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 */
31struct dma_async_tx_descriptor *
32async_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}
93EXPORT_SYMBOL_GPL(async_memcpy);
94
95MODULE_AUTHOR("Intel Corporation");
96MODULE_DESCRIPTION("asynchronous memcpy api");
97MODULE_LICENSE("GPL");
98