/*
   *	linux/kernel/resource.c
   *
   * Copyright (C) 1999	Linus Torvalds
   * Copyright (C) 1999	Martin Mares <mj@ucw.cz>
   *
   * Arbitrary resource management.
   */

  #include <linux/module.h>

  #include <linux/errno.h>
  #include <linux/ioport.h>
  #include <linux/init.h>
  #include <linux/slab.h>
  #include <linux/spinlock.h>
  #include <linux/fs.h>
  #include <linux/proc_fs.h>
  #include <linux/seq_file.h>

  #include <linux/device.h>

  #include <linux/pfn.h>

  #include <asm/io.h>
  
  
  struct resource ioport_resource = {
  	.name	= "PCI IO",

  	.start	= 0,

  	.end	= IO_SPACE_LIMIT,
  	.flags	= IORESOURCE_IO,
  };

  EXPORT_SYMBOL(ioport_resource);
  
  struct resource iomem_resource = {
  	.name	= "PCI mem",

  	.start	= 0,
  	.end	= -1,

  	.flags	= IORESOURCE_MEM,
  };

  EXPORT_SYMBOL(iomem_resource);
  
  static DEFINE_RWLOCK(resource_lock);

  static void *r_next(struct seq_file *m, void *v, loff_t *pos)
  {
  	struct resource *p = v;
  	(*pos)++;
  	if (p->child)
  		return p->child;
  	while (!p->sibling && p->parent)
  		p = p->parent;
  	return p->sibling;
  }

  #ifdef CONFIG_PROC_FS
  
  enum { MAX_IORES_LEVEL = 5 };

  static void *r_start(struct seq_file *m, loff_t *pos)
  	__acquires(resource_lock)
  {
  	struct resource *p = m->private;
  	loff_t l = 0;
  	read_lock(&resource_lock);
  	for (p = p->child; p && l < *pos; p = r_next(m, p, &l))
  		;
  	return p;
  }
  
  static void r_stop(struct seq_file *m, void *v)
  	__releases(resource_lock)
  {
  	read_unlock(&resource_lock);
  }
  
  static int r_show(struct seq_file *m, void *v)
  {
  	struct resource *root = m->private;
  	struct resource *r = v, *p;
  	int width = root->end < 0x10000 ? 4 : 8;
  	int depth;
  
  	for (depth = 0, p = r; depth < MAX_IORES_LEVEL; depth++, p = p->parent)
  		if (p->parent == root)
  			break;

  	seq_printf(m, "%*s%0*llx-%0*llx : %s
  ",

  			depth * 2, "",

  			width, (unsigned long long) r->start,
  			width, (unsigned long long) r->end,

  			r->name ? r->name : "<BAD>");
  	return 0;
  }

  static const struct seq_operations resource_op = {

  	.start	= r_start,
  	.next	= r_next,
  	.stop	= r_stop,
  	.show	= r_show,
  };
  
  static int ioports_open(struct inode *inode, struct file *file)
  {
  	int res = seq_open(file, &resource_op);
  	if (!res) {
  		struct seq_file *m = file->private_data;
  		m->private = &ioport_resource;
  	}
  	return res;
  }
  
  static int iomem_open(struct inode *inode, struct file *file)
  {
  	int res = seq_open(file, &resource_op);
  	if (!res) {
  		struct seq_file *m = file->private_data;
  		m->private = &iomem_resource;
  	}
  	return res;
  }

  static const struct file_operations proc_ioports_operations = {

  	.open		= ioports_open,
  	.read		= seq_read,
  	.llseek		= seq_lseek,
  	.release	= seq_release,
  };

  static const struct file_operations proc_iomem_operations = {

  	.open		= iomem_open,
  	.read		= seq_read,
  	.llseek		= seq_lseek,
  	.release	= seq_release,
  };
  
  static int __init ioresources_init(void)
  {

  	proc_create("ioports", 0, NULL, &proc_ioports_operations);
  	proc_create("iomem", 0, NULL, &proc_iomem_operations);

  	return 0;
  }
  __initcall(ioresources_init);
  
  #endif /* CONFIG_PROC_FS */
  
  /* Return the conflict entry if you can't request it */
  static struct resource * __request_resource(struct resource *root, struct resource *new)
  {

  	resource_size_t start = new->start;
  	resource_size_t end = new->end;

  	struct resource *tmp, **p;
  
  	if (end < start)
  		return root;
  	if (start < root->start)
  		return root;
  	if (end > root->end)
  		return root;
  	p = &root->child;
  	for (;;) {
  		tmp = *p;
  		if (!tmp || tmp->start > end) {
  			new->sibling = tmp;
  			*p = new;
  			new->parent = root;
  			return NULL;
  		}
  		p = &tmp->sibling;
  		if (tmp->end < start)
  			continue;
  		return tmp;
  	}
  }
  
  static int __release_resource(struct resource *old)
  {
  	struct resource *tmp, **p;
  
  	p = &old->parent->child;
  	for (;;) {
  		tmp = *p;
  		if (!tmp)
  			break;
  		if (tmp == old) {
  			*p = tmp->sibling;
  			old->parent = NULL;
  			return 0;
  		}
  		p = &tmp->sibling;
  	}
  	return -EINVAL;
  }

  /**
   * request_resource - request and reserve an I/O or memory resource
   * @root: root resource descriptor
   * @new: resource descriptor desired by caller
   *
   * Returns 0 for success, negative error code on error.
   */

  int request_resource(struct resource *root, struct resource *new)
  {
  	struct resource *conflict;
  
  	write_lock(&resource_lock);
  	conflict = __request_resource(root, new);
  	write_unlock(&resource_lock);
  	return conflict ? -EBUSY : 0;
  }
  
  EXPORT_SYMBOL(request_resource);

  /**

   * release_resource - release a previously reserved resource
   * @old: resource pointer
   */

  int release_resource(struct resource *old)
  {
  	int retval;
  
  	write_lock(&resource_lock);
  	retval = __release_resource(old);
  	write_unlock(&resource_lock);
  	return retval;
  }
  
  EXPORT_SYMBOL(release_resource);

  #if defined(CONFIG_MEMORY_HOTPLUG) && !defined(CONFIG_ARCH_HAS_WALK_MEMORY)

  /*
   * Finds the lowest memory reosurce exists within [res->start.res->end)
   * the caller must specify res->start, res->end, res->flags.
   * If found, returns 0, res is overwritten, if not found, returns -1.
   */

  static int find_next_system_ram(struct resource *res)

  {
  	resource_size_t start, end;
  	struct resource *p;
  
  	BUG_ON(!res);
  
  	start = res->start;
  	end = res->end;

  	BUG_ON(start >= end);

  
  	read_lock(&resource_lock);
  	for (p = iomem_resource.child; p ; p = p->sibling) {
  		/* system ram is just marked as IORESOURCE_MEM */
  		if (p->flags != res->flags)
  			continue;
  		if (p->start > end) {
  			p = NULL;
  			break;
  		}

  		if ((p->end >= start) && (p->start < end))

  			break;
  	}
  	read_unlock(&resource_lock);
  	if (!p)
  		return -1;
  	/* copy data */

  	if (res->start < p->start)
  		res->start = p->start;
  	if (res->end > p->end)
  		res->end = p->end;

  	return 0;
  }

  int
  walk_memory_resource(unsigned long start_pfn, unsigned long nr_pages, void *arg,
  			int (*func)(unsigned long, unsigned long, void *))
  {
  	struct resource res;
  	unsigned long pfn, len;
  	u64 orig_end;
  	int ret = -1;
  	res.start = (u64) start_pfn << PAGE_SHIFT;
  	res.end = ((u64)(start_pfn + nr_pages) << PAGE_SHIFT) - 1;

  	res.flags = IORESOURCE_MEM | IORESOURCE_BUSY;

  	orig_end = res.end;
  	while ((res.start < res.end) && (find_next_system_ram(&res) >= 0)) {
  		pfn = (unsigned long)(res.start >> PAGE_SHIFT);
  		len = (unsigned long)((res.end + 1 - res.start) >> PAGE_SHIFT);
  		ret = (*func)(pfn, len, arg);
  		if (ret)
  			break;
  		res.start = res.end + 1;
  		res.end = orig_end;
  	}
  	return ret;
  }

  #endif

  /*
   * Find empty slot in the resource tree given range and alignment.
   */
  static int find_resource(struct resource *root, struct resource *new,

  			 resource_size_t size, resource_size_t min,
  			 resource_size_t max, resource_size_t align,

  			 void (*alignf)(void *, struct resource *,

  					resource_size_t, resource_size_t),

  			 void *alignf_data)
  {
  	struct resource *this = root->child;
  
  	new->start = root->start;
  	/*
  	 * Skip past an allocated resource that starts at 0, since the assignment
  	 * of this->start - 1 to new->end below would cause an underflow.
  	 */
  	if (this && this->start == 0) {
  		new->start = this->end + 1;
  		this = this->sibling;
  	}
  	for(;;) {
  		if (this)
  			new->end = this->start - 1;
  		else
  			new->end = root->end;
  		if (new->start < min)
  			new->start = min;
  		if (new->end > max)
  			new->end = max;

  		new->start = ALIGN(new->start, align);

  		if (alignf)
  			alignf(alignf_data, new, size, align);

  		if (new->start < new->end && new->end - new->start >= size - 1) {

  			new->end = new->start + size - 1;
  			return 0;
  		}
  		if (!this)
  			break;
  		new->start = this->end + 1;
  		this = this->sibling;
  	}
  	return -EBUSY;
  }

  /**
   * allocate_resource - allocate empty slot in the resource tree given range & alignment
   * @root: root resource descriptor
   * @new: resource descriptor desired by caller
   * @size: requested resource region size
   * @min: minimum size to allocate
   * @max: maximum size to allocate
   * @align: alignment requested, in bytes
   * @alignf: alignment function, optional, called if not NULL
   * @alignf_data: arbitrary data to pass to the @alignf function

   */
  int allocate_resource(struct resource *root, struct resource *new,

  		      resource_size_t size, resource_size_t min,
  		      resource_size_t max, resource_size_t align,

  		      void (*alignf)(void *, struct resource *,

  				     resource_size_t, resource_size_t),

  		      void *alignf_data)
  {
  	int err;
  
  	write_lock(&resource_lock);
  	err = find_resource(root, new, size, min, max, align, alignf, alignf_data);
  	if (err >= 0 && __request_resource(root, new))
  		err = -EBUSY;
  	write_unlock(&resource_lock);
  	return err;
  }
  
  EXPORT_SYMBOL(allocate_resource);

  /*
   * Insert a resource into the resource tree. If successful, return NULL,
   * otherwise return the conflicting resource (compare to __request_resource())

   */

  static struct resource * __insert_resource(struct resource *parent, struct resource *new)

  {

  	struct resource *first, *next;

  	for (;; parent = first) {

  		first = __request_resource(parent, new);
  		if (!first)

  			return first;

  		if (first == parent)

  			return first;

  
  		if ((first->start > new->start) || (first->end < new->end))
  			break;
  		if ((first->start == new->start) && (first->end == new->end))
  			break;

  	}
  
  	for (next = first; ; next = next->sibling) {
  		/* Partial overlap? Bad, and unfixable */
  		if (next->start < new->start || next->end > new->end)

  			return next;

  		if (!next->sibling)
  			break;
  		if (next->sibling->start > new->end)
  			break;
  	}

  	new->parent = parent;
  	new->sibling = next->sibling;
  	new->child = first;
  
  	next->sibling = NULL;
  	for (next = first; next; next = next->sibling)
  		next->parent = new;
  
  	if (parent->child == first) {
  		parent->child = new;
  	} else {
  		next = parent->child;
  		while (next->sibling != first)
  			next = next->sibling;
  		next->sibling = new;
  	}

  	return NULL;
  }

  /**
   * insert_resource - Inserts a resource in the resource tree
   * @parent: parent of the new resource
   * @new: new resource to insert
   *
   * Returns 0 on success, -EBUSY if the resource can't be inserted.
   *
   * This function is equivalent to request_resource when no conflict
   * happens. If a conflict happens, and the conflicting resources
   * entirely fit within the range of the new resource, then the new
   * resource is inserted and the conflicting resources become children of
   * the new resource.
   */
  int insert_resource(struct resource *parent, struct resource *new)
  {
  	struct resource *conflict;
  
  	write_lock(&resource_lock);
  	conflict = __insert_resource(parent, new);
  	write_unlock(&resource_lock);
  	return conflict ? -EBUSY : 0;
  }
  
  /**
   * insert_resource_expand_to_fit - Insert a resource into the resource tree

   * @root: root resource descriptor

   * @new: new resource to insert
   *
   * Insert a resource into the resource tree, possibly expanding it in order
   * to make it encompass any conflicting resources.
   */
  void insert_resource_expand_to_fit(struct resource *root, struct resource *new)
  {
  	if (new->parent)
  		return;
  
  	write_lock(&resource_lock);
  	for (;;) {
  		struct resource *conflict;
  
  		conflict = __insert_resource(root, new);
  		if (!conflict)
  			break;
  		if (conflict == root)
  			break;
  
  		/* Ok, expand resource to cover the conflict, then try again .. */
  		if (conflict->start < new->start)
  			new->start = conflict->start;
  		if (conflict->end > new->end)
  			new->end = conflict->end;
  
  		printk("Expanded resource %s due to conflict with %s
  ", new->name, conflict->name);
  	}

  	write_unlock(&resource_lock);

  }

  /**
   * adjust_resource - modify a resource's start and size
   * @res: resource to modify
   * @start: new start value
   * @size: new size
   *

   * Given an existing resource, change its start and size to match the

   * arguments.  Returns 0 on success, -EBUSY if it can't fit.
   * Existing children of the resource are assumed to be immutable.

   */

  int adjust_resource(struct resource *res, resource_size_t start, resource_size_t size)

  {
  	struct resource *tmp, *parent = res->parent;

  	resource_size_t end = start + size - 1;

  	int result = -EBUSY;
  
  	write_lock(&resource_lock);
  
  	if ((start < parent->start) || (end > parent->end))
  		goto out;
  
  	for (tmp = res->child; tmp; tmp = tmp->sibling) {
  		if ((tmp->start < start) || (tmp->end > end))
  			goto out;
  	}
  
  	if (res->sibling && (res->sibling->start <= end))
  		goto out;
  
  	tmp = parent->child;
  	if (tmp != res) {
  		while (tmp->sibling != res)
  			tmp = tmp->sibling;
  		if (start <= tmp->end)
  			goto out;
  	}
  
  	res->start = start;
  	res->end = end;
  	result = 0;
  
   out:
  	write_unlock(&resource_lock);
  	return result;
  }

  static void __init __reserve_region_with_split(struct resource *root,
  		resource_size_t start, resource_size_t end,
  		const char *name)
  {
  	struct resource *parent = root;
  	struct resource *conflict;

  	struct resource *res = kzalloc(sizeof(*res), GFP_ATOMIC);

  
  	if (!res)
  		return;
  
  	res->name = name;
  	res->start = start;
  	res->end = end;
  	res->flags = IORESOURCE_BUSY;
  
  	for (;;) {
  		conflict = __request_resource(parent, res);
  		if (!conflict)
  			break;
  		if (conflict != parent) {
  			parent = conflict;
  			if (!(conflict->flags & IORESOURCE_BUSY))
  				continue;
  		}
  
  		/* Uhhuh, that didn't work out.. */
  		kfree(res);
  		res = NULL;
  		break;
  	}
  
  	if (!res) {

  		/* failed, split and try again */

  		/* conflict covered whole area */

  		if (conflict->start <= start && conflict->end >= end)
  			return;
  
  		if (conflict->start > start)
  			__reserve_region_with_split(root, start, conflict->start-1, name);
  		if (!(conflict->flags & IORESOURCE_BUSY)) {
  			resource_size_t common_start, common_end;
  
  			common_start = max(conflict->start, start);
  			common_end = min(conflict->end, end);
  			if (common_start < common_end)
  				__reserve_region_with_split(root, common_start, common_end, name);
  		}
  		if (conflict->end < end)
  			__reserve_region_with_split(root, conflict->end+1, end, name);
  	}
  
  }

  void __init reserve_region_with_split(struct resource *root,

  		resource_size_t start, resource_size_t end,
  		const char *name)
  {
  	write_lock(&resource_lock);
  	__reserve_region_with_split(root, start, end, name);
  	write_unlock(&resource_lock);
  }

  EXPORT_SYMBOL(adjust_resource);

  /**
   * resource_alignment - calculate resource's alignment
   * @res: resource pointer
   *
   * Returns alignment on success, 0 (invalid alignment) on failure.
   */
  resource_size_t resource_alignment(struct resource *res)
  {
  	switch (res->flags & (IORESOURCE_SIZEALIGN | IORESOURCE_STARTALIGN)) {
  	case IORESOURCE_SIZEALIGN:

  		return resource_size(res);

  	case IORESOURCE_STARTALIGN:
  		return res->start;
  	default:
  		return 0;
  	}
  }

  /*
   * This is compatibility stuff for IO resources.
   *
   * Note how this, unlike the above, knows about
   * the IO flag meanings (busy etc).
   *

   * request_region creates a new busy region.

   *

   * check_region returns non-zero if the area is already busy.

   *

   * release_region releases a matching busy region.
   */
  
  /**
   * __request_region - create a new busy resource region
   * @parent: parent resource descriptor
   * @start: resource start address
   * @n: resource region size
   * @name: reserving caller's ID string

   * @flags: IO resource flags

   */

  struct resource * __request_region(struct resource *parent,
  				   resource_size_t start, resource_size_t n,

  				   const char *name, int flags)

  {

  	struct resource *res = kzalloc(sizeof(*res), GFP_KERNEL);

  	if (!res)
  		return NULL;
  
  	res->name = name;
  	res->start = start;
  	res->end = start + n - 1;
  	res->flags = IORESOURCE_BUSY;

  	res->flags |= flags;

  
  	write_lock(&resource_lock);
  
  	for (;;) {
  		struct resource *conflict;
  
  		conflict = __request_resource(parent, res);
  		if (!conflict)

  			break;

  		if (conflict != parent) {
  			parent = conflict;
  			if (!(conflict->flags & IORESOURCE_BUSY))
  				continue;

  		}

  
  		/* Uhhuh, that didn't work out.. */
  		kfree(res);
  		res = NULL;
  		break;

  	}

  	write_unlock(&resource_lock);

  	return res;
  }

  EXPORT_SYMBOL(__request_region);

  /**
   * __check_region - check if a resource region is busy or free
   * @parent: parent resource descriptor
   * @start: resource start address
   * @n: resource region size
   *
   * Returns 0 if the region is free at the moment it is checked,
   * returns %-EBUSY if the region is busy.
   *
   * NOTE:
   * This function is deprecated because its use is racy.
   * Even if it returns 0, a subsequent call to request_region()
   * may fail because another driver etc. just allocated the region.
   * Do NOT use it.  It will be removed from the kernel.
   */

  int __check_region(struct resource *parent, resource_size_t start,
  			resource_size_t n)

  {
  	struct resource * res;

  	res = __request_region(parent, start, n, "check-region", 0);

  	if (!res)
  		return -EBUSY;
  
  	release_resource(res);
  	kfree(res);
  	return 0;
  }

  EXPORT_SYMBOL(__check_region);

  /**
   * __release_region - release a previously reserved resource region
   * @parent: parent resource descriptor
   * @start: resource start address
   * @n: resource region size
   *
   * The described resource region must match a currently busy region.
   */

  void __release_region(struct resource *parent, resource_size_t start,
  			resource_size_t n)

  {
  	struct resource **p;

  	resource_size_t end;

  
  	p = &parent->child;
  	end = start + n - 1;
  
  	write_lock(&resource_lock);
  
  	for (;;) {
  		struct resource *res = *p;
  
  		if (!res)
  			break;
  		if (res->start <= start && res->end >= end) {
  			if (!(res->flags & IORESOURCE_BUSY)) {
  				p = &res->child;
  				continue;
  			}
  			if (res->start != start || res->end != end)
  				break;
  			*p = res->sibling;
  			write_unlock(&resource_lock);
  			kfree(res);
  			return;
  		}
  		p = &res->sibling;
  	}
  
  	write_unlock(&resource_lock);

  	printk(KERN_WARNING "Trying to free nonexistent resource "
  		"<%016llx-%016llx>
  ", (unsigned long long)start,
  		(unsigned long long)end);

  }

  EXPORT_SYMBOL(__release_region);
  
  /*

   * Managed region resource
   */
  struct region_devres {
  	struct resource *parent;
  	resource_size_t start;
  	resource_size_t n;
  };
  
  static void devm_region_release(struct device *dev, void *res)
  {
  	struct region_devres *this = res;
  
  	__release_region(this->parent, this->start, this->n);
  }
  
  static int devm_region_match(struct device *dev, void *res, void *match_data)
  {
  	struct region_devres *this = res, *match = match_data;
  
  	return this->parent == match->parent &&
  		this->start == match->start && this->n == match->n;
  }
  
  struct resource * __devm_request_region(struct device *dev,
  				struct resource *parent, resource_size_t start,
  				resource_size_t n, const char *name)
  {
  	struct region_devres *dr = NULL;
  	struct resource *res;
  
  	dr = devres_alloc(devm_region_release, sizeof(struct region_devres),
  			  GFP_KERNEL);
  	if (!dr)
  		return NULL;
  
  	dr->parent = parent;
  	dr->start = start;
  	dr->n = n;

  	res = __request_region(parent, start, n, name, 0);

  	if (res)
  		devres_add(dev, dr);
  	else
  		devres_free(dr);
  
  	return res;
  }
  EXPORT_SYMBOL(__devm_request_region);
  
  void __devm_release_region(struct device *dev, struct resource *parent,
  			   resource_size_t start, resource_size_t n)
  {
  	struct region_devres match_data = { parent, start, n };
  
  	__release_region(parent, start, n);
  	WARN_ON(devres_destroy(dev, devm_region_release, devm_region_match,
  			       &match_data));
  }
  EXPORT_SYMBOL(__devm_release_region);
  
  /*

   * Called from init/main.c to reserve IO ports.
   */
  #define MAXRESERVE 4
  static int __init reserve_setup(char *str)
  {
  	static int reserved;
  	static struct resource reserve[MAXRESERVE];
  
  	for (;;) {
  		int io_start, io_num;
  		int x = reserved;
  
  		if (get_option (&str, &io_start) != 2)
  			break;
  		if (get_option (&str, &io_num)   == 0)
  			break;
  		if (x < MAXRESERVE) {
  			struct resource *res = reserve + x;
  			res->name = "reserved";
  			res->start = io_start;
  			res->end = io_start + io_num - 1;
  			res->flags = IORESOURCE_BUSY;
  			res->child = NULL;
  			if (request_resource(res->start >= 0x10000 ? &iomem_resource : &ioport_resource, res) == 0)
  				reserved = x+1;
  		}
  	}
  	return 1;
  }
  
  __setup("reserve=", reserve_setup);

  
  /*
   * Check if the requested addr and size spans more than any slot in the
   * iomem resource tree.
   */
  int iomem_map_sanity_check(resource_size_t addr, unsigned long size)
  {
  	struct resource *p = &iomem_resource;
  	int err = 0;
  	loff_t l;
  
  	read_lock(&resource_lock);
  	for (p = p->child; p ; p = r_next(NULL, p, &l)) {
  		/*
  		 * We can probably skip the resources without
  		 * IORESOURCE_IO attribute?
  		 */
  		if (p->start >= addr + size)
  			continue;
  		if (p->end < addr)
  			continue;

  		if (PFN_DOWN(p->start) <= PFN_DOWN(addr) &&
  		    PFN_DOWN(p->end) >= PFN_DOWN(addr + size - 1))

  			continue;

  		/*
  		 * if a resource is "BUSY", it's not a hardware resource
  		 * but a driver mapping of such a resource; we don't want
  		 * to warn for those; some drivers legitimately map only
  		 * partial hardware resources. (example: vesafb)
  		 */
  		if (p->flags & IORESOURCE_BUSY)
  			continue;

  		printk(KERN_WARNING "resource map sanity check conflict: "
  		       "0x%llx 0x%llx 0x%llx 0x%llx %s
  ",

  		       (unsigned long long)addr,
  		       (unsigned long long)(addr + size - 1),
  		       (unsigned long long)p->start,
  		       (unsigned long long)p->end,
  		       p->name);

  		err = -1;
  		break;
  	}
  	read_unlock(&resource_lock);
  
  	return err;
  }

  
  #ifdef CONFIG_STRICT_DEVMEM
  static int strict_iomem_checks = 1;
  #else
  static int strict_iomem_checks;
  #endif
  
  /*
   * check if an address is reserved in the iomem resource tree
   * returns 1 if reserved, 0 if not reserved.
   */
  int iomem_is_exclusive(u64 addr)
  {
  	struct resource *p = &iomem_resource;
  	int err = 0;
  	loff_t l;
  	int size = PAGE_SIZE;
  
  	if (!strict_iomem_checks)
  		return 0;
  
  	addr = addr & PAGE_MASK;
  
  	read_lock(&resource_lock);
  	for (p = p->child; p ; p = r_next(NULL, p, &l)) {
  		/*
  		 * We can probably skip the resources without
  		 * IORESOURCE_IO attribute?
  		 */
  		if (p->start >= addr + size)
  			break;
  		if (p->end < addr)
  			continue;
  		if (p->flags & IORESOURCE_BUSY &&
  		     p->flags & IORESOURCE_EXCLUSIVE) {
  			err = 1;
  			break;
  		}
  	}
  	read_unlock(&resource_lock);
  
  	return err;
  }
  
  static int __init strict_iomem(char *str)
  {
  	if (strstr(str, "relaxed"))
  		strict_iomem_checks = 0;
  	if (strstr(str, "strict"))
  		strict_iomem_checks = 1;
  	return 1;
  }
  
  __setup("iomem=", strict_iomem);