/*
* copy offload engine support
*
* Copyright © 2006, Intel Corporation.
*
* Dan Williams <dan.j.williams@intel.com>
*
* with architecture considerations by:
* Neil Brown <neilb@suse.de>
* Jeff Garzik <jeff@garzik.org>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope 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.,
* 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
*
*/
#include <linux/kernel.h>
#include <linux/highmem.h>
#include <linux/mm.h>
#include <linux/dma-mapping.h>
#include <linux/async_tx.h>
/**
* async_memcpy - attempt to copy memory with a dma engine.
* @dest: destination page
* @src: src page
* @offset: offset in pages to start transaction
* @len: length in bytes
* @flags: ASYNC_TX_ACK, ASYNC_TX_DEP_ACK,
* @depend_tx: memcpy depends on the result of this transaction
* @cb_fn: function to call when the memcpy completes
* @cb_param: parameter to pass to the callback routine
*/
struct dma_async_tx_descriptor *
async_memcpy(struct page *dest, struct page *src, unsigned int dest_offset,
unsigned int src_offset, size_t len, enum async_tx_flags flags,
struct dma_async_tx_descriptor *depend_tx,
dma_async_tx_callback cb_fn, void *cb_param)
{
struct dma_chan *chan = async_tx_find_channel(depend_tx, DMA_MEMCPY,
&dest, 1, &src, 1, len);
struct dma_device *device = chan ? chan->device : NULL;
struct dma_async_tx_descriptor *tx = NULL;
if (device) {
dma_addr_t dma_dest, dma_src;
unsigned long dma_prep_flags = cb_fn ? DMA_PREP_INTERRUPT : 0;
dma_dest = dma_map_page(device->dev, dest, dest_offset, len,
DMA_FROM_DEVICE);
dma_src = dma_map_page(device->dev, src, src_offset, len,
DMA_TO_DEVICE);
tx = device->device_prep_dma_memcpy(chan, dma_dest, dma_src,
len, dma_prep_flags);
}
if (tx) {
pr_debug("%s: (async) len: %zu\n", __func__, len);
async_tx_submit(chan, tx, flags, depend_tx, cb_fn, cb_param);
} else {
void *dest_buf, *src_buf;
pr_debug("%s: (sync) len: %zu\n", __func__, len);
/* wait for any prerequisite operations */
async_tx_quiesce(&depend_tx);
dest_buf = kmap_atomic(dest, KM_USER0) + dest_offset;
src_buf = kmap_atomic(src, KM_USER1) + src_offset;
memcpy(dest_buf, src_buf, len);
kunmap_atomic(dest_buf, KM_USER0);
kunmap_atomic(src_buf, KM_USER1);
async_tx_sync_epilog(cb_fn, cb_param);
}
return tx;
}
EXPORT_SYMBOL_GPL(async_memcpy);
static int __init async_memcpy_init(void)
{
return 0;
}
static void __exit async_memcpy_exit(void)
{
do { } while (0);
}
module_init(async_memcpy_init);
module_exit(async_memcpy_exit);
MODULE_AUTHOR("Intel Corporation");
MODULE_DESCRIPTION("asynchronous memcpy api");
MODULE_LICENSE("GPL");
