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

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/export.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/sched.h>
#include <linux/seq_file.h>
#include <linux/device.h>
#include <linux/pfn.h>
#include <linux/mm.h>
#include <linux/resource_ext.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);

/* 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;
};

static DEFINE_RWLOCK(resource_lock);

/*
 * For memory hotplug, there is no way to free resource entries allocated
 * by boot mem after the system is up. So for reusing the resource entry
 * we need to remember the resource.
 */
static struct resource *bootmem_resource_free;
static DEFINE_SPINLOCK(bootmem_resource_lock);

static struct resource *next_resource(struct resource *p, bool sibling_only)
{
        /* Caller wants to traverse through siblings only */
        if (sibling_only)
                return p->sibling;

        if (p->child)
                return p->child;
        while (!p->sibling && p->parent)
                p = p->parent;
        return p->sibling;
}

static void *r_next(struct seq_file *m, void *v, loff_t *pos)
{
        struct resource *p = v;
        (*pos)++;
        return (void *)next_resource(p, false);
}

#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\n",
                        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 */

static void free_resource(struct resource *res)
{
        if (!res)
                return;

        if (!PageSlab(virt_to_head_page(res))) {
                spin_lock(&bootmem_resource_lock);
                res->sibling = bootmem_resource_free;
                bootmem_resource_free = res;
                spin_unlock(&bootmem_resource_lock);
        } else {
                kfree(res);
        }
}

static struct resource *alloc_resource(gfp_t flags)
{
        struct resource *res = NULL;

        spin_lock(&bootmem_resource_lock);
        if (bootmem_resource_free) {
                res = bootmem_resource_free;
                bootmem_resource_free = res->sibling;
        }
        spin_unlock(&bootmem_resource_lock);

        if (res)
                memset(res, 0, sizeof(struct resource));
        else
                res = kzalloc(sizeof(struct resource), flags);

        return res;
}

/* 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;
}

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

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);

/*
 * Finds the lowest iomem reosurce exists with-in [res->start.res->end)
 * the caller must specify res->start, res->end, res->flags and "name".
 * If found, returns 0, res is overwritten, if not found, returns -1.
 * This walks through whole tree and not just first level children
 * until and unless first_level_children_only is true.
 */
static int find_next_iomem_res(struct resource *res, char *name,
                               bool first_level_children_only)
{
        resource_size_t start, end;
        struct resource *p;
        bool sibling_only = false;

        BUG_ON(!res);

        start = res->start;
        end = res->end;
        BUG_ON(start >= end);

        if (first_level_children_only)
                sibling_only = true;

        read_lock(&resource_lock);

        for (p = iomem_resource.child; p; p = next_resource(p, sibling_only)) {
                if (p->flags != res->flags)
                        continue;
                if (name && strcmp(p->name, name))
                        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;
}

/*
 * Walks through iomem resources and calls func() with matching resource
 * ranges. This walks through whole tree and not just first level children.
 * All the memory ranges which overlap start,end and also match flags and
 * name are valid candidates.
 *
 * @name: name of resource
 * @flags: resource flags
 * @start: start addr
 * @end: end addr
 */
int walk_iomem_res(char *name, unsigned long flags, u64 start, u64 end,
                void *arg, int (*func)(u64, u64, void *))
{
        struct resource res;
        u64 orig_end;
        int ret = -1;

        res.start = start;
        res.end = end;
        res.flags = flags;
        orig_end = res.end;
        while ((res.start < res.end) &&
                (!find_next_iomem_res(&res, name, false))) {
                ret = (*func)(res.start, res.end, arg);
                if (ret)
                        break;
                res.start = res.end + 1;
                res.end = orig_end;
        }
        return ret;
}

/*
 * 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". This function deals with
 * full ranges and not pfn. If resources are not pfn aligned, dealing
 * with pfn can truncate ranges.
 */
int walk_system_ram_res(u64 start, u64 end, void *arg,
                                int (*func)(u64, u64, void *))
{
        struct resource res;
        u64 orig_end;
        int ret = -1;

        res.start = start;
        res.end = end;
        res.flags = IORESOURCE_MEM | IORESOURCE_BUSY;
        orig_end = res.end;
        while ((res.start < res.end) &&
                (!find_next_iomem_res(&res, "System RAM", true))) {
                ret = (*func)(res.start, res.end, arg);
                if (ret)
                        break;
                res.start = res.end + 1;
                res.end = orig_end;
        }
        return ret;
}

#if !defined(CONFIG_ARCH_HAS_WALK_MEMORY)

/*
 * 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, 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_iomem_res(&res, "System RAM", true) >= 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;
                res.end = orig_end;
        }
        return ret;
}

#endif

static int __is_ram(unsigned long pfn, unsigned long nr_pages, void *arg)
{
        return 1;
}
/*
 * This generic page_is_ram() returns true if specified address is
 * registered as "System RAM" in iomem_resource list.
 */
int __weak page_is_ram(unsigned long pfn)
{
        return walk_system_ram_range(pfn, 1, NULL, __is_ram) == 1;
}
EXPORT_SYMBOL_GPL(page_is_ram);

/**
 * region_intersects() - determine intersection of region with known resources
 * @start: region start address
 * @size: size of region
 * @name: name of resource (in iomem_resource)
 *
 * Check if the specified region partially overlaps or fully eclipses a
 * resource identified by @name.  Return REGION_DISJOINT if the region
 * does not overlap @name, return REGION_MIXED if the region overlaps
 * @type and another resource, and return REGION_INTERSECTS if the
 * region overlaps @type and no other defined resource. Note, that
 * REGION_INTERSECTS is also returned in the case when the specified
 * region overlaps RAM and undefined memory holes.
 *
 * region_intersect() is used by memory remapping functions to ensure
 * the user is not remapping RAM and is a vast speed up over walking
 * through the resource table page by page.
 */
int region_intersects(resource_size_t start, size_t size, const char *name)
{
        unsigned long flags = IORESOURCE_MEM | IORESOURCE_BUSY;
        resource_size_t end = start + size - 1;
        int type = 0; int other = 0;
        struct resource *p;

        read_lock(&resource_lock);
        for (p = iomem_resource.child; p ; p = p->sibling) {
                bool is_type = strcmp(p->name, name) == 0 && p->flags == flags;

                if (start >= p->start && start <= p->end)
                        is_type ? type++ : other++;
                if (end >= p->start && end <= p->end)
                        is_type ? type++ : other++;
                if (p->start >= start && p->end <= end)
                        is_type ? type++ : other++;
        }
        read_unlock(&resource_lock);

        if (other == 0)
                return type ? REGION_INTERSECTS : REGION_DISJOINT;

        if (type)
                return REGION_MIXED;

        return REGION_DISJOINT;
}

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;
}

/*
 * 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;

        tmp.start = root->start;
        /*
         * Skip past an allocated resource that starts at 0, since the assignment
         * of this->start - 1 to tmp->end below would cause an underflow.
         */
        if (this && this->start == root->start) {
                tmp.start = (this == old) ? old->start : this->end + 1;
                this = this->sibling;
        }
        for(;;) {
                if (this)
                        tmp.end = (this == old) ?  this->end : this->start - 1;
                else
                        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.start = ALIGN(tmp.start, constraint->align);
                avail.end = tmp.end;
                avail.flags = new->flags & ~IORESOURCE_UNSET;
                if (avail.start >= tmp.start) {
                        alloc.flags = avail.flags;
                        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;
                        }
                }

next:           if (!this || this->end == root->end)
                        break;

                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.
 */
static 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.
 *      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
 * @min: minimum boundary to allocate
 * @max: maximum boundary 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,
                      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, &constraint);
        if (err >= 0 && __request_resource(root, new))
                err = -EBUSY;
        write_unlock(&resource_lock);
        return err;
}

EXPORT_SYMBOL(allocate_resource);

/**
 * lookup_resource - find an existing resource by a resource start address
 * @root: root resource descriptor
 * @start: resource start address
 *
 * Returns a pointer to the resource if found, NULL otherwise
 */
struct resource *lookup_resource(struct resource *root, resource_size_t start)
{
        struct resource *res;

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

                if (first == parent)
                        return first;
                if (WARN_ON(first == new))      /* duplicated insertion */
                        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_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);
}

static 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;

        if (!parent)
                goto skip;

        if ((start < parent->start) || (end > parent->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;
        }

skip:
        for (tmp = res->child; tmp; tmp = tmp->sibling)
                if ((tmp->start < start) || (tmp->end > end))
                        goto out;

        res->start = start;
        res->end = end;
        result = 0;

 out:
        return result;
}

/**
 * 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)
{
        int result;

        write_lock(&resource_lock);
        result = __adjust_resource(res, start, size);
        write_unlock(&resource_lock);
        return result;
}
EXPORT_SYMBOL(adjust_resource);

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 = alloc_resource(GFP_ATOMIC);
        struct resource *next_res = NULL;

        if (!res)
                return;

        res->name = name;
        res->start = start;
        res->end = end;
        res->flags = IORESOURCE_BUSY;

        while (1) {

                conflict = __request_resource(parent, res);
                if (!conflict) {
                        if (!next_res)
                                break;
                        res = next_res;
                        next_res = NULL;
                        continue;
                }

                /* conflict covered whole area */
                if (conflict->start <= res->start &&
                                conflict->end >= res->end) {
                        free_resource(res);
                        WARN_ON(next_res);
                        break;
                }

                /* failed, split and try again */
                if (conflict->start > res->start) {
                        end = res->end;
                        res->end = conflict->start - 1;
                        if (conflict->end < end) {
                                next_res = alloc_resource(GFP_ATOMIC);
                                if (!next_res) {
                                        free_resource(res);
                                        break;
                                }
                                next_res->name = name;
                                next_res->start = conflict->end + 1;
                                next_res->end = end;
                                next_res->flags = IORESOURCE_BUSY;
                        }
                } else {
                        res->start = conflict->end + 1;
                }
        }

}

void __init reserve_region_with_split(struct resource *root,
                resource_size_t start, resource_size_t end,
                const char *name)
{
        int abort = 0;

        write_lock(&resource_lock);
        if (root->start > start || root->end < end) {

                pr_err("requested range [0x%llx-0x%llx] not in root %pr\n",
                       (unsigned long long)start, (unsigned long long)end,
                       root);
                if (start > root->end || end < root->start)
                        abort = 1;
                else {
                        if (end > root->end)
                                end = root->end;
                        if (start < root->start)
                                start = root->start;
                        pr_err("fixing request to [0x%llx-0x%llx]\n",
                               (unsigned long long)start,
                               (unsigned long long)end);
                }
                dump_stack();
        }
        if (!abort)
                __reserve_region_with_split(root, start, end, name);
        write_unlock(&resource_lock);
}

/**
 * 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.
 *
 * 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, int flags)
{
        DECLARE_WAITQUEUE(wait, current);
        struct resource *res = alloc_resource(GFP_KERNEL);

        if (!res)
                return NULL;

        res->name = name;
        res->start = start;
        res->end = start + n - 1;
        res->flags = resource_type(parent);
        res->flags |= IORESOURCE_BUSY | 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;
                }
                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;
                }
                /* Uhhuh, that didn't work out.. */
                free_resource(res);
                res = NULL;
                break;
        }
        write_unlock(&resource_lock);
        return res;
}
EXPORT_SYMBOL(__request_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);
                        if (res->flags & IORESOURCE_MUXED)
                                wake_up(&muxed_resource_wait);
                        free_resource(res);
                        return;
                }
                p = &res->sibling;
        }

        write_unlock(&resource_lock);

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

#ifdef CONFIG_MEMORY_HOTREMOVE
/**
 * release_mem_region_adjustable - release a previously reserved memory region
 * @parent: parent resource descriptor
 * @start: resource start address
 * @size: resource region size
 *
 * This interface is intended for memory hot-delete.  The requested region
 * is released from a currently busy memory resource.  The requested region
 * must either match exactly or fit into a single busy resource entry.  In
 * the latter case, the remaining resource is adjusted accordingly.
 * Existing children of the busy memory resource must be immutable in the
 * request.
 *
 * Note:
 * - Additional release conditions, such as overlapping region, can be
 *   supported after they are confirmed as valid cases.
 * - When a busy memory resource gets split into two entries, the code
 *   assumes that all children remain in the lower address entry for
 *   simplicity.  Enhance this logic when necessary.
 */
int release_mem_region_adjustable(struct resource *parent,
                        resource_size_t start, resource_size_t size)
{
        struct resource **p;
        struct resource *res;
        struct resource *new_res;
        resource_size_t end;
        int ret = -EINVAL;

        end = start + size - 1;
        if ((start < parent->start) || (end > parent->end))
                return ret;

        /* The alloc_resource() result gets checked later */
        new_res = alloc_resource(GFP_KERNEL);

        p = &parent->child;
        write_lock(&resource_lock);

        while ((res = *p)) {
                if (res->start >= end)
                        break;

                /* look for the next resource if it does not fit into */
                if (res->start > start || res->end < end) {
                        p = &res->sibling;
                        continue;
                }

                if (!(res->flags & IORESOURCE_MEM))
                        break;

                if (!(res->flags & IORESOURCE_BUSY)) {
                        p = &res->child;
                        continue;
                }

                /* found the target resource; let's adjust accordingly */
                if (res->start == start && res->end == end) {
                        /* free the whole entry */
                        *p = res->sibling;
                        free_resource(res);
                        ret = 0;
                } else if (res->start == start && res->end != end) {
                        /* adjust the start */
                        ret = __adjust_resource(res, end + 1,
                                                res->end - end);
                } else if (res->start != start && res->end == end) {
                        /* adjust the end */
                        ret = __adjust_resource(res, res->start,
                                                start - res->start);
                } else {
                        /* split into two entries */
                        if (!new_res) {
                                ret = -ENOMEM;
                                break;
                        }
                        new_res->name = res->name;
                        new_res->start = end + 1;
                        new_res->end = res->end;
                        new_res->flags = res->flags;
                        new_res->parent = res->parent;
                        new_res->sibling = res->sibling;
                        new_res->child = NULL;

                        ret = __adjust_resource(res, res->start,
                                                start - res->start);
                        if (ret)
                                break;
                        res->sibling = new_res;
                        new_res = NULL;
                }

                break;
        }

        write_unlock(&resource_lock);
        free_resource(new_res);
        return ret;
}
#endif  /* CONFIG_MEMORY_HOTREMOVE */

/*
 * Managed region resource
 */
static void devm_resource_release(struct device *dev, void *ptr)
{
        struct resource **r = ptr;

        release_resource(*r);
}

/**
 * devm_request_resource() - request and reserve an I/O or memory resource
 * @dev: device for which to request the resource
 * @root: root of the resource tree from which to request the resource
 * @new: descriptor of the resource to request
 *
 * This is a device-managed version of request_resource(). There is usually
 * no need to release resources requested by this function explicitly since
 * that will be taken care of when the device is unbound from its driver.
 * If for some reason the resource needs to be released explicitly, because
 * of ordering issues for example, drivers must call devm_release_resource()
 * rather than the regular release_resource().
 *
 * When a conflict is detected between any existing resources and the newly
 * requested resource, an error message will be printed.
 *
 * Returns 0 on success or a negative error code on failure.
 */
int devm_request_resource(struct device *dev, struct resource *root,
                          struct resource *new)
{
        struct resource *conflict, **ptr;

        ptr = devres_alloc(devm_resource_release, sizeof(*ptr), GFP_KERNEL);
        if (!ptr)
                return -ENOMEM;

        *ptr = new;

        conflict = request_resource_conflict(root, new);
        if (conflict) {
                dev_err(dev, "resource collision: %pR conflicts with %s %pR\n",
                        new, conflict->name, conflict);
                devres_free(ptr);
                return -EBUSY;
        }

        devres_add(dev, ptr);
        return 0;
}
EXPORT_SYMBOL(devm_request_resource);

static int devm_resource_match(struct device *dev, void *res, void *data)
{
        struct resource **ptr = res;

        return *ptr == data;
}

/**
 * devm_release_resource() - release a previously requested resource
 * @dev: device for which to release the resource
 * @new: descriptor of the resource to release
 *
 * Releases a resource previously requested using devm_request_resource().
 */
void devm_release_resource(struct device *dev, struct resource *new)
{
        WARN_ON(devres_release(dev, devm_resource_release, devm_resource_match,
                               new));
}
EXPORT_SYMBOL(devm_release_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 (;;) {
                unsigned 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 sanity check: requesting [mem %#010llx-%#010llx], which spans more than %s %pR\n",
                       (unsigned long long)addr,
                       (unsigned long long)(addr + size - 1),
                       p->name, p);
                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;
}

struct resource_entry *resource_list_create_entry(struct resource *res,
                                                  size_t extra_size)
{
        struct resource_entry *entry;

        entry = kzalloc(sizeof(*entry) + extra_size, GFP_KERNEL);
        if (entry) {
                INIT_LIST_HEAD(&entry->node);
                entry->res = res ? res : &entry->__res;
        }

        return entry;
}
EXPORT_SYMBOL(resource_list_create_entry);

void resource_list_free(struct list_head *head)
{
        struct resource_entry *entry, *tmp;

        list_for_each_entry_safe(entry, tmp, head, node)
                resource_list_destroy_entry(entry);
}
EXPORT_SYMBOL(resource_list_free);

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);