/*
 * Copyright 2012 Red Hat Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 *
 * Authors: Ben Skeggs
 */

#include "core/os.h"
#include "core/mm.h"

#define node(root, dir) ((root)->nl_entry.dir == &mm->nodes) ? NULL : \
        list_entry((root)->nl_entry.dir, struct nouveau_mm_node, nl_entry)

void
nouveau_mm_free(struct nouveau_mm *mm, struct nouveau_mm_node **pthis)
{
        struct nouveau_mm_node *this = *pthis;

        if (this) {
                struct nouveau_mm_node *prev = node(this, prev);
                struct nouveau_mm_node *next = node(this, next);

                if (prev && prev->type == 0) {
                        prev->length += this->length;
                        list_del(&this->nl_entry);
                        kfree(this); this = prev;
                }

                if (next && next->type == 0) {
                        next->offset  = this->offset;
                        next->length += this->length;
                        if (this->type == 0)
                                list_del(&this->fl_entry);
                        list_del(&this->nl_entry);
                        kfree(this); this = NULL;
                }

                if (this && this->type != 0) {
                        list_for_each_entry(prev, &mm->free, fl_entry) {
                                if (this->offset < prev->offset)
                                        break;
                        }

                        list_add_tail(&this->fl_entry, &prev->fl_entry);
                        this->type = 0;
                }
        }

        *pthis = NULL;
}

static struct nouveau_mm_node *
region_head(struct nouveau_mm *mm, struct nouveau_mm_node *a, u32 size)
{
        struct nouveau_mm_node *b;

        if (a->length == size)
                return a;

        b = kmalloc(sizeof(*b), GFP_KERNEL);
        if (unlikely(b == NULL))
                return NULL;

        b->offset = a->offset;
        b->length = size;
        b->type   = a->type;
        a->offset += size;
        a->length -= size;
        list_add_tail(&b->nl_entry, &a->nl_entry);
        if (b->type == 0)
                list_add_tail(&b->fl_entry, &a->fl_entry);
        return b;
}

int
nouveau_mm_head(struct nouveau_mm *mm, u8 type, u32 size_max, u32 size_min,
                u32 align, struct nouveau_mm_node **pnode)
{
        struct nouveau_mm_node *prev, *this, *next;
        u32 mask = align - 1;
        u32 splitoff;
        u32 s, e;

        BUG_ON(!type);

        list_for_each_entry(this, &mm->free, fl_entry) {
                e = this->offset + this->length;
                s = this->offset;

                prev = node(this, prev);
                if (prev && prev->type != type)
                        s = roundup(s, mm->block_size);

                next = node(this, next);
                if (next && next->type != type)
                        e = rounddown(e, mm->block_size);

                s  = (s + mask) & ~mask;
                e &= ~mask;
                if (s > e || e - s < size_min)
                        continue;

                splitoff = s - this->offset;
                if (splitoff && !region_head(mm, this, splitoff))
                        return -ENOMEM;

                this = region_head(mm, this, min(size_max, e - s));
                if (!this)
                        return -ENOMEM;

                this->type = type;
                list_del(&this->fl_entry);
                *pnode = this;
                return 0;
        }

        return -ENOSPC;
}

static struct nouveau_mm_node *
region_tail(struct nouveau_mm *mm, struct nouveau_mm_node *a, u32 size)
{
        struct nouveau_mm_node *b;

        if (a->length == size)
                return a;

        b = kmalloc(sizeof(*b), GFP_KERNEL);
        if (unlikely(b == NULL))
                return NULL;

        a->length -= size;
        b->offset  = a->offset + a->length;
        b->length  = size;
        b->type    = a->type;

        list_add(&b->nl_entry, &a->nl_entry);
        if (b->type == 0)
                list_add(&b->fl_entry, &a->fl_entry);
        return b;
}

int
nouveau_mm_tail(struct nouveau_mm *mm, u8 type, u32 size_max, u32 size_min,
                u32 align, struct nouveau_mm_node **pnode)
{
        struct nouveau_mm_node *prev, *this, *next;
        u32 mask = align - 1;

        BUG_ON(!type);

        list_for_each_entry_reverse(this, &mm->free, fl_entry) {
                u32 e = this->offset + this->length;
                u32 s = this->offset;
                u32 c = 0, a;

                prev = node(this, prev);
                if (prev && prev->type != type)
                        s = roundup(s, mm->block_size);

                next = node(this, next);
                if (next && next->type != type) {
                        e = rounddown(e, mm->block_size);
                        c = next->offset - e;
                }

                s = (s + mask) & ~mask;
                a = e - s;
                if (s > e || a < size_min)
                        continue;

                a  = min(a, size_max);
                s  = (e - a) & ~mask;
                c += (e - s) - a;

                if (c && !region_tail(mm, this, c))
                        return -ENOMEM;

                this = region_tail(mm, this, a);
                if (!this)
                        return -ENOMEM;

                this->type = type;
                list_del(&this->fl_entry);
                *pnode = this;
                return 0;
        }

        return -ENOSPC;
}

int
nouveau_mm_init(struct nouveau_mm *mm, u32 offset, u32 length, u32 block)
{
        struct nouveau_mm_node *node;

        if (block) {
                INIT_LIST_HEAD(&mm->nodes);
                INIT_LIST_HEAD(&mm->free);
                mm->block_size = block;
                mm->heap_nodes = 0;
        }

        node = kzalloc(sizeof(*node), GFP_KERNEL);
        if (!node)
                return -ENOMEM;

        if (length) {
                node->offset  = roundup(offset, mm->block_size);
                node->length  = rounddown(offset + length, mm->block_size);
                node->length -= node->offset;
        }

        list_add_tail(&node->nl_entry, &mm->nodes);
        list_add_tail(&node->fl_entry, &mm->free);
        mm->heap_nodes++;
        return 0;
}

int
nouveau_mm_fini(struct nouveau_mm *mm)
{
        if (nouveau_mm_initialised(mm)) {
                struct nouveau_mm_node *node, *heap =
                        list_first_entry(&mm->nodes, typeof(*heap), nl_entry);
                int nodes = 0;

                list_for_each_entry(node, &mm->nodes, nl_entry) {
                        if (WARN_ON(nodes++ == mm->heap_nodes))
                                return -EBUSY;
                }

                kfree(heap);
        }

        return 0;
}