Subversion Repositories or1k_soc_on_altera_embedded_dev_kit

/*

 * Copyright(c) 2004 - 2006 Intel Corporation. All rights reserved.

 * Portions based on net/core/datagram.c and copyrighted by their authors.

 *

 * This program is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License as published by the Free

 * Software Foundation; either version 2 of the License, or (at your option)

 * any later version.

 *

 * This program is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for

 * more details.

 *

 * You should have received a copy of the GNU General Public License along with

 * this program; if not, write to the Free Software Foundation, Inc., 59

 * Temple Place - Suite 330, Boston, MA  02111-1307, USA.

 *

 * The full GNU General Public License is included in this distribution in the

 * file called COPYING.

 */

/*

 * This code allows the net stack to make use of a DMA engine for

 * skb to iovec copies.

 */

#include <linux/dmaengine.h>

#include <linux/socket.h>

#include <linux/rtnetlink.h> /* for BUG_TRAP */

#include <net/tcp.h>

#include <net/netdma.h>

#define NET_DMA_DEFAULT_COPYBREAK 4096

int sysctl_tcp_dma_copybreak = NET_DMA_DEFAULT_COPYBREAK;

/**

 *      dma_skb_copy_datagram_iovec - Copy a datagram to an iovec.

 *      @skb - buffer to copy

 *      @offset - offset in the buffer to start copying from

 *      @iovec - io vector to copy to

 *      @len - amount of data to copy from buffer to iovec

 *      @pinned_list - locked iovec buffer data

 *

 *      Note: the iovec is modified during the copy.

 */

int dma_skb_copy_datagram_iovec(struct dma_chan *chan,

                        struct sk_buff *skb, int offset, struct iovec *to,

                        size_t len, struct dma_pinned_list *pinned_list)

{

        int start = skb_headlen(skb);

        int i, copy = start - offset;

        dma_cookie_t cookie = 0;

        /* Copy header. */

        if (copy > 0) {

                if (copy > len)

                        copy = len;

                cookie = dma_memcpy_to_iovec(chan, to, pinned_list,

                                            skb->data + offset, copy);

                if (cookie < 0)

                        goto fault;

                len -= copy;

                if (len == 0)

                        goto end;

                offset += copy;

        }

        /* Copy paged appendix. Hmm... why does this look so complicated? */

        for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {

                int end;

                BUG_TRAP(start <= offset + len);

                end = start + skb_shinfo(skb)->frags[i].size;

                copy = end - offset;

                if ((copy = end - offset) > 0) {

                        skb_frag_t *frag = &skb_shinfo(skb)->frags[i];

                        struct page *page = frag->page;

                        if (copy > len)

                                copy = len;

                        cookie = dma_memcpy_pg_to_iovec(chan, to, pinned_list, page,

                                        frag->page_offset + offset - start, copy);

                        if (cookie < 0)

                                goto fault;

                        len -= copy;

                        if (len == 0)

                                goto end;

                        offset += copy;

                }

                start = end;

        }

        if (skb_shinfo(skb)->frag_list) {

                struct sk_buff *list = skb_shinfo(skb)->frag_list;

                for (; list; list = list->next) {

                        int end;

                        BUG_TRAP(start <= offset + len);

                        end = start + list->len;

                        copy = end - offset;

                        if (copy > 0) {

                                if (copy > len)

                                        copy = len;

                                cookie = dma_skb_copy_datagram_iovec(chan, list,

                                                offset - start, to, copy,

                                                pinned_list);

                                if (cookie < 0)

                                        goto fault;

                                len -= copy;

                                if (len == 0)

                                        goto end;

                                offset += copy;

                        }

                        start = end;

                }

        }

end:

        if (!len) {

                skb->dma_cookie = cookie;

                return cookie;

        }

fault:

        return -EFAULT;

}