module: replace DEBUGP with pr_debug
[linux-3.10.git] / kernel / resource.c
index cee12cc..7640b3a 100644 (file)
@@ -7,7 +7,7 @@
  * Arbitrary resource management.
  */
 
-#include <linux/module.h>
+#include <linux/export.h>
 #include <linux/errno.h>
 #include <linux/ioport.h>
 #include <linux/init.h>
 #include <linux/spinlock.h>
 #include <linux/fs.h>
 #include <linux/proc_fs.h>
+#include <linux/sched.h>
 #include <linux/seq_file.h>
 #include <linux/device.h>
+#include <linux/pfn.h>
 #include <asm/io.h>
 
 
@@ -36,11 +38,15 @@ struct resource iomem_resource = {
 };
 EXPORT_SYMBOL(iomem_resource);
 
-static DEFINE_RWLOCK(resource_lock);
-
-#ifdef CONFIG_PROC_FS
+/* constraints to be met while allocating resources */
+struct resource_constraint {
+       resource_size_t min, max, align;
+       resource_size_t (*alignf)(void *, const struct resource *,
+                       resource_size_t, resource_size_t);
+       void *alignf_data;
+};
 
-enum { MAX_IORES_LEVEL = 5 };
+static DEFINE_RWLOCK(resource_lock);
 
 static void *r_next(struct seq_file *m, void *v, loff_t *pos)
 {
@@ -53,6 +59,10 @@ static void *r_next(struct seq_file *m, void *v, loff_t *pos)
        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)
 {
@@ -131,14 +141,8 @@ static const struct file_operations proc_iomem_operations = {
 
 static int __init ioresources_init(void)
 {
-       struct proc_dir_entry *entry;
-
-       entry = create_proc_entry("ioports", 0, NULL);
-       if (entry)
-               entry->proc_fops = &proc_ioports_operations;
-       entry = create_proc_entry("iomem", 0, NULL);
-       if (entry)
-               entry->proc_fops = &proc_iomem_operations;
+       proc_create("ioports", 0, NULL, &proc_ioports_operations);
+       proc_create("iomem", 0, NULL, &proc_iomem_operations);
        return 0;
 }
 __initcall(ioresources_init);
@@ -193,20 +197,65 @@ static int __release_resource(struct resource *old)
        return -EINVAL;
 }
 
+static void __release_child_resources(struct resource *r)
+{
+       struct resource *tmp, *p;
+       resource_size_t size;
+
+       p = r->child;
+       r->child = NULL;
+       while (p) {
+               tmp = p;
+               p = p->sibling;
+
+               tmp->parent = NULL;
+               tmp->sibling = NULL;
+               __release_child_resources(tmp);
+
+               printk(KERN_DEBUG "release child resource %pR\n", tmp);
+               /* need to restore size, and keep flags */
+               size = resource_size(tmp);
+               tmp->start = 0;
+               tmp->end = size - 1;
+       }
+}
+
+void release_child_resources(struct resource *r)
+{
+       write_lock(&resource_lock);
+       __release_child_resources(r);
+       write_unlock(&resource_lock);
+}
+
 /**
- * request_resource - request and reserve an I/O or memory resource
+ * request_resource_conflict - 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.
+ * Returns 0 for success, conflict resource on error.
  */
-int request_resource(struct resource *root, struct resource *new)
+struct resource *request_resource_conflict(struct resource *root, struct resource *new)
 {
        struct resource *conflict;
 
        write_lock(&resource_lock);
        conflict = __request_resource(root, new);
        write_unlock(&resource_lock);
+       return conflict;
+}
+
+/**
+ * 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;
+
+       conflict = request_resource_conflict(root, new);
        return conflict ? -EBUSY : 0;
 }
 
@@ -228,13 +277,13 @@ int release_resource(struct resource *old)
 
 EXPORT_SYMBOL(release_resource);
 
-#if defined(CONFIG_MEMORY_HOTPLUG) && !defined(CONFIG_ARCH_HAS_WALK_MEMORY)
+#if !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.
+ * the caller must specify res->start, res->end, res->flags and "name".
  * If found, returns 0, res is overwritten, if not found, returns -1.
  */
-static int find_next_system_ram(struct resource *res)
+static int find_next_system_ram(struct resource *res, char *name)
 {
        resource_size_t start, end;
        struct resource *p;
@@ -250,6 +299,8 @@ static int find_next_system_ram(struct resource *res)
                /* system ram is just marked as IORESOURCE_MEM */
                if (p->flags != res->flags)
                        continue;
+               if (name && strcmp(p->name, name))
+                       continue;
                if (p->start > end) {
                        p = NULL;
                        break;
@@ -267,22 +318,30 @@ static int find_next_system_ram(struct resource *res)
                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 *))
+
+/*
+ * This function calls callback against all memory range of "System RAM"
+ * which are marked as IORESOURCE_MEM and IORESOUCE_BUSY.
+ * Now, this function is only for "System RAM".
+ */
+int walk_system_ram_range(unsigned long start_pfn, unsigned long nr_pages,
+               void *arg, int (*func)(unsigned long, unsigned long, void *))
 {
        struct resource res;
-       unsigned long pfn, len;
+       unsigned long pfn, end_pfn;
        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);
+       while ((res.start < res.end) &&
+               (find_next_system_ram(&res, "System RAM") >= 0)) {
+               pfn = (res.start + PAGE_SIZE - 1) >> PAGE_SHIFT;
+               end_pfn = (res.end + 1) >> PAGE_SHIFT;
+               if (end_pfn > pfn)
+                       ret = (*func)(pfn, end_pfn - pfn, arg);
                if (ret)
                        break;
                res.start = res.end + 1;
@@ -293,53 +352,166 @@ walk_memory_resource(unsigned long start_pfn, unsigned long nr_pages, void *arg,
 
 #endif
 
+static int __is_ram(unsigned long pfn, unsigned long nr_pages, void *arg)
+{
+       return 1;
+}
 /*
- * Find empty slot in the resource tree given range and alignment.
+ * This generic page_is_ram() returns true if specified address is
+ * registered as "System RAM" in iomem_resource list.
  */
-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)
+int __weak page_is_ram(unsigned long pfn)
+{
+       return walk_system_ram_range(pfn, 1, NULL, __is_ram) == 1;
+}
+
+void __weak arch_remove_reservations(struct resource *avail)
+{
+}
+
+static resource_size_t simple_align_resource(void *data,
+                                            const struct resource *avail,
+                                            resource_size_t size,
+                                            resource_size_t align)
+{
+       return avail->start;
+}
+
+static void resource_clip(struct resource *res, resource_size_t min,
+                         resource_size_t max)
+{
+       if (res->start < min)
+               res->start = min;
+       if (res->end > max)
+               res->end = max;
+}
+
+static bool resource_contains(struct resource *res1, struct resource *res2)
+{
+       return res1->start <= res2->start && res1->end >= res2->end;
+}
+
+/*
+ * Find empty slot in the resource tree with the given range and
+ * alignment constraints
+ */
+static int __find_resource(struct resource *root, struct resource *old,
+                        struct resource *new,
+                        resource_size_t  size,
+                        struct resource_constraint *constraint)
 {
        struct resource *this = root->child;
+       struct resource tmp = *new, avail, alloc;
 
-       new->start = root->start;
+       tmp.flags = new->flags;
+       tmp.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.
+        * of this->start - 1 to tmp->end below would cause an underflow.
         */
-       if (this && this->start == 0) {
-               new->start = this->end + 1;
+       if (this && this->start == root->start) {
+               tmp.start = (this == old) ? old->start : this->end + 1;
                this = this->sibling;
        }
        for(;;) {
                if (this)
-                       new->end = this->start - 1;
+                       tmp.end = (this == old) ?  this->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;
+                       tmp.end = root->end;
+
+               if (tmp.end < tmp.start)
+                       goto next;
+
+               resource_clip(&tmp, constraint->min, constraint->max);
+               arch_remove_reservations(&tmp);
+
+               /* Check for overflow after ALIGN() */
+               avail = *new;
+               avail.start = ALIGN(tmp.start, constraint->align);
+               avail.end = tmp.end;
+               if (avail.start >= tmp.start) {
+                       alloc.start = constraint->alignf(constraint->alignf_data, &avail,
+                                       size, constraint->align);
+                       alloc.end = alloc.start + size - 1;
+                       if (resource_contains(&avail, &alloc)) {
+                               new->start = alloc.start;
+                               new->end = alloc.end;
+                               return 0;
+                       }
                }
-               if (!this)
+
+next:          if (!this || this->end == root->end)
                        break;
-               new->start = this->end + 1;
+
+               if (this != old)
+                       tmp.start = this->end + 1;
                this = this->sibling;
        }
        return -EBUSY;
 }
 
+/*
+ * 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,
+                       struct resource_constraint  *constraint)
+{
+       return  __find_resource(root, NULL, new, size, constraint);
+}
+
+/**
+ * reallocate_resource - allocate a slot in the resource tree given range & alignment.
+ *     The resource will be relocated if the new size cannot be reallocated in the
+ *     current location.
+ *
+ * @root: root resource descriptor
+ * @old:  resource descriptor desired by caller
+ * @newsize: new size of the resource descriptor
+ * @constraint: the size and alignment constraints to be met.
+ */
+int reallocate_resource(struct resource *root, struct resource *old,
+                       resource_size_t newsize,
+                       struct resource_constraint  *constraint)
+{
+       int err=0;
+       struct resource new = *old;
+       struct resource *conflict;
+
+       write_lock(&resource_lock);
+
+       if ((err = __find_resource(root, old, &new, newsize, constraint)))
+               goto out;
+
+       if (resource_contains(&new, old)) {
+               old->start = new.start;
+               old->end = new.end;
+               goto out;
+       }
+
+       if (old->child) {
+               err = -EBUSY;
+               goto out;
+       }
+
+       if (resource_contains(old, &new)) {
+               old->start = new.start;
+               old->end = new.end;
+       } else {
+               __release_resource(old);
+               *old = new;
+               conflict = __request_resource(root, old);
+               BUG_ON(conflict);
+       }
+out:
+       write_unlock(&resource_lock);
+       return err;
+}
+
+
 /**
- * allocate_resource - allocate empty slot in the resource tree given range & alignment
+ * allocate_resource - allocate empty slot in the resource tree given range & alignment.
+ *     The resource will be reallocated with a new size if it was already allocated
  * @root: root resource descriptor
  * @new: resource descriptor desired by caller
  * @size: requested resource region size
@@ -352,14 +524,32 @@ static int find_resource(struct resource *root, struct resource *new,
 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),
+                     resource_size_t (*alignf)(void *,
+                                               const struct resource *,
+                                               resource_size_t,
+                                               resource_size_t),
                      void *alignf_data)
 {
        int err;
+       struct resource_constraint constraint;
+
+       if (!alignf)
+               alignf = simple_align_resource;
+
+       constraint.min = min;
+       constraint.max = max;
+       constraint.align = align;
+       constraint.alignf = alignf;
+       constraint.alignf_data = alignf_data;
+
+       if ( new->parent ) {
+               /* resource is already allocated, try reallocating with
+                  the new constraints */
+               return reallocate_resource(root, new, size, &constraint);
+       }
 
        write_lock(&resource_lock);
-       err = find_resource(root, new, size, min, max, align, alignf, alignf_data);
+       err = find_resource(root, new, size, &constraint);
        if (err >= 0 && __request_resource(root, new))
                err = -EBUSY;
        write_unlock(&resource_lock);
@@ -369,34 +559,43 @@ int allocate_resource(struct resource *root, struct resource *new,
 EXPORT_SYMBOL(allocate_resource);
 
 /**
- * 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.
+ * lookup_resource - find an existing resource by a resource start address
+ * @root: root resource descriptor
+ * @start: resource start address
  *
- * 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.
+ * Returns a pointer to the resource if found, NULL otherwise
  */
-int insert_resource(struct resource *parent, struct resource *new)
+struct resource *lookup_resource(struct resource *root, resource_size_t start)
 {
-       int result;
-       struct resource *first, *next;
+       struct resource *res;
 
-       write_lock(&resource_lock);
+       read_lock(&resource_lock);
+       for (res = root->child; res; res = res->sibling) {
+               if (res->start == start)
+                       break;
+       }
+       read_unlock(&resource_lock);
+
+       return res;
+}
+
+/*
+ * 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) {
-               result = 0;
                first = __request_resource(parent, new);
                if (!first)
-                       goto out;
+                       return first;
 
-               result = -EBUSY;
                if (first == parent)
-                       goto out;
+                       return first;
+               if (WARN_ON(first == new))      /* duplicated insertion */
+                       return first;
 
                if ((first->start > new->start) || (first->end < new->end))
                        break;
@@ -407,15 +606,13 @@ int insert_resource(struct resource *parent, struct resource *new)
        for (next = first; ; next = next->sibling) {
                /* Partial overlap? Bad, and unfixable */
                if (next->start < new->start || next->end > new->end)
-                       goto out;
+                       return next;
                if (!next->sibling)
                        break;
                if (next->sibling->start > new->end)
                        break;
        }
 
-       result = 0;
-
        new->parent = parent;
        new->sibling = next->sibling;
        new->child = first;
@@ -432,10 +629,79 @@ int insert_resource(struct resource *parent, struct resource *new)
                        next = next->sibling;
                next->sibling = new;
        }
+       return NULL;
+}
 
- out:
+/**
+ * insert_resource_conflict - Inserts resource in the resource tree
+ * @parent: parent of the new resource
+ * @new: new resource to insert
+ *
+ * Returns 0 on success, conflict resource if the resource can't be inserted.
+ *
+ * This function is equivalent to request_resource_conflict 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.
+ */
+struct resource *insert_resource_conflict(struct resource *parent, struct resource *new)
+{
+       struct resource *conflict;
+
+       write_lock(&resource_lock);
+       conflict = __insert_resource(parent, new);
+       write_unlock(&resource_lock);
+       return conflict;
+}
+
+/**
+ * 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.
+ */
+int insert_resource(struct resource *parent, struct resource *new)
+{
+       struct resource *conflict;
+
+       conflict = insert_resource_conflict(parent, new);
+       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\n", new->name, conflict->name);
+       }
        write_unlock(&resource_lock);
-       return result;
 }
 
 /**
@@ -484,6 +750,48 @@ int adjust_resource(struct resource *res, resource_size_t start, resource_size_t
        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;
+
+       conflict = __request_resource(parent, res);
+       if (!conflict)
+               return;
+
+       /* failed, split and try again */
+       kfree(res);
+
+       /* 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->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);
 
 /**
@@ -496,7 +804,7 @@ resource_size_t resource_alignment(struct resource *res)
 {
        switch (res->flags & (IORESOURCE_SIZEALIGN | IORESOURCE_STARTALIGN)) {
        case IORESOURCE_SIZEALIGN:
-               return res->end - res->start + 1;
+               return resource_size(res);
        case IORESOURCE_STARTALIGN:
                return res->start;
        default:
@@ -517,46 +825,60 @@ resource_size_t resource_alignment(struct resource *res)
  * release_region releases a matching busy region.
  */
 
+static DECLARE_WAIT_QUEUE_HEAD(muxed_resource_wait);
+
 /**
  * __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)
+                                  const char *name, int flags)
 {
+       DECLARE_WAITQUEUE(wait, current);
        struct resource *res = kzalloc(sizeof(*res), GFP_KERNEL);
 
-       if (res) {
-               res->name = name;
-               res->start = start;
-               res->end = start + n - 1;
-               res->flags = IORESOURCE_BUSY;
+       if (!res)
+               return NULL;
 
-               write_lock(&resource_lock);
+       res->name = name;
+       res->start = start;
+       res->end = start + n - 1;
+       res->flags = IORESOURCE_BUSY;
+       res->flags |= flags;
 
-               for (;;) {
-                       struct resource *conflict;
+       write_lock(&resource_lock);
 
-                       conflict = __request_resource(parent, res);
-                       if (!conflict)
-                               break;
-                       if (conflict != parent) {
-                               parent = conflict;
-                               if (!(conflict->flags & IORESOURCE_BUSY))
-                                       continue;
-                       }
+       for (;;) {
+               struct resource *conflict;
 
-                       /* Uhhuh, that didn't work out.. */
-                       kfree(res);
-                       res = NULL;
+               conflict = __request_resource(parent, res);
+               if (!conflict)
                        break;
+               if (conflict != parent) {
+                       parent = conflict;
+                       if (!(conflict->flags & IORESOURCE_BUSY))
+                               continue;
+               }
+               if (conflict->flags & flags & IORESOURCE_MUXED) {
+                       add_wait_queue(&muxed_resource_wait, &wait);
+                       write_unlock(&resource_lock);
+                       set_current_state(TASK_UNINTERRUPTIBLE);
+                       schedule();
+                       remove_wait_queue(&muxed_resource_wait, &wait);
+                       write_lock(&resource_lock);
+                       continue;
                }
-               write_unlock(&resource_lock);
+               /* Uhhuh, that didn't work out.. */
+               kfree(res);
+               res = NULL;
+               break;
        }
+       write_unlock(&resource_lock);
        return res;
 }
 EXPORT_SYMBOL(__request_region);
@@ -581,7 +903,7 @@ int __check_region(struct resource *parent, resource_size_t start,
 {
        struct resource * res;
 
-       res = __request_region(parent, start, n, "check-region");
+       res = __request_region(parent, start, n, "check-region", 0);
        if (!res)
                return -EBUSY;
 
@@ -624,6 +946,8 @@ void __release_region(struct resource *parent, resource_size_t start,
                                break;
                        *p = res->sibling;
                        write_unlock(&resource_lock);
+                       if (res->flags & IORESOURCE_MUXED)
+                               wake_up(&muxed_resource_wait);
                        kfree(res);
                        return;
                }
@@ -678,7 +1002,7 @@ struct resource * __devm_request_region(struct device *dev,
        dr->start = start;
        dr->n = n;
 
-       res = __request_region(parent, start, n, name);
+       res = __request_region(parent, start, n, name, 0);
        if (res)
                devres_add(dev, dr);
        else
@@ -709,7 +1033,7 @@ static int __init reserve_setup(char *str)
        static struct resource reserve[MAXRESERVE];
 
        for (;;) {
-               int io_start, io_num;
+               unsigned int io_start, io_num;
                int x = reserved;
 
                if (get_option (&str, &io_start) != 2)
@@ -731,3 +1055,104 @@ static int __init reserve_setup(char *str)
 }
 
 __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\n",
+                      (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);