280 lines
7.3 KiB
C
280 lines
7.3 KiB
C
/*
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* Copyright(c) 2004 - 2006 Intel Corporation. All rights reserved.
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* Portions based on net/core/datagram.c and copyrighted by their authors.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the Free
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* Software Foundation; either version 2 of the License, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License along with
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* this program; if not, write to the Free Software Foundation, Inc., 59
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* Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*
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* The full GNU General Public License is included in this distribution in the
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* file called COPYING.
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*/
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/*
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* This code allows the net stack to make use of a DMA engine for
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* skb to iovec copies.
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*/
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#include <linux/dmaengine.h>
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#include <linux/pagemap.h>
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#include <net/tcp.h> /* for memcpy_toiovec */
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#include <asm/io.h>
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#include <asm/uaccess.h>
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static int num_pages_spanned(struct iovec *iov)
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{
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return
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((PAGE_ALIGN((unsigned long)iov->iov_base + iov->iov_len) -
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((unsigned long)iov->iov_base & PAGE_MASK)) >> PAGE_SHIFT);
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}
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/*
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* Pin down all the iovec pages needed for len bytes.
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* Return a struct dma_pinned_list to keep track of pages pinned down.
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*
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* We are allocating a single chunk of memory, and then carving it up into
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* 3 sections, the latter 2 whose size depends on the number of iovecs and the
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* total number of pages, respectively.
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*/
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struct dma_pinned_list *dma_pin_iovec_pages(struct iovec *iov, size_t len)
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{
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struct dma_pinned_list *local_list;
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struct page **pages;
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int i;
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int ret;
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int nr_iovecs = 0;
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int iovec_len_used = 0;
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int iovec_pages_used = 0;
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/* don't pin down non-user-based iovecs */
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if (segment_eq(get_fs(), KERNEL_DS))
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return NULL;
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/* determine how many iovecs/pages there are, up front */
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do {
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iovec_len_used += iov[nr_iovecs].iov_len;
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iovec_pages_used += num_pages_spanned(&iov[nr_iovecs]);
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nr_iovecs++;
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} while (iovec_len_used < len);
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/* single kmalloc for pinned list, page_list[], and the page arrays */
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local_list = kmalloc(sizeof(*local_list)
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+ (nr_iovecs * sizeof (struct dma_page_list))
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+ (iovec_pages_used * sizeof (struct page*)), GFP_KERNEL);
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if (!local_list)
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goto out;
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/* list of pages starts right after the page list array */
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pages = (struct page **) &local_list->page_list[nr_iovecs];
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local_list->nr_iovecs = 0;
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for (i = 0; i < nr_iovecs; i++) {
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struct dma_page_list *page_list = &local_list->page_list[i];
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len -= iov[i].iov_len;
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if (!access_ok(VERIFY_WRITE, iov[i].iov_base, iov[i].iov_len))
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goto unpin;
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page_list->nr_pages = num_pages_spanned(&iov[i]);
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page_list->base_address = iov[i].iov_base;
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page_list->pages = pages;
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pages += page_list->nr_pages;
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/* pin pages down */
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down_read(¤t->mm->mmap_sem);
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ret = get_user_pages(
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current,
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current->mm,
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(unsigned long) iov[i].iov_base,
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page_list->nr_pages,
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1, /* write */
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0, /* force */
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page_list->pages,
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NULL);
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up_read(¤t->mm->mmap_sem);
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if (ret != page_list->nr_pages)
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goto unpin;
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local_list->nr_iovecs = i + 1;
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}
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return local_list;
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unpin:
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dma_unpin_iovec_pages(local_list);
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out:
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return NULL;
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}
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void dma_unpin_iovec_pages(struct dma_pinned_list *pinned_list)
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{
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int i, j;
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if (!pinned_list)
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return;
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for (i = 0; i < pinned_list->nr_iovecs; i++) {
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struct dma_page_list *page_list = &pinned_list->page_list[i];
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for (j = 0; j < page_list->nr_pages; j++) {
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set_page_dirty_lock(page_list->pages[j]);
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page_cache_release(page_list->pages[j]);
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}
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}
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kfree(pinned_list);
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}
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/*
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* We have already pinned down the pages we will be using in the iovecs.
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* Each entry in iov array has corresponding entry in pinned_list->page_list.
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* Using array indexing to keep iov[] and page_list[] in sync.
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* Initial elements in iov array's iov->iov_len will be 0 if already copied into
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* by another call.
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* iov array length remaining guaranteed to be bigger than len.
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*/
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dma_cookie_t dma_memcpy_to_iovec(struct dma_chan *chan, struct iovec *iov,
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struct dma_pinned_list *pinned_list, unsigned char *kdata, size_t len)
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{
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int iov_byte_offset;
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int copy;
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dma_cookie_t dma_cookie = 0;
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int iovec_idx;
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int page_idx;
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if (!chan)
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return memcpy_toiovec(iov, kdata, len);
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iovec_idx = 0;
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while (iovec_idx < pinned_list->nr_iovecs) {
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struct dma_page_list *page_list;
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/* skip already used-up iovecs */
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while (!iov[iovec_idx].iov_len)
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iovec_idx++;
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page_list = &pinned_list->page_list[iovec_idx];
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iov_byte_offset = ((unsigned long)iov[iovec_idx].iov_base & ~PAGE_MASK);
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page_idx = (((unsigned long)iov[iovec_idx].iov_base & PAGE_MASK)
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- ((unsigned long)page_list->base_address & PAGE_MASK)) >> PAGE_SHIFT;
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/* break up copies to not cross page boundary */
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while (iov[iovec_idx].iov_len) {
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copy = min_t(int, PAGE_SIZE - iov_byte_offset, len);
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copy = min_t(int, copy, iov[iovec_idx].iov_len);
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dma_cookie = dma_async_memcpy_buf_to_pg(chan,
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page_list->pages[page_idx],
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iov_byte_offset,
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kdata,
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copy);
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/* poll for a descriptor slot */
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if (unlikely(dma_cookie < 0)) {
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dma_async_issue_pending(chan);
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continue;
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}
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len -= copy;
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iov[iovec_idx].iov_len -= copy;
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iov[iovec_idx].iov_base += copy;
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if (!len)
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return dma_cookie;
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kdata += copy;
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iov_byte_offset = 0;
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page_idx++;
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}
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iovec_idx++;
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}
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/* really bad if we ever run out of iovecs */
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BUG();
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return -EFAULT;
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}
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dma_cookie_t dma_memcpy_pg_to_iovec(struct dma_chan *chan, struct iovec *iov,
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struct dma_pinned_list *pinned_list, struct page *page,
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unsigned int offset, size_t len)
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{
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int iov_byte_offset;
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int copy;
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dma_cookie_t dma_cookie = 0;
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int iovec_idx;
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int page_idx;
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int err;
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/* this needs as-yet-unimplemented buf-to-buff, so punt. */
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/* TODO: use dma for this */
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if (!chan || !pinned_list) {
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u8 *vaddr = kmap(page);
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err = memcpy_toiovec(iov, vaddr + offset, len);
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kunmap(page);
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return err;
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}
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iovec_idx = 0;
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while (iovec_idx < pinned_list->nr_iovecs) {
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struct dma_page_list *page_list;
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/* skip already used-up iovecs */
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while (!iov[iovec_idx].iov_len)
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iovec_idx++;
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page_list = &pinned_list->page_list[iovec_idx];
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iov_byte_offset = ((unsigned long)iov[iovec_idx].iov_base & ~PAGE_MASK);
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page_idx = (((unsigned long)iov[iovec_idx].iov_base & PAGE_MASK)
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- ((unsigned long)page_list->base_address & PAGE_MASK)) >> PAGE_SHIFT;
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/* break up copies to not cross page boundary */
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while (iov[iovec_idx].iov_len) {
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copy = min_t(int, PAGE_SIZE - iov_byte_offset, len);
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copy = min_t(int, copy, iov[iovec_idx].iov_len);
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dma_cookie = dma_async_memcpy_pg_to_pg(chan,
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page_list->pages[page_idx],
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iov_byte_offset,
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page,
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offset,
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copy);
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/* poll for a descriptor slot */
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if (unlikely(dma_cookie < 0)) {
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dma_async_issue_pending(chan);
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continue;
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}
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len -= copy;
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iov[iovec_idx].iov_len -= copy;
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iov[iovec_idx].iov_base += copy;
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if (!len)
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return dma_cookie;
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offset += copy;
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iov_byte_offset = 0;
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page_idx++;
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}
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iovec_idx++;
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}
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/* really bad if we ever run out of iovecs */
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BUG();
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return -EFAULT;
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}
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