/*
 * Copyright (c) 2007 Cisco Systems, Inc. All rights reserved.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *      - Redistributions of source code must retain the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer.
 *
 *      - Redistributions in binary form must reproduce the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer in the documentation and/or other materials
 *        provided with the distribution.
 *
 * 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 AUTHORS OR COPYRIGHT HOLDERS
 * 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.
 */

#include <linux/slab.h>

#include "mlx4_ib.h"

struct mlx4_ib_db_pgdir {
        struct list_head        list;
        DECLARE_BITMAP(order0, MLX4_IB_DB_PER_PAGE);
        DECLARE_BITMAP(order1, MLX4_IB_DB_PER_PAGE / 2);
        unsigned long          *bits[2];
        __be32                 *db_page;
        dma_addr_t              db_dma;
};

static struct mlx4_ib_db_pgdir *mlx4_ib_alloc_db_pgdir(struct mlx4_ib_dev *dev)
{
        struct mlx4_ib_db_pgdir *pgdir;

        pgdir = kzalloc(sizeof *pgdir, GFP_KERNEL);
        if (!pgdir)
                return NULL;

        bitmap_fill(pgdir->order1, MLX4_IB_DB_PER_PAGE / 2);
        pgdir->bits[0] = pgdir->order0;
        pgdir->bits[1] = pgdir->order1;
        pgdir->db_page = dma_alloc_coherent(dev->ib_dev.dma_device,
                                            PAGE_SIZE, &pgdir->db_dma,
                                            GFP_KERNEL);
        if (!pgdir->db_page) {
                kfree(pgdir);
                return NULL;
        }

        return pgdir;
}

static int mlx4_ib_alloc_db_from_pgdir(struct mlx4_ib_db_pgdir *pgdir,
                                       struct mlx4_ib_db *db, int order)
{
        int o;
        int i;

        for (o = order; o <= 1; ++o) {
                i = find_first_bit(pgdir->bits[o], MLX4_IB_DB_PER_PAGE >> o);
                if (i < MLX4_IB_DB_PER_PAGE >> o)
                        goto found;
        }

        return -ENOMEM;

found:
        clear_bit(i, pgdir->bits[o]);

        i <<= o;

        if (o > order)
                set_bit(i ^ 1, pgdir->bits[order]);

        db->u.pgdir = pgdir;
        db->index   = i;
        db->db      = pgdir->db_page + db->index;
        db->dma     = pgdir->db_dma  + db->index * 4;
        db->order   = order;

        return 0;
}

int mlx4_ib_db_alloc(struct mlx4_ib_dev *dev, struct mlx4_ib_db *db, int order)
{
        struct mlx4_ib_db_pgdir *pgdir;
        int ret = 0;

        mutex_lock(&dev->pgdir_mutex);

        list_for_each_entry(pgdir, &dev->pgdir_list, list)
                if (!mlx4_ib_alloc_db_from_pgdir(pgdir, db, order))
                        goto out;

        pgdir = mlx4_ib_alloc_db_pgdir(dev);
        if (!pgdir) {
                ret = -ENOMEM;
                goto out;
        }

        list_add(&pgdir->list, &dev->pgdir_list);

        /* This should never fail -- we just allocated an empty page: */
        WARN_ON(mlx4_ib_alloc_db_from_pgdir(pgdir, db, order));

out:
        mutex_unlock(&dev->pgdir_mutex);

        return ret;
}

void mlx4_ib_db_free(struct mlx4_ib_dev *dev, struct mlx4_ib_db *db)
{
        int o;
        int i;

        mutex_lock(&dev->pgdir_mutex);

        o = db->order;
        i = db->index;

        if (db->order == 0 && test_bit(i ^ 1, db->u.pgdir->order0)) {
                clear_bit(i ^ 1, db->u.pgdir->order0);
                ++o;
        }

        i >>= o;
        set_bit(i, db->u.pgdir->bits[o]);

        if (bitmap_full(db->u.pgdir->order1, MLX4_IB_DB_PER_PAGE / 2)) {
                dma_free_coherent(dev->ib_dev.dma_device, PAGE_SIZE,
                                  db->u.pgdir->db_page, db->u.pgdir->db_dma);
                list_del(&db->u.pgdir->list);
                kfree(db->u.pgdir);
        }

        mutex_unlock(&dev->pgdir_mutex);
}

struct mlx4_ib_user_db_page {
        struct list_head        list;
        struct ib_umem         *umem;
        unsigned long           user_virt;
        int                     refcnt;
};

int mlx4_ib_db_map_user(struct mlx4_ib_ucontext *context, unsigned long virt,
                        struct mlx4_ib_db *db)
{
        struct mlx4_ib_user_db_page *page;
        struct ib_umem_chunk *chunk;
        int err = 0;

        mutex_lock(&context->db_page_mutex);

        list_for_each_entry(page, &context->db_page_list, list)
                if (page->user_virt == (virt & PAGE_MASK))
                        goto found;

        page = kmalloc(sizeof *page, GFP_KERNEL);
        if (!page) {
                err = -ENOMEM;
                goto out;
        }

        page->user_virt = (virt & PAGE_MASK);
        page->refcnt    = 0;
        page->umem      = ib_umem_get(&context->ibucontext, virt & PAGE_MASK,
                                      PAGE_SIZE, 0);
        if (IS_ERR(page->umem)) {
                err = PTR_ERR(page->umem);
                kfree(page);
                goto out;
        }

        list_add(&page->list, &context->db_page_list);

found:
        chunk = list_entry(page->umem->chunk_list.next, struct ib_umem_chunk, list);
        db->dma         = sg_dma_address(chunk->page_list) + (virt & ~PAGE_MASK);
        db->u.user_page = page;
        ++page->refcnt;

out:
        mutex_unlock(&context->db_page_mutex);

        return err;
}

void mlx4_ib_db_unmap_user(struct mlx4_ib_ucontext *context, struct mlx4_ib_db *db)
{
        mutex_lock(&context->db_page_mutex);

        if (!--db->u.user_page->refcnt) {
                list_del(&db->u.user_page->list);
                ib_umem_release(db->u.user_page->umem);
                kfree(db->u.user_page);
        }

        mutex_unlock(&context->db_page_mutex);
}