/*
* 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;
/* 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)
goto out;
/* list of pages starts right after the page list array */
pages = (struct page **) &local_list->page_list[nr_iovecs];
local_list->nr_iovecs = 0;
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))
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(¤t->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(¤t->mm->mmap_sem);
if (ret != page_list->nr_pages)
goto unpin;
local_list->nr_iovecs = i + 1;
}
return local_list;
unpin:
dma_unpin_iovec_pages(local_list);
out:
return NULL;
}
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);
/* poll for a descriptor slot */
if (unlikely(dma_cookie < 0)) {
dma_async_issue_pending(chan);
continue;
}
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);
/* poll for a descriptor slot */
if (unlikely(dma_cookie < 0)) {
dma_async_issue_pending(chan);
continue;
}
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;
}
