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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * copy offload engine support4 *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 page23 * @src: src page24 * @dest_offset: offset into 'dest' to start transaction25 * @src_offset: offset into 'src' to start transaction26 * @len: length in bytes27 * @submit: submission / completion modifiers28 *29 * honored flags: ASYNC_TX_ACK30 */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