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/*
* memory fill 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/interrupt.h>
#include <linux/mm.h>
#include <linux/dma-mapping.h>
#include <linux/async_tx.h>
/**
* async_memset - attempt to fill memory with a dma engine.
* @dest: destination page
* @val: fill value
* @offset: offset in pages to start transaction
* @len: length in bytes
*
* honored flags: ASYNC_TX_ACK
*/
struct dma_async_tx_descriptor *
async_memset(struct page *dest, int val, unsigned int offset, size_t len,
struct async_submit_ctl *submit)
{
struct dma_chan *chan = async_tx_find_channel(submit, DMA_MEMSET,
&dest, 1, NULL, 0, len);
struct dma_device *device = chan ? chan->device : NULL;
struct dma_async_tx_descriptor *tx = NULL;
if (device) {
dma_addr_t dma_dest;
unsigned long dma_prep_flags;
dma_prep_flags = submit->cb_fn ? DMA_PREP_INTERRUPT : 0;
dma_dest = dma_map_page(device->dev, dest, offset, len,
DMA_FROM_DEVICE);
tx = device->device_prep_dma_memset(chan, dma_dest, val, len,
dma_prep_flags);
}
if (tx) {
pr_debug("%s: (async) len: %zu\n", __func__, len);
async_tx_submit(chan, tx, submit);
} else { /* run the memset synchronously */
void *dest_buf;
pr_debug("%s: (sync) len: %zu\n", __func__, len);
dest_buf = page_address(dest) + offset;
/* wait for any prerequisite operations */
async_tx_quiesce(&submit->depend_tx);
memset(dest_buf, val, len);
async_tx_sync_epilog(submit);
}
return tx;
}
EXPORT_SYMBOL_GPL(async_memset);
static int __init async_memset_init(void)
{
return 0;
}
static void __exit async_memset_exit(void)
{
do { } while (0);
}
module_init(async_memset_init);
module_exit(async_memset_exit);
MODULE_AUTHOR("Intel Corporation");
MODULE_DESCRIPTION("asynchronous memset api");
MODULE_LICENSE("GPL");
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