crypto/async_tx/async_memcpy.c

   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");