/**************************************************************************
 *
 * Copyright 2006 Tungsten Graphics, Inc., Bismarck, ND. USA.
 * All Rights Reserved.
 *
 * 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, sub license, 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 (including the
 * next paragraph) 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 NON-INFRINGEMENT. IN NO EVENT SHALL
 * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS 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.
 *
 *
 **************************************************************************/
/*
 * Simple open hash tab implementation.
 *
 * Authors:
 * Thomas Hellström <thomas-at-tungstengraphics-dot-com>
 */

#include <drm/drmP.h>
#include <drm/drm_hashtab.h>
#include <linux/hash.h>
#include <linux/slab.h>
#include <linux/export.h>

int drm_ht_create(struct drm_open_hash *ht, unsigned int order)
{
        unsigned int size = 1 << order;

        ht->order = order;
        ht->table = NULL;
        if (size <= PAGE_SIZE / sizeof(*ht->table))
                ht->table = kcalloc(size, sizeof(*ht->table), GFP_KERNEL);
        else
                ht->table = vzalloc(array_size(size, sizeof(*ht->table)));
        if (!ht->table) {
                DRM_ERROR("Out of memory for hash table\n");
                return -ENOMEM;
        }
        return 0;
}
EXPORT_SYMBOL(drm_ht_create);

void drm_ht_verbose_list(struct drm_open_hash *ht, unsigned long key)
{
        struct drm_hash_item *entry;
        struct hlist_head *h_list;
        unsigned int hashed_key;
        int count = 0;

        hashed_key = hash_long(key, ht->order);
        DRM_DEBUG("Key is 0x%08lx, Hashed key is 0x%08x\n", key, hashed_key);
        h_list = &ht->table[hashed_key];
        hlist_for_each_entry(entry, h_list, head)
                DRM_DEBUG("count %d, key: 0x%08lx\n", count++, entry->key);
}

static struct hlist_node *drm_ht_find_key(struct drm_open_hash *ht,
                                          unsigned long key)
{
        struct drm_hash_item *entry;
        struct hlist_head *h_list;
        unsigned int hashed_key;

        hashed_key = hash_long(key, ht->order);
        h_list = &ht->table[hashed_key];
        hlist_for_each_entry(entry, h_list, head) {
                if (entry->key == key)
                        return &entry->head;
                if (entry->key > key)
                        break;
        }
        return NULL;
}

static struct hlist_node *drm_ht_find_key_rcu(struct drm_open_hash *ht,
                                              unsigned long key)
{
        struct drm_hash_item *entry;
        struct hlist_head *h_list;
        unsigned int hashed_key;

        hashed_key = hash_long(key, ht->order);
        h_list = &ht->table[hashed_key];
        hlist_for_each_entry_rcu(entry, h_list, head) {
                if (entry->key == key)
                        return &entry->head;
                if (entry->key > key)
                        break;
        }
        return NULL;
}

int drm_ht_insert_item(struct drm_open_hash *ht, struct drm_hash_item *item)
{
        struct drm_hash_item *entry;
        struct hlist_head *h_list;
        struct hlist_node *parent;
        unsigned int hashed_key;
        unsigned long key = item->key;

        hashed_key = hash_long(key, ht->order);
        h_list = &ht->table[hashed_key];
        parent = NULL;
        hlist_for_each_entry(entry, h_list, head) {
                if (entry->key == key)
                        return -EINVAL;
                if (entry->key > key)
                        break;
                parent = &entry->head;
        }
        if (parent) {
                hlist_add_behind_rcu(&item->head, parent);
        } else {
                hlist_add_head_rcu(&item->head, h_list);
        }
        return 0;
}
EXPORT_SYMBOL(drm_ht_insert_item);

/*
 * Just insert an item and return any "bits" bit key that hasn't been
 * used before.
 */
int drm_ht_just_insert_please(struct drm_open_hash *ht, struct drm_hash_item *item,
                              unsigned long seed, int bits, int shift,
                              unsigned long add)
{
        int ret;
        unsigned long mask = (1UL << bits) - 1;
        unsigned long first, unshifted_key;

        unshifted_key = hash_long(seed, bits);
        first = unshifted_key;
        do {
                item->key = (unshifted_key << shift) + add;
                ret = drm_ht_insert_item(ht, item);
                if (ret)
                        unshifted_key = (unshifted_key + 1) & mask;
        } while(ret && (unshifted_key != first));

        if (ret) {
                DRM_ERROR("Available key bit space exhausted\n");
                return -EINVAL;
        }
        return 0;
}
EXPORT_SYMBOL(drm_ht_just_insert_please);

int drm_ht_find_item(struct drm_open_hash *ht, unsigned long key,
                     struct drm_hash_item **item)
{
        struct hlist_node *list;

        list = drm_ht_find_key_rcu(ht, key);
        if (!list)
                return -EINVAL;

        *item = hlist_entry(list, struct drm_hash_item, head);
        return 0;
}
EXPORT_SYMBOL(drm_ht_find_item);

int drm_ht_remove_key(struct drm_open_hash *ht, unsigned long key)
{
        struct hlist_node *list;

        list = drm_ht_find_key(ht, key);
        if (list) {
                hlist_del_init_rcu(list);
                return 0;
        }
        return -EINVAL;
}

int drm_ht_remove_item(struct drm_open_hash *ht, struct drm_hash_item *item)
{
        hlist_del_init_rcu(&item->head);
        return 0;
}
EXPORT_SYMBOL(drm_ht_remove_item);

void drm_ht_remove(struct drm_open_hash *ht)
{
        if (ht->table) {
                kvfree(ht->table);
                ht->table = NULL;
        }
}
EXPORT_SYMBOL(drm_ht_remove);