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ipath_dma.c

/*
 * Copyright (c) 2006 QLogic, Corporation. 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/scatterlist.h>
#include <rdma/ib_verbs.h>

#include "ipath_verbs.h"

#define BAD_DMA_ADDRESS ((u64) 0)

/*
 * The following functions implement driver specific replacements
 * for the ib_dma_*() functions.
 *
 * These functions return kernel virtual addresses instead of
 * device bus addresses since the driver uses the CPU to copy
 * data instead of using hardware DMA.
 */

static int ipath_mapping_error(struct ib_device *dev, u64 dma_addr)
{
      return dma_addr == BAD_DMA_ADDRESS;
}

static u64 ipath_dma_map_single(struct ib_device *dev,
                          void *cpu_addr, size_t size,
                          enum dma_data_direction direction)
{
      BUG_ON(!valid_dma_direction(direction));
      return (u64) cpu_addr;
}

static void ipath_dma_unmap_single(struct ib_device *dev,
                           u64 addr, size_t size,
                           enum dma_data_direction direction)
{
      BUG_ON(!valid_dma_direction(direction));
}

static u64 ipath_dma_map_page(struct ib_device *dev,
                        struct page *page,
                        unsigned long offset,
                        size_t size,
                        enum dma_data_direction direction)
{
      u64 addr;

      BUG_ON(!valid_dma_direction(direction));

      if (offset + size > PAGE_SIZE) {
            addr = BAD_DMA_ADDRESS;
            goto done;
      }

      addr = (u64) page_address(page);
      if (addr)
            addr += offset;
      /* TODO: handle highmem pages */

done:
      return addr;
}

static void ipath_dma_unmap_page(struct ib_device *dev,
                         u64 addr, size_t size,
                         enum dma_data_direction direction)
{
      BUG_ON(!valid_dma_direction(direction));
}

static int ipath_map_sg(struct ib_device *dev, struct scatterlist *sgl,
                  int nents, enum dma_data_direction direction)
{
      struct scatterlist *sg;
      u64 addr;
      int i;
      int ret = nents;

      BUG_ON(!valid_dma_direction(direction));

      for_each_sg(sgl, sg, nents, i) {
            addr = (u64) page_address(sg_page(sg));
            /* TODO: handle highmem pages */
            if (!addr) {
                  ret = 0;
                  break;
            }
      }
      return ret;
}

static void ipath_unmap_sg(struct ib_device *dev,
                     struct scatterlist *sg, int nents,
                     enum dma_data_direction direction)
{
      BUG_ON(!valid_dma_direction(direction));
}

static u64 ipath_sg_dma_address(struct ib_device *dev, struct scatterlist *sg)
{
      u64 addr = (u64) page_address(sg_page(sg));

      if (addr)
            addr += sg->offset;
      return addr;
}

static unsigned int ipath_sg_dma_len(struct ib_device *dev,
                             struct scatterlist *sg)
{
      return sg->length;
}

static void ipath_sync_single_for_cpu(struct ib_device *dev,
                              u64 addr,
                              size_t size,
                              enum dma_data_direction dir)
{
}

static void ipath_sync_single_for_device(struct ib_device *dev,
                               u64 addr,
                               size_t size,
                               enum dma_data_direction dir)
{
}

static void *ipath_dma_alloc_coherent(struct ib_device *dev, size_t size,
                              u64 *dma_handle, gfp_t flag)
{
      struct page *p;
      void *addr = NULL;

      p = alloc_pages(flag, get_order(size));
      if (p)
            addr = page_address(p);
      if (dma_handle)
            *dma_handle = (u64) addr;
      return addr;
}

static void ipath_dma_free_coherent(struct ib_device *dev, size_t size,
                            void *cpu_addr, u64 dma_handle)
{
      free_pages((unsigned long) cpu_addr, get_order(size));
}

struct ib_dma_mapping_ops ipath_dma_mapping_ops = {
      ipath_mapping_error,
      ipath_dma_map_single,
      ipath_dma_unmap_single,
      ipath_dma_map_page,
      ipath_dma_unmap_page,
      ipath_map_sg,
      ipath_unmap_sg,
      ipath_sg_dma_address,
      ipath_sg_dma_len,
      ipath_sync_single_for_cpu,
      ipath_sync_single_for_device,
      ipath_dma_alloc_coherent,
      ipath_dma_free_coherent
};

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