arch/x86/pci/i386.c - kernel/msm - Gitiles

 /*
  *	Low-Level PCI Access for i386 machines
  *
  * Copyright 1993, 1994 Drew Eckhardt
  *      Visionary Computing
  *      (Unix and Linux consulting and custom programming)
  *      Drew@Colorado.EDU
  *      +1 (303) 786-7975
  *
  * Drew's work was sponsored by:
  *	iX Multiuser Multitasking Magazine
  *	Hannover, Germany
  *	hm@ix.de
  *
  * Copyright 1997--2000 Martin Mares <mj@ucw.cz>
  *
  * For more information, please consult the following manuals (look at
  * http://www.pcisig.com/ for how to get them):
  *
  * PCI BIOS Specification
  * PCI Local Bus Specification
  * PCI to PCI Bridge Specification
  * PCI System Design Guide
  *
  */

 #include <linux/types.h>
 #include <linux/kernel.h>
 #include <linux/export.h>
 #include <linux/pci.h>
 #include <linux/init.h>
 #include <linux/ioport.h>
 #include <linux/errno.h>
 #include <linux/bootmem.h>

 #include <asm/pat.h>
 #include <asm/e820.h>
 #include <asm/pci_x86.h>
 #include <asm/io_apic.h>


 /*
  * This list of dynamic mappings is for temporarily maintaining
  * original BIOS BAR addresses for possible reinstatement.
  */
 struct pcibios_fwaddrmap {
 	struct list_head list;
 	struct pci_dev *dev;
 	resource_size_t fw_addr[DEVICE_COUNT_RESOURCE];
 };

 static LIST_HEAD(pcibios_fwaddrmappings);
 static DEFINE_SPINLOCK(pcibios_fwaddrmap_lock);

 /* Must be called with 'pcibios_fwaddrmap_lock' lock held. */
 static struct pcibios_fwaddrmap *pcibios_fwaddrmap_lookup(struct pci_dev *dev)
 {
 	struct pcibios_fwaddrmap *map;

 	WARN_ON(!spin_is_locked(&pcibios_fwaddrmap_lock));

 	list_for_each_entry(map, &pcibios_fwaddrmappings, list)
 		if (map->dev == dev)
 			return map;

 	return NULL;
 }

 static void
 pcibios_save_fw_addr(struct pci_dev *dev, int idx, resource_size_t fw_addr)
 {
 	unsigned long flags;
 	struct pcibios_fwaddrmap *map;

 	spin_lock_irqsave(&pcibios_fwaddrmap_lock, flags);
 	map = pcibios_fwaddrmap_lookup(dev);
 	if (!map) {
 		spin_unlock_irqrestore(&pcibios_fwaddrmap_lock, flags);
 		map = kzalloc(sizeof(*map), GFP_KERNEL);
 		if (!map)
 			return;

 		map->dev = pci_dev_get(dev);
 		map->fw_addr[idx] = fw_addr;
 		INIT_LIST_HEAD(&map->list);

 		spin_lock_irqsave(&pcibios_fwaddrmap_lock, flags);
 		list_add_tail(&map->list, &pcibios_fwaddrmappings);
 	} else
 		map->fw_addr[idx] = fw_addr;
 	spin_unlock_irqrestore(&pcibios_fwaddrmap_lock, flags);
 }

 resource_size_t pcibios_retrieve_fw_addr(struct pci_dev *dev, int idx)
 {
 	unsigned long flags;
 	struct pcibios_fwaddrmap *map;
 	resource_size_t fw_addr = 0;

 	spin_lock_irqsave(&pcibios_fwaddrmap_lock, flags);
 	map = pcibios_fwaddrmap_lookup(dev);
 	if (map)
 		fw_addr = map->fw_addr[idx];
 	spin_unlock_irqrestore(&pcibios_fwaddrmap_lock, flags);

 	return fw_addr;
 }

 static void pcibios_fw_addr_list_del(void)
 {
 	unsigned long flags;
 	struct pcibios_fwaddrmap *entry, *next;

 	spin_lock_irqsave(&pcibios_fwaddrmap_lock, flags);
 	list_for_each_entry_safe(entry, next, &pcibios_fwaddrmappings, list) {
 		list_del(&entry->list);
 		pci_dev_put(entry->dev);
 		kfree(entry);
 	}
 	spin_unlock_irqrestore(&pcibios_fwaddrmap_lock, flags);
 }

 static int
 skip_isa_ioresource_align(struct pci_dev *dev) {

 	if ((pci_probe & PCI_CAN_SKIP_ISA_ALIGN) &&
 	    !(dev->bus->bridge_ctl & PCI_BRIDGE_CTL_ISA))
 		return 1;
 	return 0;
 }

 /*
  * We need to avoid collisions with `mirrored' VGA ports
  * and other strange ISA hardware, so we always want the
  * addresses to be allocated in the 0x000-0x0ff region
  * modulo 0x400.
  *
  * Why? Because some silly external IO cards only decode
  * the low 10 bits of the IO address. The 0x00-0xff region
  * is reserved for motherboard devices that decode all 16
  * bits, so it's ok to allocate at, say, 0x2800-0x28ff,
  * but we want to try to avoid allocating at 0x2900-0x2bff
  * which might have be mirrored at 0x0100-0x03ff..
  */
 resource_size_t
 pcibios_align_resource(void *data, const struct resource *res,
 			resource_size_t size, resource_size_t align)
 {
 	struct pci_dev *dev = data;
 	resource_size_t start = res->start;

 	if (res->flags & IORESOURCE_IO) {
 		if (skip_isa_ioresource_align(dev))
 			return start;
 		if (start & 0x300)
 			start = (start + 0x3ff) & ~0x3ff;
 	}
 	return start;
 }
 EXPORT_SYMBOL(pcibios_align_resource);

 /*
  *  Handle resources of PCI devices.  If the world were perfect, we could
  *  just allocate all the resource regions and do nothing more.  It isn't.
  *  On the other hand, we cannot just re-allocate all devices, as it would
  *  require us to know lots of host bridge internals.  So we attempt to
  *  keep as much of the original configuration as possible, but tweak it
  *  when it's found to be wrong.
  *
  *  Known BIOS problems we have to work around:
  *	- I/O or memory regions not configured
  *	- regions configured, but not enabled in the command register
  *	- bogus I/O addresses above 64K used
  *	- expansion ROMs left enabled (this may sound harmless, but given
  *	  the fact the PCI specs explicitly allow address decoders to be
  *	  shared between expansion ROMs and other resource regions, it's
  *	  at least dangerous)
  *	- bad resource sizes or overlaps with other regions
  *
  *  Our solution:
  *	(1) Allocate resources for all buses behind PCI-to-PCI bridges.
  *	    This gives us fixed barriers on where we can allocate.
  *	(2) Allocate resources for all enabled devices.  If there is
  *	    a collision, just mark the resource as unallocated. Also
  *	    disable expansion ROMs during this step.
  *	(3) Try to allocate resources for disabled devices.  If the
  *	    resources were assigned correctly, everything goes well,
  *	    if they weren't, they won't disturb allocation of other
  *	    resources.
  *	(4) Assign new addresses to resources which were either
  *	    not configured at all or misconfigured.  If explicitly
  *	    requested by the user, configure expansion ROM address
  *	    as well.
  */

 static void __init pcibios_allocate_bus_resources(struct list_head *bus_list)
 {
 	struct pci_bus *bus;
 	struct pci_dev *dev;
 	int idx;
 	struct resource *r;

 	/* Depth-First Search on bus tree */
 	list_for_each_entry(bus, bus_list, node) {
 		if ((dev = bus->self)) {
 			for (idx = PCI_BRIDGE_RESOURCES;
 			    idx < PCI_NUM_RESOURCES; idx++) {
 				r = &dev->resource[idx];
 				if (!r->flags)
 					continue;
 				if (!r->start ||
 				    pci_claim_resource(dev, idx) < 0) {
 					/*
 					 * Something is wrong with the region.
 					 * Invalidate the resource to prevent
 					 * child resource allocations in this
 					 * range.
 					 */
 					r->start = r->end = 0;
 					r->flags = 0;
 				}
 			}
 		}
 		pcibios_allocate_bus_resources(&bus->children);
 	}
 }

 struct pci_check_idx_range {
 	int start;
 	int end;
 };

 static void __init pcibios_allocate_resources(int pass)
 {
 	struct pci_dev *dev = NULL;
 	int idx, disabled, i;
 	u16 command;
 	struct resource *r;

 	struct pci_check_idx_range idx_range[] = {
 		{ PCI_STD_RESOURCES, PCI_STD_RESOURCE_END },
 #ifdef CONFIG_PCI_IOV
 		{ PCI_IOV_RESOURCES, PCI_IOV_RESOURCE_END },
 #endif
 	};

 	for_each_pci_dev(dev) {
 		pci_read_config_word(dev, PCI_COMMAND, &command);
 		for (i = 0; i < ARRAY_SIZE(idx_range); i++)
 		for (idx = idx_range[i].start; idx <= idx_range[i].end; idx++) {
 			r = &dev->resource[idx];
 			if (r->parent)		/* Already allocated */
 				continue;
 			if (!r->start)		/* Address not assigned at all */
 				continue;
 			if (r->flags & IORESOURCE_IO)
 				disabled = !(command & PCI_COMMAND_IO);
 			else
 				disabled = !(command & PCI_COMMAND_MEMORY);
 			if (pass == disabled) {
 				dev_dbg(&dev->dev,
 					"BAR %d: reserving %pr (d=%d, p=%d)\n",
 					idx, r, disabled, pass);
 				if (pci_claim_resource(dev, idx) < 0) {
 					/* We'll assign a new address later */
 					pcibios_save_fw_addr(dev,
 							idx, r->start);
 					r->end -= r->start;
 					r->start = 0;
 				}
 			}
 		}
 		if (!pass) {
 			r = &dev->resource[PCI_ROM_RESOURCE];
 			if (r->flags & IORESOURCE_ROM_ENABLE) {
 				/* Turn the ROM off, leave the resource region,
 				 * but keep it unregistered. */
 				u32 reg;
 				dev_dbg(&dev->dev, "disabling ROM %pR\n", r);
 				r->flags &= ~IORESOURCE_ROM_ENABLE;
 				pci_read_config_dword(dev,
 						dev->rom_base_reg, &reg);
 				pci_write_config_dword(dev, dev->rom_base_reg,
 						reg & ~PCI_ROM_ADDRESS_ENABLE);
 			}
 		}
 	}
 }

 static int __init pcibios_assign_resources(void)
 {
 	struct pci_dev *dev = NULL;
 	struct resource *r;

 	if (!(pci_probe & PCI_ASSIGN_ROMS)) {
 		/*
 		 * Try to use BIOS settings for ROMs, otherwise let
 		 * pci_assign_unassigned_resources() allocate the new
 		 * addresses.
 		 */
 		for_each_pci_dev(dev) {
 			r = &dev->resource[PCI_ROM_RESOURCE];
 			if (!r->flags || !r->start)
 				continue;
 			if (pci_claim_resource(dev, PCI_ROM_RESOURCE) < 0) {
 				r->end -= r->start;
 				r->start = 0;
 			}
 		}
 	}

 	pci_assign_unassigned_resources();
 	pcibios_fw_addr_list_del();

 	return 0;
 }

 void __init pcibios_resource_survey(void)
 {
 	DBG("PCI: Allocating resources\n");
 	pcibios_allocate_bus_resources(&pci_root_buses);
 	pcibios_allocate_resources(0);
 	pcibios_allocate_resources(1);

 	e820_reserve_resources_late();
 	/*
 	 * Insert the IO APIC resources after PCI initialization has
 	 * occurred to handle IO APICS that are mapped in on a BAR in
 	 * PCI space, but before trying to assign unassigned pci res.
 	 */
 	ioapic_insert_resources();
 }

 /**
  * called in fs_initcall (one below subsys_initcall),
  * give a chance for motherboard reserve resources
  */
 fs_initcall(pcibios_assign_resources);

 static const struct vm_operations_struct pci_mmap_ops = {
 	.access = generic_access_phys,
 };

 int pci_mmap_page_range(struct pci_dev *dev, struct vm_area_struct *vma,
 			enum pci_mmap_state mmap_state, int write_combine)
 {
 	unsigned long prot;

 	/* I/O space cannot be accessed via normal processor loads and
 	 * stores on this platform.
 	 */
 	if (mmap_state == pci_mmap_io)
 		return -EINVAL;

 	prot = pgprot_val(vma->vm_page_prot);

 	/*
  	 * Return error if pat is not enabled and write_combine is requested.
  	 * Caller can followup with UC MINUS request and add a WC mtrr if there
  	 * is a free mtrr slot.
  	 */
 	if (!pat_enabled && write_combine)
 		return -EINVAL;

 	if (pat_enabled && write_combine)
 		prot |= _PAGE_CACHE_WC;
 	else if (pat_enabled || boot_cpu_data.x86 > 3)
 		/*
 		 * ioremap() and ioremap_nocache() defaults to UC MINUS for now.
 		 * To avoid attribute conflicts, request UC MINUS here
 		 * as well.
 		 */
 		prot |= _PAGE_CACHE_UC_MINUS;

 	prot |= _PAGE_IOMAP;	/* creating a mapping for IO */

 	vma->vm_page_prot = __pgprot(prot);

 	if (io_remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
 			       vma->vm_end - vma->vm_start,
 			       vma->vm_page_prot))
 		return -EAGAIN;

 	vma->vm_ops = &pci_mmap_ops;

 	return 0;
 }
	/*
	* Low-Level PCI Access for i386 machines
	*
	* Copyright 1993, 1994 Drew Eckhardt
	* Visionary Computing
	* (Unix and Linux consulting and custom programming)
	* Drew@Colorado.EDU
	* +1 (303) 786-7975
	*
	* Drew's work was sponsored by:
	* iX Multiuser Multitasking Magazine
	* Hannover, Germany
	* hm@ix.de
	*
	* Copyright 1997--2000 Martin Mares <mj@ucw.cz>
	*
	* For more information, please consult the following manuals (look at
	* http://www.pcisig.com/ for how to get them):
	*
	* PCI BIOS Specification
	* PCI Local Bus Specification
	* PCI to PCI Bridge Specification
	* PCI System Design Guide
	*
	*/

	#include <linux/types.h>
	#include <linux/kernel.h>
	#include <linux/export.h>
	#include <linux/pci.h>
	#include <linux/init.h>
	#include <linux/ioport.h>
	#include <linux/errno.h>
	#include <linux/bootmem.h>

	#include <asm/pat.h>
	#include <asm/e820.h>
	#include <asm/pci_x86.h>
	#include <asm/io_apic.h>


	/*
	* This list of dynamic mappings is for temporarily maintaining
	* original BIOS BAR addresses for possible reinstatement.
	*/
	struct pcibios_fwaddrmap {
	struct list_head list;
	struct pci_dev *dev;
	resource_size_t fw_addr[DEVICE_COUNT_RESOURCE];
	};

	static LIST_HEAD(pcibios_fwaddrmappings);
	static DEFINE_SPINLOCK(pcibios_fwaddrmap_lock);

	/* Must be called with 'pcibios_fwaddrmap_lock' lock held. */
	static struct pcibios_fwaddrmap pcibios_fwaddrmap_lookup(struct pci_dev dev)
	{
	struct pcibios_fwaddrmap *map;

	WARN_ON(!spin_is_locked(&pcibios_fwaddrmap_lock));

	list_for_each_entry(map, &pcibios_fwaddrmappings, list)
	if (map->dev == dev)
	return map;

	return NULL;
	}

	static void
	pcibios_save_fw_addr(struct pci_dev *dev, int idx, resource_size_t fw_addr)
	{
	unsigned long flags;
	struct pcibios_fwaddrmap *map;

	spin_lock_irqsave(&pcibios_fwaddrmap_lock, flags);
	map = pcibios_fwaddrmap_lookup(dev);
	if (!map) {
	spin_unlock_irqrestore(&pcibios_fwaddrmap_lock, flags);
	map = kzalloc(sizeof(*map), GFP_KERNEL);
	if (!map)
	return;

	map->dev = pci_dev_get(dev);
	map->fw_addr[idx] = fw_addr;
	INIT_LIST_HEAD(&map->list);

	spin_lock_irqsave(&pcibios_fwaddrmap_lock, flags);
	list_add_tail(&map->list, &pcibios_fwaddrmappings);
	} else
	map->fw_addr[idx] = fw_addr;
	spin_unlock_irqrestore(&pcibios_fwaddrmap_lock, flags);
	}

	resource_size_t pcibios_retrieve_fw_addr(struct pci_dev *dev, int idx)
	{
	unsigned long flags;
	struct pcibios_fwaddrmap *map;
	resource_size_t fw_addr = 0;

	spin_lock_irqsave(&pcibios_fwaddrmap_lock, flags);
	map = pcibios_fwaddrmap_lookup(dev);
	if (map)
	fw_addr = map->fw_addr[idx];
	spin_unlock_irqrestore(&pcibios_fwaddrmap_lock, flags);

	return fw_addr;
	}

	static void pcibios_fw_addr_list_del(void)
	{
	unsigned long flags;
	struct pcibios_fwaddrmap entry, next;

	spin_lock_irqsave(&pcibios_fwaddrmap_lock, flags);
	list_for_each_entry_safe(entry, next, &pcibios_fwaddrmappings, list) {
	list_del(&entry->list);
	pci_dev_put(entry->dev);
	kfree(entry);
	}
	spin_unlock_irqrestore(&pcibios_fwaddrmap_lock, flags);
	}

	static int
	skip_isa_ioresource_align(struct pci_dev *dev) {

	if ((pci_probe & PCI_CAN_SKIP_ISA_ALIGN) &&
	!(dev->bus->bridge_ctl & PCI_BRIDGE_CTL_ISA))
	return 1;
	return 0;
	}

	/*
	* We need to avoid collisions with `mirrored' VGA ports
	* and other strange ISA hardware, so we always want the
	* addresses to be allocated in the 0x000-0x0ff region
	* modulo 0x400.
	*
	* Why? Because some silly external IO cards only decode
	* the low 10 bits of the IO address. The 0x00-0xff region
	* is reserved for motherboard devices that decode all 16
	* bits, so it's ok to allocate at, say, 0x2800-0x28ff,
	* but we want to try to avoid allocating at 0x2900-0x2bff
	* which might have be mirrored at 0x0100-0x03ff..
	*/
	resource_size_t
	pcibios_align_resource(void data, const struct resource res,
	resource_size_t size, resource_size_t align)
	{
	struct pci_dev *dev = data;
	resource_size_t start = res->start;

	if (res->flags & IORESOURCE_IO) {
	if (skip_isa_ioresource_align(dev))
	return start;
	if (start & 0x300)
	start = (start + 0x3ff) & ~0x3ff;
	}
	return start;
	}
	EXPORT_SYMBOL(pcibios_align_resource);

	/*
	* Handle resources of PCI devices. If the world were perfect, we could
	* just allocate all the resource regions and do nothing more. It isn't.
	* On the other hand, we cannot just re-allocate all devices, as it would
	* require us to know lots of host bridge internals. So we attempt to
	* keep as much of the original configuration as possible, but tweak it
	* when it's found to be wrong.
	*
	* Known BIOS problems we have to work around:
	* - I/O or memory regions not configured
	* - regions configured, but not enabled in the command register
	* - bogus I/O addresses above 64K used
	* - expansion ROMs left enabled (this may sound harmless, but given
	* the fact the PCI specs explicitly allow address decoders to be
	* shared between expansion ROMs and other resource regions, it's
	* at least dangerous)
	* - bad resource sizes or overlaps with other regions
	*
	* Our solution:
	* (1) Allocate resources for all buses behind PCI-to-PCI bridges.
	* This gives us fixed barriers on where we can allocate.
	* (2) Allocate resources for all enabled devices. If there is
	* a collision, just mark the resource as unallocated. Also
	* disable expansion ROMs during this step.
	* (3) Try to allocate resources for disabled devices. If the
	* resources were assigned correctly, everything goes well,
	* if they weren't, they won't disturb allocation of other
	* resources.
	* (4) Assign new addresses to resources which were either
	* not configured at all or misconfigured. If explicitly
	* requested by the user, configure expansion ROM address
	* as well.
	*/

	static void __init pcibios_allocate_bus_resources(struct list_head *bus_list)
	{
	struct pci_bus *bus;
	struct pci_dev *dev;
	int idx;
	struct resource *r;

	/* Depth-First Search on bus tree */
	list_for_each_entry(bus, bus_list, node) {
	if ((dev = bus->self)) {
	for (idx = PCI_BRIDGE_RESOURCES;
	idx < PCI_NUM_RESOURCES; idx++) {
	r = &dev->resource[idx];
	if (!r->flags)
	continue;
	if (!r->start \|\|
	pci_claim_resource(dev, idx) < 0) {
	/*
	* Something is wrong with the region.
	* Invalidate the resource to prevent
	* child resource allocations in this
	* range.
	*/
	r->start = r->end = 0;
	r->flags = 0;
	}
	}
	}
	pcibios_allocate_bus_resources(&bus->children);
	}
	}

	struct pci_check_idx_range {
	int start;
	int end;
	};

	static void __init pcibios_allocate_resources(int pass)
	{
	struct pci_dev *dev = NULL;
	int idx, disabled, i;
	u16 command;
	struct resource *r;

	struct pci_check_idx_range idx_range[] = {
	{ PCI_STD_RESOURCES, PCI_STD_RESOURCE_END },
	#ifdef CONFIG_PCI_IOV
	{ PCI_IOV_RESOURCES, PCI_IOV_RESOURCE_END },
	#endif
	};

	for_each_pci_dev(dev) {
	pci_read_config_word(dev, PCI_COMMAND, &command);
	for (i = 0; i < ARRAY_SIZE(idx_range); i++)
	for (idx = idx_range[i].start; idx <= idx_range[i].end; idx++) {
	r = &dev->resource[idx];
	if (r->parent) /* Already allocated */
	continue;
	if (!r->start) /* Address not assigned at all */
	continue;
	if (r->flags & IORESOURCE_IO)
	disabled = !(command & PCI_COMMAND_IO);
	else
	disabled = !(command & PCI_COMMAND_MEMORY);
	if (pass == disabled) {
	dev_dbg(&dev->dev,
	"BAR %d: reserving %pr (d=%d, p=%d)\n",
	idx, r, disabled, pass);
	if (pci_claim_resource(dev, idx) < 0) {
	/* We'll assign a new address later */
	pcibios_save_fw_addr(dev,
	idx, r->start);
	r->end -= r->start;
	r->start = 0;
	}
	}
	}
	if (!pass) {
	r = &dev->resource[PCI_ROM_RESOURCE];
	if (r->flags & IORESOURCE_ROM_ENABLE) {
	/* Turn the ROM off, leave the resource region,
	* but keep it unregistered. */
	u32 reg;
	dev_dbg(&dev->dev, "disabling ROM %pR\n", r);
	r->flags &= ~IORESOURCE_ROM_ENABLE;
	pci_read_config_dword(dev,
	dev->rom_base_reg, &reg);
	pci_write_config_dword(dev, dev->rom_base_reg,
	reg & ~PCI_ROM_ADDRESS_ENABLE);
	}
	}
	}
	}

	static int __init pcibios_assign_resources(void)
	{
	struct pci_dev *dev = NULL;
	struct resource *r;

	if (!(pci_probe & PCI_ASSIGN_ROMS)) {
	/*
	* Try to use BIOS settings for ROMs, otherwise let
	* pci_assign_unassigned_resources() allocate the new
	* addresses.
	*/
	for_each_pci_dev(dev) {
	r = &dev->resource[PCI_ROM_RESOURCE];
	if (!r->flags \|\| !r->start)
	continue;
	if (pci_claim_resource(dev, PCI_ROM_RESOURCE) < 0) {
	r->end -= r->start;
	r->start = 0;
	}
	}
	}

	pci_assign_unassigned_resources();
	pcibios_fw_addr_list_del();

	return 0;
	}

	void __init pcibios_resource_survey(void)
	{
	DBG("PCI: Allocating resources\n");
	pcibios_allocate_bus_resources(&pci_root_buses);
	pcibios_allocate_resources(0);
	pcibios_allocate_resources(1);

	e820_reserve_resources_late();
	/*
	* Insert the IO APIC resources after PCI initialization has
	* occurred to handle IO APICS that are mapped in on a BAR in
	* PCI space, but before trying to assign unassigned pci res.
	*/
	ioapic_insert_resources();
	}

	/**
	* called in fs_initcall (one below subsys_initcall),
	* give a chance for motherboard reserve resources
	*/
	fs_initcall(pcibios_assign_resources);

	static const struct vm_operations_struct pci_mmap_ops = {
	.access = generic_access_phys,
	};

	int pci_mmap_page_range(struct pci_dev dev, struct vm_area_struct vma,
	enum pci_mmap_state mmap_state, int write_combine)
	{
	unsigned long prot;

	/* I/O space cannot be accessed via normal processor loads and
	* stores on this platform.
	*/
	if (mmap_state == pci_mmap_io)
	return -EINVAL;

	prot = pgprot_val(vma->vm_page_prot);

	/*
	* Return error if pat is not enabled and write_combine is requested.
	* Caller can followup with UC MINUS request and add a WC mtrr if there
	* is a free mtrr slot.
	*/
	if (!pat_enabled && write_combine)
	return -EINVAL;

	if (pat_enabled && write_combine)
	prot \|= _PAGE_CACHE_WC;
	else if (pat_enabled \|\| boot_cpu_data.x86 > 3)
	/*
	* ioremap() and ioremap_nocache() defaults to UC MINUS for now.
	* To avoid attribute conflicts, request UC MINUS here
	* as well.
	*/
	prot \|= _PAGE_CACHE_UC_MINUS;

	prot \|= _PAGE_IOMAP; /* creating a mapping for IO */

	vma->vm_page_prot = __pgprot(prot);

	if (io_remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
	vma->vm_end - vma->vm_start,
	vma->vm_page_prot))
	return -EAGAIN;

	vma->vm_ops = &pci_mmap_ops;

	return 0;
	}