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torvalds
GitHub Repository: torvalds/linux
 Path: blob/master/crypto/async_tx/async_memcpy.c
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// SPDX-License-Identifier: GPL-2.0-only

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/*

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 * copy offload engine support

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 *

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 * Copyright © 2006, Intel Corporation.

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 *

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 *      Dan Williams <[email protected]>

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 *

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 *      with architecture considerations by:

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 *      Neil Brown <[email protected]>

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 *      Jeff Garzik <[email protected]>

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 */

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#include <linux/kernel.h>

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#include <linux/highmem.h>

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#include <linux/module.h>

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#include <linux/mm.h>

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#include <linux/dma-mapping.h>

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#include <linux/async_tx.h>

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/**

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 * async_memcpy - attempt to copy memory with a dma engine.

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 * @dest: destination page

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 * @src: src page

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 * @dest_offset: offset into 'dest' to start transaction

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 * @src_offset: offset into 'src' to start transaction

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 * @len: length in bytes

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 * @submit: submission / completion modifiers

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 *

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 * honored flags: ASYNC_TX_ACK

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 */

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struct dma_async_tx_descriptor *

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async_memcpy(struct page *dest, struct page *src, unsigned int dest_offset,

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	     unsigned int src_offset, size_t len,

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	     struct async_submit_ctl *submit)

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{

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	struct dma_chan *chan = async_tx_find_channel(submit, DMA_MEMCPY,

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						      &dest, 1, &src, 1, len);

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	struct dma_device *device = chan ? chan->device : NULL;

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	struct dma_async_tx_descriptor *tx = NULL;

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	struct dmaengine_unmap_data *unmap = NULL;

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	if (device)

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		unmap = dmaengine_get_unmap_data(device->dev, 2, GFP_NOWAIT);

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	if (unmap && is_dma_copy_aligned(device, src_offset, dest_offset, len)) {

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		unsigned long dma_prep_flags = 0;

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		if (submit->cb_fn)

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			dma_prep_flags |= DMA_PREP_INTERRUPT;

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		if (submit->flags & ASYNC_TX_FENCE)

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			dma_prep_flags |= DMA_PREP_FENCE;

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		unmap->to_cnt = 1;

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		unmap->addr[0] = dma_map_page(device->dev, src, src_offset, len,

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					      DMA_TO_DEVICE);

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		unmap->from_cnt = 1;

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		unmap->addr[1] = dma_map_page(device->dev, dest, dest_offset, len,

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					      DMA_FROM_DEVICE);

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		unmap->len = len;

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		tx = device->device_prep_dma_memcpy(chan, unmap->addr[1],

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						    unmap->addr[0], len,

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						    dma_prep_flags);

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	}

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	if (tx) {

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		pr_debug("%s: (async) len: %zu\n", __func__, len);

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		dma_set_unmap(tx, unmap);

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		async_tx_submit(chan, tx, submit);

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	} else {

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		void *dest_buf, *src_buf;

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		pr_debug("%s: (sync) len: %zu\n", __func__, len);

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		/* wait for any prerequisite operations */

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		async_tx_quiesce(&submit->depend_tx);

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		dest_buf = kmap_atomic(dest) + dest_offset;

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		src_buf = kmap_atomic(src) + src_offset;

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		memcpy(dest_buf, src_buf, len);

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		kunmap_atomic(src_buf);

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		kunmap_atomic(dest_buf);

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		async_tx_sync_epilog(submit);

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	}

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	dmaengine_unmap_put(unmap);

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	return tx;

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}

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EXPORT_SYMBOL_GPL(async_memcpy);

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MODULE_AUTHOR("Intel Corporation");

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MODULE_DESCRIPTION("asynchronous memcpy api");

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MODULE_LICENSE("GPL");

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