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/mm.h>
29 #include <linux/dma-mapping.h>
30 #include <linux/async_tx.h>
31 
32 /**
33  * async_memcpy - attempt to copy memory with a dma engine.
34  * @dest: destination page
35  * @src: src page
36  * @offset: offset in pages to start transaction
37  * @len: length in bytes
38  * @flags: ASYNC_TX_ACK, ASYNC_TX_DEP_ACK,
39  * @depend_tx: memcpy depends on the result of this transaction
40  * @cb_fn: function to call when the memcpy completes
41  * @cb_param: parameter to pass to the callback routine
42  */
43 struct dma_async_tx_descriptor *
44 async_memcpy(struct page *dest, struct page *src, unsigned int dest_offset,
45 	unsigned int src_offset, size_t len, enum async_tx_flags flags,
46 	struct dma_async_tx_descriptor *depend_tx,
47 	dma_async_tx_callback cb_fn, void *cb_param)
48 {
49 	struct dma_chan *chan = async_tx_find_channel(depend_tx, 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) {
55 		dma_addr_t dma_dest, dma_src;
56 		unsigned long dma_prep_flags = cb_fn ? DMA_PREP_INTERRUPT : 0;
57 
58 		dma_dest = dma_map_page(device->dev, dest, dest_offset, len,
59 					DMA_FROM_DEVICE);
60 
61 		dma_src = dma_map_page(device->dev, src, src_offset, len,
62 				       DMA_TO_DEVICE);
63 
64 		tx = device->device_prep_dma_memcpy(chan, dma_dest, dma_src,
65 						    len, dma_prep_flags);
66 	}
67 
68 	if (tx) {
69 		pr_debug("%s: (async) len: %zu\n", __func__, len);
70 		async_tx_submit(chan, tx, flags, depend_tx, cb_fn, cb_param);
71 	} else {
72 		void *dest_buf, *src_buf;
73 		pr_debug("%s: (sync) len: %zu\n", __func__, len);
74 
75 		/* wait for any prerequisite operations */
76 		async_tx_quiesce(&depend_tx);
77 
78 		dest_buf = kmap_atomic(dest, KM_USER0) + dest_offset;
79 		src_buf = kmap_atomic(src, KM_USER1) + src_offset;
80 
81 		memcpy(dest_buf, src_buf, len);
82 
83 		kunmap_atomic(dest_buf, KM_USER0);
84 		kunmap_atomic(src_buf, KM_USER1);
85 
86 		async_tx_sync_epilog(flags, depend_tx, cb_fn, cb_param);
87 	}
88 
89 	return tx;
90 }
91 EXPORT_SYMBOL_GPL(async_memcpy);
92 
93 static int __init async_memcpy_init(void)
94 {
95 	return 0;
96 }
97 
98 static void __exit async_memcpy_exit(void)
99 {
100 	do { } while (0);
101 }
102 
103 module_init(async_memcpy_init);
104 module_exit(async_memcpy_exit);
105 
106 MODULE_AUTHOR("Intel Corporation");
107 MODULE_DESCRIPTION("asynchronous memcpy api");
108 MODULE_LICENSE("GPL");
109