pci108e,8000", psycho_init },
{ "SUNW,schizo", schizo_init },
{ "pci108e,8001", schizo_init },
{ "SUNW,schizo+", schizo_plus_init },
{ "pci108e,8002", schizo_plus_init },
{ "SUNW,tomatillo", tomatillo_init },
{ "pci108e,a801", tomatillo_init },
};
#define PCI_NUM_CONTROLLER_TYPES (sizeof(pci_controller_table) / \
sizeof(pci_controller_table[0]))
static int __init pci_controller_init(char *model_name, int namelen, int node)
{
int i;
for (i = 0; i < PCI_NUM_CONTROLLER_TYPES; i++) {
if (!strncmp(model_name,
pci_controller_table[i].model_name,
namelen)) {
pci_controller_table[i].init(node, model_name);
return 1;
}
}
printk("PCI: Warning unknown controller, model name [%s]\n",
model_name);
printk("PCI: Ignoring controller...\n");
return 0;
}
static int __init pci_is_controller(char *model_name, int namelen, int node)
{
int i;
for (i = 0; i < PCI_NUM_CONTROLLER_TYPES; i++) {
if (!strncmp(model_name,
pci_controller_table[i].model_name,
namelen)) {
return 1;
}
}
return 0;
}
static int __init pci_controller_scan(int (*handler)(char *, int, int))
{
char namebuf[64];
int node;
int count = 0;
node = prom_getchild(prom_root_node);
while ((node = prom_searchsiblings(node, "pci")) != 0) {
int len;
if ((len = prom_getproperty(node, "model", namebuf, sizeof(namebuf))) > 0 ||
(len = prom_getproperty(node, "compatible", namebuf, sizeof(namebuf))) > 0) {
int item_len = 0;
/* Our value may be a multi-valued string in the
* case of some compatible properties. For sanity,
* only try the first one. */
while (namebuf[item_len] && len) {
len--;
item_len++;
}
if (handler(namebuf, item_len, node))
count++;
}
node = prom_getsibling(node);
if (!node)
break;
}
return count;
}
/* Is there some PCI controller in the system? */
int __init pcic_present(void)
{
return pci_controller_scan(pci_is_controller);
}
/* Find each controller in the system, attach and initialize
* software state structure for each and link into the
* pci_controller_root. Setup the controller enough such
* that bus scanning can be done.
*/
static void __init pci_controller_probe(void)
{
printk("PCI: Probing for controllers.\n");
pci_controller_scan(pci_controller_init);
}
static void __init pci_scan_each_controller_bus(void)
{
struct pci_controller_info *p;
for (p = pci_controller_root; p; p = p->next)
p->scan_bus(p);
}
/* Reorder the pci_dev chain, so that onboard devices come first
* and then come the pluggable cards.
*/
static void __init pci_reorder_devs(void)
{
struct list_head *pci_onboard = &pci_devices;
struct list_head *walk = pci_onboard->next;
while (walk != pci_onboard) {
struct pci_dev *pdev = pci_dev_g(walk);
struct list_head *walk_next = walk->next;
if (pdev->irq && (__irq_ino(pdev->irq) & 0x20)) {
list_del(walk);
list_add(walk, pci_onboard);
}
walk = walk_next;
}
}
extern void clock_probe(void);
extern void power_init(void);
static int __init pcibios_init(void)
{
pci_controller_probe();
if (pci_controller_root == NULL)
return 0;
pci_scan_each_controller_bus();
if (pci_device_reorder)
pci_reorder_devs();
isa_init();
ebus_init();
clock_probe();
power_init();
return 0;
}
subsys_initcall(pcibios_init);
void pcibios_fixup_bus(struct pci_bus *pbus)
{
struct pci_pbm_info *pbm = pbus->sysdata;
/* Generic PCI bus probing sets these to point at
* &io{port,mem}_resouce which is wrong for us.
*/
pbus->resource[0] = &pbm->io_space;
pbus->resource[1] = &pbm->mem_space;
}
int pci_claim_resource(struct pci_dev *pdev, int resource)
{
struct pci_pbm_info *pbm = pdev->bus->sysdata;
struct resource *res = &pdev->resource[resource];
struct resource *root;
if (!pbm)
return -EINVAL;
if (res->flags & IORESOURCE_IO)
root = &pbm->io_space;
else
root = &pbm->mem_space;
pbm->parent->resource_adjust(pdev, res, root);
return request_resource(root, res);
}
/*
* Given the PCI bus a device resides on, try to
* find an acceptable resource allocation for a
* specific device resource..
*/
static int pci_assign_bus_resource(const struct pci_bus *bus,
struct pci_dev *dev,
struct resource *res,
unsigned long size,
unsigned long min,
int resno)
{
unsigned int type_mask;
int i;
type_mask = IORESOURCE_IO | IORESOURCE_MEM;
for (i = 0 ; i < 4; i++) {
struct resource *r = bus->resource[i];
if (!r)
continue;
/* type_mask must match */
if ((res->flags ^ r->flags) & type_mask)
continue;
/* Ok, try it out.. */
if (allocate_resource(r, res, size, min, -1, size, NULL, NULL) < 0)
continue;
/* PCI config space updated by caller. */
return 0;
}
return -EBUSY;
}
[PATCH] PCI: restore BAR values after D3hot->D0 for devices that need it Some PCI devices (e.g. 3c905B, 3c556B) lose all configuration (including BARs) when transitioning from D3hot->D0. This leaves such a device in an inaccessible state. The patch below causes the BARs to be restored when enabling such a device, so that its driver will be able to access it. The patch also adds pci_restore_bars as a new global symbol, and adds a correpsonding EXPORT_SYMBOL_GPL for that. Some firmware (e.g. Thinkpad T21) leaves devices in D3hot after a (re)boot. Most drivers call pci_enable_device very early, so devices left in D3hot that lose configuration during the D3hot->D0 transition will be inaccessible to their drivers. Drivers could be modified to account for this, but it would be difficult to know which drivers need modification. This is especially true since often many devices are covered by the same driver. It likely would be necessary to replicate code across dozens of drivers. The patch below should trigger only when transitioning from D3hot->D0 (or at boot), and only for devices that have the "no soft reset" bit cleared in the PM control register. I believe it is safe to include this patch as part of the PCI infrastructure. The cleanest implementation of pci_restore_bars was to call pci_update_resource. Unfortunately, that does not currently exist for the sparc64 architecture. The patch below includes a null implemenation of pci_update_resource for sparc64. Some have expressed interest in making general use of the the pci_restore_bars function, so that has been exported to GPL licensed modules. Signed-off-by: John W. Linville <linville@tuxdriver.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2005-07-27 14:19:44 +00:00
void pci_update_resource(struct pci_dev *dev, struct resource *res, int resno)
{
/* Not implemented for sparc64... */
BUG();
}
int pci_assign_resource(struct pci_dev *pdev, int resource)
{
struct pcidev_cookie *pcp = pdev->sysdata;
struct pci_pbm_info *pbm = pcp->pbm;
struct resource *res = &pdev->resource[resource];
unsigned long min, size;
int err;
if (res->flags & IORESOURCE_IO)
min = pbm->io_space.start + 0x400UL;
else
min = pbm->mem_space.start;
size = res->end - res->start + 1;
err = pci_assign_bus_resource(pdev->bus, pdev, res, size, min, resource);
if (err < 0) {
printk("PCI: Failed to allocate resource %d for %s\n",
resource, pci_name(pdev));
} else {
/* Update PCI config space. */
pbm->parent->base_address_update(pdev, resource);
}
return err;
}
/* Sort resources by alignment */
void pdev_sort_resources(struct pci_dev *dev, struct resource_list *head)
{
int i;
for (i = 0; i < PCI_NUM_RESOURCES; i++) {
struct resource *r;
struct resource_list *list, *tmp;
unsigned long r_align;
r = &dev->resource[i];
r_align = r->end - r->start;
if (!(r->flags) || r->parent)
continue;
if (!r_align) {
printk(KERN_WARNING "PCI: Ignore bogus resource %d "
"[%lx:%lx] of %s\n",
i, r->start, r->end, pci_name(dev));
continue;
}
r_align = (i < PCI_BRIDGE_RESOURCES) ? r_align + 1 : r->start;
for (list = head; ; list = list->next) {
unsigned long align = 0;
struct resource_list *ln = list->next;
int idx;
if (ln) {
idx = ln->res - &ln->dev->resource[0];
align = (idx < PCI_BRIDGE_RESOURCES) ?
ln->res->end - ln->res->start + 1 :
ln->res->start;
}
if (r_align > align) {
tmp = kmalloc(sizeof(*tmp), GFP_KERNEL);
if (!tmp)
panic("pdev_sort_resources(): "
"kmalloc() failed!\n");
tmp->next = ln;
tmp->res = r;
tmp->dev = dev;
list->next = tmp;
break;
}
}
}
}
void pcibios_update_irq(struct pci_dev *pdev, int irq)
{
}
void pcibios_align_resource(void *data, struct resource *res,
unsigned long size, unsigned long align)
{
}
int pcibios_enable_device(struct pci_dev *pdev, int mask)
{
return 0;
}
void pcibios_resource_to_bus(struct pci_dev *pdev, struct pci_bus_region *region,
struct resource *res)
{
struct pci_pbm_info *pbm = pdev->bus->sysdata;
struct resource zero_res, *root;
zero_res.start = 0;
zero_res.end = 0;
zero_res.flags = res->flags;
if (res->flags & IORESOURCE_IO)
root = &pbm->io_space;
else
root = &pbm->mem_space;
pbm->parent->resource_adjust(pdev, &zero_res, root);
region->start = res->start - zero_res.start;
region->end = res->end - zero_res.start;
}
void pcibios_bus_to_resource(struct pci_dev *pdev, struct resource *res,
struct pci_bus_region *region)
{
struct pci_pbm_info *pbm = pdev->bus->sysdata;
struct resource *root;
res->start = region->start;
res->end = region->end;
if (res->flags & IORESOURCE_IO)
root = &pbm->io_space;
else
root = &pbm->mem_space;
pbm->parent->resource_adjust(pdev, res, root);
}
EXPORT_SYMBOL(pcibios_bus_to_resource);
char * __init pcibios_setup(char *str)
{
if (!strcmp(str, "onboardfirst")) {
pci_device_reorder = 1;
return NULL;
}
if (!strcmp(str, "noreorder")) {
pci_device_reorder = 0;
return NULL;
}
return str;
}
/* Platform support for /proc/bus/pci/X/Y mmap()s. */
/* If the user uses a host-bridge as the PCI device, he may use
* this to perform a raw mmap() of the I/O or MEM space behind
* that controller.
*
* This can be useful for execution of x86 PCI bios initialization code
* on a PCI card, like the xfree86 int10 stuff does.
*/
static int __pci_mmap_make_offset_bus(struct pci_dev *pdev, struct vm_area_struct *vma,
enum pci_mmap_state mmap_state)
{
struct pcidev_cookie *pcp = pdev->sysdata;
struct pci_pbm_info *pbm;
struct pci_controller_info *p;
unsigned long space_size, user_offset, user_size;
if (!pcp)
return -ENXIO;
pbm = pcp->pbm;
if (!pbm)
return -ENXIO;
p = pbm->parent;
if (p->pbms_same_domain) {
unsigned long lowest, highest;
lowest = ~0UL; highest = 0UL;
if (mmap_state == pci_mmap_io) {
if (p->pbm_A.io_space.flags) {
lowest = p->pbm_A.io_space.start;
highest = p->pbm_A.io_space.end + 1;
}
if (p->pbm_B.io_space.flags) {
if (lowest > p->pbm_B.io_space.start)
lowest = p->pbm_B.io_space.start;
if (highest < p->pbm_B.io_space.end + 1)
highest = p->pbm_B.io_space.end + 1;
}
space_size = highest - lowest;
} else {
if (p->pbm_A.mem_space.flags) {
lowest = p->pbm_A.mem_space.start;
highest = p->pbm_A.mem_space.end + 1;
}
if (p->pbm_B.mem_space.flags) {
if (lowest > p->pbm_B.mem_space.start)
lowest = p->pbm_B.mem_space.start;
if (highest < p->pbm_B.mem_space.end + 1)
highest = p->pbm_B.mem_space.end + 1;
}
space_size = highest - lowest;
}
} else {
if (mmap_state == pci_mmap_io) {
space_size = (pbm->io_space.end -
pbm->io_space.start) + 1;
} else {
space_size = (pbm->mem_space.end -
pbm->mem_space.start) + 1;
}
}
/* Make sure the request is in range. */
user_offset = vma->vm_pgoff << PAGE_SHIFT;
user_size = vma->vm_end - vma->vm_start;
if (user_offset >= space_size ||
(user_offset + user_size) > space_size)
return -EINVAL;
if (p->pbms_same_domain) {
unsigned long lowest = ~0UL;
if (mmap_state == pci_mmap_io) {
if (p->pbm_A.io_space.flags)
lowest = p->pbm_A.io_space.start;
if (p->pbm_B.io_space.flags &&
lowest > p->pbm_B.io_space.start)
lowest = p->pbm_B.io_space.start;
} else {
if (p->pbm_A.mem_space.flags)
lowest = p->pbm_A.mem_space.start;
if (p->pbm_B.mem_space.flags &&
lowest > p->pbm_B.mem_space.start)
lowest = p->pbm_B.mem_space.start;
}
vma->vm_pgoff = (lowest + user_offset) >> PAGE_SHIFT;
} else {
if (mmap_state == pci_mmap_io) {
vma->vm_pgoff = (pbm->io_space.start +
user_offset) >> PAGE_SHIFT;
} else {
vma->vm_pgoff = (pbm->mem_space.start +
user_offset) >> PAGE_SHIFT;
}
}
return 0;
}
/* Adjust vm_pgoff of VMA such that it is the physical page offset corresponding
* to the 32-bit pci bus offset for DEV requested by the user.
*
* Basically, the user finds the base address for his device which he wishes
* to mmap. They read the 32-bit value from the config space base register,
* add whatever PAGE_SIZE multiple offset they wish, and feed this into the
* offset parameter of mmap on /proc/bus/pci/XXX for that device.
*
* Returns negative error code on failure, zero on success.
*/
static int __pci_mmap_make_offset(struct pci_dev *dev, struct vm_area_struct *vma,
enum pci_mmap_state mmap_state)
{
unsigned long user_offset = vma->vm_pgoff << PAGE_SHIFT;
unsigned long user32 = user_offset & pci_memspace_mask;
unsigned long largest_base, this_base, addr32;
int i;
if ((dev->class >> 8) == PCI_CLASS_BRIDGE_HOST)
return __pci_mmap_make_offset_bus(dev, vma, mmap_state);
/* Figure out which base address this is for. */
largest_base = 0UL;
for (i = 0; i <= PCI_ROM_RESOURCE; i++) {
struct resource *rp = &dev->resource[i];
/* Active? */
if (!rp->flags)
continue;
/* Same type? */
if (i == PCI_ROM_RESOURCE) {
if (mmap_state != pci_mmap_mem)
continue;
} else {
if ((mmap_state == pci_mmap_io &&
(rp->flags & IORESOURCE_IO) == 0) ||
(mmap_state == pci_mmap_mem &&
(rp->flags & IORESOURCE_MEM) == 0))
continue;
}
this_base = rp->start;
addr32 = (this_base & PAGE_MASK) & pci_memspace_mask;
if (mmap_state == pci_mmap_io)
addr32 &= 0xffffff;
if (addr32 <= user32 && this_base > largest_base)
largest_base = this_base;
}
if (largest_base == 0UL)
return -EINVAL;
/* Now construct the final physical address. */
if (mmap_state == pci_mmap_io)
vma->vm_pgoff = (((largest_base & ~0xffffffUL) | user32) >> PAGE_SHIFT);
else
vma->vm_pgoff = (((largest_base & ~(pci_memspace_mask)) | user32) >> PAGE_SHIFT);
return 0;
}
/* Set vm_flags of VMA, as appropriate for this architecture, for a pci device
* mapping.
*/
static void __pci_mmap_set_flags(struct pci_dev *dev, struct vm_area_struct *vma,
enum pci_mmap_state mmap_state)
{
vma->vm_flags |= (VM_IO | VM_RESERVED);
}
/* Set vm_page_prot of VMA, as appropriate for this architecture, for a pci
* device mapping.
*/
static void __pci_mmap_set_pgprot(struct pci_dev *dev, struct vm_area_struct *vma,
enum pci_mmap_state mmap_state)
{
/* Our io_remap_pfn_range takes care of this, do nothing. */
}
/* Perform the actual remap of the pages for a PCI device mapping, as appropriate
* for this architecture. The region in the process to map is described by vm_start
* and vm_end members of VMA, the base physical address is found in vm_pgoff.
* The pci device structure is provided so that architectures may make mapping
* decisions on a per-device or per-bus basis.
*
* Returns a negative error code on failure, zero on success.
*/
int pci_mmap_page_range(struct pci_dev *dev, struct vm_area_struct *vma,
enum pci_mmap_state mmap_state,
int write_combine)
{
int ret;
ret = __pci_mmap_make_offset(dev, vma, mmap_state);
if (ret < 0)
return ret;
__pci_mmap_set_flags(dev, vma, mmap_state);
__pci_mmap_set_pgprot(dev, vma, mmap_state);
ret = io_remap_pfn_range(vma, vma->vm_start,
vma->vm_pgoff,
vma->vm_end - vma->vm_start,
vma->vm_page_prot);
if (ret)
return ret;
vma->vm_flags |= VM_IO;
return 0;
}
/* Return the domain nuber for this pci bus */
int pci_domain_nr(struct pci_bus *pbus)
{
struct pci_pbm_info *pbm = pbus->sysdata;
int ret;
if (pbm == NULL || pbm->parent == NULL) {
ret = -ENXIO;
} else {
struct pci_controller_info *p = pbm->parent;
ret = p->index;
if (p->pbms_same_domain == 0)
ret = ((ret << 1) +
((pbm == &pbm->parent->pbm_B) ? 1 : 0));
}
return ret;
}
EXPORT_SYMBOL(pci_domain_nr);
int pcibios_prep_mwi(struct pci_dev *dev)
{
/* We set correct PCI_CACHE_LINE_SIZE register values for every
* device probed on this platform. So there is nothing to check
* and this always succeeds.
*/
return 0;
}
#endif /* !(CONFIG_PCI) */