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doorbell.c

/*
 * 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);
}

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