release/src-rt-6.x.4708/linux/linux-2.6.36/drivers/infiniband/hw/mlx4/doorbell.c

   1 /*
   2  * Copyright (c) 2007 Cisco Systems, Inc. All rights reserved.
   3  *
   4  * This software is available to you under a choice of one of two
   5  * licenses.  You may choose to be licensed under the terms of the GNU
   6  * General Public License (GPL) Version 2, available from the file
   7  * COPYING in the main directory of this source tree, or the
   8  * OpenIB.org BSD license below:
   9  *
  10  *     Redistribution and use in source and binary forms, with or
  11  *     without modification, are permitted provided that the following
  12  *     conditions are met:
  13  *
  14  *      - Redistributions of source code must retain the above
  15  *        copyright notice, this list of conditions and the following
  16  *        disclaimer.
  17  *
  18  *      - Redistributions in binary form must reproduce the above
  19  *        copyright notice, this list of conditions and the following
  20  *        disclaimer in the documentation and/or other materials
  21  *        provided with the distribution.
  22  *
  23  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  24  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  25  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  26  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  27  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  28  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  29  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  30  * SOFTWARE.
  31  */
  32
  33 #include <linux/slab.h>
  34
  35 #include "mlx4_ib.h"
  36
  37 struct mlx4_ib_user_db_page {
  38         struct list_head        list;
  39         struct ib_umem         *umem;
  40         unsigned long           user_virt;
  41         int                     refcnt;
  42 };
  43
  44 int mlx4_ib_db_map_user(struct mlx4_ib_ucontext *context, unsigned long virt,
  45                         struct mlx4_db *db)
  46 {
  47         struct mlx4_ib_user_db_page *page;
  48         struct ib_umem_chunk *chunk;
  49         int err = 0;
  50
  51         mutex_lock(&context->db_page_mutex);
  52
  53         list_for_each_entry(page, &context->db_page_list, list)
  54                 if (page->user_virt == (virt & PAGE_MASK))
  55                         goto found;
  56
  57         page = kmalloc(sizeof *page, GFP_KERNEL);
  58         if (!page) {
  59                 err = -ENOMEM;
  60                 goto out;
  61         }
  62
  63         page->user_virt = (virt & PAGE_MASK);
  64         page->refcnt    = 0;
  65         page->umem      = ib_umem_get(&context->ibucontext, virt & PAGE_MASK,
  66                                       PAGE_SIZE, 0, 0);
  67         if (IS_ERR(page->umem)) {
  68                 err = PTR_ERR(page->umem);
  69                 kfree(page);
  70                 goto out;
  71         }
  72
  73         list_add(&page->list, &context->db_page_list);
  74
  75 found:
  76         chunk = list_entry(page->umem->chunk_list.next, struct ib_umem_chunk, list);
  77         db->dma         = sg_dma_address(chunk->page_list) + (virt & ~PAGE_MASK);
  78         db->u.user_page = page;
  79         ++page->refcnt;
  80
  81 out:
  82         mutex_unlock(&context->db_page_mutex);
  83
  84         return err;
  85 }
  86
  87 void mlx4_ib_db_unmap_user(struct mlx4_ib_ucontext *context, struct mlx4_db *db)
  88 {
  89         mutex_lock(&context->db_page_mutex);
  90
  91         if (!--db->u.user_page->refcnt) {
  92                 list_del(&db->u.user_page->list);
  93                 ib_umem_release(db->u.user_page->umem);
  94                 kfree(db->u.user_page);
  95         }
  96
  97         mutex_unlock(&context->db_page_mutex);
  98 }