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 */
44 struct dma_async_tx_descriptor *
async_memcpy(struct page * dest,struct page * src,unsigned int dest_offset,unsigned int src_offset,size_t len,struct async_submit_ctl * submit)45 async_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 }
95 EXPORT_SYMBOL_GPL(async_memcpy);
96
97 MODULE_AUTHOR("Intel Corporation");
98 MODULE_DESCRIPTION("asynchronous memcpy api");
99 MODULE_LICENSE("GPL");
100