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/*

 * 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/pagemap.h>

#include <net/tcp.h> /* for memcpy_toiovec */

#include <asm/io.h>

#include <asm/uaccess.h>

static int num_pages_spanned(struct iovec *iov)

{

        return

        ((PAGE_ALIGN((unsigned long)iov->iov_base + iov->iov_len) -

        ((unsigned long)iov->iov_base & PAGE_MASK)) >> PAGE_SHIFT);

}

/*

 * Pin down all the iovec pages needed for len bytes.

 * Return a struct dma_pinned_list to keep track of pages pinned down.

 *

 * We are allocating a single chunk of memory, and then carving it up into

 * 3 sections, the latter 2 whose size depends on the number of iovecs and the

 * total number of pages, respectively.

 */

struct dma_pinned_list *dma_pin_iovec_pages(struct iovec *iov, size_t len)

{

        struct dma_pinned_list *local_list;

        struct page **pages;

        int i;

        int ret;

        int nr_iovecs = 0;

        int iovec_len_used = 0;

        int iovec_pages_used = 0;

        long err;

        /* don't pin down non-user-based iovecs */

        if (segment_eq(get_fs(), KERNEL_DS))

                return NULL;

        /* determine how many iovecs/pages there are, up front */

        do {

                iovec_len_used += iov[nr_iovecs].iov_len;

                iovec_pages_used += num_pages_spanned(&iov[nr_iovecs]);

                nr_iovecs++;

        } while (iovec_len_used < len);

        /* single kmalloc for pinned list, page_list[], and the page arrays */

        local_list = kmalloc(sizeof(*local_list)

                + (nr_iovecs * sizeof (struct dma_page_list))

                + (iovec_pages_used * sizeof (struct page*)), GFP_KERNEL);

        if (!local_list) {

                err = -ENOMEM;

                goto out;

        }

        /* list of pages starts right after the page list array */

        pages = (struct page **) &local_list->page_list[nr_iovecs];

        for (i = 0; i < nr_iovecs; i++) {

                struct dma_page_list *page_list = &local_list->page_list[i];

                len -= iov[i].iov_len;

                if (!access_ok(VERIFY_WRITE, iov[i].iov_base, iov[i].iov_len)) {

                        err = -EFAULT;

                        goto unpin;

                }

                page_list->nr_pages = num_pages_spanned(&iov[i]);

                page_list->base_address = iov[i].iov_base;

                page_list->pages = pages;

                pages += page_list->nr_pages;

                /* pin pages down */

                down_read(&current->mm->mmap_sem);

                ret = get_user_pages(

                        current,

                        current->mm,

                        (unsigned long) iov[i].iov_base,

                        page_list->nr_pages,

                        1,      /* write */

                        0,       /* force */

                        page_list->pages,

                        NULL);

                up_read(&current->mm->mmap_sem);

                if (ret != page_list->nr_pages) {

                        err = -ENOMEM;

                        goto unpin;

                }

                local_list->nr_iovecs = i + 1;

        }

        return local_list;

unpin:

        dma_unpin_iovec_pages(local_list);

out:

        return ERR_PTR(err);

}

void dma_unpin_iovec_pages(struct dma_pinned_list *pinned_list)

{

        int i, j;

        if (!pinned_list)

                return;

        for (i = 0; i < pinned_list->nr_iovecs; i++) {

                struct dma_page_list *page_list = &pinned_list->page_list[i];

                for (j = 0; j < page_list->nr_pages; j++) {

                        set_page_dirty_lock(page_list->pages[j]);

                        page_cache_release(page_list->pages[j]);

                }

        }

        kfree(pinned_list);

}

/*

 * We have already pinned down the pages we will be using in the iovecs.

 * Each entry in iov array has corresponding entry in pinned_list->page_list.

 * Using array indexing to keep iov[] and page_list[] in sync.

 * Initial elements in iov array's iov->iov_len will be 0 if already copied into

 *   by another call.

 * iov array length remaining guaranteed to be bigger than len.

 */

dma_cookie_t dma_memcpy_to_iovec(struct dma_chan *chan, struct iovec *iov,

        struct dma_pinned_list *pinned_list, unsigned char *kdata, size_t len)

{

        int iov_byte_offset;

        int copy;

        dma_cookie_t dma_cookie = 0;

        int iovec_idx;

        int page_idx;

        if (!chan)

                return memcpy_toiovec(iov, kdata, len);

        iovec_idx = 0;

        while (iovec_idx < pinned_list->nr_iovecs) {

                struct dma_page_list *page_list;

                /* skip already used-up iovecs */

                while (!iov[iovec_idx].iov_len)

                        iovec_idx++;

                page_list = &pinned_list->page_list[iovec_idx];

                iov_byte_offset = ((unsigned long)iov[iovec_idx].iov_base & ~PAGE_MASK);

                page_idx = (((unsigned long)iov[iovec_idx].iov_base & PAGE_MASK)

                         - ((unsigned long)page_list->base_address & PAGE_MASK)) >> PAGE_SHIFT;

                /* break up copies to not cross page boundary */

                while (iov[iovec_idx].iov_len) {

                        copy = min_t(int, PAGE_SIZE - iov_byte_offset, len);

                        copy = min_t(int, copy, iov[iovec_idx].iov_len);

                        dma_cookie = dma_async_memcpy_buf_to_pg(chan,

                                        page_list->pages[page_idx],

                                        iov_byte_offset,

                                        kdata,

                                        copy);

                        len -= copy;

                        iov[iovec_idx].iov_len -= copy;

                        iov[iovec_idx].iov_base += copy;

                        if (!len)

                                return dma_cookie;

                        kdata += copy;

                        iov_byte_offset = 0;

                        page_idx++;

                }

                iovec_idx++;

        }

        /* really bad if we ever run out of iovecs */

        BUG();

        return -EFAULT;

}

dma_cookie_t dma_memcpy_pg_to_iovec(struct dma_chan *chan, struct iovec *iov,

        struct dma_pinned_list *pinned_list, struct page *page,

        unsigned int offset, size_t len)

{

        int iov_byte_offset;

        int copy;

        dma_cookie_t dma_cookie = 0;

        int iovec_idx;

        int page_idx;

        int err;

        /* this needs as-yet-unimplemented buf-to-buff, so punt. */

        /* TODO: use dma for this */

        if (!chan || !pinned_list) {

                u8 *vaddr = kmap(page);

                err = memcpy_toiovec(iov, vaddr + offset, len);

                kunmap(page);

                return err;

        }

        iovec_idx = 0;

        while (iovec_idx < pinned_list->nr_iovecs) {

                struct dma_page_list *page_list;

                /* skip already used-up iovecs */

                while (!iov[iovec_idx].iov_len)

                        iovec_idx++;

                page_list = &pinned_list->page_list[iovec_idx];

                iov_byte_offset = ((unsigned long)iov[iovec_idx].iov_base & ~PAGE_MASK);

                page_idx = (((unsigned long)iov[iovec_idx].iov_base & PAGE_MASK)

                         - ((unsigned long)page_list->base_address & PAGE_MASK)) >> PAGE_SHIFT;

                /* break up copies to not cross page boundary */

                while (iov[iovec_idx].iov_len) {

                        copy = min_t(int, PAGE_SIZE - iov_byte_offset, len);

                        copy = min_t(int, copy, iov[iovec_idx].iov_len);

                        dma_cookie = dma_async_memcpy_pg_to_pg(chan,

                                        page_list->pages[page_idx],

                                        iov_byte_offset,

                                        page,

                                        offset,

                                        copy);

                        len -= copy;

                        iov[iovec_idx].iov_len -= copy;

                        iov[iovec_idx].iov_base += copy;

                        if (!len)

                                return dma_cookie;

                        offset += copy;

                        iov_byte_offset = 0;

                        page_idx++;

                }

                iovec_idx++;

        }

        /* really bad if we ever run out of iovecs */

        BUG();

        return -EFAULT;

}