linux/crypto/async_tx/async_memcpy.c
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   1/*
   2 * copy offload engine support
   3 *
   4 * Copyright © 2006, Intel Corporation.
   5 *
   6 *      Dan Williams <dan.j.williams@intel.com>
   7 *
   8 *      with architecture considerations by:
   9 *      Neil Brown <neilb@suse.de>
  10 *      Jeff Garzik <jeff@garzik.org>
  11 *
  12 * This program is free software; you can redistribute it and/or modify it
  13 * under the terms and conditions of the GNU General Public License,
  14 * version 2, as published by the Free Software Foundation.
  15 *
  16 * This program is distributed in the hope it will be useful, but WITHOUT
  17 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  18 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  19 * more details.
  20 *
  21 * You should have received a copy of the GNU General Public License along with
  22 * this program; if not, write to the Free Software Foundation, Inc.,
  23 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
  24 *
  25 */
  26#include <linux/kernel.h>
  27#include <linux/highmem.h>
  28#include <linux/module.h>
  29#include <linux/mm.h>
  30#include <linux/dma-mapping.h>
  31#include <linux/async_tx.h>
  32
  33/**
  34 * async_memcpy - attempt to copy memory with a dma engine.
  35 * @dest: destination page
  36 * @src: src page
  37 * @dest_offset: offset into 'dest' to start transaction
  38 * @src_offset: offset into 'src' to start transaction
  39 * @len: length in bytes
  40 * @submit: submission / completion modifiers
  41 *
  42 * honored flags: ASYNC_TX_ACK
  43 */
  44struct dma_async_tx_descriptor *
  45async_memcpy(struct page *dest, struct page *src, unsigned int dest_offset,
  46             unsigned int src_offset, size_t len,
  47             struct async_submit_ctl *submit)
  48{
  49        struct dma_chan *chan = async_tx_find_channel(submit, DMA_MEMCPY,
  50                                                      &dest, 1, &src, 1, len);
  51        struct dma_device *device = chan ? chan->device : NULL;
  52        struct dma_async_tx_descriptor *tx = NULL;
  53
  54        if (device && is_dma_copy_aligned(device, src_offset, dest_offset, len)) {
  55                dma_addr_t dma_dest, dma_src;
  56                unsigned long dma_prep_flags = 0;
  57
  58                if (submit->cb_fn)
  59                        dma_prep_flags |= DMA_PREP_INTERRUPT;
  60                if (submit->flags & ASYNC_TX_FENCE)
  61                        dma_prep_flags |= DMA_PREP_FENCE;
  62                dma_dest = dma_map_page(device->dev, dest, dest_offset, len,
  63                                        DMA_FROM_DEVICE);
  64
  65                dma_src = dma_map_page(device->dev, src, src_offset, len,
  66                                       DMA_TO_DEVICE);
  67
  68                tx = device->device_prep_dma_memcpy(chan, dma_dest, dma_src,
  69                                                    len, dma_prep_flags);
  70        }
  71
  72        if (tx) {
  73                pr_debug("%s: (async) len: %zu\n", __func__, len);
  74                async_tx_submit(chan, tx, submit);
  75        } else {
  76                void *dest_buf, *src_buf;
  77                pr_debug("%s: (sync) len: %zu\n", __func__, len);
  78
  79                /* wait for any prerequisite operations */
  80                async_tx_quiesce(&submit->depend_tx);
  81
  82                dest_buf = kmap_atomic(dest) + dest_offset;
  83                src_buf = kmap_atomic(src) + src_offset;
  84
  85                memcpy(dest_buf, src_buf, len);
  86
  87                kunmap_atomic(src_buf);
  88                kunmap_atomic(dest_buf);
  89
  90                async_tx_sync_epilog(submit);
  91        }
  92
  93        return tx;
  94}
  95EXPORT_SYMBOL_GPL(async_memcpy);
  96
  97MODULE_AUTHOR("Intel Corporation");
  98MODULE_DESCRIPTION("asynchronous memcpy api");
  99MODULE_LICENSE("GPL");
 100
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