1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * copy offload engine support
4  *
5  * Copyright © 2006, Intel Corporation.
6  *
7  *      Dan Williams <dan.j.williams@intel.com>
8  *
9  *      with architecture considerations by:
10  *      Neil Brown <neilb@suse.de>
11  *      Jeff Garzik <jeff@garzik.org>
12  */
13 #include <linux/kernel.h>
14 #include <linux/highmem.h>
15 #include <linux/module.h>
16 #include <linux/mm.h>
17 #include <linux/dma-mapping.h>
18 #include <linux/async_tx.h>
19 
20 /**
21  * async_memcpy - attempt to copy memory with a dma engine.
22  * @dest: destination page
23  * @src: src page
24  * @dest_offset: offset into 'dest' to start transaction
25  * @src_offset: offset into 'src' to start transaction
26  * @len: length in bytes
27  * @submit: submission / completion modifiers
28  *
29  * honored flags: ASYNC_TX_ACK
30  */
31 struct dma_async_tx_descriptor *
32 async_memcpy(struct page *dest, struct page *src, unsigned int dest_offset,
33 	     unsigned int src_offset, size_t len,
34 	     struct async_submit_ctl *submit)
35 {
36 	struct dma_chan *chan = async_tx_find_channel(submit, DMA_MEMCPY,
37 						      &dest, 1, &src, 1, len);
38 	struct dma_device *device = chan ? chan->device : NULL;
39 	struct dma_async_tx_descriptor *tx = NULL;
40 	struct dmaengine_unmap_data *unmap = NULL;
41 
42 	if (device)
43 		unmap = dmaengine_get_unmap_data(device->dev, 2, GFP_NOWAIT);
44 
45 	if (unmap && is_dma_copy_aligned(device, src_offset, dest_offset, len)) {
46 		unsigned long dma_prep_flags = 0;
47 
48 		if (submit->cb_fn)
49 			dma_prep_flags |= DMA_PREP_INTERRUPT;
50 		if (submit->flags & ASYNC_TX_FENCE)
51 			dma_prep_flags |= DMA_PREP_FENCE;
52 
53 		unmap->to_cnt = 1;
54 		unmap->addr[0] = dma_map_page(device->dev, src, src_offset, len,
55 					      DMA_TO_DEVICE);
56 		unmap->from_cnt = 1;
57 		unmap->addr[1] = dma_map_page(device->dev, dest, dest_offset, len,
58 					      DMA_FROM_DEVICE);
59 		unmap->len = len;
60 
61 		tx = device->device_prep_dma_memcpy(chan, unmap->addr[1],
62 						    unmap->addr[0], len,
63 						    dma_prep_flags);
64 	}
65 
66 	if (tx) {
67 		pr_debug("%s: (async) len: %zu\n", __func__, len);
68 
69 		dma_set_unmap(tx, unmap);
70 		async_tx_submit(chan, tx, submit);
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(&submit->depend_tx);
77 
78 		dest_buf = kmap_atomic(dest) + dest_offset;
79 		src_buf = kmap_atomic(src) + src_offset;
80 
81 		memcpy(dest_buf, src_buf, len);
82 
83 		kunmap_atomic(src_buf);
84 		kunmap_atomic(dest_buf);
85 
86 		async_tx_sync_epilog(submit);
87 	}
88 
89 	dmaengine_unmap_put(unmap);
90 
91 	return tx;
92 }
93 EXPORT_SYMBOL_GPL(async_memcpy);
94 
95 MODULE_AUTHOR("Intel Corporation");
96 MODULE_DESCRIPTION("asynchronous memcpy api");
97 MODULE_LICENSE("GPL");
98